99-Day Study Schedule for USMLE Step 1

Pulmonary Hypertension Medication: Outline of Pharmacological Therapy

In this article, we will be reviewing mainly about the advanced therapies which are available for pulmonary hypertension with the brief coverage of primary therapy. The advanced therapies are especially studied for IPAH.

Alpha 1 Antitrypsin Deficiency: Etiology, Clinical Manifestations and More

Without the liver, we would not be able to metabolize some components of the food, drinks, and medications that we eat; there would be problems in hemostasis and we would not be able to properly digest the food that we eat, particularly fatty ones. These are only a few among the many contributions of the liver to homeostasis. However, there are also a lot of factors that can bring damage to the liver. Although the pathogenesis of liver diseases are most likely caused by a combination of a lot of factors, there have been well-studied disorders where genetics play the most crucial role in initiating disease. An example of which is alpha 1 antitrypsin deficiency.

Acetaminophen Overdose and Drug-Induced Liver Injury

The advances in modern medicine have brought about a lot of changes in how we deal with illnesses. One of these relatively new found technologies is the use of medications. However, this has led many to assume that all of the diseases suffered can be treated with medications alone. The danger is more prominent among those who take these without the consultation of health care providers. A poor understanding of the mechanism of actions of the readily available medications can also bring more harm than good for individuals who prefer to deal with their sickness by themselves. An example of a heavily affected organ during drug toxicities is the liver. In this article, we will understand how excessive and inappropriate intake of medications affect the function of the organ.

Peutz-Jegher's Syndrome, Juvenile Polyposis and HNPCC

The small and large bowels are parts of the digestive tract, they are responsible for digestion and absorption. The large intestine plays a large role in fecal formation and storage, as well as absorption of water, minerals, and vitamins. Any alterations in the integrity of this region of the digestive tract can result in subsequent issues. One of the most prevalent conditions that could lead to this is the development of new growths or neoplasms in any of the layers of the intestines. Among the two, neoplasms occur more commonly in the large intestine. In this article, we shall look into different types of polyps and cancerous growths, particularly hamartomatous polyps and the Lynch syndrome.

Small Intestinal Bacterial Overgrowth (SIBO) — Symptoms and Treatment

Our body is able to make use of the metabolic sources in the environment by way of the alimentary tract. In order for it to serve as a conduit for the food and other essential substances, it has to undergo specific functions such as food propulsion, secretion of digestive juices, and absorption of simplified nutrients and vitamins, among others. Needless to say, any interruptions in the continuity of any portion of the digestive tract would result in a lot of problems, including absorption. Small intestine bacterial overgrowth is an example of a condition that could result in malabsorptive conditions.

Drugs of Abuse: Stimulants, Steroids and More

There are many illicit and licit drugs that are abused worldwide; it is estimated that approximately 9% of the population above 12 years of age use some form of illicit substance in the United States. Drug addiction and dependence contribute to significant morbidity and reduced quality of life and should be treated appropriately with medications and psychological interventions. Acute poisoning is also common; timely diagnosis and appropriate management could be life-saving. In this chapter, we will study the important pharmacological and clinical characteristics of commonly abused drugs from examination perspective.

Definition and Processes of Pharmacokinetics

How a drug works and what happens to it upon entering the body are important factors in drug design, in order to ensure optimal action in the desired amount of time. Drugs are absorbed from the site of administration into the systemic circulation, where they may interact with the proteins; they then reach their target tissues, changed or unchanged, and act on them. The moment a drug enters the systemic circulation, it starts to be simultaneously eliminated by certain biological processes. All these together constitute pharmacokinetics of the drug.

Multifocal Atrial Tachycardia — Symptoms and Treatment

Multifocal atrial tachycardia is a type of atrial arrhythmia characterized by rapid heart rate with at least 3 or more P wave morphologies. It is termed multifocal since the signals arise exclusively from atrial tissues instead of the sinus node. For an adult, normal heart rate ranges between 60 and 100 beats per minutes. In multifocal atrial tachycardia, the heart rate range between 100 and 250 beats per minute. It is more common in people with serious cardiopulmonary diseases (heart-lungs).

Hereditary Hemochromatosis: Risk Factors, Classifications, Diagnosis

Hereditary hemochromatosis (HH), also termed “genetic hemochromatosis”, is a genetic autosomal recessive disorder which occurs as a result of genetic mutations of certain genes (HFE gene) involved in the metabolism of iron, resulting in increased intestinal iron absorption. Common initial symptoms comprise abdominal pain, paleness, lethargy, and weight loss. The start of symptoms is between 30 to 50 years in males and afterward menopause in females. If left untreated, hemochromatosis could cause serious disease and early death. The keystone of screening is the level of serum transferrin saturation as well as the serum ferritin level. Definition, risk factors, pathophysiology, clinical features, investigations and treatment of hemochromatosis will be discussed in this article.

Crohn’s Disease (Ileitis) and Ulcerative Colitis (UC) — Causes and Treatment

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tracts and is comprised of two major disorders: ulcerative colitis (UC) and Crohn's disease (CD). Both diseases have characteristics that may be overlapping while other characteristics may be different. Characteristics which will be discussed in detail throughout this article.  

Thyroid During Pregnancy: Maternal Fetal Thyroid Pathology

Thyroid hormones are amine hormones produced by the thyroid gland. There are two types of thyroid hormones: triiodothyronine (T3) and thyroxine (T4). They are stored in thyroid follicles as a component of thyroglobulin. Once released in the blood, 2/3 of the hormones are transported while bound to Thyroxine-Binding Globulin.

Congenital Hypothyroidism — Causes and Treatment

Congenital hypothyroidism is a condition caused by lack of thyroid hormones. This condition found in newborn infants. If left untreated, it may lead to severe complications including permanent intellectual disability or growth failure.

Hypersensitivity and its Types: Immunologically Mediated Tissue Injuries

The human body is capable of many things: from organizing various cells into functioning tissues and organs to housing an entire human being. However, in between these processes, a lot of damages and repairs can occur. Although it is normal for us to employ certain defense mechanisms in order to prevent serious illnesses and to repair damage caused by such, there are some conditions wherein we get to have some trouble with our own immune system. An example of which is having any type of hypersensitivity. Read on to learn everything about it.

Pulmonary Embolism (PE) — Symptoms and Treatment

Pulmonary embolism (PE) is a fatal clinical condition that occurs as a result of mechanical obstruction of the pulmonary artery or its branches by any material (such as thrombus, air or fat) from anywhere in the body. Pulmonary embolism can be an acute condition, in which the signs and symptoms develop immediately after the event (i.e., the obstruction of the pulmonary vessels), or it can be chronic, in which the signs and symptoms develop progressively for years. In this article, you will be able to understand the definition, incidence, pathophysiology, risk factors, symptoms and signs and the prognosis of pulmonary embolism.

Abnormal Looking Cervix: Cervical Fibroids and Cancer and Ectropion

Abnormal looking cervix can be seen commonly in gynecology in day to day practice. It becomes necessary to differentiate between normal physiological changes brought by normal menstrual cycle from the anatomical and pathological disorders. Colposcopic examination of cervix with a stereoscopic binocular magnifying glasses is extremely helpful for identification of the possible etiology behind and exclusion of any cancerous growth to establish the diagnosis. The etiologic reasons of abnormal cervix can be physiological, infectious, abnormal growth and iatrogenic. This article provides a step-by-step approach to differentiating them.

Asbestosis and Silicosis — Causes and Treatments

Occupational lung disease covers a specific area of knowledge in respiratory medicine. In these cases, information on the patients's history play an important role in the detection of these disorders, guiding investigations and management. Awareness of this topic is essential.

PCSK9 Inhibitors – Lipid Control

Science has taught us that fats and cholesterols, despite their negative connotation, play a significant role in keeping ourselves in tiptop shape. From structural purposes to that of hormone production, lipids are an essential part of our body’s efforts to maintain homeostasis. However, problems do occur if there is an imbalance in the way that lipids are controlled by our system; this is where disorders such as the dyslipidemias come in. Fortunately, treatment modalities are also available to address this issue. In this case, it is important for us to understand the physiology of how our body maintains a healthy amount of lipids in order for us to gain some insight on how we approach patients with excessive lipid levels.

Fat Absorption and MTP Inhibitors: Orlistat and Lomitapide

The availability of fast food and the automation of most daily activities in our society today have predisposed the majority of the world’s population to obesity and its related complications. Although the intermittent nature of our food intake requires us to store carbohydrates, proteins and fats in excess, it is undeniable that resources, particularly those from developed countries, have proven our efforts in doing this somewhat excessive. Fortunately, there are a lot of treatment plans available for people who are already having problems with nutrient metabolism, particularly that of lipids. This includes medications that can hasten our efforts to maintain a healthy level of lipids in the body.

Renal Glucose Reabsorption: Glucose in the Urine & Disease Correlation

The kidney is a key player in glucose hemostasis by two mechanisms. It filters and reabsorbs glucose from the urine and it releases the sugar during times of fasting through gluconeogenesis. Here you will read everything about it.

Gastrointestinal Motility: Gastric Motility and Intestinal Motility

Gastrointestinal motility is one of the major roles played by the alimentary canal. In the esophagus, it serves to get the ingested bolus of food from the oropharynx to the stomach. In the stomach, this motility is responsible for the churning and mixing of food and turning it into chyme. This continues in the small and large intestines until the digested food can be excreted out of the anus. There are various anatomical and physiological components of gastrointestinal motility. It is very important for medical students and healthcare professionals to have a clear clinical understanding of these components.

Pharmacodynamics: Upregulation and Downregulation, Dose-Response Curves and More

As opposed to pharmacokinetics, pharmacodynamics is what a drug does to the body. When a drug is administered, it acts on the target cell populations by means of certain receptors. There are various types of receptors, and the drug-receptor complexes can produce a specific or a variety of pharmacological effects, based on the mechanisms activated. These effects can be desirable (therapeutic) or toxic/lethal and are often dose dependent. Thus, it is crucial to learn the pharmacodynamics of the drug to arrive at not only an effective, but also a safe dose, to the individual.

Lipid Control: HMG-CoA Reductase Inhibitors

Despite its negative connotation, cholesterol actually plays an important role in our body’s homeostasis. It basically makes up the most important parts which keeps us alive and functioning. For example, the membranes that keep our cells together are made up of cholesterol. However, major problems do arise when there is an alteration along its metabolic pathway in the body. For one, an excessive amount of cholesterol in the body has been linked to a lot of disorders, such as atherosclerosis and fatty liver disease. In this article, we will tackle how cholesterol is metabolized in the body and see where, in the pathway, HMG-CoA reductase inhibitors alter the whole process.

Lipid Control: Niacin, Bile Acid Sequestrants, Fibrates

From the name itself, lipoproteins are made up of complexes of lipids and proteins that primarily work as the transport system for cholesterol, triglycerides and other significant lipids needed by the body. Previously, the study of conditions related to problems in the metabolism of lipoproteins has been exclusive only for researchers focusing on lipids. However, it has been integrated into the inquiry of internists and other specialties as many researchers have provided a link between dyslipidemia and other highly prevalent conditions, such as atherosclerosis and fatty liver disease.

Vasodilators: Calcium Channel Blockers, Nitrodilators & More

Hypertension has consistently made its way to the leading causes of morbidity and mortality in recent years. Millions of deaths and disabilities are being documented worldwide because of its complications, such as cerebrovascular accidents and ischemia in various locations in the body. Despite its notorious nature, hypertension is preventable and controllable. This is made possible by making use of various pharmacologic managements that are available today. One of the most common medications used to control blood pressure is a direct vasodilator.

Postganglionic Sympathetic Nerve Terminal Blockers and Monoamine Oxidase Inhibitors

Every day, more and more people are being diagnosed with hypertension. This increase in prevalence worldwide can be attributed to non-modifiable factors other than heredity, age and sex. Without the incorporation of a healthy lifestyle and the promotion of wellness, it would not be shocking for someone to be put at a higher risk for developing complications brought about by the ‘silent killer’. Fortunately, there are already a lot of programs and campaigns that promote lifestyle modifications present in our society. As for the people already stricken with the disorder, many treatment programs are also already available and are tailor made to fit any patient. In connection to this, many drugs are developed to alleviate patients from high blood pressure.

Alpha Blockers: Mechanism of Action and Uses for Hypertension

Along with the automation of daily activities and improvement in the availability of food in our society, comes the increasing incidence of persons having chronic lifestyle diseases. One of the most prevalent of these is hypertension. It is also important to emphasize that this ‘silent killer’ is becoming more popular among younger populations nowadays. Fortunately, organizations have come up with ways to tackle this problem, including a wide variety of pharmacologic management that would help lower and maintain blood pressure. One of which is the use of α-adrenergic blockers.

Elimination Kinetics: Types, Half-Life and Bioavailability

Pharmacokinetics, in simpler terms, is what a body does to a drug. Elimination or excretion of a drug is a part of the pharmacokinetic process. In this article, we will study the elimination kinetics of a drug. Various factors which affect the elimination of a drug are half-life, bioavailability, volume of distribution and first pass metabolism. To understand the pharmacokinetics or elimination kinetics of a drug effectively, these factors need to be understood first.

Hypocalcemia: Etiology, Symptoms, Treatment

The calcium levels are regulated by a hormone known as the parathyroid hormone (PTH) which is secreted by the parathyroid gland. If the body fails to maintain the calcium levels within the normal ranges, hypercalcemia or hypocalcemia results. This article will focus on hypocalcemia. Hypocalcemia is the condition in which the serum calcium levels in the blood are low. The presentation of the patients with hypocalcemia can vary from asymptomatic to life threatening situations. Read on to learn about the etiology, symptoms, differential diagnosis, investigations and treatment of hypocalcemia.

Class 4: Calcium Channel Blockers – Antiarrhythmic Drugs

Calcium channel blockers have different scopes of application: they are used for the treatment of arterial hypertension or cardiac arrhythmia. Calcium channel blockers are also applied for the treatment of the coronary heart disease. They are often used if beta blockers cannot be applied due to intolerances or adverse effects.

Effects of Barometric Pressure on the Pulmonary System

Barometric pressure is also called atmospheric pressure. It presents the pressure applied by the weight of the air in the atmosphere. Changes in barometric pressure experienced by breath-hold divers or mountain climbers have a significant impact on the body’s pulmonary physiology.

Drugs of Abuse: Alcoholism, Opioids, Cocaine, Hallucinogens and More

Every physician gets in touch with addicted patients, as 5–7 % of the population is addicted to legal or illegal drugs. But studies have revealed that primary care physicians only identify every 10th patient suffering from dependency syndrome. This article is supposed to help you recognize the typical symptoms of the respective drug consume and treat intoxications as well as withdrawal symptoms.

Tumor Pathology: Definition, Development & Metastases

Tumor malignancy is the second leading cause of death in the United States today with increasing incidence. Furthermore, the general public usually associates the term with disease leading to death. Not every diagnosis of a tumor, however, translates to a shortened lifespan in actuality. The following article will define the word “tumor”, will shed light on the mechanism of tumor development and detail means of classification with respect to treatment plans.

Antihypertensives: ACE-Inhibitors and Sartans

The arterial hypertonia can be reduced with general measures often. However, medicinal approaches are also advisable in order to reach target blood pressures, which are in an area, as normal as possible. The most commonly prescribed drug are ACE-inhibitors, as they are cheap in price, followed by sartans. Both substances affect the renin-angiotensine-aldosterone system (RAAS) and reduce the blood pressure by the thereby conveyed effects.

Tumor Classification: Staging and Grading

Malignant neoplasms are among the leading causes of death in recent US statistic: death from malignancy is currently only second to cardiovascular diseases. As an aspiring medical professional, you will find cancer in nearly every clinical field. As widely varied as tumors can be, characterization through staging and grading is virtually universally applicable. Both indicators help to make statements regarding prognosis and treatment. Here you will learn the appropriate terminology, and how to classify and differentiate between them.

Wolff-Parkinson-White (WPW) Syndrome — Causes, ECG and Treatment

Wolff-Parkinson-White Syndrome (WPW) is a term referring to Louis Wolff who published an article in 1930 that describes 11 patients suffering from episodes of tachycardia with characteristic ECG findings (ECG pattern shows bundle branch block and shortened P-R interval). In 1943, anatomical accessory pathway of conducting tissue has been described that bypasses the atrioventricular (AV) conduction system. This article will describe definition, pathophysiology, clinical manifestations, diagnosis and treatment of Wolff-Parkinson-White Syndrome.

Cell Surface Receptors: Types & Downstream Mechanisms

Receptors are proteins. They receive signals from outside the cell; when located on the surface of the cell, they are called cell surface receptors. Learn about the different types and their downstream mechanisms in the following article.

Hypercalcemia — Causes and Treatment

The normal calcium level in the body is between 2.2–2.6 mmol/L. The calcium levels are regulated by a hormone known as the parathyroid hormone (PTH) which is secreted by the parathyroid gland. If the body fails to maintain the calcium levels within the normal ranges, hypercalcemia or hypocalcemia results. This article focuses on hypercalcemia. Read on to learn about the causes, symptoms, diagnosis and management of hypercalcemia.

Helicobacter Pylori Infections — Differential Diagnosis and Medical Treatment

Helicobacter pylori is a type of bacteria, which results in gastric infection. It is estimated to be found in more than 50% of the international population. It is not sure how exactly the bacteria can be spread; however, unclean food or water may aid in the spreading of the infection and result in different gastric diseases or conditions, including peptic ulcer disease or gastric cancer in severe complications.

Paget's Disease of Bone (PDB) — Causes and Treatment

For the purposes of the USMLE, it is important to be able to identify and understand the pathophysiology of the Paget's disease and how to differentiate it from other musculoskeletal disorders. Throughout this article you will find the details of Paget’s disease and the key points bolded.

Overview of Anemia: Microcytic, Macrocytic and Normocytic Anemia

Anemia is one of the major reasons why patients present with shortness of breath, fatigue, pallor and weakness in clinics. Anemia is a reduction of the oxygen carrying capacity of the blood that results in decreased oxygen supply to tissue cells. It is of utmost importance for doctors to rule out anemia as a cause of this range of symptoms as not giving prompt medical treatment can result in severer symptoms and even fatality.

Regulation of ADH & Syndrome of Inappropriate ADH Secretion

Antidiuretic hormone or arginine vasopressin, is a peptide hormone released by the posterior pituitary in response to low plasma volume or increased plasma osmotic pressure. The hormone increases reabsorption of water at the kidney and increases systemic vascular resistance. When ADH is released in an unregulated fashion the circulating plasma becomes diluted, resulting in hyponatremia. This is called syndrome of inappropriate antidiuretic hormone secretion.

Veins of the Arm: Cutaneous Innervation and Venous Drainage

This article provides an overview of the cutaneous innervation and venous drainage of the upper limb, reviewing several of the veins in this area of the body. Both superficial and deep veins are presented, giving an overview of the progression of veins in the arms.

Water Balance: Regulation of Fluid Balance

Fluid balance is a carefully regulated system with many mechanisms to monitor and modify the absorption and secretion of water. Water is in constant motion between compartments that make up the body. When the body senses a drop in the effective circulating volume it stimulates a response to restore blood pressure and retain fluids. When there is too much fluid the body increases secretion and excretion of the excess.

Definition of Embryology, Fertilization & Cell Differentiation

Embryology plays a vital role in the clear and thorough understanding of how the human body comes into being and the underlying pathophysiology of congenital disorders that affect neonates and people at different stages of their lives. The study of embryology has proven to play a significant role in the clinical understanding and management of such embryological disorders.

Gastrointestinal Bleeding (GI Bleed) — Symptoms, Diagnosis and Treatment

Disorders of the digestive tract may result in gastrointestinal bleeding. The blood is not always visible in the stool or vomit; however, it may result in tarry black stools. Bleeding can be life-threatening in some cases. Identifying the source of bleeding is not always easy, especially if its origin is in the small intestines.

Respiratory Failure: Hypoxemia, Hypercapnia and Hypoxia

The inspiration of oxygen and expiration of carbon dioxide are vital functions of the human body. A decrease in PO2 and increase in PCO2 can alter many normal physiologic processes, and may eventually be fatal. The human body has various reflex mechanisms to manage such changes. Understanding of these reflexes and identification and management of any impairment in them is essential in the management of many respiratory and renal diseases.

Pituitary Hormones: Posterior Pituitary & Anterior Pituitary

The pituitary gland, also known as hypophysis, is a small pea-sized gland about 1 cm in diameter and 0.5 to 1 gram in weight. The pituitary gland resides in a small bony cavity situated at the base of the brain, known as sella turcica, and a pituitary stalk (infundibulum) maintains a connection between the pituitary gland and hypothalamus. The secretion of hormones by the pituitary gland is under the influence of the hypothalamus through its various hormonal and neuronal signals. There are two distinct divisions of the pituitary gland: the posterior pituitary and the anterior pituitary. Between these two, there is a small zone, which is relatively avascular and less well-developed in humans, known as pars intermedia.

Steroids and Bile Acid: Lipid Metabolism

Lipid metabolism is the process by which lipids are synthesized and degraded in cells. In this article, important lipids discussed are bile salts, cholesterols, steroids and ketone bodies. Also covered in this article are the structures and functions of these types of lipids. The biosynthesis and metabolism of these lipid molecules are also covered in this article.

Laxative Abuse — Causes, Symptoms and Treatment

Laxatives are an effective treatment for occasional constipation, but laxative abuse and misuse is very common and can damage the intestines and lead to malabsorption and dehydration. Individuals abuse laxatives for a variety of reasons including weight loss (the most common form of laxative abuse), as a method to improve health, and as a part of a factitious disorder. There are gross and histological changes to the intestines that are usually reversible. Treatment consists of laxative sensation and treating the underlying condition.

Inflammatory Bowel Disease (IBD) — Types, Causes and Treatment

Inflammatory bowel disease (IBD) is a group of conditions that affect the gastrointestinal system. IBD consists of autoimmune diseases that attack the GI mucosa, resulting in inflammation of the gut wall. For this discussion, we will be focusing on ulcerative colitis (UC) and Crohn’s disease (CD). The main differences between the two are that ulcerative colitis mainly involves the large intestine and rectum while Crohn’s disease can affect the GI system anywhere from the mouth to the anus and usually skips the rectum. Other conditions such as microscopic colitis and Behçet's disease are also types of IBD. IBD is different from irritable bowel syndrome (IBS) which is a functional disorder that is defined as abdominal pain and bowel movement changes.

Angiodysplasia — Symptoms and Treatment

Angiodysplasia describes abnormal vascular malformations found in the gastrointestinal (GI) tract, especially in the cecum and right colon. These malformations are prone to bleed and may be responsible for painless hematochezia, melena and concomitant anemia. Diagnosis can be made by direct visualization during endoscopy or angiography. Treatment consists of endoscopic interventions, including embolization and coagulation, antifibrinolytic medications and surgery as a last resort.

Carcinoid Syndrome — Symptoms, Diagnosis and Treatment

The carcinoid syndrome describes the signs and symptoms associated with unregulated vasoactive hormone production by neuroendocrine tumors. Carcinoid tumors can be found anywhere throughout the body, but these will not result in carcinoid syndrome unless they form in the liver as a primary tumor or as a metastasis. Symptoms of carcinoid syndrome include flushing, diarrhea, and wheezing. VIPomas usually form in the pancreas and release vasoactive intestinal peptide (VIP) which results in profound chronic diarrhea with concomitant hypokalemia and dehydration, wheezing, and flushing (similar to carcinoid syndrome). VIPomas are often associated with multiple endocrine neoplasia type 1 (MENI). Diagnosis is based off blood or urine measurements of serotonin and VIP. Treatment consists of minimizing symptoms with medication and complete surgical removal of the tumor.

Radiation Colitis — Symptoms and Differential Diagnosis

Radiative colitis is an enteropathy syndrome that may develop after radiation therapy to the abdomen or pelvis. Radiation therapy is a treatment option for cancers in that area. Symptoms start weeks to years after initial radiation dose and include diarrhea, malabsorption, abdominal pain, and nausea. Therapy involves treating symptoms and allowing the bowels to heal. In severe cases partial colectomy may provide the best chance at recovery.

Biotechnology: Analytical Techniques

Biotechnology is an emerging field that allows scientists to use analytical techniques to study the structure and function of biomolecules. Protein purification is an all but mandatory step for studying macromolecules; but this task is not necessarily easy. Several experimental methods, deductive logic, and even a little bit of luck make this possible. Here you'll read about some of the methods.

Whipple’s Disease — Symptoms and Diagnosis

Whipple's disease is a rare infection affecting several tissues throughout the body including the GI tract, central nervous system, and heart by the bacteriaTropheryma whipplei. Symptoms include malabsorption, weight loss, and diarrhea with extra GI symptoms including arthritis and joint pain. The following article contains all important facts about the Whipple's disease.

Arterial Blood Gas (ABG) Analysis

ABG analysis is an indispensable test for critically ill patients or patients treated in an ICU. Interpretation of ABG analysis seems complicated; however, an understanding of the basic physiology can ease the interpretation. In this article, the basic physiology behind ABG analysis and a stepwise approach to interpreting ABG analysis will be discussed in detail.

Pulmonary Hypertension (PH) — Categories, Causes and Treatment

Pulmonary hypertension (PH) is a clinical condition that is characterized by elevated pulmonary arterial pressure. It can lead to serious clinical consequences, thus early detection and treatment is important before it becomes advanced and less responsive to therapy. PH is a feature of advanced underlying disease that are usually caused by cardiac, pulmonary, or intrinsic vascular diseases. Therefore, suspected cases will undergo diagnostic testing to confirm the condition and identify the underlying cause. The definition, epidemiology, classification and etiologies, pathophysiology, clinical features, diagnostic evaluation and treatment all will be discussed in this article.

Second Messenger Systems

Signaling pathways are complex systems in which a single extracellular signal can elicit multiple intracellular events, some of which may also be triggered by other signaling pathways. We will discuss how this process occurs through kinase cascades and second messengers, and then apply these to processes to the regulation of protein expression and the fight or flight response, respectively.

Electron Transport & Oxidative Phosphorylation

The complete aerobic catabolism of one molecule of glucose yields between 36 and 38 ATP; energy obtained mostly as the reduced coenzymes NADH and FADH2 are conveyed through the electron transport system. Three of the four respiratory complexes comprising the mitochondrial respiratory chain, as well as ATP synthase, are embedded in the inner mitochondrial membrane. Coenzyme Q and cytochrome c transfer electrons between complexes, which will ultimately meet oxygen, the terminal electron acceptor. Metabolic water is the product of oxygen reduction.

Types of Parasites: Plasmodium, Leishmania & Trypanosoma Species, Toxoplasma Gondii and Helminths

Parasites are organisms that live in or on another organism and benefits by deriving nutrients at the host’s expense. In this case, humans are the definitive host.

Pharmacokinetics and Pharmacodynamics

For drugs to produce significant effects, they must be able to interact with the body. This interaction is affected by a number of factors which include the properties of the drugs and mechanism by which drugs are absorbed through the body systems. In this article, basics of pharmacokinetics and pharmacodynamics are discussed. Given emphasis are some of the factors affecting drug action, namely lipophilicity, acid sensitivity and BBB penetration.

Arrhythmia (Irregular Heartbeat) — Classification and Types

Cardiac arrhythmia is an abnormal heartbeat, either the heart is beating too fast, too slow, or in an irregular manner. A healthy heart beats in a coordinated and regular way. Electrical and chemical impulses develop into specialized cells. These impulses stimulate the heart muscle cells (myocytes) to contract. When the heart is irritated or damaged, these impulses can develop spontaneously in the atria or the ventricle. Some spontaneous contractions are normal, but certain contraction patterns are very dangerous and can result in permanent heart damage, stroke, or death.

RNA: Basic Knowledge

Ribonucleic acid (RNA) is a polymeric molecule, which is implicated in different biological roles such as coding, decoding, expression of genes and regulation. Biological reactions within cells are catalyzed by some RNA molecules, which control gene expression and communicate responses to cellular signals. The structure of RNA is similar to that of DNA, but there are some differences between them.

Stomach Ulcer (Peptic Ulcer) — Symptoms and Treatment

Approximately 10% of the US population experience peptic ulcer disease, which has significantly impacted the health care system; both men and women appear to be affected equally with the condition. Peptic ulcer disease may lead to several complications, including an upper gastrointestinal hemorrhage.

List and Characteristics of Enteric Bacteria

The enteric species of bacteria are gram-negative rods inhabit the gastrointestinal tract. Some species are part of the normal flora that incidentally cause illness while some are regularly pathogenic. Physicians need to familiarize themselves with all members of this bacterial group and their treatment strategies.

Hypopituitarism — Symptoms, Diagnosis and Treatment

The pituitary gland also referred to as Hypophysis, or “Master gland” is a pea-sized organ, that lies in a protective bony enclosure called the sella turcica (saddle/chair) at the base of our brain. Read on to learn all about the pituitary gland and its hormones, as well as Hypopituitarism.

Metabolic Regulation

Integration of cellular metabolism is controlled by insulin and the opposing actions of glucagon and epinephrine. When food is available in abundance, or when the body needs to make stored energy available, changes in the circulating levels of these hormones allow the body to respond accordingly. This discussion of metabolic regulation will be tailored to fit two scenarios, the fed and fasted states, and highlight how metabolite flux is modulated by the direct activating or inhibiting of enzymes, or by inducing or repressing their transcription in the nucleus.

Chronic Bronchitis — Symptoms and Treatment

Chronic bronchitis is characterized by expectoration for a period of more than three months, in more than two consecutive years. Chronic irritation caused by smoking promotes hyperplasia of mucus glands and increases the production of mucus. Central and peripheral airways are involved in the pathophysiology of the disease and it includes inflammation, oxidative stress, inhibited repair processes, and an imbalance of proteinases/anti- proteinases. This article will prepare you perfectly well for your next exam!

Infant Respiratory Distress Syndrome (IRDS) — Symptoms and Treatment

Respiratory Distress Syndrome (RDS), also known as "Hyaline membrane disease", is caused by the deficiency of lung surfactant in a pre-term infant due to the immaturity of the lungs. The risk of RDS is inversely related to the gestational age, and, most commonly occurs in infants less than 28 weeks of gestational age. Neonatal respiratory distress syndrome is associated with high morbidity and mortality in pre-term infants and considered one of the most common causes of neonatal death. Respiratory distress syndrome should be differentiated from the other causes of respiratory distress after birth, which will be discussed in details in this article.

Introduction to Biochemistry

Biochemistry is the study of life from a chemical perspective and asks how living organisms arose from biomolecules that are lifeless. These biomolecules can be isolated from organisms and examined individually, and they conform to both the chemical and physical laws that govern inanimate matter. A biochemist studies the properties that organisms have that distinguish them from non-living matter.

Genetics: Organization and Function of Genes

In the medical field, the topic of Genetics is of significant importance. The topic explains how an organism is able to pass on its characteristics to its offspring. In this article, you will be able to learn about the structure and function of the human gene. Processes such as replication, transcription and translation are also explained in detail to help you get the required insight on what happens in each process. Furthermore, there are a few questions at the end of the article that will help you to test your understanding. You will find the answers to these questions below the references.

Hypersensitivity Pneumonitis & Eosinophilic Pneumonia

Hypersensitivity pneumonitis (HP), also called "extrinsic allergic alveolitis," is an immunologically-induced inflammatory disease affecting the alveoli and terminal airways (bronchioles), caused by repeated inhalation of a variety of inciting agents in a susceptible host. A wide range of organic antigens have been identified from different occupations. The clinical presentations of hypersensitivity pneumonitis vary depending upon the frequency, length, and intensity of exposure to the inciting agent. Surprisingly, cigarette smoking reduces the risk of developing the disease due to decreased antibody reaction to the antigen.

Pulmonary Function Tests (PFT)

Pulmonary function tests (PFT) are a battery of tests that measure lung function and aid in the management of patients with respiratory disease. They are performed using standardized equipment and can be used for diagnosis, prognostication, management and follow-up of patients with pulmonary pathology. Although PFT may not identify the exact pathology, it broadly classifies respiratory disorders as either obstructive or restrictive. In this article, the role of PFT in the measurement of lung mechanics and diagnosis of various diseases will be discussed in detail.

Vasospastic Angina (Prinzmetal Angina) — Definition and Treatment

Vasospastic angina is a variety of angina pectoris (chest pain) occurring at rest in which myocardial ischemia is due to transient vasospasm, with or without any underlying pathology. It is one of the syndromes that cause ischemic myocardial pain (angina pectoris), the other two being stable and unstable angina. Although rare in comparison, students are expected to know about it for the purposes of USMLE, as well as for their clinical knowledge.

Homeostasis — Definition and Examples

The cell is the morphological unit of all modern life forms, of which there are two major classifications: eukaryotes (Greek: eu, good or true, karyon, kernel or nut), which have a nucleus that encloses their DNA, and prokaryotes (Greek: pro, before), which do not have a nucleus. We will discuss the similarities and differences between these two cell types, as well as viruses, which are non-living protein particles. Further, this article will provide all the relevant facts for your medical education turning attention to a key theme in human physiology: the homeostasis.

Dyspnea (Shortness of Breath) — Causes and Symptoms

Dyspnea or shortness of breath is a normal manifestation of heavy exertion, but it can also be caused by different underlying diseases, therefore understanding the etiology, pathophysiology and differential diagnosis of dyspnea is important in the diagnosis of serious underlying clinical conditions. In this article, the etiology, pathophysiology and differential diagnosis of dyspnea will be discussed in detail.

Emphysema — Causes and Treatment

Emphysema is a condition characterized by the dilation of air spaces, with decreased elasticity and increased compliance, due to alveolar wall destruction; capillaries are also destroyed along with the alveoli. The most common cause for developing emphysema is smoking. Alpha-1-antitrypsin deficiency may also result in the development of emphysema.

Adenosine Triphosphate (ATP): Chemical Properties and Synthesis

Adenosine triphosphate is a purine nucleotide with three phosphate groups connected to a carbon ring. It provides energy to the all cells of the human body. It is derived from phosphorylation of ADP. ATP is needed as the storage form of energy needed for cellular respiration. Understanding how ATP can be synthesized, and how it is used by the body, forms a fundamental part of pre-med biochemistry.

Acute Respiratory Distress Syndrome (ARDS) — Phases and Treatment

Acute Respiratory Distress Syndrome (ARDS) is a severe inflammatory reaction of the lung that is characterized by presence of pulmonary infiltrates due to alveolar fluid accumulation, without evidence suggestive of a cardiogenic etiology. SIRS and sepsis are the major causes of ARDS. The main finding of ARD is respiratory failure. Chest x-ray usually shows diffuse bilateral lung infiltrates described as " (“butterfly opacity”). Management depends mainly on treating the underlying etiology, and maintaining adequate oxygenation, which may requires intubation and mechanical ventilation.

Heart Sounds

The detection and recognition of heart sounds play an important role in the diagnosis of various cardiac and valvular conditions. Because familiarity with heart sounds has such practical importance, students undertaking the USMLE are expected to have a good understanding of its theory and clinical applications.

The Four Classes of Macromolecules

The four classes of macromolecules are carbohydrates, proteins, nucleic acids, and lipids. These biomolecules can also be referred to as polymers. In turn, we will discuss how these four classes of macromolecules are synthesized in the cell from their constituent building blocks or monomers. Next, we will review the types of reactions that bring monomers together, namely hydrolysis reactions, where water is used to break chemical bonds. Lastly, we will cover the carbohydrate monomer glucose and delve into a discussion of several types of polysaccharides relevant to your studies.

Ventricular Tachycardia (VT) — Types and ECG

Ventricular tachyarrhythmias are a group of arrhythmias that result in a heartbeat greater than 100 beats per minute and originate anywhere in the ventricle. There are three main types of ventricular tachyarrhythmias: ventricular fibrillation, monomorphic ventricular tachycardia, and polymorphic ventricular tachycardia. Each one is associated with a high mortality rate. Symptoms include chest pain, palpations, hemodynamic collapse, and end-organ damage. If the ventricular tachyarrhythmia is suspected, start advanced cardiac life support measures immediately.

Practical Guide to Cardiovascular Examination (Cardiac Exam)

The cardiovascular exam is one of the most important parts of the physical. You will repeat this exam throughout your training and perform it on almost every patient in a hospital or a clinic. This part of the physical evaluates the heart and peripheral blood vessels (both arteries and veins). We use the stethoscope to auscultate, the fingers and palm to palpate and the eyes to observe.

Energy, Enzymes and Metabolism

Metabolism is the sum of both catabolism (pathways that break down molecules for generation of cellular energy) and anabolism (pathways that build macromolecules using cellular energy). Here, we will discuss metabolism with regards to the Laws of Thermodynamics, Enzymology, and go over some of the major metabolic pathways utilized by organisms to perfectly prepare you for upcoming exams.

Celiac Disease (Celiac Sprue, Gluten Enteropathy) — Symptoms and Treatment

Celiac disease, also called gluten-sensitive enteropathy or nontropical sprue, is a type of malabsorption syndrome. Relevant exam topics include the symptoms of gluten sensitivity and the clinical presentation of chronic malabsorption. Diagnosis is led by the characteristic histological findings and specific autoantibodies.

Cough and Wheezing — Definition and Treatments

A cough is one of the common presenting symptoms in the clinic and is associated with a number of respiratory and non-respiratory diseases. It can have a number of distinguishing characteristics such as quality, sputum production, timing, onset, duration and associated symptoms. The physiological mechanisms underlying cough involve a reflex arc with a command center in the medulla. Common non-respiratory causes include gastroesophageal reflux disease and postnasal drip, whereas, the most common respiratory etiologies are infectious diseases, chronic obstructive pulmonary disease, asthma and interstitial lung disease. Wheezes are high-pitched, loud sounds that usually accompany asthma, while stridor is most prominent with upper respiratory obstruction. In this article, physiology, different causes of cough and wheezing will be discussed in detail.

Colon Cancer (Colorectal Cancer) — Causes, Symptoms and Prognosis

Colorectal cancer originates from the colon and rectum in the body. It is a very common type of cancer in the United States. The molecular pathogenesis of colorectal cancer involves complex pathways. There are different types of colonic polyps associated with colorectal cancer; mostly are precancerous in nature. In this article, different pathological mechanisms, colonic polyps, symptoms, diagnostic tests, treatment and prognosis of colorectal cancer will be discussed in detail.

Thiazide Diuretics

Thiazide diuretics are some of the most common diuretics currently in use. Their mechanism of action involves inhibition of the Na/Cl co-transporter channel in the proximal part of the distal convoluted tubule, leading to increased sodium and chloride secretion. Their effects on reducing peripheral vascular resistance further contribute to their antihypertensive properties, in addition to their ability in decreasing effective blood volume. Besides hypertension, they are indicated for the treatment of heart failure exacerbation, hypercalciuria and diabetes insipidus. Important side effects include hypokalemia, hypercalcemia, hyponatremia, hyperglycemia, hyperuricemia and hypomagnesemia.

Atrial Flutter — Symptoms and Diagnosis

Atrial flutter is an irregular heart rhythm of the atria. It is classified as a supraventricular tachycardia. This rhythm is associated with heart disease and hypertension. Symptoms include palpitations. Complications include increased risk of stroke and congestive heart failure. Diagnosis is made by observing sawtooth “flutter” P waves on EKG at a rate of 240–400 contractions per minute. Treatment through ablation is usually curative, though medication can also play a role.

Loop Diuretics

Loop diuretics are one of the important classes of diuretics. Furosemide is the most commonly used loop diuretics. Other loop diuretics used are bumetanide, torasemide and ethacrynic acid. Loop diuretics are the most efficacious in causing diuresis in all the classes of diuretics. All the loop diuretics have the same mechanism of action, but different pharmacokinetic properties. They are used to treat/manage numerous diseases such as edema associated with CHF and liver cirrhosis. Diuretics most commonly cause electrolyte imbalance in the body on prolonged use.

Heart Failure Pharmacology: Aldosterone Antagonist (Antimineralocorticoid, MCRA)

Aldosterone antagonist are diuretic drugs that used in treatment of congestive heart failure or hypertension and increase survival rate in cardiac patients. They act at by competitive antagonism of mineralcorticoid receptors on the distal convoluting tubules and the upper collecting duct of the nephrons. They reduce the edema and workload on heart. Spironolactone is an important and widely used aldosterone antagonist. Other drugs in this category are eplerenone and finerenone.

Usual Interstitial Pneumonia (UIP) and Idiopathic Pulmonary Fibrosis (IPF) — Symptoms and Treatments

Idiopathic pulmonary fibrosis (IPF) belongs to a group of diseases whose specific cause is not well known, which keeps clinicians and researchers worried: the often rapid progression of IPF is very distressing. Also the underlying causes are mostly unknown, pathophysiologic explanations and findings are still unsatisfying. With only a 5-year survival rate of 20–40 %, only quick decisions such as initiating a lung transplantation, might help prolong a patient’s life.

Types of Intravenous Fluids

Intravenous fluids are most commonly administered in acute and severe hypovolemic conditions. In the therapeutics, two classes of i.v. fluids are most commonly utilized: crystalloids and colloids; both have their own advantages and disadvantages. The effect of various clinical conditions on the volume of ICF and ECG can be best studied by Darrow-Yannet diagrams.

Types of Kidney Cysts (Renal Cysts) — Diagnosis and Treatment

A kidney cyst can arise in any part of the nephron and collecting ducts, and can be found incidentally on imaging tests, or can be part of a renal or systemic disease. Renal cystic diseases consist of a large spectrum of diseases that differ in regards to pathophysiology, prognosis and treatment and that can be usefully divided into hereditary, acquired and developmental conditions. Hereditary renal cystic diseases often lead to kidney failure and are commonly associated with extrarenal manifestations, whereas non-genetic cystic disorders are usually limited to the kidney and rarely result in kidney functional deterioration.

Dysarrhytmias & Conduction System Disease: Bradyarrhythmias

Bradyarrhythmias, an arrhythmia with bradycardia (less than 60 ventricular depolarizations per minute) can result in a drop in cardiac output, low perfusion and hemodynamic instability. Bradycardia is occasionally seen in professional athletes due to their increased vagal tone. It is not a concern in this group, but may pose a risk when found in the general population. There are many causes for a slow heart rate including medication, electrolyte imbalance and physical changes to the heart associated with deterioration or fibrosis.

Urinalysis (Clinical Urine Tests) — Components and Results

Urinalysis is the test performed to analyze the physical, chemical and microscopic characteristics of urine. The information from this test might be used to diagnose or rule out diseases based on the findings. Urinalysis is most commonly used in identifying diseases of the urinary tract and diabetes. It includes macroscopic, microscopic/cytological and chemical analysis of the individual elements in urine.

Constrictive Pericarditis — Symptoms and ECG

Constrictive pericarditis is characterized by a thickened and scarred pericardial sac that lays around the heart and prevents proper diastolic filling. Diagnosis is very difficult because this condition mimics many other diseases.

Acute Pericarditis — Causes and Treatment

Pericarditis is an inflammation of the pericardium resulting from infection, autoimmune disease, radiation, surgery or myocardial infarction, or after cardiac surgery. It is manifested as fever, pleuritic chest pain that increases with lying supine, and audible pericardial rub by auscultation. Diagnosis is made by clinical suspicion with, supported by diffuse ST elevation in ECG and sometimes pericardial effusion by echocardiography. It is usually a self-limiting condition within 2-6 weeks, therefore management is usually conservative. Constrictive pericarditis is a well-known complication that is characterized by thickening and rigidity of the pericardium.

Kidney Stone (Nephrolithiasis) — Classification, Symptoms and Treatment

Nephrolithiasis is a clinical condition characterized by the presence of stones in the kidney. Calcium oxalate stones are the most common stones. Clinical presentation is with acute flank pain. Non-contrast CT is the investigation of choice in nephrolithiasis and can diagnose all types of stones. Management depends on the location and size of the stone. Smaller stones have a greater chance to pass spontaneously, while stones larger than 5 mm need surgical management with percutaneous nephrolithotomy, extracorporeal lithotripsy, or open surgery.

Paroxysmal Nocturnal Hemoglobinuria (PNH) — Symptoms and Diagnosis

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired defect in the myeloid stem cell lineage and can be seen as a rare, chronic, morbid disorder. Formally known as Marchiafava-Micheli syndrome, it received its current name as a descriptive term for the disease. Individuals afflicted with the disease wake up to dark, “cola” colored urine due to RBC breakdown and release of hemoglobin in the urine overnight. The discoloration of urine is seen in several other disorders, which is why it is important to discern the disease from other hemolytic disorders as the article depicts.

Bronchiectasis — Diagnosis and Treatment

Bronchiectasis can develop from chronic lung diseases or pulmonary infectious diseases. Since it is irreversible, it is most important to diagnose it timely. Only then, it is possible to prevent it from progressing by implementing appropriate measures. This article will introduce you to the pathophysiological and etiological basics of bronchiectasis, and will prepare you for the treatment of affected patients.

Water and Sodium Balance and Their Associated Disorders

Sodium is one of the most important active osmotic solutes in the human body, which is maintained in constant amounts in extracellular and intracellular fluid compartments. Understanding the normal physiological basis of water and sodium balance, and the associated clinical implications of any change in this balance, are of clinical significance, as even small changes can result in emergency conditions. This will be discussed in detail in this article.

Acute Blood Loss — Causes, Symptoms and Treatments

Acute blood loss is the leading cause of acute anemia. Damage to blood vessels due to several etiology results in disruption of integrity of blood vessel leading to blood loss. It is of two types, internal and external bleeding. Internal bleeding may not easily diagnosed in many cases because of bleeding inside organs, which may result in hematoma formation. External bleeding occurs through skin from injuries and wounds. Acute blood loss usually requires emergent surgical interventions to avoid further complications.

Microcytic Anemias: Sideroblastic Anemia — Causes and Treatment

Sideroblastic anemias are a heterogeneous group of disorders with two common features: ring sideroblasts and affected heme biosynthesis. In this article, the most important forms of sideroblastic anemia are presented as well as their etiology, diagnosis and therapy.

Atrial Fibrillation (AF) — Symptoms and ECG

Atrial fibrillation is the most common form of supraventricular arrhythmia. In its chronic form, it poses an increased risk of thromboembolic events, especially for people in advanced age. As this disease entails a reduced quality of life and increased mortality for the affected individuals, it is of the utmost importance that a physician knows the different forms of this widespread disease very well as to be able to make the opportune treatment decisions. The following article will provide you with an overview of the underlying mechanisms of disease and different treatment approaches.

Pericardial Effusion And Cardiac Tamponade — Symptoms and ECG

Pericardial effusion is the condition of having an abnormal amount of fluid in the pericardial cavity of the heart. The pericardium does not expand. If enough fluid accumulates it will restrict cardiac filling and lead to acute heart failure, this is called cardiac tamponade. Small effusions are usually asymptomatic. Symptoms of a large effusion include Beck’s triad of distended neck veins, low blood pressure and muffled, distant heart sounds. Larger effusions are treated by pericardiocentesis, carefully removing the fluid with a needle.

Chronic Obstructive Pulmonary Disease (COPD) — Classification, Symptoms and Diagnosis

Chronic obstructive pulmonary disease (COPD) is the most common chronic disease of the airways that is caused in 90 % of cases by smoking. COPD is a preventable and treatable disease. However, many patients do not know that they suffer from the disease, so the number of unreported cases of patients is very high. In this article, you will find important information on the epidemiology, etiology, pathophysiology and diagnosis, as well as the differential diagnosis and treatment of COPD.

AIDS (Human Immunodeficiency Virus, HIV) — Etiology, Stages and Prognosis

Human immunodeficiency virus (HIV) disease is caused by single stranded RNA virus of the retroviridae family. It is transmitted through exchange of body fluids such as semen and blood. The presentation is marked by deteriorating immune system organized in WHO stages beginning with constitutional symptoms such as lymphadenopathy in early stages to advance into WHO stage IV characterized by AIDS defining illnesses. The prognosis is good with adherence to HAART.

Phlebothrombosis and Deep Vein Thrombosis (DVT) — Diagnosis and Classification

Phlebothrombosis is a very common and very serious condition. Blood clots in veins can mobilize and cause significant harm and even death in some cases by blocking downstream vessels. This condition needs to be thought of in all new hospital admissions, especially those who will be particularly immobile or those undergoing operations, so they can be given medical prophylaxis to reduce the chance of a blood clot forming in the venous system.

Thyroid Cancer — Classification and Treatment

Thyroid cancer is an uncommon cancer that can be managed well if detected early enough. It arises from follicular or parafollicular cells within the thyroid. There are subtypes of cancer depending on the cell involved and the mutations that occur. The most common cure for this cancer is surgical removal of the thyroid, along with chemotherapy or radiotherapy.

Anatomy of the Torso: The Thorax

The human chest is a complex assembly of different osseous, ligamentary and muscular structures. It protects vital organs like the heart and lungs and is indispensable for the respiratory function. For medical students, it is advisable to learn the thorax in combination with the thoracic spine, as the thoracic spine and ribs form the rib vertebral joints and, therefore, you can save time studying, which may be urgently needed for other subjects.

Anatomy, Functions, and Diseases of the Pancreas

The pancreas is an organ that actually consists of two glands: one exocrine and one endocrine gland. The glandular epithelium is a specialized epithelial tissue which produces and excretes substances to control our bodily functions. The exocrine gland secretes its fluids via ducts (into the intestinal lumen), while the endocrine gland secretes its substances via the extracellular space into the vascular- and the lymphatic-system. The two parts of the pancreas differ both in structure and function. The following article should give you an overview about the histological features of the two glandular parts.

Anatomy of the Upper Limb: Finger and Thumb Joints

None of us can imagine a life without fingers. We would no longer be able to use a computer, play an instrument or greet a friend or colleague with a friendly handshake. Hardly any other joint is as frequently affected by joint rheumatism as the finger joints. Countless metacarpophalangeal joints, like the second knuckles of people living in industrialized nations, are affected by chronic polyarthritis. Knowledge of the anatomy and pathology of the fingers and thumb is thus indispensable for every (aspiring) medical practitioner.

Structure, Functions, and Diseases of the Autonomic Nervous System (ANS)

The nervous system serves the regulation and adaptation of the organism to changing conditions of the environment and the internal body. It is a communicating and controlling organ which innervates all organs of the body. The nervous system can be subdivided into an anatomic (CNS and PNS) and a functional (SNS and ANS/VNS) part which, however, are intrinsically tied to each other. The following article will give you detailed insight into the structure, functionality and pathology of the vegetative/autonomic nervous system (VNS or ANS).

Aortic Dissection — Classification and Diagnosis

Aortic dissection is a rare but serious medical condition. It can be suddenly fatal and needs to be detected early. 40% of people do not survive once the aorta dissects and therefore despite its rare nature, patients with related symptoms should be thoroughly investigated.

Oral Cavity and Gastrointestinal Tract: Overview

Digestion is the mastication and breakdown of nutrients and their subsequent incorporation into an organism. Thereafter, the bloodstream carries all nutrients to the cells of the body. This article is a compact overview of the anatomy of the oral cavity as well as the specific features of the gastro-intestinal tract and the liver.

Anatomy of the Upper Limb: Hand Joint

For humans, life would be far more complicated without hands. Any right-handed person who has had a broken right hand and subsequently received a cast can remember years later how stressful the simplest of everyday tasks could be. In 2015, 30 % of all fall injuries in sports affected the hand or hand joint. With such a high rate of injury, it is scarcely surprising that students of human medicine must be familiar with the hand joint in all its anatomical and biomechanical details.

Types of Shock — Definitions

One mainly realizes the importance of functioning blood circulation if it suddenly stops working. If the circulation system decompensates and tissue cannot sufficiently be supplied, the state of the patient can severely worsen within very little time – and you have to act quickly. Shock is life threatening. Thus, it is absolutely necessary that you know all about it as a prospective physician. Here you learn the 3 main causes of shock, and how to treat each of them.

Abdominal Aortic Aneurysm (AAA) — Risk Factors and Prognosis

Abdominal Aortic aneurysm results from loss of strength and thinning of the aortic wall. It often implies the threat of rupture of aneurysm demanding of emergency interventions. Being asymptomatic, delayed discovery of AAA is a common phenomenon. The exact etiology of AAA is not known. Males develop AAA more commonly than females. The risk factors of AAA involves hyperlipidemia, hypertension, heart disease, smoking and family history. With the proper evolution of the case, elective surgical repair can be opted as definite cure.

Gene Mutations and Repair Mechanisms of the Human Cell

Mutations are associated with diseases and defective genes. Mutated genes are actually the cause of many diseases, although they are also necessary. Without permanent change in the genome, evolution is not possible, and purely static DNA would prevent any development. DNA is also the only molecule of the cell that is repaired. The information stored in the DNA is so important that the energy expended by repairing it is worthwhile. The cell must find the correct balance between the loss of evolution by mutation, and evolution by mutation.

Placenta – Functions and Insufficiency

During pregnancy, the placenta develops and adapts to the needs of the child. The placenta fulfils numerous tasks, but mainly serves the child’s oxygen and nutrients supply. Due to various causes, a malfunction is possible, whereby the child is under-supplied and can no longer grow properly. Early diagnosis with therapeutic measures is therefore important.

Anatomy of the Upper Limb: Elbow Joint

15 % of all injuries of the elbow joint lead to occupational disability with premature pension. Thus, it is understandable that the health system has great interest to limit the consequences of such injuries, in case previous prevention measures have failed. Hence, there is need for physicians and therapists who invariably master the (functional) anatomy and pathology of the elbow joint, so patients with elbow lesions would be treated appropriately. This article is supposed to help medical students to learn the routine of dealing with the elbow joint – both for the exams in university and for later professional practice.

Acute Lymphoblastic Leukemia (ALL) — Classification, Laboratory Evaluation and Survival Rate

Acute lymphoblastic leukemia is a malignant neoplastic disease that arise from lymphoid cell lines. It is the most malignancy in childhood. The disease manifests quickly over a span of days or weeks. Excessive proliferation of immature blasts replaces the normal bone marrow cells resulting in bruises, bleeding and infection that associated with fever. Diagnosis of ALL is established by complete blood count (CBC) which shows leukocytosis , bone marrow study which shows more than 20% blast cells. It has a good prognosis.

Atherosclerosis (Atherosclerotic Cardiovascular Disease) — Definition and Pathology

Atherosclerosis is an incurable disease, but for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. It is the most abundant primary disease of the arterial vascular system and is responsible for coronary heart disease, the leading cause of death worldwide.

Acute Myeloid Leukemia (AML) — Classification and Survival Rate

Acute myeloid leukemia is due to a malignant transformation of the hematopoietic stem cells. It is predominantly seen in the age group of 50 – 60 years and is characterized by the arrest of leukocyte development in the early stage of development. Diagnosis is based on the presence of blast cells in the peripheral circulation. It is treated by chemotherapy, which includes treatment of remission and post-induction remission. Refractory cases of acute myeloid leukemia are treated by bone marrow transplants. Complications of AML include anemia, infections and bleeding, along with acute medical emergencies such as necrotizing enterocolitis, hyperleukocytosis and tumor lysis syndrome.

Boerhaave Syndrome and Mallory-Weiss Syndrome (MWS) — Diagnosis and Complications

In clinical practice, Boerhaave and Mallory-Weiss syndromes rarely appear. However, you should have these two syndromes in mind when dealing with patients in acute pain or bleeding after an episode of violent vomiting in order to make a correct diagnosis at the crucial moment. Questions about this subject are also likely to be asked in tests. Therefore, medical students should be able to keep these two syndromes apart, particularly their epidemiology and clinical symptoms.

Zenker's Diverticulum and Other Esophageal Diverticula — Definition and Symptoms

Diverticula can be found in various organs, in particular in the colon, but also in the duodenum or ileum, and in the esophagus. Every medical student should internalize the differences between true and pseudo-diverticula. Zenker's diverticulum, in particular, is often quizzed in exams.

Anatomy of the Spinal Column

The human spine has various tasks. It helps us to be upright, ensures stability, provides muscles, tendons and other tissues with osseous starting points and passage openings, can distribute loads and is still flexible and movable. The downside of this is that such a complex structure with so many functionalities is, unfortunately, an equally versatile focus for diseases. In 2011, approximately 230,000 spinal surgeries were performed, and an upward trend has been observed. Students of human medicine should be introduced to the anatomy of the spine early on, to diagnose pathologies timely and spare patients’ problems associated with such an operation.

Pneumonia — Classification, Diagnosis and Treatment

Its high morbidity and mortality make pneumonia one of the major infectious diseases worldwide. Learn about the pathogenic causes as well as the individual types of pneumonia, in order to be able to reliably differentiate and treat it in clinical practice.

Abnormalities of the Female Reproductive Organs: Adenomyosis, Uterine Fibroids, Macromastia, and More

Abnormalities of Female reproductive organs has been matter of concern in females of reproductive age. These abnormalities can be congenital, or acquired. Environmental or genetic anamolies can result in congenital abnormalities in female organs of infants. Acquired abnormalities implies infections, physical damage brought during delivery or surgery or hormonal imblances as their etiology. Amenorrhea and infertility are the important representing symptoms of these abnormalities. Diagnosis and identification of abnormalities such as adenomyosis, uterine fibroids, etc. along with their exact location establishes the accurate treatment procedures.

Achalasia (Cardiospasm) — Diagnosis and Surgery

Achalasia (cardiospasm) is a functional disorder caused by narrow position of lower esophageal muscles. It is marked by reduced or absent peristaltic movement of esophagus and relaxed lower esophageal sphincterat swallowing. This abnormality result in functional obstruction at the junction of esophagus and stomach with symptoms such as dysphagia, regurgitation, heartburn, stomach pain and weight loss. It is diagnosed by the help of barium swallow, esophageal monitoring and endoscopy. Pharmacological and non-surgical interventions are adopted to treat achalasia.

Breast Cancer (Mammary Carcinoma) — Diagnosis, Treatment and Survival Rate

As mammary carcinoma is the most frequent malignant disease in women, early detection is important. There are numerous diagnostic tools available, the mammogram being the gold standard. The next step would be developing a treatment plan that is individualized for the patient and the type of carcinoma. The following article will teach you to accurately diagnose mammary carcinoma and to initiate the appropriate therapy.

Anatomy of the Torso: Thoracic and Abdominal Muscles

The complexity of the musculoskeletal system is often a big issue for medical students. To learn about muscles effectively, a clear and logical grouping into systems with unique structures is needed. In this article, in addition to detailed descriptions of the origin, insertion, action and innervation, medical students will obtain an overview in tabular form for visualization of the muscle groups. Attention: Due to conflicting information in primary literature about the muscles' origins and insertions, it is advisable to always consult the latest copies for studying.

Uterine Rupture — Symptoms and Treatment

A uterine rupture represents an important complication during pregnancy, as well as during delivery. A uterine rupture can become a life-threatening emergency which requires an immediate Caesarean section. The patient complains about severe, devastating pain. The uterus feels rigid when palpated, and signs of hypovolemic shock are visible. This article presents you with a compact overview of this complication.

The Male Reproductive System

The male reproductive system with testicles and spermatic duct can be divided into different sections, but are treated as one unit in anatomy. This article is concerned with the anatomy and physiology of the male sexual organs. At the end, final pathology concludes with a general view on the most important dysfunctions.

Upper Limb Nerve Injuries: Carpal Tunnel Syndrome (Median Nerve Compression), Ulnar Claw (Claw Hand), Median Nerve Palsy and More

In this article, you get an overview of the pathology of the brachial nerves and understand how a hand of benediction or a median claw hand, an ulnar claw and a hand extension loss with the radial nerve paralysis may develop.

Hyperthyroidism (Overactive Thyroid), Graves' Disease (Basedow Disease) and more

Hyperthyroidism is caused by the excess of thyroid hormones T3 and T4. Graves’ disease is the most common cause of hyperthyroidism. Clinical features of hyperthyroidism are mostly due to the increased body’s metabolic rate. Hyperthyroidism is diagnosed by estimation of TSH and free T4 and T3. It is treated by pharmacological and surgical means.

Chemistry for Physicians — Introduction

Even though you do not want to become a chemist, as a doctor-to-be you will need some basic knowledge in the field of chemistry. Although this science does not explain the mechanics of life, it helps us to understand it better. In this summary, you get the most important information about test-relevant topics from the atomic structure through the understanding of the PSE to the reaction types.

Breast Cancer (Mammary Carcinoma) — Causes, Classification and Symptoms

Breast cancer (mastocarcinoma) is the most common form of cancer among women. Consequently, it will be encountered by doctors as part of their work in hospitals and medical practice. This disease exhibits a heterogeneous pattern including different histological subtypes, which may differ considerably in their degree of malignity and, consequently, in their clinical symptoms and therapy. The following article helps you to understand the clinical picture of mastocarcinoma, identify its symptoms and to classify its histology correctly.

Hypothyroidism (Underactive Thyroid) — Medication and TSH Levels

Hypothyroidism is caused by the deficiency of T3 and T4. Hashimoto's disease (autoimmune thyroiditis) is the leading cause of hypothyroidism in non-iodine deficient regions. Clinical features of hypothyroidism are primarily due to the accumulation of matrix substances and a decreased metabolic rate. Hypothyroidism is diagnosed by the estimation of TSH and free T4. It is treated by administration of synthetic T4.

Bacterial Infections: Gram-Positive Cocci

Although there are countless types of bacteria, it is of particular importance for a physician to know the most common ones. Knowing them includes the typical clinical picture they cause, as well as the basics about their structure, virulence, morphology and bacterial culture in order to be able to recognize and distinguish them from other bacteria and to treat and target them properly.

Tuberculosis (TB, Consumption) — Diagnosis and Treatment

Mycobacterium tuberculosis: Ca. 30 % of humankind are infected with this pathogen, 10 % sicken from manifested tuberculosis. The special feature of these bacteria is that they are very acid-fast, they grow very slowly, and can survive in macrophages. This way, they are a great challenge in terms of therapy and prevention for physicians and scientists. The following article distinctly presents you all the relevant facts for exams concerning tuberculosis which are needed for the second state examination and clinical practice.

Bacterial Infections: Definition, Pathogenesis and More

Every physician confronts potential bacterial infections everyday during his or her professional life. Whether to avoid them in the operating room or to treat a patient’s disease, bacteria and their antidotes – antibiotics – should always be treated with the utmost care. To treat microorganisms in the right way, each doctor of medicine must have knowledge and understanding of the basics of these life forms, their virulence factors, and their vulnerability.

Coronary Artery Disease (CAD, Atherosclerotic Heart Disease) — Risk Factors and Prevention

Coronary heart disease (CHD) is the leading cause of death in industrialized countries. Numerous risk factors, which can be reduced through both behavioral and lifestyle changes as well as drug therapy, are known for its origin.

Normocytic Anemia: Aplastic Anemia (Bone Marrow Aplasia) — Primary and Secondary Causes

If not treated the aplastic anemia diseases leads to death. Everything you have to know as a future physician in this article.

Pleural Effusion — Diagnoses, Treatment, Transudate and Exudate

Medical students often encounter patients with pleural effusion during internships and their residency. These patients do not always suffer from dyspnea and an accurate clinical examination is crucial for the diagnosis. In oral and written exams, explaining the difference between transudate and exudate is a frequent task. In this article, you can find all the important information regarding pleural effusion – for clinical practice and your studies!

Aortic Stenosis (Aortic Valve Stenosis) — Diagnosis and Treatment

Acquired valvular heart diseases may manifest as insufficiencies (i.e., the incomplete closure of the valve), as a stenosis (i.e., a narrowing of the valve), or as a combined valvular defect. In principle, all valves can be affected. The aortic valve stenosis and the mitral regurgitation are particularly frequent.

Aortic Insufficiency (Aortic Regurgitation) — Symptoms and Treatment

Acquired valvular heart diseases may manifest as insufficiencies (i.e. incomplete closure of the valve), as a stenosis (i.e. a narrowing of the valve), or as a combined valvular defect. In principle, all valves can be affected. The aortic valve stenosis and the mitral regurgitation are particularly frequent.

Biology for Physicians: Formal Genetics and Population Genetics

Mendel’s laws, phenotype and genotype, recessive and dominant. Do these terms sound familiar to you from your biology lessons? This article regarding formal genetics will introduce you to all important genetic fundamentals regarding biology that you need to know as a physician. By studying and revising the contents of this article, you will be in a better position to do well both in your preclinical studies as well as in your preliminary exams. This content will help you master the key fundamentals of Genetics.

Arachidonic Acid (AA, ARA) Derivatives

When it comes to joint pain, it is mostly the cartilage that is inflamed and chronic headaches often result from neural inflammatory processes. Overcoming this pain will often seem impossible. What is little known: Superhormones, which can regulate the hormonal balance of the body, exist – these are eicosanoids, derivatives of arachidonic acid, an omega-6 fatty acid. What effect do the arachidonic acid derivatives have on the body? How can inflammatory responses be influenced and rheumatic diseases completely cured? You will learn about this and much more, in this article!

Guillain-Barré Syndrome (GBS) — Symptoms, Diagnosis and Variations

Inflammatory and immune-mediated polyneuropathies represent an important differential diagnosis of hereditary and acquired polyneuropathies. In this article, we will provide you with all the relevant facts concerning the Guillain-Barré syndrome, the Miller-Fisher syndrome, and the Elsberg syndrome. Also, we will cover the chronic-inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy with conduction blocks. Via the concise, selected preparation of the factual knowledge and through several learning tips, you will be perfectly prepared for your exams.

Deoxyribonucleic Acid – Structure, Organization and Various Types of DNA

The chemical structure that carries genetic information is called DNA. In this article, you will learn about the structure, organization and various types of DNA. For exams, the phases of the cell cycle are of great importance. After reading this article, you can test your newly acquired knowledge with a few exam questions on this topic.

Hemolytic Anemia

Hemolytic anemia is characterized by intravascular and extravascular destruction of erythrocytes. It manifests if the production of the erythrocytes in the bone marrow is slower than their degradation. A first good differentiation of the several forms of hemolytic anemia can be made between ‘hereditary’ and ‘acquired’. In this article, the most important forms of hereditary and acquired hemolytic anemia are presented, emphazising on their etiology, clinic and therapy.

Cardiac Insufficiency (CHF, Heart Failure) and Pulmonary Edema — Classification and Treatments

Heart insufficiency as a disease of old age constitutes a serious clinical picture as its complications often result in death. Cardiogenic pulmonary edema, as a consequence of heart insufficiency, as well as non-cardiogenic pulmonary edema, are diseases indicating immediate measures as they are accompanied by rapid respiratory insufficiency. This article will provide you with everything you need to know about the epidemiology, etiology, classifications, diagnostics and therapy for cardiac insufficiency and pulmonary edema.

Antibiotics – Types and Antibiotic Therapy

Antibiotics are an indispensable part of modern medicine. Many infectious diseases caused by bacteria are fatal without antibiotic treatment. Therefore, the empirical use of antibiotics is the basic component of many therapies. However, due to increasing resistance and the increased incidence of long underestimated problematic bacteria, such as Acinetobacter baumanii complex, every medical student and practitioner should know the common antibiotics, their indications, and frequent side effects.

Biology for Physicians: The Basics of Medical Microbiology

Microorganisms play a big role in the pathogenesis of diseases in human beings. Prophylaxis and treatment are only possible if you have an exact understanding of the structure and metabolism of bacteria, viruses, and fungi. Get to know different morphological criteria, important facts concerning structure as well as reproduction and growth of the most important microorganisms. Many tips and important information will help you get a high score in your biology exams.

Asthma (Bronchial Asthma) — Classification, Diagnosis and Treatment

It is the chameleon of pulmonology: With as many different clinical phenotypes, making a diagnosis isn’t always easy, and pathogenesis is complex. In the following article, you will find all the important information about one of the most common chronic diseases in human beings: bronchial asthma.

Biochemistry for Physicians: Cholesterol Metabolism

Cholesterol (Greek for: ‘gall’ and ‘solid’) is a media star: For decades, no other biochemical substrate draws as much attention as cholesterol has. But what are the hard pre-clinical facts? How is cholesterol synthesized and degraded in the human body? How is cholesterol metabolism regulated? The following article presents you with useful information that will aid you in your exam preparation.

Adrenal Gland Disorders: Cushing´s Syndrome, Conn’s Syndrome, Addison's Disease, and Phaeochromocytoma

The adrenal glands are paired endocrine organs that produce hormones secondary to neuronal influence. The glands are organized into an inner adrenal medulla that secretes Adrenaline and Noradrenaline and an outer cortex consisting of three anatomically and functionally different layers producing mineralocorticoids (aldosterone), glucocorticoids (cortisol) and androgens (androstenedione).The gland may suffer disorders of hyperfunction such as hypercortisolism, pheochromocytoma and hyperaldosteronism or disorders of insufficiency such as Addison’s disease. This article will provide outlines for each disease separately.

Affective Disorders — Definition and Treatment

Affective or mood disorders are characterized by various types of psychiatric diseases that can be disruptive to patient's life. They can involve abrupt onsets of manic or depressive episodes of mood changes and and often combinations of the two. Patients usually experiences depressive episodes of agitation, sleep disturbance, eating disturbances, lack of interest and feelings of worthlessness or guilt. The mania is usually associated with violence to others. Psychotherapy, medical treatment or even electroconvulsive therapy in extreme cases are the mainstay treatment of affective disorders.

Vaginal Diseases and Vulvular Disorders: Bacterial Vaginosis, Vulvitis and more

Colpitis and bacterial vaginoses are diseases of the vagina. Apart from the symptoms themselves, there is always the risk of an ascending infection. Also inflammations of the outer genitals are an important clinical issue. For one thing, vulvitis is very frequent and ubiquitous. Furthermore, the outer genitals are so sensitive that diseases can cause great discomfort for the patient, even if they often are harmless. Here you can read all about pathogens, diagnostics and treatment.

Anatomy of the Abdominal Wall and Pelvic Floor

Do not fear the pelvic floor—although this topic is popular amongst examiners and seems to be complicated at first glance, there is no need for fear. Here, you get a compact overview and learn everything you need to know about the pelvic floor, the abdominal wall and the inguinal canal.

Development of the Branchial Arches

For many students, embryology belongs to the more unpleasant topics of preclinical studies. Nonetheless, the knowledge around the branchial arches (Latin: arcus branchiales, synonyms: pharyngeal arches, visceral arches) and their derivatives, are not only a popular exam topic, but are also essential for understanding the anatomy of the face and neck. In order for you to shine in your next anatomy test with your embryological knowledge, you will find detailed information regarding the branchial arches and the structures originating from them in the following article.

Biology for Physicians: Human Genetics – Inheritance in Human Beings

"This is genetic!" Which diseases are inherited as an autosomal dominant trait and which as a X-chromosomal recessive trait? What is the purpose of our gonosomes? How do you calculate a risk for inheritance? What do you know about genomic imprinting and the inheritance of blood types? In this article, we offer you everything you need to know about human genetics including the most important facts and genealogical trees of major genetic diseases.

Anatomy of the Lower Limb: Muscles of the Hip and Thigh

The hip is one of the strongest joints of the human body. This circumstance is due to the variety of muscles that surrounds, stabilizes and moves it. Medical students often have difficulties to properly understand the large number of individual muscles with their structures and functions. It is, therefore, advisable to divide the muscles into groups in order to obtain a better overview that will, in turn, facilitate the learning process. This article is intended to provide the desired overview.

Microscopic Anatomy: Blood

Blood (Latin: sanguis, Greek: haima) is a suspension of cells in a saline solution containing protein. It makes up 6-8 % of the total body weight and has a pH value of 7.4. The blood carries out many essential functions and is the pivotal point of the whole organism. The following article provides, at a glance, the most important facts about this vital body fluid called blood.

Allergies (Allergic Diseases) and Atopy (Atopic Syndrome) — Pathophysiology and Most Common Diseases

Allergies are exaggerated response of the immune system that mediated by IgE antibodies to specific harmful allergens (e.g: pollen, mites, molds, certain foods). Atopic syndrome is a disease of genetic predisposition characterized by high production of IgE. Symptoms appear after the release of certain chemicals from mast cells with their attachment to IgE antibodies. Allergic asthma, allergic rhinitis, allergic conjunctivitis, food allergy and atopic dermatitis are common diseases.

Anatomy of the Upper Limb: Musculature of the Arm and Forearm

The large number of different muscles makes the forearm and the hand one of the most complex structures in our musculoskeletal system and can cause issues for both medical professionals and students. The most common arm injuries occur in the upper arm, especially the radius.

Anatomy of the Lower Extremity: Knee Joint

Besides the shoulder joint, the knee joint is one of the most complex capsuloligamentous structure systems of the human body. Hardly any other joint has as many different stabilizing ligaments and simultaneously such a great degree of movement. Most of all, medical students should be familiar with the functional anatomy since even slight disorders, e.g. in the gliding movements of the menisci, can lead to severe movement impairments and pain. After the hip, the knee is the second most frequent location for the implantation of total endoprostheses.

Telencephalon – Language Centers, Structure of the Limbic System and Basal Ganglia

The language centres of the telencephalon, i.e. the Broca's area and the Wernicke's area, are highly relevant as exam topics. The same goes for the structure of the limbic system and the basal ganglia.

Anatomy of the Lower Extremity: Hip Joint

Every year, a great number of endoprostheses are implanted in the hip joint region. This shows the extreme vulnerability of the capsular ligament complex and, thus, why a physician should be able to know its anatomy, functional anatomy, and pathophysiology. Orthopedists and surgeons hear patients complaining about pain in the hip joint every day. Without sufficient knowledge, it is impossible to help these people competently.

Anatomy & Pathology of the Heart and Components of the Cardiovascular System

The heart is a hollow muscular organ that contracts approx. 100,000 times a day and pumps approx. five liters of blood into the circulation every minute. It is not only characterized by the unique features of muscle tissue specialized to meet the constant physical demands of pumping blood, but also by muscle cells that send spontaneous rhythmic electrical impulses to stimulate contraction. This article gives an overview of the structure of the heart wall and of cardiac muscle tissue.

Anatomy and Structure of the Spinal Cord and Spinal Cord Injuries

The spinal cord (medulla spinalis) is part of the central nervous system, while simultaneously connecting the body to the brain. On the posterior side of the spinal cord, sensory information from the skin, skeletal musculature, joints and intestines, flows in from the afferent nerves via the dorsal root of the spinal nerves. On the frontal side, in turn, spinal nerve roots exit as efferences and deliver information to the peripheral nervous system – to the skeletal musculature and the intestines, and so forth. The following article will provide you with a first impression of the structure and function of this fascinating organ.

Physiology of the Heart

Our heart is a powerful pump that performs its duty around the clock. It pumps 7,000l of blood through the body each day. This is possible due to, among other things, its autonomous regulation and unique musculature. This article covers the aspects of cardiac physiology that are relevant in medical exams and creates a basic understanding of the mechanics of the heart.

Stages of Neurulation and Development of the Heart

In the 3rd week of embryonic development, both the neurulation as well as the development of the cardiovascular system begins. The neurulation denotes the formation of the neural tube in the development of the central nervous system. These complex processes are a combination of numerous factors and interactions. Embryology is always relevant for the understanding of an organ. By understanding the development we can understand the anatomy and possible malformations. The processes relevant for the examination are explained step by step in this article.

Anatomy of the Upper Limb: Shoulder Joint and Subacromial Joint Space

The shoulder joint is one of the most mobile joints in the human body and is extremely susceptible to injury, among other reasons, due to its high mobility. Physicians, not only surgeons or orthopedists, should, therefore, be familiar with its anatomy and functional anatomy. This article provides an overview of the osseous and articular structures of the shoulder joint and the subacromial joint space.

Triacylglyceride Metabolism

Triacylglycerides are a group of insoluble compounds that serve as energy reserves in the body. Their storage occurs in adipocytes, which are built up or depleted in response to the constantly changing energy demands of the cell. Both of these processes are under tight hormonal regulation. This discussion will also include the absorption and transport of fatty acids, as well as the production of ketone bodies.

Physiology of Sleep and Common Sleep Disorders

Etymologically, the term "sleep" comes from a word meaning "to slack"; the term's similarity to the word "slack" is no accident. Sleep is susceptible to various interferences, and many diseases, some harmless and some serious, first exhibit symptoms during sleep. It is therefore important to deal not only with the scientific findings, but also with possible sleep theories because many facts about sleep remain unknown. In the following guide, you will see what sleep is actually about, what stages it occurs in, and what sleep disturbances individuals may experience.

Blood Vessels — Wall Structure of Arteries and Veins

In this article, you will get an overview of the most important facts concerning the histology of veins and arteries, as well as their functions based on their histology. In addition, we cover the crucial structural and functional differences between veins and arteries, and the way they interact within the circulatory system.

Bones: Fundamentals of Anatomy for Physicians

The skeletal system has important functions as protection and support during movements, for the mineral balance, blood production and the storage of triglycerides. In this process, bones (latin: os, greek: ost-, oste- or osteo-) give us stability and shape. Now, how many bones do humans have? This is easily answered numerically, 206. However, for exams it is more important for physicians to understand the structure and composition of bones than the amount.

Anatomy of the Upper Limb: Muscles of the Hand and Fingers

Hardly any other muscle group has so many small intricate complexes as those of the thumb and fingers and causes such a headache to medical students. And yet, the muscles and their functions can be very easily remembered on the basis of their denominations and the majority of them is innervated by the deep branch. It is, therefore, advisable for aspiring doctors to study with the help of mnemonics in order to be able to go relaxed into their next exam.

Parts and Functions of the Cardiovascular System (Circulatory System)

The purpose of the blood circulation system of the human body is the convective transport of respiratory gases, nutrients, hormones, and warmth. The blood acts as a vehicle that is pumped by the heart through the blood vessels and back to the heart. The blood circulation is a rapidly adjustable system that is vitally important for maintaining the body functions. High blood pressure (arterial hypertension) is one of the most common diseases in our society. Thus, a physician must know and understand the blood circulation. This article provides an extensive overview.

Anatomy, Functions, and Diseases of the Esophagus

The gullet (Greek 'oesophagus') is a hollow organ, approximately 25 cm long, assigned the task of actively sending our food to the stomach. The following article will provide you with a compact overview of the anatomy as well as the most important diseases of this organ and explains the physiology of the act of swallowing in understandable steps.

Anatomy and Function of the Male Urogenital System

Understanding male anatomy: here we present key information on the structure and the functions of the male inner and outer genital organs and exam-relevant facts on spermatogenesis.

Anatomy of the Upper Extremities: Muscles of the Shoulder and the Upper Arm

The human shoulder is the most mobile joint of the body. Since it is a muscle-guided and muscle-stabilized joint, it is susceptible to instability and inflammation. It is essential for doctors to learn about the muscular stabilization of the shoulder joint and its functional anatomy. We can imagine how tiring (if not impossible) a life without a properly functioning shoulder joint would be. The muscle groups of the shoulder are distinguished by location and origin: the muscles of the shoulder and the muscles of the upper arm.

Development of the Kidneys and the Efferent Urinary Tract (Weeks 3-6)

The development of the kidneys and the efferent urinary tract is complex and unalterably interconnected. It is an essential part of embryonic development and closely connected to sexual development. Malformations lead to severe consequences and are often not compatible with postnatal life. In medical studies this is one of the most important themes in embryology.

Physiology of the Endocrine System

The special field of endocrinology deals with the hormonal system. This includes, among other things, the function of hormones, the anatomy and physiology of endocrine glands and the feedback mechanisms of hormone regulation. This article explains the physiology of the endocrine system and provides graphical illustrations. The physiology of the endocrine system is a vast field that plays a role in all medical specialties, and it demands a lot of medical students to master it.

The Sensory Systems of the Human Body

The sensory organs enable us to interact with our surroundings and perceive things outside our body. As fascinating as their function is, as complex and vast seems the topic during medical studies. Despite the large variety of sensory organs, they all follow a few fundamental principles in their structure and function. From the fundamentals to the necessary detailed knowledge of the different sensory perceptions is only a short way.

Anatomy, Functions and Pathology of the Large Intestine (Large Bowel)

The large intestine (lat. intestinum crassum) is distally adjacent to the small intestine, extending from the ileo-caecal valve to the anus. It is divided into the caecum with vermiform appendix, colon, and rectum. Thus, it is forming the terminal part of the human digestive tract. Particularly relevant for the exam are the relation of distinct intestinal sections with regard to the peritoneum, the differences between large and small intestine, and the general understanding of anatomy and physiology. The overview below provides all important basics about the large intestine.

Anatomy, Structure, and Pathology of the Small Intestine (Small Bowel)

The small intestine (Latin: intestinum tenue) spans a range of about 3-5m from the pylorus of the stomach to the Bauhin’s valve located at the passage to the colon. This section of the digestive tract represents the body’s most essential site of nutrient uptake and water resorption. Understanding the small intestine’s structure and processes is a crucial part of any physician’s education. The following article comprehensively sums up the most important facts about this central part of the gastrointestinal tract and its three sections – the duodenum, jejunum and ileum.

Anatomy, Functions, and Diseases of the Liver

The liver (Latin: Iecur, Greek: Hepar) is the generalist among all organs – acting universally as center of metabolism, storage unit, detoxifying- and excreting organ. Medical staff is frequently confronted with diseases such as liver cirrhosis, hepatitis and fatty liver. Therefore, anatomical and biochemical knowledge of the liver is part of every medicine student`s basic training. Read this compact overview on structure, functions and diseases of the liver.

Anatomy and Functions of the Kidneys and Kidney Stones

The kidney (Latin: Ren, Greek: Nephrós) is the urinary system’s main organ. In order to understand the microscopic structure of this organ, it is useful to comprehend well its function. And for this, one has to learn about the different cell types and their structure. The nephron is the kidney’s functional unit and shall be particularly discussed here. After studying this article, you will be able to explain its components. These are the renal corpuscles, renal tubules and the collecting duct system. You will now read a short overview of the functions of the human kidney.

12 Cranial Nerves – Functions and Mnemonics

Nerves emerge as spinal nerves from segments of the spinal cord. Cranial nerves emerge directly and without “detour” via the spinal cord from the bony skull because they supply cranial structures or fulfil specific functions. As the 31 pairs of spinal nerves, they are considered components of the peripheral nervous system (PNS). The cranial nerves I and II are exceptions since they do not emerge from the brain and therefore are not considered peripheral nerves. During medical studies, cranial nerves are an essential element of the subjects of the brain and the nervous system. In the following, you will find a concise overview of the classification, the functions and the course of the 12 cranial nerves.

Hypocalcemia — Definition and Treatment

Calcium levels are regulated by a hormone known as the parathyroid hormone (PTH), which is secreted by the parathyroid gland. If the body fails to maintain the calcium levels within the normal ranges, hypercalcemia or hypocalcemia results. Hypocalcemia is the condition in which the serum calcium levels in the blood are low. The presentation of the patients with hypocalcemia can vary from asymptomatic to life threatening situations.

Gallstones — Causes, Risks and Treatment

Gallstones are common in the United States, especially among the Hispanic population. They are common among the fatty fertile females in their forties. The gallstones are mostly asymptomatic that do not need treatment except in certain high-risk groups. The symptomatic patients present with right upper quadrant abdominal pain and cholecystectomy is the primary treatment option in these patients.

Acromegaly — Symptoms and Treatment

Excess production of growth hormone by pituitary gland in the body is given the name Acromegaly. The exact cause behind Acromegaly can be benign, noncancerous tumors formed in the pituitary gland. Middle aged adults are more prone to develop acromegaly. It is often diagnosed very late because of its slow and insidious onset. The symptoms varies from swelling of hands and feet to protruded lower jaws, joint pain, and deep voice. Accurate diagnosis is established by elevated level of growth hormone (GH) and Insulin-like Growth Factor I (IGF-1) in the blood.

Amebicides

Amebiasis is caused by Entamoeba histolytica. Infection occurs by ingestion of water and food contaminated with feces (containing cysts of Entamoeba histolytica). In this article, we will study in detail about the various amebicides, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important therapeutic aspects of individual drugs will also be studied.

Anti-herpes Drugs

In this article, we will study in detail various anti-herpes drugs, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important pharmacological and therapeutic aspects of individual drugs will also be studied.

Sedative and Hypnotic Drugs

In this article, we will study in detail about the various sedative and hypnotic drugs, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important pharmacological and therapeutic aspects of individual drugs will also be studied.

Types of Germ Cell Tumors (GCT) and Non Germ Cell Tumors

Testicular tumors are common and potentially annihilating to the male population. With a brief prologue to testicular tumors; this article focuses on the significant, relevant types of testicular tumors such as Germ Cell Tumors (GCTs) and Non-Germ Cell Tumors (NGCT).Various clinical, patho-physiological and prognostic aspects of the same have been expatiated.

Somatoform Disorders

Somatoform disorders are a group of psychological conditions where the physical symptoms are present in the patient and it cannot be attributed to any medical condition or substance abuse. The term somatoform disorder has been replaced by a newer term in DSM 5 namely the somatic symptom disorder. The cognitive behavioral therapy constitutes the main mode of treatment of this disorder. The antidepressant has shown beneficial effect in the pain of the somatoform disorder. This disorder would be described in detail in this article.

Transport Across Cell Membrane

A number of cellular processes involves transport of materials in and outside the cell. The transport of these materials are governed by a number of factors which include presence of a concentration as well as an electrochemical gradient. This article summarizes the different types of transport that can occur across the cell membrane. Specifically, the article differentiates active and passive transport. The different factors that can affect the transport are also discussed in this article.

Pancreatic Enzyme Replacement Therapy

Patients with chronic pancreatic insufficiency develop improper digestion due to the lack of digestive pancreatic enzymes. Such patients might complain of diarrhea and multi-nutrient deficiencies. Children with cystic fibrosis are at an increased risk of developing pancreatic insufficiency, while adults can develop chronic pancreatitis due to gallbladder disease or alcohol consumption. Regardless of the etiology, these patients might develop exocrine pancreatic deficiency and are at risk of developing malabsorption. Pancreatic enzyme replacement therapy is indicated in patients with malabsorption due to exocrine pancreatic insufficiency.

Gastrointestinal Motility — Clinical Presentation and Treatment

Patients with intestinal motility disorders, whether hypomotility or intestinal dysmotility syndromes, might need a diverse array of medications for symptomatic relief. These medications fall into one of the following categories: antibiotics, antidiarrheals, opioid antagonists, cholinergic and promotility drugs. Additionally, antiemetics might be needed as these patients can complain of nausea or vomiting.

Research Ethics

Whether you are working in basic science, transitional or clinical research, a set of ethics and morals should guide your decision making process. This collection of ethics can be learned from our supervisors, our colleagues, lab seminars, professional organizations concerned for example for ethical handling of animals, and courses specifically dealing with ethical issues. Finally, our family, friends and our own religious beliefs also help form our moral compass and can make us make ethical decisions related to our research.

Biotechnology: Recombinant DNA and Gene Amplification

Biotechnology is the use of biological organisms or processes to develop products or improve the quality of life. One common technology studied is the Recombinant DNA technology. DNA of two organisms are combined to improve characteristics and properties of an organism. Modification of the DNA also is done to develop new pharmaceutical therapies and diagnostic tests. In this article different techniques in biotechnology are discussed, namely, recombinant DNA technology, Polymerase Chain Reaction, Gel Electrophoresis and CRISPR Cas9.

Anti-Hepatitis Agents

In this article, we will study the details about the various antiviral agents used to treat hepatitis, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important pharmacological and therapeutic aspects of individual drugs will also be studied.

Drugs for Influenza and CMV Retinitis

Antiviral agents are chemotherapeutic drugs that are effective against different viruses. Influenza is a common infection; anti-influenza agents are useful for both prophylaxis and the treatment of influenza. CMV retinitis is a common opportunistic infection in immunocompromised patients; there are several antiviral drugs effective against CMV. Pharmacology of all the drugs will be discussed briefly.

Antifungal Drugs — List of Drugs and Classification

In this article, we will study the details about various antifungal drugs, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important pharmacological and therapeutic aspects of individual drugs will also be discussed.

Gastrointestinal Pharmacology: Antiemetics

Antiemetics are used to prevent or stop vomiting; they act on the esophagus, stomach, intestines and even on the central nervous system where the vomiting center is located. In this article, we will cover in detail the various antiemetics, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important pharmacological and therapeutic aspects of individual drugs will also be noted.

Scrotal Mass, Congenital- & Acquired Hydrocele and Spermatocele

Scrotal masses are embarrassing and seemingly exigent trouble for males. Benign scrotal lesions present as testicular masses that transilluminate as against solid testicular tumors which do not transilluminate. This article expounds about benign, relevant, common scrotal masses such as congenital and acquired hydrocele and spermatocele.

Biotechnology: DNA Libraries, Analysis and Applications

There is a variety of applications that can be done using recombinant DNA technology. This is why it important to develop libraries for the genomes of organisms so that it will be easier for scientist to isolate desired genes of interest. This topic review discusses DNA libraries and how they are developed. Also given in this article are the applications of biotechnology in the field of forensics, medicine and agriculture. Blotting techniques and how they apply in forensic investigation are included in this article as well.

Amino Acids — Structural Features, Classification and Ionization

Amino acids are the simplest unit of a protein. It has distinct structural characteristics that are responsible for the different types of interaction it can make inside the body. It is important to study the structure of amino acids as the functioning of proteins is highly affected by the type of comprised amino acids. In this article, the structural features and properties of an amino acid will be discussed. Also included in this article are the classification of the amino acids based on the side chain it has. Focus is also given to the ionization of amino acids.

Respiratory Physiology: Control and Regulation of Breathing

Respiration is the process by which our body takes in air containing oxygen into the lungs and exchange oxygen with carbon dioxide in the alveoli. Breathing is an involuntary, rhythmic process of inhalation and exhalation of air. Respiration includes both breathing and ventilation (gas exchange in the alveoli). Lungs along with the respiratory tract are the major organ system involved in respiration. The part of the respiratory tract where gas exchange occurs is the alveolar space. The part of the respiratory tract where no gas exchange occurs is called the dead space.

Pediatric Allergic Proctocolitis

Pediatric allergic proctocolitis is considered an IgE-mediated allergic reaction to dietary proteins; most commonly is Cow’s milk protein, which represents about 50-65% of the cases. It's a frequent, significant cause of infant colitis. This article explains the main clinic-patho-physiological aspects of the disease.

Pediatric Meconium Ileus — Signs and Symptoms

Meconium originates from the Greek word “mekonion” which stands for poppy. The nomenclature attests to the tarry, black appearance of meconium which resembles raw opium preparation. Meconium ileus implies the presence of an intestinal obstruction in-utero or in neonatal period secondary to abnormally thick meconium. This article expatiates on patho-physiological aspects of meconium ileus and expounds on clinical features of the same. The article concludes with treatment, complications and prognosis of meconium ileus.

Complement System and Chronic Inflammation

The complement system is a part of the innate immunity that functions to identify foreign materials (pathogens, apoptotic cells and cellular debris), and induce immune response to eliminate these materials.

Types of Primary Immunodeficiency (PI) Disorders — Definition and Pathogenesis

Primary immunodeficiencies differ from secondary immunodeficiencies (acquired immunodeficiencies) in that they arise from birth as a result of genetic defects. However, not all primary immunodeficiencies are present at birth and many present in adolescence or adulthood. In contrast, secondary immunodeficiencies are typically secondary to infection (e.g., HIV) or therapies (e.g., corticosteroids). The following article covers the most important primary immunodeficiencies and their underlying pathophysiology.

Reproductive Pharmacology

Sex hormones are needed for human development, induction of secondary sexual characteristics and reproduction. In males, androgens function to influence sperm production. In females, estrogen and progesterone function during the menstrual cycle and in maintenance of pregnancy. Excess androgens can result in prostatic hyperplasia while loss of testosterone gradually occurs as men age. Excess estrogen can lead to endometrial hyperplasia while a loss of estrogen leads to menopause.

Drugs for Acid Peptic Diseases

Acid peptic diseases are common gastrointestinal disorders, which include gastroesophageal reflux disease, peptic ulcers, non-ulcer dyspepsia and stress-related gastric mucosal injury. Drugs commonly used in the management of these disorders include antacids, H2 blockers, proton pump inhibitors and mucosal protective agents. In this chapter, pharmacology of these drugs will be discussed, followed by brief description of their roles in the management of common acid peptic diseases.

Antiasthmatics (Antiasthmatic Drugs) — Definition and Classification

Asthma is a chronic airway hyperresponsiveness (with acute exacerbations), which is widespread all over the world in both children and adults. In most cases, it is in response to environmental stimuli. The main pathological changes are bronchospasm, edema and mucosal plugging, and the symptoms are wheezing, cough and breathlessness. Asthma therapy is directed against bronchospasms or inhibition of inflammation in general or their mediators such as leukotrienes. The most common drugs used are inhaled β2 agonists and inhaled corticosteroids.

Lymphatic Drainage of Abdominopelvic Organs

The lymphatic drainage of the abdominopelvic organs can be described easily by dividing the drainage into four groups. The lymphatic drainage from these organs is clinically very important due to its role in the spread of malignancies and infections.

Connective Tissue: Bone Marrow and Hematopoiesis

Bone marrow is the type of tissue in the marrow cavities of bones where blood cells are formed and later released into the circulation. The process of production of blood cells is called hematopoiesis. This includes erythropoiesis (the production of red blood cells), leucopoiesis (the production of white blood cells) and thrombopoiesis (the production of platelets).

Adrenal Gland: Physiology, Pathology, and Pharmacology (Mineralocorticoids & Glucocorticoids)

Suprarenal glands are located on the superior pole of each kidney. Each gland has two distinct developmental origins that divide it into two regions. The catecholamine secreting medulla is derived from the neural crest and is made of chromaffin cells. The cortex is derived from the mesoderm and it consists of three layers: the catecholamine secreting zona glomerulosa, cortisol secreting zona fasciculata and the zona reticularis that secretes androgens.There are many common pathologies that can present, e.g., adrenal hypo-plasia, hyperplasia and adrenal tumors specific to each region.

Chambers and Great Vessels of the Heart

The heart performs the function of receiving and pumping blood. In order to perform this function, it has four compartments, or chambers – the two atria and the two ventricles. The left atrium receives oxygen-rich blood from the pulmonary circulation and drains it into the left ventricle, which then pumps it to the rest of the body. The right atrium receives oxygen-poor blood from the systemic circulation and drains it into the right ventricle, which then sends it to the pulmonary circulation for oxygenation.

Joints of the Lower Limb

The joints in the lower limb include the sacroiliac joint, hip joint and knee joint, plus two important foot joints: the subtalar and the transverse tarsal joint, which permit inversion and eversion of the foot. The other joints in the foot allow foot and toe movement and include the cuneonavicular joint, the cuboideonavicular joint, the tarsometatarsal joint, the intermetatarsal joint, the metatarsophalangeal joint, the interphalangeal joint and the distal phalangeal joint.

Wound Repair

A wound is the loss of the normal integrity of the skin and underlying soft tissue leading to a devitalized structure. Wounds can result from a skin injury, such as in the case of surgery, puncture wounds and abrasions or can be secondary to skin necrosis as a result of ischemia or pressure. People with diabetes mellitus, peripheral ischemia, venous stasis, infection and bad nutritional status are vulnerable to wounds due easy skin disruption and difficult healing processes that may lead to chronic ulcers. The process of wound healing occurs to protect the underlying structures from infection or blood loss. Wound healing occurs through several physiological stages in healthy individuals that include hemostasis, inflammation, epithelialization (granulation) or proliferation and finally fibroplasia or remodeling.

Inflammation

Inflammation is the physiologic body reaction in response to injury. The body tries to protect itself from harmful pathogens and physical or chemical irritants. Immune cells, fibroblasts, intra- and extra-cellular mediators are all involved in protecting the body, clearing the inflammatory products and help with the healing damaged parts. Sometimes the whole pathologic disorder is secondary to the body's reaction and inflammation as in cases of hypersensitivity, granulomas and autoimmune diseases. The following article describes various forms of inflammation as well as the body's reaction to them.

Amebicidal Drugs

Amebiasis is an infection of colon caused by Entamoeba histolytica. Infection occurs by ingestion of water and food contaminated with feces (containing cysts of Entamoeba histolytica). In this article, we will study in detail the various amebicides, their mechanism of action, adverse effects/toxicity, contraindications, drug interactions and drugs of choice. Other important therapeutic aspects of individual drugs will also be studied.

General Anesthetics: Inhaled and Intravenous Anesthetics

Inhaled anesthetics are either volatile or gaseous anesthetics used to induce general anesthesia. Volatile anesthetics include halothane, enflurane, isoflurane, desflurane and sevoflurane. These anesthetics are liquid at room temperature. Gaseous anesthetics include nitrous oxide and xenon both of which are gaseous at room temperature.

Secondary Immunodeficiencies (Acquired Immunodeficiencies): Malignancy, Infections and more

Secondary immunodeficiency can be defined as the occurrence of cellular or humoral immunodeficiency in an individual who had an intact immune system before the onset of the condition. These acquired forms of immunodeficiency result from a diverse number of environmental causes as a side effect of cytotoxic drugs, malignancy and malnutrition.

Cancer Immunology — Anticancer Therapies and Cancer Vaccines

Recently, it has become clear that cancer and our immune system communicate with each other. Because of this, our immune system eventually allows cancer cells to go unchecked, and at a certain point, cancer cells ‘escape’ our immune system's response. With this understanding, more recent anti-cancer medications are targeting the different immune checkpoints that are known to fail in identification of cancer cells.

Transplantation

Transplantation medicine can be subdivided into solid organ transplantation and blood transfusion. Blood transfusion examples include packed red blood cells, plasma and platelets concentrates. Solid organ transplantation can be xenograft, autograft, isograft and allograft.

Burkitt Lymphoma — Causes and Symptoms

Burkitt lymphoma (small non-cleaved cell lymphoma) is one of the most aggressive and rapidly growing non-Hodgkin's lymphomas, with obvious predominance in children and young adults. This type of tumor requires urgent therapeutic intervention as the CNS and the bone marrow are involved in the malignant process since early stages of the disease.

Androgen Receptor Antagonists

Androgen receptor antagonists are compounds that block androgen receptors and antagonize the effect of androgens such as testosterone. Several conditions such as hirsutism, acne and prostate cancer are known to be dependent on androgens and antiandrogens can help alleviate the symptoms of these condition or even improve the outcome in patients with metastatic prostate cancer.

Hypothalamic–Pituitary–Gonadal (HPG) Axis Differentials

The endocrine system of the body consists of endocrine glands which produce metabolic changes through the secretion of chemicals called hormones. The Pituitary gland is considered the ‘Master’ gland of the body. Hormones produced by different endocrine glands have different mechanism of actions. The hypothalamic-pituitary- gonadal axis is a system of interrelated endocrine glands that work like a single entity with a series of communications that regulate hormone secretion between them.

Hormone-Binding Proteins

Proteins which bind to hormones and carry them to the target tissues to produce a desired effect are called hormone-binding proteins (HBP). There are four major categories of HBPs depending on the type of hormone they carry. These include: sex hormone-binding proteins (SHBG), thyroid hormone-binding proteins, cortisol binding proteins (CBG), steroid hormone-binding protein – serum albumin.

Syphilis (Treponema pallidum)

Treponema pallidum is member of family Spirochaetaceae. They are Gram negative bacteria, but some regard them too thin to be Gram stained. It is a delicate, tightly spiraled, motile spirochete having tapered ends. It is microaerophilic bacteria that cannot be grown on standard culture media. These microbes are poorly stained, so not detected by conventional light microscopy.

Pediatric Vomiting and Diarrhea

Pediatric gastrointestinal disturbances are common, often simple to manage and yet, unfortunately, life threatening in some instances. Sometimes, seemingly innocuous vomiting can be a harbinger of a serious underlying disease. This article expounds on various patho-physiological aspects of pediatric vomiting and diarrhea, and expatiates on the rapid aggressive treatment of accompanying dehydration.

Pediatric Constipation and Encopresis — Diagnosis and Treatment

Constipation is a very frequent, rather tantalizing presentation in the pediatric population. One needs to be wary of organic causes of constipation and treat the same judiciously. This article expatiates on pediatric constipation and encopresis.

Autonomic Nerves of Abdominopelvic Organs

The primitive embryonic foregut, midgut and hindgut form the gastrointestinal tract. The foregut extends from the mouth to the proximal two thirds of the duodenum. The midgut extends from the distal one thirds of the duodenum to the proximal two thirds of the transverse colon, while the hindgut extends from the distal one third of the transverse colon to the anus. The autonomic nervous system with its sympathetic and parasympathetic fibers and their opposing actions control all these organs.

Perineum and External Genitalia

The perineum is a diamond shaped region situated inferior to the pelvic floor which separates it from the pelvic cavity. Several urinary, external genital and lower gastrointestinal structures are located within the perineum. Therefore the perineum plays an important role in bodily functions like defecation, micturition, procreation and parturition. This article will discuss the boundaries of the perineum, the perineal membrane, the Ischioanal fossa and its contents with their clinical relevance.

Plasma Cell Neoplasms including Multiple Myeloma

Plasma cells neoplasms are the cancers of plasma cells that are responsible for producing antibodies in our bodies. These abnormal plasma cells proliferate rapidly in the bone marrow causing extensive bone destruction. They also produce increased quantities of monoclonal immunoglobulins (M-protein) that build up in our body, leading to the thickening of the blood and damaging our kidneys.

Splenomegaly

Splenomegaly is the enlargement of the spleen. The spleen is an integral part of the immune system that provides efficient immunosurveillance (production of WBCs defending the body from various infections) and hematopoiesis (“cemetery” for damaged and worn off erythrocytes). The spleen is allocated in the left upper quadrant of the abdomen behind the ribs 9-11, on the left from the stomach, and the tail of the pancreas, above the left kidney, the splenic flexure of the colon.

Types of Leukemia

Leukemia is blood cancer, this condition is characterized by exceeded amount of immature white blood cells in the blood stream (blasts), which normally remain in the bone marrow for their further maturity or sent to special organs (spleen, thymus) to get ready for their proper functioning. White blood cells are responsible for the adequate immune reaction of the body to various antigens (infections, malignant cells, foreign bodies, allergens); hence, immature cells cannot cover this function fully and fail to perform in the way m proper white cell do. Thus, the body easily contracts different infections as it is not capable to fight them, as the disease advances the bone morrow becomes exhausted shooting even more damaged cells or stops producing blood cells at all (hemogenic collapse).

Penis Disorders: Types and Clinical Representation

Penile disorders are heterogenous and desolating to the male population. This article succinctly expounds Hypospadiasis, Epispadiasis, Phimosis, Paraphimosis, Peyronie’s disease, Priapism, Penile carcinoma in situ and Squamous cell carcinoma.

Lymphoid Neoplasms

Lymphoid neoplasms are divided into the two main groups: Hodgkin and Non-Hodgkin Lymphomas. The former ones are the most curable due to the specific pathogenesis of the ailment and recent advance in the methods of treatment (5 years survival for the patients with favorable prognosis 98 % and 85 % with a less benign one). The malignant cells form in the lymphatic system; mainly, they are represented by white blood cells, namely, immature B-lymphocytes. HL may take place in any part of the lymphatic system. This disease was described by Dr. Thomas Hodgkin in 1832 as a type of cancer of the lymph nodes.

Follicular Lymphoma — Diagnosis and Survival Rate

There are two types of lymphomas - Hodgkin Lymphoma (Hodgkin`s Disease) and Non-Hodgkin Lymphoma. The follicular lymphoma belongs to the second group. It is a slow-growing B-cell lymphoma, and the second most common sub-type of NHL; most often occurs due to chromosomal translocation t(14;18) causing bcl-2 gene rearrangement. Most of the patients with FL are asymptomatic; hence they remain undiagnosed for years and usually detected in the advanced stages.

Diffuse Large B-Cell Lymphoma (DLBCL; DLBL) — Classification and Prognosis

Diffuse Large B-Cell Lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL), accounting for one-third of all NHLs in the western world. It is a very aggressive, fast-growing neoplasm unless diagnosed and treated timely (survival is less than one year without a cure). This illness is characterized by painless enlarged lymph nodes. It has a very close affiliation with genetic issues, Epstein-Barr virus (EBV) and immunocompromised conditions (congenital and acquired: HIV, AIDS).

Immunodiagnostics

The science of Immunodiagnostics has recently progressed in leaps and bounds. As proficient clinicians, we need to be aware of some of them. This article focuses on core techniques customized for immunodiagnosis, namely Immunodiagnostic Methods (Agglutination, Nephelometry, Immunoprecipitationa and Radial Immunodiffusion), Electrophoresis and Western Blot, Immunoassays (ELISA, RIA and Luminex:tm:), Immunofluorescence and Immunohistochemistry, Flow Cytometry and Fluorescence-Activated Cell Sorter (FACS), Evaluation of Cellular Activity and Preparation of Antibodies.

Antipsychotics (Neuroleptics) — Classification and Side Effects

Antipsychotic drugs have been used to treat schizophrenia for many decades. However, they have other uses, too, including the treatment of bipolar disorder. Antipsychotic drugs principally work through their inhibition of post-synaptic dopamine receptors. These drugs are classified as first generation typical antipsychotics and second-generation atypical antipsychotics. Students should be aware of the mechanism of action, side effect profile and uses of these drugs.

Physiology of Blood Vessels and Blood Pressure

The blood pressure is monitored and regulated inside the body and is called mean arterial pressure (MAP). The clinical measurement of the blood pressure with a sphygmomanometer depicts the systolic and diastolic arterial pressures and gives relative information of the mean arterial pressure. MAP is the driving force that propels the blood to organ tissues. As all body tissues require oxygen for the process of respiration and energy, a constant supply of blood is mandatory. MAP, therefore, needs to be regulated for two reasons. Firstly, the driving force created by MAP should be sufficient enough to supply blood to the organs lying above the level of the heart, i.e., against gravity. Secondly, it should not be above the normal limits as it will then cause an extra load on the heart, which will have to pump blood with an extra force.

Hypothalamic Pituitary Ovarian Axis

The female reproductive cycle is interplay of hormones secreted by the hypothalamus, pituitary and ovaries. Together they form the hypothalamic-pituitary-ovarian axis. The primary outcome of this axis is ovulation. If pregnancy occurs, this axis will act through feedback mechanism to maintain the pregnancy. The development of the embryo requires a specific level of hormones in the maternal blood. If there is any disruption, it may result into missed abortion or preterm labor. Similarly, if the female does not conceive, there is a decrease in the amount of one hormone that will initiate the next cycle.

Ambulatory Blood Pressure (ABP) Regulation

The regulation of arterial blood pressure is essential in order to maintain perfusion to the vital organs. While a drop in blood pressure is dangerous as no blood flows to the brain, at the same time a high blood pressure may result in various unfavorable outcomes such as cerebrovascular accidents and myocardial infarction.

Cardiovascular Response to Exercise

Exercise physiology is the study of effect of exercise on the body systems. Exercise is beneficial for the health. However, as a result, oxygen and nutrient demand increases several folds, a lot of energy is required, which comes from the stored energy resources of the body. In order to provide sufficient oxygen for respiration to occur, the workload on the lungs and heart increases several folds. The blood supply to other organs is also compromised; for example, during exercise, the blood flow to the digestive tract is reduced. This is to allow sufficient blood flow to the skeletal muscles.

Regulation of Venous Pressure: Combination of Cardiac and Vascular Function Curves

The heart pumps the blood to the aorta, which divides into arteries to supply the various organs of the body. Inside an organ, a main artery is divided into smaller arterioles, which further divide into capillaries at tissue level. As the wall of the capillary is only one-celled thick, rapid diffusion of gases and nutrients takes place. The capillaries combine to form venules, which drain into larger veins. Finally all the veins of the body drain either into superior vena cava or inferior vena cava.

Mechanoreceptors, Encapsulated & Unencapsulated and Free Nerve Ending (FNE)

A mechanoreceptor is a sensory receptor which detects the mechanical stimulus of stretch and distortion. It is also known as the tactile receptor. In human beings, four types of mechanoreceptors are present in the hairless skin, which will be discussed in this article along with encapsulated and unencapsulated nerve endings and free nerve endings.

Muscle Nerve Fiber Properties, Renshaw Cells and Muscle Reflexes

A nerve fiber is an extension of a neuron that mainly consists of an axon either myelinated or unmyelinated. These nerve fibers are present in the central nervous system (CNS), as well as in the peripheral nervous system (PNS). Inside CNS, the oligodendrocytes produce the myelin sheath while in the PNS the Schwann cells do the job.

Bones of the Lower Extremity — Femur, Tibia, Fibula, Phalanges and More

The lower limb connects the body to the foot. It bears the weight of the body when standing and during movement. Altogether, there are 32 bones in the lower limb; this includes the hip bone (with its three components: ilium, ischium, pubis), femur, tibia, fibula, patella, tarsal bones (8), the metatarsals (5) and the phalanges (5) on either side.

Descriptive and Analytic Epidemiology — Incidence, Prevalence and The Mortality Rate

Epidemiology is the science of studying distribution with regards to the various determinants that play a significant role in health related issues within a specified population as well as the implications of the study results in order to control health problems. Descriptive epidemiology is intended to classify the details of a disease based on person, place and timing factors. The methods of causal reasoning, which are used to test the hypothesis are carried out mainly using inputs derived out of descriptive epidemiology. The various aspects of descriptive epidemiology are covered in the following article.

Cell Division: Meiosis

According to the Cell Theory, new cells can be produced by the division of existing cells. Two types of cellular division occur in eukaryotes. These are mitosis and meiosis. Mitosis is done to make more of a specific body cell while meiosis is done to create gametes (egg or sperm). Meiosis and the different processes involved in it will be covered by this article. The processes involved in oogenesis and spermatogenesis are also discussed in this article.

Non-Hodgkin's Lymphoma — Diagnosis and Staging

Non-Hodgkin's lymphomas (NHL) are hematological malignancies with high prevalence worldwide (accounts for about 4 % of all cancer cases and 2.7 % of all cancer deaths). They are cancers of the lymphatic tissues (mainly lymph nodes), affecting the lymphocytes, either B-cells (70 %) or T-cells/NK cells (30 %). NHLs are five times more common than the Hodgkin's lymphoma (HL). The following article discusses both B-cell type NHLs and T-cell type NHLs.

Antimalarial Drugs — Quinine, Quinidine, Sulfonamides, Chloroquine and More

Malaria is a protozoan infection. Malaria is caused by the bite of female Anopheles mosquito. In this article, we will study the various antimalarial drugs, mechanism of action, adverse effects/toxicity and drugs of choice in detail. Important therapeutic aspects of individual drugs will also be studied.

Haemophilus Ducreyi — Chancroid, Diagnosis and Treatment

In 1889, Auguste Ducrey at the University of Naples published his research about the causing agent of chancroid associated with the presence of genital ulcers, Haemophilus ducreyi, which is a gram-negative bacillus, was named after the scientist. Chancroid is a highly contagious sexually transmitted disease (STD) presenting with extremely painful genital ulcers accompanied by enlarged inguinal lymph nodes (buboes).

Gardnerella Vaginalis — Symptoms and Differential Diagnosis

In 1955, a cause of nonspecific vaginitis (bacterial vaginosis) was described by two scientists: Gardner and Dukes. The bug was named Haemophilus vaginalis, later the name was changed to Corynebacterium vaginale, and finally, the bacterium responsible for the condition obtained the name Gardnerella vaginalis (1980) after the scientist who discovered it. Gardnerella vaginosisis a non-specific infection of the vaginal tract caused by gram negative bacteria named as Gardnerella vaginalis. This condition is not regarded as sexually transmitted disease, but sexual activity enhances the development of the infection.

Syphilis — Types, Diagnosis and Treatment

The causative factor of syphilis is Treponema pallidum (TP), family motile Spirochaetaceae, which is very common all over the world. TP can be transmitted via close sexual contact or transplacentally (vertical way). Also, syphilis can be acquired or congenital, both of them having early and late stages. TP invades the host body through the breaches in the squamous or columnar epithelium affecting lymphatic nodes and disseminates with the blood stream to all parts of the body.

Anthelmintic — Ivermectin, Praziquantel, Pyrantel Parmoate and More

Infection caused by various helminths (worms) is among the most widespread of chronic infections and its occurrence is more common in developing regions with poor personal and environmental hygiene. In this article, we will study in detail the various anthelmintic (anti-parasitic) drugs, mechanism of action, adverse effects/toxicity and drugs of choice. Important therapeutic aspects of individual drugs will also be studied.

Kallmann Syndrome — Diagnosis and Treatment

Kallmann’s syndrome is one form of reproductive failure due to severe hypogonadism that is associated with complete loss of the sense of smell. Kallmann’s syndrome is a genetic disorder and several genes such as KAL1, FGFR1, FGF8 and PROKR2 have been associated with the condition. While KAL1 is responsible for the x-linked inherited form of the disease, the other genes are found in patients with autosomal dominant Kallmann’s syndrome. Hormonal replacement therapy is indicated to correct the severe hypogonadism.

Chemotherapy Drugs — Steroids, Alkylating Agents, Antimetabolites and More

Chemotherapy (chemo) is the specific systematic treatment administered in oncological practice for malignant neoplasms in order to destroy chaotically dividing abnormal cells. Chemo is a part of anticancer treatment along with radiotherapy, immunotherapy and surgery. The drugs used in chemotherapeutic protocols cannot be purchased over the counter; they can be taken with prescription only. Cancer drugs influence and actions are directed to the malignant cell reproduction, cure, control, palliation or chemoprevention.

Thymoma — Staging and Treatment

The thymus is an important part of our immune system, located in the anterior mediastinum. Due to this fact, the diagnostics, access, and management of its neoplasms (thymomas) are somewhat difficult. The thymomas often involve the contiguous organs and are also frequently associated with other paraneoplastic conditions, making the condition even more complicated.

Abnormal Uterine Bleeding and Endometrial Polyp — Symptoms and Diagnosis

Abnormal uterine bleeding (AUB) is calamitous for many women. With a brief prologue to AUB, this article focuses on the significantly relevant causes of AUB, such as endometrial polyp, leiomyoma and leiomyosarcoma.

Special Circulations of the Cardiovascular System — Cerebral, Coronary and Cutaneous Circulation

Blood flows through the body in a complex circulatory system supplying even the most complex structures, like brain and heart, in the cerebral and coronary circulation respectively. The skin as the outermost border of the organism requires special conditions of the cutaneous circulation, owing to the external temperature.

Hypothalamus, Brain Stem, the Circumventricular Organs (CVOs) and the Cerebrospinal Fluid (CSF)

The Hypothalamus is located below the thalamus. The brain stem, consisting of midbrain, pons and medulla oblongata follows, connecting the superior brain structures with the spinal cord. A clear, colorless liquid flows in the brain as well as in the spinal cord – the cerebrospinal fluid. Its functions and clinical relevance will be discussed in this article along with the functions of the different circumventricular organs.

Neurotransmission and Postsynaptic Potential (PSP)

A nerve is made up of countless neurons which are responsible for carrying signals from different parts of the body to the nervous system and vice versa. Neurons which carry the signals from the sense organ to the nervous system are called sensory neurons and form the sensory nerve fibers. Similarly, neurons which carry signals from the nervous system to the effector organs, muscles or glands are called the motor neurons. These motor neurons form the motor nerve fibers. Relay neurons carry the signals across the nervous system. The signal transmission from the sense organs to the nervous system and then to the effectors is essential in the maintenance of homeostasis. Any disruption in this pathway leads to the loss of a specific sensation or response.

Endometrial Hyperplasia — Diagnosis and Treatment

Endometrial hyperplasia is abnormal growth of the endometrium in the uterus. It is caused by excess estrogen unopposed by progesterone. Pathology shows an increased gland-to-stroma ratio and can show atypia. Atypia is linked to endometrial cancer, the most common gynecological malignancy in the developed world. Treatment includes progesterone therapy and if there is atypic hysterectomy is recommended. Lynch syndrome has a high lifetime risk of developing endometrial cancer.

Lymphocyte Development — B- and T-Cell Development

Lymphocytes are the cornerstone of the adaptive immune system and afford the body a diverse protection against all kinds of pathogens. In this article, we explore the different types of lymphocytes and the processes involved in their development.

Lymphocyte Activation — B- and T-Cell Activation, Germinal Center and Co-stimulation

The adaptive or acquired immune system is the body’s main line of defense against ever-evolving pathogens. This subsystem of over all immune system comprises of specialized cells to eliminate lethal organisms which otherwise may lead to death. Read on to find where the cells of the adaptive immune system reside, and what their mechanisms of action are.

Gynecomastia — Symptoms and Treatment

Gynecomastia is the breast enlargement in males, due to increased glandular proliferation. This is very common condition and mostly physiological in neonates, pubertal boys and elderly persons. Some cases are pathologic and secondary to drugs, chronic liver and kidney disease or hyperthyroidism. Majority are asymptomatic and do not need treatment. If treatment is needed, it should be tailored against the etiology of gynecomastia. Symptomatic gynecomastia that does not resolve with treating the cause can respond to antiestrogens or aromatase inhibitors. Finally, surgical intervention should be offered only to severely symptomatic cases.

Erectile Dysfunction (ED; Impotence) — Symptoms and Diagnosis

Erectile dysfunction is defined as the inability to achieve or maintain a penile erection that would result in the inability to perform vaginal sexual intercourse. Systemic, neurologic and local diseases can cause erectile dysfunction which include but are not limited to diabetes, multiple sclerosis and Peyronie’s disease respectively. History and physical examination are important for the diagnosis of erectile dysfunction. Treatment can be medical with testosterone, sildenafil, or specific medical treatment according to the etiology. Surgical correction might include a penile prosthesis.

Male Hypogonadism — Symptoms and Diagnosis

Male hypogonadism is a condition characterized by decreased testosterone production and sperm quality or production. This can be the result of primary testicular failure or secondary testicular failure due to pituitary or hypothalamic disorders. Symptoms of hypogonadism include erectile dysfunction, decreased libido, and regression or absence of secondary sexual characteristics. Total testosterone levels are below 300 ng/Dl. Testosterone replacement therapy is the mainstay of treatment.

True Hermaphroditism — Ovotesticular Disorder of Sexual Development

Ovotesticular disorder of sexual development is characterized by the presence of an ovotesticular gonad that contains both ovarian and testicular elements. Patients are usually born with ambiguous genitalia but the diagnosis is rarely confirmed before puberty. The most common karyotype is 46, XX but 46, XY can be identified in approximately 10% of the cases. Medical treatment of ambiguous genitalia is usually emergency based to treat life threatening conditions such as salt-wasting syndrome in congenital adrenal hyperplasia. Conservative surgery to remove part of the ovotestis gonad is the treatment of choice for this condition.

Leydig Cells and Sertoli Cells — Sex Cord-Stromal Tumor of the Testis

Sex cord stromal tumors of the testis can originate from either Leydig cells or Sertoli cells. Leydig cells tumors are responsible for 70%. These testicular tumors are known to cause estrogen excess production and a low testosterone-estrogen ratio. Alpha-fetoprotein, human chorionic gonadotropin and lactate dehydrogenase levels are normal in this type of tumors. Ultrasonography confirms the diagnosis of a testicular mass, while biopsy and histologic examination confirm the diagnosis of either Leydig cells or Sertoli cells tumor. Treatment of choice is radical inguinal orchiectomy.

Intraductal Papilloma — Symptoms and Diagnosis

Ductal papillomas are commonly identified in women presenting with pathological nipple discharge. However, pathological nipple discharge can also be identified in patients with breast cancer. Patients with ductal papillomas can have either a solitary lesion or multiple papillomas. Solitary papillomas are usually central and large, while multiple papillomas tend to be peripheral and small in size. Whereas large solitary papillomas are not thought to be precancerous, small multiple papillomas seem to increase the risk of breast cancer. Patients with a single papilloma might benefit from microductectomy while those who have multiple papillomas are possible candidates for surgical intervention due to their increased risk of developing breast cancer.

Fibroadenoma of Breast — Diagnosis and Treatment

Fibroadenomas are benign breast tumors that arise in young women. Histological examination of these lesions usually reveals lobular hyperplasia. Known risk factors for breast cancer, such as early age of menarche or nulliparity, do not increase the risk of fibroadenomas. The diagnosis of fibroadenomas is based on the physical finding of a mobile, non-tender breast mass, that is slightly hypoechoic on ultrasonography and that has cell clusters in fine needle aspiration. Fibroadenomas that are asymptomatic and small in size should be treated conservatively, while ones that are growing rapidly in size and are symptomatic should be surgically excised.

Mastitis — Symptoms and Treatment

Mastitis is the inflammation of the mammary gland tissue, which can be lactational or non-lactational. It is most common in women within child bearing age. Routes of transmitted infection can be from the skin, lymph nodes or primarily in the mammary glands. Organisms isolated include staphylococcus aureus, staph epidemidis or streptococci. Swelling and rupture of mammary ducts will result in an abscess which will mimic breast mass or carcinoma.

Medial and Lateral Pontine Syndrome, Superior Cerebellar Artery Syndrome, Parinaud's Syndrome, Weber's Syndrome

In the following article you will learn how to differentiate between medial and lateral pontine syndrome, superior cerebellar artery syndrome, Parinaud's syndrome and Weber's syndrome, what their main characteristics are and where the site of lesion is to be expected.

Limbic System Disorders: Wernicke-Korsakoff Syndrome, Klüver-Bucy Syndrome, Alzheimer's Disease

The limbic system is a cluster of brain structures located on both sides of the thalamus immediately below the cerebrum, mainly responsible for the emotion, behavior, memory, and arousal response. It is thought to be an outcome of the evolutionary response that occurred in all mammals including human beings. It is not a different system, but a group of organs derived from the telencephalon, diencephalon, and mesencephalon.However, the development of this system is far greater in human beings compared to other mammals.

Cell-Mediated Immunity

Cell-mediated immunity is an integral part of our body’s immune system. This type of immunity is mediated by T-lymphocytes, also called T-cells. The functions of cell-mediated immunity are important and include defense against intracellular bacterial and viral infections. This is achieved by activating macrophages to destroy phagocytosed microbes via helper T-lymphocytes, or by directly killing infected cells via cytotoxic T-lymphocytes.

Antigen Processing and Presentation

All foreign antigens are recognized by the cells via specific receptors called the major histocompatibility complex. These MHC molecules encompass a wide diversity in structure and actions. What follows is a review of the MHC molecules and their interactions with an antigen.

Innate Immunity — Pattern Recognition Receptors (PRRs), Inflammasome, Complement System

Various infectious agents are constantly attacking and posing a threat to human health. Under normal conditions, our body manages to remain healthy. Our innate immune system provides the first line of protection against such pathogens and harmful agents. Read on to find out the different components of the innate immune system and how they interact with each other to form the body’s primary line of defence.

Types of Ovarian Cancer: Germ Cell Tumor (GCT), Dysgerminoma, Metastatic Ovarian Cancer and more

Ovarian cancer is becoming challenging every year due to the ever increasing number of new diagnoses. It is considered the 5th leading cause of cancer deaths among women; with about 14,000 deaths and more than 20,000 new cases every year.

Lymphocyte Recirculation and Homing

Lymphocytes have a miraculous ability to get attracted to the site of pathogen attack. This complex process is the interplay of a wide variety of molecules and processes within the body. Read on to find out what constitutes these mechanisms of lymphocyte circulation.

Varicocele (Scrotum Varicose Veins) — Diagnosis and Treatment

Varicoceles are defined as abnormal dilations of the spermatic vein or the pampiniform plexus and are more common on the left side. Careful physical examination of the contralateral scrotal side is essential as bilateral varicoceles are common. While the diagnosis of varicoceles can be done clinically especially when seminal fluid analysis is impaired, imaging studies with color-flow Doppler remain an important part of the diagnostic workup. Symptomatic varicoceles or subfertile men with varicoceles should have their varicoceles surgically corrected either by a minimally invasive procedure, or by percutaneous embolization.

Cervical Cancer — Diagnostics and Therapy

Thanks to the early detection program, the incidence of cervical cancer is declining. Every woman from the age of 20 is admitted once a year and includes various examinations. If a malignant disease is suspected, further diagnostic steps should be taken and a treatment plan adapted to the patient should be developed. The following article will help you to diagnose cervical cancer reliably and to initiate the right steps in the therapy.

Testicular Cancer (Malignant Neoplasm of Testis) — Diagnosis and Treatment

Testicular cancer is an uncommon malignancy. Most of testicular cancers are of the germ cell tumor type and they can be classified into seminomas or nonseminomas. The most common presentation of testicular cancer is a painless testicular nodule. Alpha-fetoprotein can be elevated in nonseminomas, while beta-human chorionic gonadotropin is usually elevated in both seminomas and nonseminomas. Radical inguinal orchiectomy along with retroperitoneal lymph node dissection helps in confirming the diagnosis and can be curative in early stages of testicular seminomas.

Testicular Torsion — Diagnosis and Treatment

Testicular torsion is the most common cause of acute testicular and scrotal emergency pain. Patients usually have unilateral testicular torsion and the most common etiology is a high abnormal attachment of the tunica vaginalis. Abnormal attachment of the tunica vaginalis results in spermatic cord increased mobility and predisposes to spermatic cord twisting and subsequent testicular torsion. Testicular infarction and necrosis can ensue if the testis is not detwisted in the first 8 hours and is usually complete by 24 hours of torsion onset. Bilateral testicular fixation to the tunica vaginalis is recommended.

Prostatitis (Prostate Inflammation) — Diagnosis and Treatment

Prostatitis is a term that indicates inflammation of the prostate which can be infectious or non-infectious. Bacterial prostatitis is easier to identify clinically and their management is better established. The main diagnostic tools for prostatitis are clinical history and physical examination. Prostate massage by digital rectal examination is only recommended in patients with chronic prostatitis and not in acute bacterial prostatitis. Broad spectrum antibiotics are the mainstay therapy for bacterial prostatitis, while symptomatic treatment is indicated for chronic pelvic pain syndrome without evidence for uropathogens.

Cryptorchidism (Undescended Testicle) — Diagnosis and Treatment

Cryptorchidism is a term used to describe the failure of descent of the testicle into the scrotum. This condition is common among premature boys, 33% of them, and can still be identified in full-term boys in approximately 5%. Ultrasonography can help localize inguinal testicles, while abdominal magnetic resonance imaging or laparoscopy can identify non-palpable intraabdominal testis. Hormonal treatment is indicated at 6 months of life and surgical correction is needed if hormonal therapy failed. Surgical treatment should be attempted before one year of life to achieve better fertility outcome.

Non-Invasive Breast Cancer: Ductal Carcinoma In Situ (DCIS) — Diagnosis and Treatment

Non-invasive breast cancer can be either ductal carcinoma in situ or less commonly lobular carcinoma in situ. Ductal carcinoma in situ is of epithelial type, and there is usually no basement membrane invasiveness. Because of the lack of invasiveness, these tumors are unlikely to metastasize by the lymphatics or blood vessels. Ductal carcinoma in situ is usually diagnosed by a mammography and not by physical examination. Microcalcifications on mammography are the most common presenting feature. Local excision of the lesion is recommended to obtain histopathologic data and guide treatment. Total mastectomy or breast conservation therapy are the two options for the treatment of ductal carcinoma in situ.

Ureter, Urethra, Urinary Bladder — The Urogenital System

The term urogenital system compromises the genital and urinary organs. Besides having different tasks, they have a common embryological origin and are often discussed in relation to each other in a clinical perspective. The following article focuses on the diverting urinary organs, therefore the part from the ureters to the urinary bladder up to the urethra is regarded. The physiology also attracts attention concerning the micturition process apart from the anatomic aspect.

Types of Peptide Hormones: Oxytocin and Vasopressin

The posterior pituitary secretes two hormones, oxytocin and vasopressin (anti-diuretic hormone). The word oxytocin literally means "quick birth" in Greek, which is an accurate description of the hormone's action. The following article discusses the positive and negative effects of oxytocin and vasopressin as well as their use as therapeutic options.

Branches of Internal Iliac Artery

The reproductive organs in women and men, as well as the urinary bladder, the pelvic part of the colon and the rectum, are located within the pelvic cavity. All these important organs receive their oxygenated blood via the internal iliac artery (formerly known as the hypogastric artery) and its myriad branches. The arrangement of the branches is very variable and, occasionally, a listed branch may originate from a direct branch instead of from the internal iliac artery. The anatomical variations are surgically important for surgery in the pelvic cavity. The uterus, ovaries and fallopian tubes receive their blood supply from the internal iliac. The blood supply to the external genitalia in both sexes is derived from the internal pudendal branch of the internal iliac artery. During sexual arousal, the branches of the internal iliac arteries provide for the increased demand of blood flow which causes the engorgement of the tissues.

Physiological Effects of Estradiol and Progesterone & Menstrual and Endometrial Cycle

The female reproductive system consists of two ovaries, two fallopian tubes, the uterus, cervix and external genitalia. Every female undergoes a monthly cycle of 28 days, in which an egg is released from either ovary and the lining of the uterus is prepared for the implantation of an embryo, which eventually sheds off in case fertilization does not occur. This normal physiological mechanism is controlled by a number of hormones, secreted by the hypothalamus, pituitary gland and ovaries themselves. Any aberration in the release of these hormones may result in menstrual cycle abnormalities or infertility.

Lactation and Breastfeeding

Human breast milk is the primary source of nutrition for the newborn, which can solely fulfill the nutrient requirements up to six months of age. When a woman conceives, several physiological changes occur in her body under the influence of hormones. One of them is the development of breasts and the production of milk. Several hormones play a role in this process. The hypothalamus secretes stimulatory or inhibitory factor, the pituitary gland secretes prolactin and oxytocin, while the placenta keeps a regulated level of estrogen and progesterone in the blood by producing these hormones. Other hormones, as mentioned in the text, are also essential for the production of milk as they are required for the provision of the basic nutrient components of the milk.

Maternal Physiological Changes During Pregnancy and Birth and Fetal Circulation

The process of reproduction is an essential characteristic of all living organisms. While other animals lay eggs, mammals give birth to a newborn. The anatomy and physiology of the new born baby is similar to that of an adult where all the body systems are in a functioning state. The process of embryogenesis is very complex and critical. The developing embryo gets all the nutrients required for its growth and development from the mother; therefore, certain physiological changes occur in the maternal body to be able to support the embryo. Any nutritional or hormonal deficiency at this stage, may not only result in under-weighed babies with birth defects, but also affects the quality of life of the mother after delivery.

Vitamin D Deficiency (Hypovitaminosis D) and Osteomalacia — Symptoms and Treatment

Vitamin D is a fat-soluble substance vitamin. This vitamin is essential for proper function of the human body and is considered a hormone rather than a vitamin. Its synthesis takes place in the body – under ideal conditions, it may not be required in our diet. In bone tissue, where vitamin D is required the most, it is needed for deposition of calcium in bone and its lack usually leads to various pathologies including rickets in children and osteomalacia in adults. To understand the pathology of these diseases, we must first learn how this vitamin is produced and the effects it has on various systems in the human body.

Wilson's Disease (Hepatolenticular Degeneration) — Staging and Treatment

Wilson disease is an autosomal recessive inherited disorder related with copper metabolism. This rare condition is characterized by excessive deposition of copper in target organs like liver, brain, and other tissues.

Anatomy of the Shoulder

The shoulder is the region of the body that connects the upper limb with the trunk. The shoulder girdle (composed of the articulation between the scapula and clavicle) and pelvic girdle are the two points in the body where the axial and the appendicular skeletons meet.

Anatomy of the Arm

Arm is the region of the upper limb that extends from the shoulder to the elbow joint. It connects inferiorly to the forearm through the cubital fossa (located anterior to the elbow). Axilla, region inferior to the shoulder, lies medially to the arm. The arm contains one long bone, humerus, in addition to numerous muscles, tendons, ligaments and neurovasculature structures that assist in bringing about all its movements.

Anatomy of the Forearm

Forearm is the region of the upper limb located between the elbow and the wrist. Its structure is maintained by two long bones, radius and ulna, along with numerous muscles, tendons and ligaments. Bones of the forearm contribute in the formation of elbow joint proximally, and the wrist distally. Two additional joints found within the forearm are proximal and distal radioulnar joints.

Rickets (Osteomalacia) — Symptoms and Treatment

Rickets, though not a common disease in the affiliated population, is one of the diseases which affect the growth of children in the developing countries (where the nutritional deficiency is common). Rickets can be characteristically identified using the clinical features and they can be confirmed using biochemical investigation. In this article, we will discuss the various features of rickets in detail.

Vaccine Immunology — Types of Vaccines

Autumn time is flu time! A reason for many medical doctors to get vaccinated and to take the opportunity to take a look at their vaccination certificate. But what else do you know about tetanus, diphtheria, and co? And how are the different vaccines different in their nature and preparation?

Lupus (Systemic Lupus Erythematosus; SLE) — Diagnosis and Treatment

The autoimmune disease lupus erythematosus belongs to the collagenoses and can show very different clinical symptoms: The symptoms range from mild conditions to severe organ manifestations which makes the diagnosis not easy sometimes. Read all the important facts about lupus erythematosus here to be prepared for the exam and the subsequent medical daily routine.

Infantile Hypertrophic Pyloric Stenosis (IHPS) — Causes and Symptoms

Pyloric stenosis, also known as infantile hypertrophic pyloric stenosis (IHPS), is a condition that is characterized by pyloric muscle hypertrophy and hyperplasia, which leads to gastric outlet obstruction. Infants usually present in their third week of life with repeated, projectile vomiting, that is often associated by an abdominal olive-like palpable mass. The clinical picture is usually enough to make the diagnosis, but ultrasonography can help confirm the diagnosis of pyloric stenosis in most of the patients. Surgical correction with pyloromyotomy is the treatment of choice.

Hirschsprung Disease (Congenital Aganglionic Megacolon) — Symptoms and Causes

Pediatric Hirschsprung Disease occurs when there is an absence of the ganglionic layer in the myenteric layer of the anus and the submucosa of the colon. This leads to the failure of relaxation of the colon, delayed passage of meconium, abdominal distension and constipation. Laboratory investigations are helpful if the patient develops enterocolitis where leukocytosis might be evident. Barium enema studies and histologic examination of biopsies confirm the diagnosis of Hirschsprung disease, and surgical resection of the aganglionic part of the colon is the current treatment of choice.

Salpingitis — Diagnosis and Treatment

Salpingitis is the inflammation of the fallopian tubes usually due to gonorrheal or chlamydial infections, but other gram-negative and anaerobic bacterial pathogens have been also implicated. Patients can present with lower abdominal pain, fever and an elevated erythrocyte sedimentation rate. Ultrasonography and diagnostic laparoscopy can help confirm the diagnosis of salpingitis and exclude other differential diagnoses or associated complications such as hydrosalpinx, adhesions, and tubo-ovarian abscesses. Antimicrobial management is the mainstay of treatment and surgical management should be reserved to patients with non-responsive tubo-ovarian abscesses or ruptured abscesses.

Anovulatory Cycles — Diagnosis and Treatment

Anovulatory cycles are a symptom and not a disease. Polycystic ovary syndrome, pituitary microadenoma, impaired GnRH release, and hypothyroidism are common etiologies for anovulation and should be excluded. Patients can present with amenorrhea which needs etiology-specific treatment or with acute dysfunctional uterine bleeding which might need emergency treatment. Emergency treatment can be either medical with estrogen or surgical with dilation and curettage. Oral contraceptive pills can be used in an attempt to make the menstrual cycle more regular before trying more specific treatments.

Fallopian Tube Cancer — Diagnosis and Treatment

Fallopian tube tumors are rare with an incidence of 3.6 per one million. Fallopian tube carcinoma is of epithelial origin and share similar pathogenesis mechanisms with epithelial ovarian cancer. Early obstruction of the fallopian tube results in rapid onset of symptoms such as abdominal pain and distension and patients with fallopian tube carcinoma usually present at an early stage. Treatment of choice for early stage fallopian tube carcinoma is surgical removal of the tumor and any involved pelvic structures.

Endometriosis — Causes and Symptoms

Endometriosis is a common disease in which ectopic normal endometrial tissue is implanted outside the uterus. The ovaries along with other pelvic organs can be involved. While laboratory investigations have a limited utility in the diagnosis, imaging and laparoscopic evaluation can be used to confirm the diagnosis of endometriosis. Medical treatment of endometriosis involves hormonal manipulation with oral contraceptive pills, danazol, GnRH analogues and progesterone supplementation. Surgical treatment can be either conservative or radical, depending on whether reproduction is wished to be preserved or not.

Pediatric Appendicitis — Symptoms and Surgery

Appendicitis is considered a serious surgical emergency in medicine, therefore early diagnosis and management is important to a successful outcome and preventing serious complications as gangrene and perforation. This article will describe the incidence of appendicitis the younger children, and how can be diagnosed and managed.

Intussusception — Symptoms and Differential Diagnosis

Intussusception occurs when a distal segment of bowel telescopes into the lumen of proximal bowel. This can happen at any age, but is most common in infants between three and eighteen months. It is the most common cause of bowel obstruction in three months of age to six year old children. This article gives you brief information about the epidemiology, etiology, pathology, signs and symptoms, diagnosis and treatment of pediatric intussusception.

Baby Colic (Infantile Colic) — Symptoms and Treatment

Pediatric colic is a very common symptom that occurs in infants during the first few months of life, and tends to disappear by the fourth month. Its causes are poorly understood and there are various theories explaining it as a reaction to food allergies, parental stress, gastrointestinal immaturity, maternal smoking and other factors. This article gives an overview of the condition with its epidemiology, etiology, symptom, diagnosis and differential diagnosis, and treatment.

Acute Abdominal Pain in Children — Differential Diagnosis

Acute abdominal pain is common in the pediatric population. Abdominal pain is usually associated with fever, vomiting of bile, bloody diarrhea, rigidity and tenderness in the abdomen. The etiology and differential diagnosis depends on the age of the child. For instance, Infants and toddlers will have congenital anomalies, school aged children may have gastroenteritis and other infectious causes. Appendicitis is the most common cause behind onset of acute abdominal pain in children.

Euthyroid Hyperthyroxinemia and Euthyroid Hypothyroxinemia — Differential Diagnosis and T3-Resin Uptake

The thyroid gland is an endocrine organ that secretes the hormones triiodothyronine (T3) and thyroxine (T4), which are, in turn, under the influence of the TSH and the TRH. Though hyper- and hypothyroidism remain the common clinically manifesting condition of the thyroid, in some cases, the patient remains symptomless with either excess or decrease in thyroxine levels, along with normal TSH levels. This is termed as euthyroid hyperthyroxinemia and euthyroid hypothyroxinemia, respectively. The cause is altogether different from the thyroid and should not be inappropriately managed as hyperthyroid and hypothyroid states.

Head and Neck Embryology and Infant Skull Development

This article will help you understand how the brain develops in a human embryo from the very beginning: gastrulation, the formation and fate of the primitive streak, neurulation with possible neurocristopathies, closure of the neuropores, embryonic folding, regionalization of the brain, and potential birth defects of the brain. After that, the article will focus on the development of the cranium and possible cranial birth defects.

Anatomy of the Posterior Abdominal Wall

The abdominal cavity is bounded by the abdominal wall which is divided into an anterior wall, lateral wall and the posterior wall. The posterior abdominal wall is a musculoskeletal structure formed by the posterior abdominal muscles, their fascia, the lumbar vertebrae and the pelvic girdle. It is related to the lower thoracic and lumbar vertebrae, the abdominal aorta, the inferior vena cava as well as important retroperitoneal organs like the kidneys, the suprarenal glands, the pancreas and the duodenum.

Ovarian Cancer — Stages and Survival Rate

Ovarian cancer is of epithelial origin in 60% of the patients. Most patients present at an advanced stage due to the lack of specific symptoms except for mucinous ovarian cancer where abdominal distension is so severe that patients present very early in the disease. Once ovarian cancer is suspected, the patient usually undergoes a transvaginal ultrasonography, abdomen-pelvic CT scan and CA-125 concentration measurement. If an ovarian cyst or mass is identified, its characteristics will be noted and a risk of malignancy index can be calculated. Treatment involves neoadjuvant platinum-based chemotherapy with or without surgery. Newer treatments include antiangiogenic antivascular endothelial growth factor bevacizumab and pazopanib.

Polycystic Ovary Syndrome (PCOS, Polycystic Ovaries) — Causes and Treatment

Polycystic ovary syndrome or disease is a multisystem endocrinological disorder where there is hyperandrogenism, ovarian dysfunction, obesity, menstrual abnormalities and multiple ovarian cysts. The most common presenting features are hirsutism, acne, metabolic syndrome and biochemical hyperandrogenism. Patients also have hyperlipidemia and an impaired glucose metabolism. Treatment involves oral contraceptive pills for menstrual abnormalities and hyperandrogenism, metformin for hyperandrogenism and infertility and clomiphene for infertility. Infertile women who do not respond to clomiphene might benefit from gonadotropins or laparoscopic ovarian drilling (LOD).

Pre-eclampsia (Toxemia) — Symptoms and Treatment

Pre-eclampsia is a condition that is characterized by an elevated blood pressure and proteinuria and that usually happens after 20 weeks of gestation. Women with pre-eclampsia can also develop hemolysis, thrombocytopenia and elevated liver enzymes known as HELLP syndrome or microangiopathic hemolytic anemia. Due to wide-spread endothelial dysfunction, they might also develop brain edema and eclampsia. Laboratory investigations show thrombocytopenia, proteinuria > 30 mg/day, hemolysis and elevated liver enzymes. The only known curative treatment for pre-eclampsia is delivery of the fetus.

Gestational Trophoblastic Disease (GTD) — Symptoms and Treatment

GTD are diseases that arise from aberrant fertilization tissue within the maternal host and are identified early due to markedly elevated hCG levels and characteristic ultrasound findings. Uterine evacuation is the recommended treatment, while chemotherapy can be reserved for patients with recurrent disease or neoplastic GTD.

Primary Sclerosing Cholangitis (PSC) — Symptoms and Life Expectancy

Primary sclerosing cholangitis is a common cause of chronic liver disease in patients with ulcerative colitis. It is an autoimmune disorder and patients usually present with jaundice, fever, abdominal pain and elevated alkaline phosphatase. Endoscopic retrograde cholangiopancreatography is the best diagnostic tool to confirm the diagnosis of primary sclerosing cholangitis. Multiple strictures and dilations of the biliary system is usually observed. Symptomatic treatment, immunosuppression and ursodeoxycholic acid are used in early stage PSC. In later stages, liver transplantation might be the only option available to alter prognosis and survival.

Candidiasis (Yeast Infection) — Symptoms and Treatment

Candidiasis is an opportunistic fungal infection that can affect the gastrointestinal tract, skin, or be systemic in immunocompromised patients. Clinical presentation is different from one patient to another and is dependent on the severity of immunosuppression and the anatomical site of the infection. Patients with candidiasis need topical antifungals for localized disease and systemic antifungals for esophagitis and systemic candidiasis. The important distinction between patients with neutropenia and without neutropenia can affect the choice of antifungals in systemic candidiasis.

Pelvic Inflammatory Disease (PID, Pelvic Infection) — Diagnosis and Treatment

Pelvic inflammatory disease is infectious in etiology and is closely linked to sexually transmitted disease. Pelvic inflammatory disease is common in the United States with an estimated incidence of 2.5 million. The condition can be diagnosed clinically, with lower abdominal pain, cervical motion tenderness, an elevated erythrocyte sedimentation rate and fever. Once diagnosed, the patient should be put on empirical antibiotic therapy that should cover gonorrhea, chlamydia, gram-negative organisms and anaerobes. Patients with complications, such as abscess formation or sepsis, might benefit from laparoscopic surgery.

Duodenal Atresia — Symptoms and Treatment

Duodenal atresia is one of the most common inborn defects of the digestive system, namely of the intestine, that is often associated with other congenital malformations and genetic pathologies (21 trisomy). The frequency of occurrence of this disorder is affected by the hypoxia of the fetus in the first trimester of pregnancy and is caused by severe chronic respiratory and cardiovascular diseases, stress, diabetes, drug and alcohol abuse during pregnancy. Nowadays, duodenal atresia is one of the most common congenital defects in the neonates. Moreover, it is well-diagnosed and curable in most of the cases, if timely detected and not neglected.

Local Anesthetic (LA) — Classification and Chemistry

Local anesthesia is required for many surgical procedures, be it minor or major. Local anesthetics act by blocking the neuronal impulses in the area they have been administered at, and this is achieved primarily by blocking voltage-gated sodium channels. Local anesthetic drugs have a variable onset and duration of action, ranging from a few minutes to a few hours. While they are generally safe, they may cause an allergy, cardiotoxicity or neurotoxicity. In this article, we will study the pharmacodynamics, pharmacokinetics, mechanism of action, important indications and toxicity of local anesthesia.

Statistical Bias

The article aims to describe the concept of information bias in the experimental research studies and to throw light on the issues concerning the bias, the types of bias, and the methods of disposal of these errors.

Thyroglossal Cyst — Differential Diagnosis and Complications

The thyroglossal cyst forms one of the most common pathologies of the neck after lymphadenopathy. Though it is a benign condition, the complications which might arise because of it are a major concern. This condition is dealt with in a surgical point of view and is discussed in detail in this article.

Alcoholic Liver Disease — Laboratory Evaluation and Prognosis

Alcoholic liver disease occurs as a result of excessive alcohol consumption. Up to 20% of heavy drinkers will develop liver cirrhosis. The amount, pattern and duration of alcohol consumption along with inflammatory changes in liver, diet, nutritional status and genetic predisposition of the patient predicts the severity and prognosis of the disease. Blood test, liver function test and liver biopsy are helpful to establish the diagnosis. General supportive measures, Prednisolone or Tumor necrosis alpha inhibitors can be used but with caution along with alcohol abstinence is adopted to manage the case. Liver transplantation is preserved for patients with severe liver cirrhosis.

Nonalcoholic Steatohepatitis (NASH) — Symptoms and Treatment

Non-alcoholic steatohepatitis, one form of the non-alcoholic fatty liver disease spectrum, has been associated with obesity and lipid dysregulation. The patient usually presents with abnormal lipid and liver profiles. The most evidence based treatment for non-alcoholic steatohepatitis involves around weight loss, glycemic control and avoiding liver insulting drugs. Our current understanding of the pathogenesis of non-alcoholic steatohepatitis is still limited but novel and more specific treatments are being developed.

Gastrointestinal Circulation (Blood Supply of the GI Tract) — Superior Mesenteric Artery (SMA) and Inferior Mesenteric Artery (IMA)

The gastrointestinal tract (GIT) is a long tubular structure having an important role in digestion, absorption, and elimination of food and waste. The GIT has a rich arterial blood supply derived embryologically from the three unpaired arteries of the foregut, midgut and the hindgut that are celiac trunk (artery), superior mesenteric artery and inferior mesenteric artery, respectively.

Liver Transplantation — Clinical Presentation and Post-Transplant Complications

In patients with end-stage liver disease (ESLD), the definitive treatment is a liver transplant. In the United States, the most common indication for liver transplantation is hepatitis C followed by alcoholic liver disease. Immunosuppression is indicated post-implantation and the most common complications are rejection and infection.

Anticonvulsants (Antiseizure Drugs) — Classification and Side Effects

A seizure is a brief episode of signs/symptoms resulting due to uncontrolled, abnormal electrical activity in the brain. In this article, we will study in detail about the classification, mechanism of action, and adverse effects and interactions of antiseizure drugs. First and second line drugs for various types of seizures will also be studied.

Ischemic Colitis — Physical Examination and Diagnosis

Ischemic colitis (ischemic disease of the colon) was first described in 1966. It occurs when there is an occlusion of branches of the superior mesenteric (SMA) or inferior mesenteric arteries; the vast majority of cases describe the lesion in the splenic flexure and left colon. This severe illness is very common among the elderly with pronounced cardiovascular disorders. An acute stabbing abdominal pain and rectal bleeding with diarrhea in most of the cases follow the onset. Ischemic disease of the colon requires immediate actions; the sooner the treatment is administered, the more benign the outcome is.

Schatzki Ring — Signs and Symptoms

Esophageal rings are the most common esophageal abnormality and Schatzki rings represent the majority of them. Schatzki rings occur in the lower end of the esophagus and can be classified into types A and B rings. Type A ring is a muscular ring while type B is mucosal constriction. Schatzki rings respond very well to dilation therapy.

Diabetes Insipidus (DI) — Causes and Symptoms

Patients with diabetes insipidus present with polyuria, urinary output > 3 L per day and can be central or nephrogenic in origin. In central diabetes insipidus, there is a decrease in the secretion of antidiuretic hormone (ADH), while in nephrogenic diabetes insipidus, the kidneys are unable to concentrate the urine due to ADH resistance.

C. Difficile Enteritis — Symptoms and Treatment

Hospitalized patient receiving broad-spectrum antibiotics are at risk of developing Clostridium difficile infection (CDI). Antibiotics change the normal colonic bacterial flora and C. difficile colonizes the colon in these patients. C. difficile produces toxins that cause inflammation of the colonic mucosa. Even though clindamycin has been traditionally linked to the development of C. difficile colitis, almost all antibiotics can cause the disease.

Pancreatic Pseudocysts — Diagnosis and Treatment

Pancreatic pseudocysts are a complication of acute pancreatitis, and they are more common when the etiology is alcohol-related. These pseudocysts do not have an epithelial wall, and their fluid content is rich in amylase, lipase and trypsin. Abdominal CT scan is the diagnostic modality of choice to confirm the diagnosis of pancreatic pseudocysts and exclude complications. MRI or ERCP can be used to assess communication between the pseudocyst and the pancreatic duct, and if present, transpapillary drainage of the pseudocyst can be attempted.

Bronchogenic Carcinoma — Diagnosis and Treatment

Bronchogenic carcinomas include small cell carcinoma, squamous cell carcinoma, adenocarcinoma, large-cell carcinoma and undifferentiated carcinoma. Bronchogenic carcinoma is clearly associated with tobacco smoking. Once the diagnosis of bronchogenic carcinoma is confirmed by a biopsy study, disease staging with CT or FDG-PET is indicated because treatment is stage-based. While stage I and II disease benefit from surgical lobectomy, chemotherapy is essential for patients with stage III and IV.

Steroid Hormone Receptors

Endocrinology refers to the study of endocrine system; more specifically, it is the study of hormones, the receptors to which the hormones bind, the intracellular signaling cascade they invoke, and the diseases and conditions associated with them. It is a communication system comprising of endocrine glands and the hormones they produce. The hormones are released into the blood to guide processes such as metabolic activity, growth, sexual development, sleep-wake homeostasis, regulation of emotions, and others. The effect produced by the hormones might rest with a single organ or multiple organs throughout the body. This article specifically focuses on the intricacies of the steroid hormone receptors, which are generally intracellular in nature and can be found at all three places namely nucleus, cytoplasm and the plasma membrane.

Malignant Neoplasms — Metastasis

Malignant neoplasms have the ability to invade adjacent structures, spread through the lymphatic system or metastasize to distant organs by the bloodstream. In order for tumorous cells to be able to metastasize, they should first become motile and be able to migrate. This is achieved by altered cell-to-cell and cell-to-matrix adhesion properties in addition to an epithelial-to-mesenchymal transformation process. In addition to this, angiogenesis and lymphangiogenesis play an important role in metastatic disease by providing access for the tumor cells to the bloodstream and lymphatic system respectively.

Benign Neoplasms — Teratoma

Teratomas are germ-cell tumors and can be mature “benign” or immature “malignant”. They usually arise in the sacrococcygeal region, ovaries, testes or mediastinum. Sacrococcygeal teratomas can be diagnosed antenatally, while teratomas in other locations are usually diagnosed postnatally. The treatment of teratomas is surgical. Complete excision of benign teratomas can virtually result in a cure with minimal risk of recurrence in the majority of the cases.

AIDS Cholangiopathy — Diagnosis and Treatment

AIDS cholangiopathy is an advanced fatal disease caused due to biliary obstruction resulted from opportunistic infections of biliary tract strictures. Choliangiapathy developed in 25 out of 100 patients of AIDS before the arrival of antiretroviral therapy, especially in patients with low CD4 count(<100/μL). Its symptoms are right upper quadrant and epigastric pain, fever, diarrhea and sometimes jaundice. The severity of pain depends on the lesion of biliary tract. Endoscopic retrograde cholangiopancreatography establishes the diagnosis of cholangiographic abnormalities. Antimicrobial therapy is sometimes ineffective and highly active antiretroviral therapy is the best therapy for AIDS cholangiopathy. Surgical intervention is recommended to patients with terminal disease and intractable pain in abdomen.

End-stage Liver Disease (ESLD) — Pathogenesis and Liver Transplantation

Approximately, 5.5 million people in the United States have liver cirrhosis. End-stage liver disease affects mainly the middle-aged population and is considered as the seventh commonest cause of death in the United States. The majority of these patients die due to the limited availability of donor livers. Several complications are encountered in end-stage liver disease and include ascites, hepatic encephalopathy, malnutrition and renal failure. Hepatocellular carcinoma is another possible complication in chronic liver cirrhosis.

Polycythemia — Symptoms, Causes and Treatment

Red blood cells perform an important function of supplying adequate oxygen to all tissues. Increased synthesis of these red blood cells, arising either de novo or secondary to other conditions, is called polycythemia. Read on to find out more about the different types of polycythemia and how they may present.

Anatomy of the Peritoneum

The peritoneum is a transparent serous membrane lining the interior of the abdominal cavity. It is extensive and encloses almost all the intra-abdominal organs.

Dehydration — Isotonic, Hypotonic and Hypertonic Fluid Disorders

Dehydration is an imbalance in the body fluid environment. The imbalance is due to less water intake while there is more water loss. The body can lose water through normal physiologic processes in respiration, urination and sweating, or some pathologic diseases through vomiting, diarrhea and fever.

Anatomy and Function of the Dural Venous Sinuses

Dural venous sinuses are venous blood reservoirs contained between the two layers of the dura mater. Absence of lymphatic drainage in the brain places the venous outflow system at a pedestal of prime importance. Following a prologue to dural venous sinuses, this article focuses on arachnoid granulations, tributaries and the drainage pattern of the venous sinuses.

The Vestibular System-Caloric Reflex Test and Horizontal Gaze Nystagmus Test

Integration of vestibular input, vision and proprioceptive feedback is instrumental in maintaining orientation and balance of the body in both static and kinetic environment. In this article, a prelude to organization of vestibular system is followed by discussion on caloric test and control of horizontal gaze.

Anatomy and Clinical Relevance of the Cavernous Sinus

The cavernous sinus is one of the most important dural venous sinuses located between the endosteal dura and meninges. The roof of the sinus is formed by the inner layer of meningeal dura, which is continuous with the diaphragm sellae covering the pituitary gland.

Hepatic Encephalopathy — Definition, Pathogenesis and Clinical Features

Hepatic encephalopathy syndrome (HES) is a condition which occurs in patients with severely impaired detoxification function of the damaged hepatocytes of the liver because of various reasons, mostly due to cirrhosis or other liver diseases that can lead to fulminant hepatic failure. It is a neuropsychiatric syndrome characterized by disturbances in consciousness, behavior, personality, fluctuating neurologic signs and distinct EEG changes.

Thoracic Vessels and Nerves

The thorax consists of two major organs: the heart and lungs. These are supplied by an extensive network of blood vessels, nerves, and lymphatic vessels. The rib cage surrounds the thorax and provides protection to the delicate organs.

Antidepressants — List of Drugs and Side Effects

The lifetime prevalence of major depressive disorder falls within 12—17 %. Therefore, every clinician will come in contact with patients suffering from symptoms of depression or taking antidepressant medications. For this reason, it is important to know the indications, adverse effects, and interactions of antidepressants.

Topographic Anatomy of the Back

The skin of the back is divided into six regions. The central vertebral region is the area of the skin overlying the vertebral column. The deltoid area lies over the shoulder joints. The scapular region encloses the scapula on both sides. The area of the skin beneath the scapula is called infra-scapular region. The area beneath the ribs and above the hip bone forms the lumbar region on both sides. The sacral region is the area of skin between the two hip bones.

Venous Drainage and Cutaneous Innervation of the Lower Limb

The venous system of the lower limb consists of a superficial and a deep system. The superficial veins drain into the deep veins of the lower limb, which eventually drain into common iliac vein and inferior vena cava. This article also provides information about the cutaneous innervation (dermatomes) of the lower limb.

Arterial Supply of the Lower Limb

The lower limb is mainly supplied by the femoral artery at the thigh, popliteal artery at the knee and tibial arteries at the lower leg and foot. The femoral artery is an important vessel as it is frequently used to access the arterial circulation during invasive procedures such as coronary angiography. Other vessels such as popliteal, posterior tibial and dorsalis pedis are also palpable.

Gastroparesis — Causes, Diagnosis and Diet

Gastroparesis is defined as a chronic motility disorder where there is a delayed emptying of the stomach without an apparent mechanical obstruction. Usually, both solids and liquids are affected. Gastroparesis is usually of undetermined causes, but can also be linked to previous abdominal surgeries or diabetes mellitus. Symptoms include nausea, vomiting and early satiety. Once diagnosed, the patient is instructed to follow a diet that has more liquid, promotility agents could be prescribed and antiemetics are used for symptomatic relief.

Esophageal Stricture — Symptoms and Treatment

The topic of this article is peptic strictures associated with benign and malignant after-effects of this condition and the management of these ailments as the number of such cases makes up to 80% of all esophageal strictures and represents a great interest for the researchers.

Meckel's Diverticulum — Symptoms, Diagnosis and Treatments

Meckel's diverticulum is named in honor of Johann Friedrich Meckel, who, in 1809, described the intrauterine origin of the condition, which is one of the most common inborn defects of the baby's small intestine stipulated by the partial obliteration of the vitelline duct (omphalomesenteric duct).

Types of Study Designs: Interventional Studies

Scientific studies in the medical field are done in order to come up with a solution to a particular health problem based on data that is collected during the studies. Data is collected with a very high degree of accuracy and in an authenticated manner. Scientific studies are planned according to evidence which is currently available. This evidence is used to find the solution for unclear problems or the shadow areas in medicine. This remains the overall aim of most studies with a few exceptions.

Oral Hypoglycemic Drugs

Diabetes is one of the most common metabolic disorders of the world and is a major cause of morbidity in the elderly population. The treatment of diabetes has gone into a number of refinements, and currently, the majority of people who are suffering from the disease can be treated with the help of oral hypoglycemic drugs. These drugs form the first line of pharmacological treatment for patients with type 2 diabetes mellitus, whereas in patients with type 1 diabetes mellitus, the first line of treatment is insulin. This article discusses in detail the various oral hypoglycemic drugs, which are currently available on the market.

Dumping Syndrome — Causes and Treatment

Dumping syndrome, or “too rapid drainage of the stomach,” is a condition most often found in patients post-gastrectomy. Symptoms of this condition can be separated into vasomotor symptoms (such as palpitations, flushing or diaphoresis) and abdominal symptoms (such as diarrhea, nausea or cramps). The symptoms often resolve within several months. Medication is often helpful and surgical intervention is rarely necessary.

Brain Stem: Medial and Lateral Medullary Syndrome

Brain stem syndromes are characterized by infliction of precise structural entities with specific consequent clinical manifestations. Relevant appraisal of anatomy and blood supply of medulla is essential to understand the peculiar features of medullary syndromes. In this article, we emphasize on clinical characteristics of medial medullary syndrome and lateral medullary syndrome in perspective of the topographical organization of medulla. We conclude with therapy and prognosis.

Parkinson's Disease and Other Movement Disorders

Abnormal movements can be presenting features of several neurodegenerative disorders, most commonly parkinsonism, or can occur as side effects of drugs, most commonly antipsychotics. A few other disorders can also present with abnormal movements. Drugs used in treatment of parkinsonism and other movement disorders mainly act on the central nervous system. In this article, we will study the pharmacology of these drugs.

Skeletal Muscle Relaxants

In this article, we will study the important pharmacological aspects of skeletal muscle relaxants such as classification, pharmacokinetics, mechanism of action, clinical uses, drug interactions, adverse effects and toxicity.

Brainstem Components: Midbrain, Pons and Medulla Oblongata

Comprised of midbrain, pons and medulla oblongata, the brainstem is the central relay station between the cerebrum and the cerebellum. Cranial nerves originate in the brainstem. This article enhances the understanding of the organization and purpose of the brainstem and its components. Antero-posterior orientation of the brainstem is crucial in the pathogenesis of various diseases – the structures involved and the consequent manifestations. The article concludes with a discussion on glossopharyngeal and vagal nerve nuclei.

Brown-Séquard Syndrome and Tabes Dorsalis — Anatomy and Lesions of the Spinal Cord

The spinal cord is the continuation of the brain stem medulla below the foramen magnum. This article discusses lesions and diseases of the spinal cord, highlighting the Brown-Sequard syndrome and Tabes Dorsalis.

Syringomyelia — Anatomy and Lesions of the Spinal Cord

Syringomyelia is characterised by progressive abnormal CSF accumulation in the spinal cord. It causes dissociated suspended anaesthesia affecting pain and temperature sensation predominantly in the upper limbs. Etiology is unclear. There are many theories proposed but the accepted fact is that it is a manifestation of an underlying pathology rather than being a disease itself. Treatment of the primary cause often leads to regression of the syrinx.

Overdose and Side Effects of Cholinomimetic Agents – ANS Pharmacology

Toxicology of cholinomimetics, especially nicotine and cholinesterase inhibitors, is important for clinical implications. In this article, clinical features of adverse effects, resulting from acute and chronic exposures to cholinomimetics, are described. Management of poisoning, including the role of atropine and cholinesterase reactivators, is also discussed.

Sympathomimetic Agents – ANS Pharmacology

The sympathetic autonomous system works by the release of neurotransmitters that act on the adrenoreceptors, with their various types and subtypes. The effects produced can be mimicked by drugs that stimulate these receptors, known as sympathomimetics. Some sympathomimetics have a higher affinity for a certain receptor type or subtype while others are rather non-selective.

Cholinomimetic Agents – ANS Pharmacology

Cholinomimetics are an important class of drugs affecting the autonomic nervous system. They act on receptors that are activated by acetylcholine. They are broadly classified into direct-acting and indirect-acting drugs. In this article, we will study the mechanism of action and pharmacological actions, specific characteristics and clinical uses of individual cholinomimetic drugs.

Class 2: Alpha and Beta Blockers – Antiarrhythmic Drugs

In this article, we will study the important pharmacological aspects of alpha and beta blockers such as classification, pharmacokinetics, mechanism of action, important actions on various organ systems, clinical uses and toxicity.

Class 3: Potassium Channel Blockers – Antiarrhythmic Drugs

The main role of antiarrhythmic agents is to prevent the occurrence of arrhythmia and, in the case of those patients in which abnormal rhythm has occurred; it helps in the termination of the arrhythmia. Antiarrhythmics are classified in various types by means of many classifications. The Vaughan-Williams classification is one of the widely accepted among those. Class 3 drugs constitute potassium channel blockers. These will be discussed in this article.

Class 1: Sodium Channel Blockers – Antiarrhythmic Drugs

The Vaughan-Williams classification is one of the most commonly used classifications for antiarrhythmic drugs. Class 1 consists of sodium channel blockers, which in turn is divided into 3 subgroups namely 1A, 1B and 1C. This article discusses the class 1 antiarrhythmic drugs in detail, along with a description of the salient features of individual drugs.

Insulin in Diabetes

Diabetes not only causes destruction of the body as a whole but also leads to a lot of psychological stress. The patients need to do a lot of self-care, which remains a vital and essential factor in maintaining the glycemic control. Hence, a thorough understanding is expected from the physician side to explain the intricacies to the patient.

Temporal Arteritis (Giant Cell Arteritis) and Carotid Artery Stenosis — Symptoms and Treatments

Temporal arteritis, also known as giant cell arteritis (GCA), is the vasculitis of the superficial temporal artery. Inflammation of the vessel wall produces systemic, neurologic and ophthalmologic signs and symptoms. Carotid artery disease, also called carotid artery stenosis, is the narrowing of the lumen of the carotid arteries due to fats and cholesterol deposition (plaque). The complete blockage of the artery, called carotid artery occlusion, can lead to cerebral ischemia and stroke.

Subclavian Arteries

The human body comprises of a single pair of subclavian arteries, one on the right side, the other on the left. Both show different patterns while originating from their source. Right subclavian artery arises from the right brachiocephalic artery while the left subclavian artery arises from the arch of aorta. Both these arteries supply various parts of the brain through the circle of Willis formed at the base of the brain. They also supply the cerebellum, parts of the posterior neck and upper limbs along with the upper chest portion.

Anatomy of the Thoracic Outlet and the Thoracic Outlet Syndrome

The superior thoracic aperture, or thoracic outlet, is an upper chest area located below the clavicles and between the neck and the shoulders. Many important anatomical structures pass from the neck into the thorax and chest cavity from the thoracic outlet. Thoracic outlet syndrome is caused by the compression of the structures at the thoracic outlet, especially those passing through the inter-scalene triangle.

Circle of Willis

The circle of Willis, also called circulus arteriosus cerebri, is one of the anastomotic systems of arteries in the body which supplies blood to the brain. It is located at the base of the brain. Willis is the name of the author of Cerebri Anatome, a book that described this ring of blood vessels present at the base of the brain. The circle of Willis is present around the stalk of the pituitary gland. It connects the blood supply of the forebrain and the hindbrain.

Testosterone: Synthesis, Effects and Regulation

Testosterone is a lipid-soluble molecule synthesized mainly from cholesterol in the testes, ovaries, and adrenal glands and is important for spermatogenesis and the development of both primary and secondary male sex characteristics. Anabolic steroids, which have similar properties to testosterone, are commonly taken by athletes and body builders to increase performance, however, they possess dangerous side effects.

Anatomy of the Thyroid Gland

The thyroid gland is one of the largest and actively functioning endocrine glands. It is a highly vascular, brownish-red gland located in the visceral compartment of the anterior part of the neck, spanning between the C5 and T1 vertebrae.

Anatomy of the Upper Limb: Axilla and Brachial Plexus

The axilla is the entrance to the upper limb, providing a smooth transition between the neck and the arm. This article provides an overview of the structure and contents located within the axilla.

Anti-hypertensive Medications — List of Drugs and Lines of Therapy

Hypertension is the rise in blood pressure beyond the defined set point (conventionally ≥ 140/90 mmHg). Hypertension is the known risk factor for a number of cardiovascular events like myocardial infarction, angina and heart failure, sudden cardiac death. The pharmacological therapy for hypertension is discussed in this section. The therapies have evolved over time and the current line of therapy offers tremendous response and decreases the morbidity and mortality associated with this condition. It should be noted that non-pharmacological therapy like exercise and healthy food habits also play an important part in controlling hypertension.

Autoimmune Diseases: Goodpasture´s Syndrome and more

Autoimmune diseases are a group of disorders that are characterized by abnormal reactions of the immune system against one’s own body. These usually manifest during the middle years and are, most of the time, chronic. Approximately 3.2 % of the global population is composed of people who are afflicted with these, being generally more common among women.

Acute Liver Failure (ALF) — Causes and Treatment

Acute (or fulminant) liver failure is basically the end point of severe liver damage brought about by many different causes. It is characterized by a rapidly developing dysfunction in the hepatocytes. Affected persons may or may not have known past experiences of liver disease. The manifestations of fulminant liver failure can manifest systemically and are caused by changes in the integrity of hemostasis and mental status. Being a fatal condition, a rapid and accurate diagnosis of acute liver failure when a case is present should be done. This can be done clinically by using key observations in the history and physical examination. The timely use of other supplemental tools to reinforce the diagnosis should also be instigated.

Hepatorenal Syndrome — Classification and Treatment

Aside from the many metabolic and synthetic functions of the liver, it also plays a crucial part in the maintenance of other organ systems. This is why any alterations in its functions, such as in liver cirrhosis and portal hypertension can result in detrimental effects on the major organs and tissues remote from the liver such as the lungs, heart, and kidneys. Although liver diseases can affect different extrahepatic organ systems, there is somewhat a similar pattern when it comes to the development of the pathophysiology. One of the many extrahepatic syndromes that can manifest in patients having liver problems such as cirrhosis and portal hypertension is the hepatorenal syndrome.

Humoral Immunity and Cell-Mediated Immunity

Humoral immunity, or antibody-mediated beta cellular system, is a type of immunity which is mediated by macromolecules found in fluids such as the secreted antibodies, complement proteins, and bound antimicrobial peptides. In contrast to cell-mediated immunity, the term "humoral" describes the non-cellular compositions of the blood, such as plasma and lymphatics. However, the cellular components of the blood, such as lymphocytes and antigen presenting cells, are important for mediating antigen-specific antibody reaction.

Inotropes – Angina and Heart Failure Management

The inotropic agent in the context of heart failure and angina is classified into positive and negative inotropic agent. The positive agent increases the contractility and will be discussed in detail in this article. A brief about the negative inotropic agent, which decreases the myocardial contractility, is mentioned. The inotropic agent, when mentioned alone without any prefix, stands for a positive inotropic agent in this article.

Liver Diseases of Pregnancy

There are so many changes in the anatomy and physiology of the female human body during pregnancy. Aside from the profound reproductive system changes, there are also many reversible modifications in the other internal organ systems, all of which happen in order to accommodate the changing needs of the childbearing woman all throughout the 3 trimesters of pregnancy. One of the organs that change during pregnancy is the liver. Along with its changes comes the female individual’s predisposition to certain hepatic conditions that could put her and the fetus at increased risk for morbidity or mortality.

Nitrates in the Treatment of Angina and Heart Failure

The organic nitrate includes drug like nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate. The newer organic nitrate, which has recently been evaluated, is pentaerythrityl tetranitrate. The nitrates are available in various forms like intravenous, oral, sublingual, spray, ointment, patch, transdermal and buccal preparations.

Space-Occupying Lesions in the Liver

The significant prevalence of mass lesions in the liver among the general population has prompted the emphasis on understanding each of the condition’s clinical presentation, diagnosis, and treatment. Another reason to fully understand the characteristics of the different space-occupying lesions in the liver is the fact that the treatment varies depending on the type of lesion found in the liver. Here, we briefly discuss the epidemiology and features of the different space-occupying lesions in the liver.

Spontaneous Bacterial Peritonitis — Symptoms and Treatment

The most prominent complications of having liver diseases such as cirrhosis include ascites. Derived from the Greek word “askos” which means “sack”, ascites is characterized as the collection of fluid in the peritoneal cavity. Aside from liver diseases, it can also be caused by a wide range of reasons necessitating different means of definitive management. Therefore, the identification of the nature and development of the fluid collection in the peritoneal space of a specific patient is very important. Once the population of bacteria in the intestinal lumen reaches certain numbers, they tend to translocate to the mesenteric lymph nodes, leading to the eventual invasion and colonization of the bacteria in the ascitic fluid.

Portal Hypertension and Esophageal Varices — Symptoms and Causes

The development of varices in the esophagus and the gastrointestinal tract is only one of the 3 complications caused by increased pressure within the portal system, the others being ascites and hepatic encephalopathy. All of these conditions are essentially brought about by diseases that impair the flow of blood through the liver such as in liver cirrhosis. The presence of collateral blood vessels in the portosystemic circulation allows for a normal blood flow into and out of the liver. However, these collateral do not hold blood well in times of increased portal pressure, making them vulnerable to massive dilatation and rupture.

Alcoholic Hepatitis, Alcoholic Cirrhosis & Non-Alcoholic Fatty Liver Disease (NAFLD)

Alcoholic hepatitis is a progressive disease characterized by inflammation and damage of liver caused by long term excessive intake of ethanol. Non-Alcoholic fatty liver disease is the also progressive disease of liver characterized by accumulation of fat in liver without the abuse of alcohol. Both the disease show similar pathological changes resulting in fibrosis or scarring of liver. The extensive fibrosis of liver due to continued abuse of alcohol is called alcoholic cirrhosis. These diseases remain asymptomatic at early stages and common symptoms are slight discomfort at right side of upper abdomen with fatigue and unexplained weight loss. Lifestyle modification and alcohol abstinence is essential for management along with required therapeutic and surgical interventions.

Arteries in the Neck: The Carotid Arterial System

The carotid arterial system provides blood supply to the head and neck. The aorta arches towards the left and backward, before going downwards to supply freshly oxygenated blood to the body. Three major vessels branch off from the arch of the aorta to supply blood to the upper limbs and head and neck.

Maxillary Bone and Le Fort Fractures

The human skull is a complex combination of several bones ranging from small to large sizes – usually in pairs (right and left side). These bones grow from birth and fuse together to form the skull. This section will discuss the facial bones of the skull.

Extraocular Muscles – Basic and Clinical Anatomy

All the muscles controlling the movement of the eye are known as the extraocular muscles of the eye. The orbit, or eye socket, holds the eye and its muscles, nerves, and blood vessels. There are six extraocular eye muscles. These muscles contract to rotate the eye up, down, and side to side.

Intracranial Hemorrhage: Different Types and Epidemiology

Intracranial hemorrhage is a medical emergency that occurs in adults, but can also occur in children and neonates. As the name suggests, intracranial hemorrhage is bleeding and the accumulation of blood within the skull at an abnormal location leading to the formation of a hematoma. A hematoma is the collection of blood outside of blood vessel. Intracranial bleeding can lead to stroke, neurological deficit, brain matter herniation, and even death.

Lung Cancer (Bronchial Carcinoma) — Classification, Staging and Treatment

The lung is the major organ of the respiratory system and used to inhale oxygen and remove the metabolic waste in the form of CO2 from the body. Malfunctioning of the lungs can lead to serious complications and disturbs the normal living conditions. Lung cancer is one of the severe conditions which have a relatively high mortality risk. Previously, it was the leading cause of death among men in more than 25 developed countries. Now it has become a worldwide cause of death among men. Most common cause of lung cancer is smoking, especially in men. Prognosis of this condition is still poor for malignant tumors. Read everything important about it here.

Diagnostic Imaging: X-Ray and CT Scan in the Integrated Pulmonary Pathology

Radiological investigations like x-ray and CT scan are required for the confirmation of clinical findings. The field of radiology in the 21st century has become very advanced and through various radiological investigations, even the smallest calcifications and vascular pathologies can be diagnosed. The chest radiograph (CXR) is the most common radiological investigation.

Irritable Bowel Syndrome (IBS) — Pathophysiology, Clinical Features and Symptoms

Nowadays, junk foods like burgers, pizzas, and other flour-based meals are more likely consumed by the young generation. Mostly they are unfamiliar with the consequences of the usage, which then may lead to severe and painful irritable bowel conditions. Cramping, bloating, constipation, abdominal pain, gas, and diarrhea are some of the common problems that are to be tackled for the patients of IBS. One must have an eye on the signs and symptoms of IBS to reach to its severe conditions. Have a detailed description of IBS here.

Diabetes Complications: Diabetic Retinopathy, Nephropathy & Neuropathy

Patients who have been suffering for years from high blood sugar concentration can expect serious consequences for their entire bodies. Accurate knowledge of the complications that may arise in the course of the disease is important not only for the exam. Physicians may significantly contribute to the problem, so that amputations, blindness, kidney damage and cardiovascular disease can be avoided.

Liver Cancer: Types of Hepatobiliary Tumors

Liver tumors are some of the more common neoplasms and are classified as either primary or secondary. Management varies depending on several factors such as type, size, and the spread of the cancer. Continue to read this article to learn key facts about the tumors of the liver including incidence, pathology, clinical features, diagnosis, and treatment.

Zollinger-Ellison Syndrome — Presentation, Diagnosis, Therapy

Zollinger-Ellison syndrome is one of the rare conditions that affect the duodenum or the pancreas. Tumors (gastrinomas) form in the duodenum or the pancreas, which secrete huge amounts of gastrin leading to excess acid production in the stomach. This excess acid results in the formation of related symptoms as well as peptic ulcers.

Physiology of Cell Membrane: Partitioning and Transporting

It is quite notable that fluids inside a human being are also compartmentalized into the extracellular and intracellular fluid compartments. Between these spaces comes a difference in terms to the amount of ions, proteins and other substrates dissolved or suspended in them. These substrates are prevented from unnecessarily mixing with each other due to the partitioned nature of the cell’s structure.

A-A Gradient & Alveolar Gas Equation – Laboratory Diagnostics

A-A Gradient & Alveolar Gas equation are very evident to determine various causes of hypoxemia. Alveolar gas equation is useful for calculation of the partial pressure of oxygen in lung alveoli and A-A Gradient is the value that shows the difference between alveolar oxygen pressure and arterial oxygen pressure. The etiology of hypoxemia can be hypoventilation, diffusion impairment, and presence of shunt, V/Q mismatch and high altitude. The variation in the values of alveolar gas equation and A-A Gradient establish the laboratory diagnosis of the lung pathologies.

Modes of Ventilation

Sometimes ventilation is the only way to save a patient's life. Here you'll read about the different forms of mechanical ventilation, how it is different from spontaneous breathing and what modes of ventilation exist.

Comparative Genomics

Comparative genomics allow researchers to use a robust repertoire of techniques to compare the gene sequences of different organisms. Among these techniques are analytics, which can be used to not only draw structure/function comparisons between species but to also make predictions about unknowns. This knowledge is cutting edge in the development of new strategies to remedy human disease.

Interstitial Nephritis (Tubolainterstitial Nephritis) — Pathophysiology and Laboratory Investigations

Tubulointerstitial nephritis is an inflammatory condition affecting the tubules and interstitium, while sparing the glomerulus. Acute and chronic pyelonephritis, along with drug induced interstitial nephritis, is the predominant cause of tubulointerstitial nephritis. Urine examination shows characteristic eosinophiluria and WBC casts. The treatment involves the discontinuation of the offending drug, along with steroids, while treatment is mainly supportive in the chronic type. Progression to end-stage renal disease is seen in the majority of tubulointerstitial disorders.

Chronic Kidney Disease (CKD) — Pathophysiology and Diagnosis

Kidneys are central metabolic organs in our body. They regulate our water and electrolyte balance amongst other things, and are responsible for the removal of potentially toxic substances and medications. Shockingly, many of today’s widespread diseases can lead to damaged kidneys and an impairment of their function. Chronic renal failure is a systemic disease with massive effects on the whole organism. It is not always easy to understand all of the various facets of the disease. This article should make the mechanisms and processes easier to understand, and will explain them in more detail.

Ketone Body Synthesis

Ketone bodies are an important energy source for our bodies during periods of fasting. They provide the brain, the myocardial muscles and the skeletal muscles with energy whenever our body has to live off its reserves. The following article addresses the synthesis and degradation of ketone bodies, their impact on the pH-level of the blood, as well as their clinical relevance with regard to diabetes - all of which is based on pre-med biochemistry knowledge.

Acute Coronary Syndrome (ACS) — Causes and Treatment

Acute coronary syndrome is defined as acute anginal pain because of partial or total occlusion of one or more coronary arteries due to advanced coronary heart disease. Three clinical entities can be identified: Unstable angina (UA), Non-ST-segment elevation MI (NSTEMI) and ST-segment elevation MI. They can be differentiated based on the ECG changes and the cardiac markers. ACS is initially managed medically with a well-known algorithm. Revascularization of the coronaries either by cardiac catheterization or surgery should be planned as soon as possible.

Acute Renal Insult (ARI) — Symptoms and Treatment

Acute renal failure covers 5 % cases of emergency hospitalization. Acute renal failure is classified into prerenal, intrinsic or postrenal based on the etiology behind. Pre-renal acute renal failure is the most common type. The physician determines the etiology of acute renal failure through systematic approach involving blood tests, urine tests and abdominal ultrasonography. Treatment is focused on the supportive therapy based on fluid and electrolyte replacement to reduce the waste accumulation and sustain nutrition.

Anatomy of the Respiratory System and the Respiratory Muscles

Without oxygen, the human organism is not capable of living. It gains a major part of its energy from oxidative degradation of nutrients. The processes involved in this are called pulmonary respiration or external respiration. The carbon dioxide that is formed in the process of combustion has to be released. The gas exchange between air and blood takes place in the lung. When nutrients are degraded in order to gain energy, oxygen is consumed – a process that takes place in every individual cell of the body and is therefore called cell respiration or internal respiration. The detailed processes of cell respiration are the subject of biochemistry and will not be discussed here.

An Overview of the Larynx

The larynx, or voice box, is a cylindrical space which lies at the upper end of the trachea opposite to the 3rd—6th cervical cartilages. It is a cartilaginous structure made up of 6 different types of cartilages. Major structures forming the framework of the larynx are the thyroid cartilage, cricoid cartilage and epiglottis. The unpaired cartilages are three in number, namely arytenoids, corniculate and cuneiform. Cricoid cartilage forms a complete ring which lies below the thyroid cartilage. Vocal cords are attached to the thyroid and arytenoid cartilages. Various muscles wrap the cartilages which produce movements at the cricoarytenoid and cricothyroid joints.

Anatomy, Functions, and Histology of the Human Nose

Our nose, paranasal sinuses, as well as the throat (pharynx) are part of the upper respiratory tract, which consists of two parts. Anatomically, the external and internal parts of the nose can be illustrated. The first consists of nasal bones and nasal cartilages and the internal nose is formed by the nasal cavity and the nasal concha also known as turbinates (choanae), are separated by the nasal septum (septum nasi) with their openings and the paranasal sinuses.

Anatomy and Most Common Diseases of the Rectum and Anal Canal

Rectum (in Latin: Rectum, in Greek: Proktos) and anal canal (in Latin: Canalis analis) form the straight intestine. They form a functional unit and are part of the digestive system, which controls defecation. If this function is disturbed, fecal incontinence occurs. Hemorrhoids and anal fistulas are also diseases of the straight intestine that a physician will often be faced with in practice. Read a compact outline about the structure, function and diseases of the final part of the digestive tract here.

Citric Acid Cycle (CAC; Tricarboxyl Acid Cycle; Krebs Cycle) — Definition and Glyoxylate Cycle

As the final stage of food utilization, the citric acid cycle is primarily responsible for many anabolic and katabolic processes of the human body. As the ‘hub of metabolism’, it is a very popular subject in medical examinations. The following article will help you to better understand its functions, the different reaction steps, and their regulation.

Anatomy of the Lower Airways – Larynx and Trachea

The Larynx, trachea and the main bronchi together form the extrapulmonary lower airways. After air has been warmed and moistened in the upper airways (nose and pharynx), it passes through the larynx – the guardian of the airways. the larynx separates the trachea from the esophagus and is the organ from which voice is produced. The air then passes the tube-shaped trachea, which bifurcates into two main bronchi at its end, which then split apart to form the bronchial tree. Intrapulmonary, the air reaches its destination in the small bronchioles and in the adjoining alveoli, where gas exchange takes place. This article provides you with an extensive overview of the lower airways – larynx and trachea.

Anatomy, Function, and Diseases of the Oral Cavity

The oral cavity (Latin: Cavitas oris) is the beginning of the human digestive tract. Its anatomy ranging from the lips to the pharynx; the salivary glands and their function; and the Waldeyer’s tonsillar ring are all popular topics in examinations. The articulation of sounds and food comminution with the teeth are two of the main functions of the oral cavity and the saliva of the mouth starts the process of breaking up food components. Pathological changes in the oral cavity, like redness in the area of the pharynx or bad breath, can be indications for certain clinical pictures. In this article, you will get a compact overview of all there is to know about the oral cavity.

Normocytic Anemia: Sickle Cell Anemia (Sickle Cell Disease)

Sickle cell anemia leads to sickling of red cells during hypoxia. This can cause blockage in blood vessels with a range of clinical problems. Treatment is with red cell transfusions and hydroxycarbamide.

Macrocytic Anemia: Megaloblastic Anemia (Vitamin B 12-Deficiency and Folate Deficiency)

In practice, anemia often appears in the blood count, accompanying many acute and chronic diseases. Clarification is definitely recommended because already a lowered hemoglobin value alone can be the first important hint for an undetected underlying disease.

Hydrocephalus (Water on the Brain) — Symptoms and Surgery (Shunt and More)

Hydrocephalus or water in the brain is referred to accumulation of the cerebrospinal fluid (CSF) in the subarachnoid space and cerebral ventricles leading to increased intracranial pressure.

Central Nervous System Cancers — Diagnosis and Treatment

This article explains basic facts about tumors of the CNS. It includes neuroepithelial tumors like astrocytomas and fibrillary astrocytomas. It also runs through oligodendroglioma, medulloblastoma and meningeal tumors like meningioma and primary CNS lymphoma. The article covers the definition, epidemiology, etiology and causes of CNS tumors, in addition to classification, pathophysiology, symptoms, diagnosis (including history and examination), therapy and prognosis.

Pediatric Neurology: Autism, Cerebral Palsy and More

This article covers a lot on the topic of pediatric neurology. It explores embryological deficits which are fully covered in the etiology section. It will also cover definitions of intellectual disability, autism, developmental regression and neurocutaneous disorders. Etiology, diagnosis and management of these conditions is also discussed. This article runs complementary to Dr. Rangaraj’s lecture on pediatric neurology.

Hemorrhagic Stroke (Cerebrovascular Accident, CVA) — Symptoms and Treatment

Hemorrhagic stroke is the second most common form of acute strokes. Patients can develop a hemorrhagic stroke due to many risk factors which include hypertension, cerebral amyloid angiopathy, neoplastic diseases and cerebral aneurysms. Hemorrhagic strokes can be classified into subarachnoid or intracerebral hemorrhage depending on the site of the hematoma formation. The semiology is usually similar to ischemic stroke; therefore, adequate brain imaging is very important for proper diagnosis and management.

Viral Encephalitis — Causes and Symptoms

Viral encephalitis is defined as the inflammation of the central nervous system due to viral agents. Several viruses can cause encephalitis, but herpes viruses are the most commonly implicated. Patients present with confusion, altered level of consciousness, seizures and focal neurologic signs. Polymerase chain reaction testing can help identify the causative organism in a few cases, but antiviral therapy should be initiated immediately in any suspected case regardless of the diagnosis confirmation.

Albinism (Achromasia) — Definition and Genetics

Albinism is a hereditary condition that is characterized by low or complete absence of melanin production that can be confined to the eyes or wide-spread in the body. People with albinism present with white skin, white or yellow hair and blue eyes. While the condition is rarely associated with any significant mortality, people with albinism tend to suffer from bleeding disorders, photosensitivity and impaired vision. Treatment of visual impairment with low-vision aids and early-age eye patching might be needed.

Prion Disease (Transmissible Spongiform Encephalopathy, TSEs) — Symptoms and Diagnosis

Prion-related encephalopathies are uncommon causes of severe, progressive cognitive impairment that are fatal. Sporadic and familial cases have been described, but familial cases seem to be extremely rare. Sporadic cases are usually more severe compared to familial prion-related encephalopathies. Patients develop symptoms after a long period of incubation. The symptoms are mainly of global cognitive impairment, cerebellar signs and neurodegeneration on MRI. There is no current treatment for prion-related encephalopathies.

Skin Infections: Erysipelas and Molluscum Contagiosum — Symptoms and Treatment

Erysipelas and Molluscum Contagiosum are two different skin infections, the former caused by streptococci, the latter caused by one of the Molluscum Contagiosum viruses. While erysipelas is more common in diabetics and patients with preexisting medical conditions such as lymphedema, Molluscum Contagiosum infection can affect healthy children and adults. Erysipelas treatment includes antibiotics and symptomatic relief. Molluscum Contagiosum therapy consists of neglect, topical treatment, immune response modulators, or antiviral therapy.

Herpes Simplex (HSV, Herpes Simplex Virus Infection) — Symptoms and Treatment

Herpes simplex virus infections are caused by either herpes simplex virus type 1 or 2. Type 1 viruses are more commonly associated with non-genital herpes, while type 2 viruses are more likely to be responsible for genital herpes diseases. The most common presenting sign is ulcers. While the healing process is usually excellent and subsequent scarring is very rare, topical and systemic antiviral therapy might be indicated to fasten the healing process, or prevent complications in the immunosuppressed.

Folliculitis (Inflammation of Hair Follicles) — Symptoms and Treatment

Folliculitis is an inflammatory condition that is characterized by inflammatory cellular infiltrate of the hair follicles. Patients present with acute onset pustules and papules. Treatment is not indicated in most cases, but those with intense pain might benefit from antibacterial soaps, warm compressors and perhaps topical antibiotics. Patients with resistant folliculitis should receive systemic antibiotics, usually a cephalosporin. Those who have deep folliculitis should undergo incision and drainage of their dermal abscess.

Toxic Shock Syndrome (TSS) and Necrotizing Fasciitis (Flesh-eating Disease) — Symptoms and Treatment

Toxic shock syndrome and necrotizing fasciitis have been both linked to streptococcal infections, staphylococcus infections and anaerobic infections. Both conditions are life-threatening and treatment should not be delayed until diagnosis confirmation. While the main point in the management of necrotizing fasciitis is surgical debridement of the infected sites, antibiotic therapy is the most important therapeutic approach for toxic shock syndrome. Clindamycin seems to be a good choice for toxic shock syndrome and necrotizing fasciitis.

Impetigo (School Sores) — Causes and Treatment

Impetigo is defined as infectious maculopapular skin eruption. It can be caused by staphylococcus organisms or anaerobic bacteria. The condition is usually self-limited, but topical antibiotics are indicated to fasten the healing process. Patients with staphylococcal scalded skin syndrome can develop fever, fatigue, localized or diffuse bullous impetigo and cellulitis. The condition is caused by the exfoliation toxins produced by staphylococcus aureus and needs penicillinase resistant antibiotics such as oxacillin.

Bovine Spongiform Encephalopathy (Mad Cow Disease) — Symptoms and Diagnosis

Bovine spongiform encephalopathy is also commonly known as mad cow disease. It causes spongy neurodegeneration in the brain and spinal cord of adult cattle. The main causative agent of bovine spongiform encephalopathy is prion, which is a misfolded protein.

Chronic Wasting Disease (CWD) — Symptoms and Transmission Pathways

Chronic wasting disease is a chronic weight loss disease that till 2016 has only been found in the deer family. It is a transmissible spongiform encephalopathy (TSE) of mule deer, elk (wapiti), moose or white-tailed deer.

Aspergillosis — Symptoms and Treatment

Aspergillosis is an opportunistic fungal infection caused by a fungus named Aspergillus Fumigatus. As the organism is opportunistic, it causes disease mostly in immunocompromised patients such as those going through transplantation, chemotherapy or leukemia.

Prions — Definition, Structure and Sterilization

Prion is a proteinaceous infectious agent that causes fatal degenerative disease. The protein is able to structurally transform a normal occurring protein into an abnormal structural protein that is transmissible to other prion proteins. They are the main cause of transmissible spongiform encephalopathies.

Childhood Epilepsy — Symptoms and Treatment

Seizures are the result of abnormal excessive neuronal discharge from the cerebral cortex that can lead to motor, sensory and autonomic manifestations. Seizures in children differ from adults in the etiology, presentation, treatment and prognosis. The children have less brain threshold for seizure activity so they are more vulnerable to seizure episodes than adults. At least 1% of children will experience afebrile pattern of seizure before the age of 14. EEG diagnosis is also different than adult seizures. Fortunately, childhood seizures can disappear with age without residual effects.

Membranoproliferative Glomerulonephritis (MPGN) — Prognosis and Treatment

Membranoproliferative glomerulonephritis (MPGN) is a type of immune mediated glomerular disease. The name is an indication of its pathology, with thickening of the basement membrane and proliferative changes. MPGN is categorized into three types: type I, type II (also called dense deposit disease) and type III. Students should be familiar with an overview of this condition, including its pathological features that set it apart from other glomerular disorders, as well as the diagnostic approach and management of MPGN.

Intracranial Aneurysm (Cerebral Aneurysm) — Symptoms and Differential Diagnosis

This article looks at the basic science, diagnosis and treatment of ruptured and unruptured cerebral aneurysms. It provides a brief overview of cerebral aneurysm management.

Vertigo — Causes, Symptoms and Treatment

This article provides an overview of vertigo in clinical practice – how it presents, how to differentiate it from dizziness, common differentials, their pathophysiology, treatments and complications. It also introduces the reader to the Dix-Hallpike manoeuvre used in vertigo diagnosis and the Epley manoeuvre used in the treatment of benign paroxysmal positional vertigo (BPPV).

Congenital Heart Disease (CHD) — Classification and Management

Congenital heart diseases are a broad set of structural defects in the heart present since birth that manifest from the perinatal period to late adulthood. Owing to specific chromosomal and single gene disorders, patients with CHD usually have significant problems involving other organ systems. A proper history and physical examination, along with an array of investigations, usually are sufficient to reach a diagnosis. While some diseases may resolve spontaneously (fossa ovalis ASD and small muscular VSD can close on their own), most of the children with cyanotic heart disease rarely survive beyond early childhood and hence, necessitate corrective surgical interventions.

Dementia — Signs and Symptoms

The reason for the more often occurring dementia is an increasing life expectancy, which leads before the background of the postulated age-depending prevalence to a drastic increase of cases of sickness, but what is dementia and how can it be diagnosed?

Hemoptysis — Etiology and Diagnostic Approach

Hemoptysis can be defined as the expectoration of blood during coughing that originates from the lower respiratory tract. Per this definition, coughing of blood from an upper respiratory tract illness can be excluded. While coughing blood can be alarming to the patient, it is usually a self-limiting symptom. In clinical practice, only 5% of the patients who present with hemoptysis are found to have a serious medical condition that needs further treatment.

Types of Seizures and Epilepsy during Pregnancy

Seizures are the result of abnormal electrical activity in the brain, which can be either stimulatory or inhibitory. The abnormal activity consists of repeated consistent discharges that can lead to motor, sensory, autonomic or behavioral dysfunction.

Sporotrichosis (Rose Gardener's Disease) and Classification of Mycosis

Mycosis is a fungal infection, affecting all animals, including human beings. It is subacute or chronic infection caused by saprophytic dimorphic fungus sporothrixschenckii. In addition to the pathophysiological state of the body, the environmental factors are equally contributing to the development of mycosis. The fungal infection usually begins either with the inhalation of the spores or through direct cutaneous invasion of the organism.

Coccidiomycosis (Valley Fever) — Symptoms and Diagnosis

Coccidiomycosis is a fungal infection caused by Coccidioides immitis and Coccidioides posadasii. The two organisms are genetically different but phenotypically identical. The clinical symptoms produced by these two species and the immunological response of the body are similar.

The Development of the Tongue

The tongue is the sensory organ for taste. The development of the tongue occurs between 4th and 8th week of the embryonic period of life. The first four pharyngeal arches contribute to its formation.

Cell Membranes — Fluid Mosaic Model, Membrane Proteins and Cytoskeleton

Membranes serve different functions in a cell. They are responsible for keeping unwanted particles out of the cell while letting important macromolecules enter the cell. They are also important in partitioning the cell into segregated and functional compartments. Given emphasis in this article is the fluid mosaic model for cellular membranes, the different proteins embedded in the membranes and the different roles they play in cell activity. Cytoskeleton and extracellular matrix are also discussed in this article.

Obstructive Sleep Apnea (OSA) — Symptoms and Treatment

Obstructive sleep apnea (OSA) is defined as episodic apnea, or cessation of breathing, during sleep, in which the period of apnea should last for more than 10 seconds. It is usually due to partial or complete collapse of the upper airway and is associated with snoring, restlessness, daytime headache and somnolence. The diagnosis relies on history and requires polysomnography for confirmation. Several medical as well as surgical treatment modalities are currently recommended and essential to prevent complications.

Types of Headache — Migraine, Cluster Headache and more

Headache is one of the most common symptoms in the emergency department and outpatient clinics. It can be a sign for serious illness that needs immediate action to prevent fatal consequences e.g. subarachnoid hemorrhage, meningitis and temporal arteritis. Headache also can be a sign of chronic physical and mental illnesses. Careful history taking and physical examination should be performed to any patient complaining of headache for proper diagnosis and management.

Lipid Metabolism: Fatty Acid Metabolism

Lipids are organic molecules that are composed of the elements carbon, hydrogen and oxygen, with the hydrogen to oxygen ratio greater than 2:1. They are highly hydrophobic because of having a long hydrocarbon chain. This family of compound includes fats, waxes, steroids and phospholipids. This article focuses more on the metabolic processes involved in processing fats and fatty acids.

Pregnancy Nutrition

All women during pregnancy have an increased demand for a nutrient supply. When the nutrient intake is compromised, the body uses the stored nutrients, and that makes a pregnant woman weak. Energy demands are the highest in the third trimester of pregnancy. Certain nutrient deficiencies are associated with congenital disabilities and other complications. The increase in energy requirements is due to increase in body weight of a pregnant woman, the energy needs of the fetus, and physiological changes occurring in the events of pregnancy. There is about 20 percent increase in caloric needs, 50 percent increase in micronutrients, and an additional 350-450 calories are required during 2nd and 3rd trimester. Energy requirements increase up to 12 percent and BMR increases on an average of 10-15 percent.

Spinal Cord Pathologies: Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), Poliomyelitis and More

This article looks at spinal cord pathologies. It runs through various conditions including spinal cord compression, syringomyelia, anterior spinal artery occlusion, multiple sclerosis, amyotrophic lateral sclerosis and B12 deficiency.

Angioedema (Angiooedema, Quinck's Edema, Angioneurotic Edema) — Causes and Treatment

Angioedema refers to swelling involving skin, mucosa, and subcutaneous tissues. It may be an isolated symptom or may be a manifestation of an underlying disorder. Etiology of angioedema with urticaria and angioedema without urticaria differs significantly and clinical presentation guides further investigations. In this article, etiology, pathophysiology, clinical features, diagnosis, differential diagnosis, and management of angioedema are described.

Lichen Planus (Lichen Ruber Planus) — Causes and Symptoms

The primary pathophysiology of lichen planus is CD8 cell-mediated damage to keratinocytes. Lichen planus can be found in various sites on the body. Topical steroids remain the mainstay of the treatment, but there are many others medications (e.g., retinoids) and therapies (e.g., UV-B) that have been tried. In this article, we will study the etiology, pathophysiology, clinical features, diagnostic techniques and the common treatment modalities for this condition.

Ichthyosis Vulgaris — Causes and Treatment

Ichthyosis vulgaris is a skin disease in which patients present with a scaly skin. Though there is no perfect cure for this disease, many therapies have been used successfully to limit the disease. In this article, we will study the etiology, pathophysiology, clinical features, diagnostic techniques and the common treatment modalities for this condition.

Allergic Contact Dermatitis (ACD) — Causes and Treatment

Allergic contact dermatitis is a delayed cell-medicated immune reaction from exposure to contact allergens. The substances that trigger ACD can be nickel, poison ivy and fragrances. ACD of acute onset usually represent erythema, pruritic vesicles and bulla whereas lichen with cracks and fissures are seen in chronic cases. Symptoms usually disappear with avoidance of known causative substance. Localized application of mid or high potency topical steroids like triamcinolone and clobetasol relives the acute ACD. Systemic steroid therapy is required in long standing and relapsing ACD. Patch testing is recommended if treatment fails.

Mononeuropathy (Peripheral Neuropathy) — Causes and Diagnosis

This article runs through the common presentations, pathophysiology, differential diagnoses and common therapies for mononeuropathies. It looks in detail at a number of common nerve injuries, including radial nerve, ulnar nerve, brachial plexus, phrenic nerve, common peroneal nerve and the femoral nerve. It covers common examination findings in order to make an accurate and specific diagnosis.

Bullous Pemphigoid (BP) — Causes and Treatment

Amongst all autoimmune blistering diseases, bullous pemphigoid is the most common one. Circulating antibodies are produced against the proteins present in the dermoepidermal junction (DEJ). In this article, we will study the epidemiology, pathophysiology, diagnosis, differential diagnosis, therapy and prognosis of bullous pemphigoid.

Pemphigus Vulgaris (PV) — Pathology Outlines and Treatment

Pemphigus vulgaris (PV) is a rare, chronic, autoimmune, intraepithelial disease characterized by blister formation involving skin and mucous membrane. PV is caused by autoantibodies, which are directed against target antigens present on the cell surface of keratinocytes. In this article, epidemiology, pathophysiology, sign and symptoms, differential diagnosis, diagnosis, prognosis and treatment of PV will be discussed.

Angelman Syndrome (AS; Happy Puppet Syndrome) — Symptoms and Genetics

Angelman syndrome (AS) is an infrequent, unusual autosomal neuro-developmental disease resulting from epigenetic sex-specific genomic imprinting and uniparental disomy of paternal chromosome 15 with a simultaneous functional loss of the maternal part 15q11-q13. With a focus on clinical, diagnostic and management aspects, this article encompasses a detailed discussion on the genetic mechanisms involved in AS.

Prader-Willi Syndrome (PWS) — Diagnosis and Treatment

Prader-Willi syndrome (PWS) is an unusual, rare complex autosomal neuro-developmental disease resulting from genomic imprinting and uniparental disomy of maternal chromosome 15 with a simultaneous functional loss of the parental part 15q11.2-q13. This article briefly elucidates the phenomenon of genomic imprinting, focuses on the diverse clinical features of PWS and concludes with the management of the same.

Morphea (Localized Scleroderma) — Symptoms and Prognosis

Morphea or localized scleroderma is a rare disorder with characteristic clinical features. The treatment of this disease involves the use of long-term immunomodulators. In this article, we will learn about the clinical features including the different types of morphea, pathophysiology, laboratory diagnosis, treatment using different modalities, and the prognosis of morphea.

Atopic Dermatitis (Eczema) — Symptoms and Treatment

Atopic dermatitis is a common, chronic dermatological disorder of unknown origin characterized by intense itching and eczematous lesions. In this chapter, after an introduction to general terminology for skin lesions, epidemiology, clinical features, diagnosis and management of atopic dermatitis are briefly discussed. As the diagnosis is purely clinical, differentiation from alternative diagnoses is also important. Emollients, topical corticosteroids and trigger avoidance constitute the mainstay of management.

Leading Causes of Death in the United States

Ranking the common causes of death among different age groups can be a useful tool in finding out the options to reduce cause-specific morbidity and mortality rates. It should be kept in mind that rankings, however, do not illustrate the mortality risk. The ranking of a specific cause as a reason for frequent deaths may change over time, even if the mortality rates have not changed. Similarly, ranking of a specific cause may remain the same, even though the mortality rate declines; therefore, it is not intelligible to conclude the mortality risk from the rankings of mortality rates.

Seborrhoeic Dermatitis (Seborrhoeic Eczema) — Causes and Treatment

Seborrhoeic dermatitis is a common chronic papulosquamous dermatosis with distinct infantile and adult forms, easily recognised clinically. Owing to its frequent recurrence in patients with HIV and AIDS, a careful evaluation of this pathology is warranted. The disease varies from mild to severe exhibiting a variety of forms including psoriasiform, pityriasiform and erythroderma.

Atypical Moles: Dysplastic Nevi and Benign Nevi

A nevus is a condition which occurs due to the increase in the number of melanocytes. The occurrence of the melanocytes can be both congenital, as well as acquired, and the melanin pigmentation can also be hypo- or hyper-pigmentation. The atypical mole differs from the benign nevus by the irregularity of shape, as well as an increase in size and number. The biopsy is required for diagnosis in doubtful cases and in which the confirmation is required. The treatment varies from observation (in the majority of cases) to medical (chemical peels using beta-hydroxy and retinoic acid) and, lastly, surgical treatment for the removal of the nevus.

Plexopathy — Definition and Causes

Plexopathy is a peripheral neuropathy at the level of the brachial or lumbosacral plexuses leading to sensory, motor or sometimes autonomic deficits. The etiology for this pathology vary from compression, inflammation, or ischemia to radiation.

Lyme Disease (Borreliosis) and Relapsing Fever — Diagnosis and Stages

In the following article, we present you all the relevant facts, tips and exam questions from the first symptoms to the treatment of the infection with borrelia.

Viral Hepatitis — Epidemiology and Symptoms

Viral hepatitis can be caused by different kinds of viruses which include hepatitis A, B, C, D, and E. These viruses cause targeted inflammation of the liver. In the acute stage, patients develop non-specific symptoms, such as nausea, vomiting, anorexia and abdominal pain. Later on, jaundice becomes evident. During this stage, supportive therapy is important. Antiviral therapy is indicated in the acute and chronic stages of hepatitis B and C.

Pediatric Atrial Septal Defects — Classification and Surgery

Atrial septal defect and patent foramen ovale, represent diverse congenital heart diseases with the common denominator being a defect of a closure of atrial septum. Embryologic development of atrial septum is essential in order to understand anatomic, pathophysiologic and clinical presentation of ASD that presents as asymptomatic, usually in children, to symptomatic forms that are mainly found in adults with long-term complications such as atrial arrhythmias, pulmonary hypertension, and heart failure. Clinically symptomatic patients present with fatigue, dyspnea, exercise intolerance and atrial arrhythmias. Management options, when needed, include defect closure either by transcatheter device closure or open surgery procedure.

Lichen Simplex Chronicus (Neurodermatitis) — Causes and Symptoms

Lichen simplex chronicus (LSC), also known as localized neurodermatitis, is a skin disorder characterized by the thickening of the skin (lichenification) due to excessive scratching. This is frequently due to an itch–scratch cycle that can develop due to various skin or psychogenic causes. The common sites are the ends of extremities, genitals and neck, and the symptoms can vary in severity. Stopping the scratching is crucial, and treatment (often with topical steroid cream/ointment) can be lifelong if the disease is recurrent.

Developmental Milestones in Newborns: Adaptation to Extrauterine Life

In the early phases of extrauterine life, the human body goes through various circulatory, thermoregulatory, renal, pulmonary, immune and metabolic adaptations to achieve proper function outside the protective environment of the womb. The process of birth lays significant challenges for the newborn.

Developmental Milestones in Newborns: Apgar Score and Low Birth Weight

APGAR score is a standard tool for the assessment of newborn babies. APGAR is an acronym for Appearance, Pulse, Grimace, Activity, Respiration. It is a short test performed at 1 and 5 minutes after the baby’s birth that is done to determine the need for breathing aid and any heart trouble the newborn might be experiencing.

Developmental Milestones from Birth to 3 Years of Age: General Facts

Developmental milestones are the functioning skills or acts which most children can perform when they reach a certain age. The pediatrician uses these milestones to check the development of a child at different stages. Each milestone determines an age. However, the actual development stage of the child can vary based on the fact that children are not identical. There are four major types of developments in each milestone, namely motor, sensory, communication and feeding.

Neuromuscular Disease: Myasthenia Gravis, Guillain-Barré Syndrome, Duchenne Muscular Dystrophy, ALS and More

Disorders of neuromuscular origin can be caused by muscular diseases, neuromuscular junction or their neurological supply. Neurological disorders can be in the peripheral nerves, motor cells in the spinal cord, motor tracts in the spinal cord, brain stem nuclei, tracts and cerebral cortex.

Tinea Infections — Symptoms and Treatment

Tinea infections are caused by different fungi species that are known to infest the skin, nails and hair. The infections can be classified according to the affected site into Tinea corporis, Tinea pedis and Tinea capitis. Tinea corporis and Tinea pedis can be easily diagnosed clinically and patients should receive topical anti-fungal therapy once the diagnosis is confirmed. Patients with Tinea capitis should receive combined topical and systemic anti-fungal therapy. Patients with Tinea nail infections should undergo a confirmatory test, such as potassium hydroxide preparation or culture, before initiating therapy.

Plantar Wart (Foot Wart) — Causes and Treatment

Plantar warts are hyper-keratinized skin lesions that are found on the planter surfaces of the feet and hands. They are caused by the human papillomavirus and are usually painless. Despite being painless, they can cause embarrassment to the patient and can interfere with normal daily functions such as walking when they are found in the plantar surface of the feet. Treatment can either be ignorance of the warts, topical non-specific therapy or destruction of the epidermal cell layer by chemical or physical agents.

Squamous Cell Carcinoma (SCC, SqCC) — Classification, Symptoms and Treatment

Cutaneous squamous cell carcinoma represents one of the most common malignancies in humans. The malignant tumour arises from suprabasal epidermal keratinocytes that invade the dermis and together with basal cell carcinoma, forms the most common malignancies of skin to affect humans. But unlike basal cell carcinoma that is thought to arise de novo, this non-melanoma skin cancer is thought to evolve from precursor lesions of actinic keratosis (AK) and Bowen’s disease. The clinical appearance is highly variable but a strong suspicion must be kept in mind if a non-healing lesion presents, specially on sun exposed areas. Histopathological evidence helps in establishing the diagnosis. While a multitude of treatment options are available, prevention in patients with predispositions should attract more attention.

Berylliosis — Symptoms and Treatment

Inhalation of Beryllium (Be) dust, or its vapors or compounds, or subcutaneous implantation of Beryllium can lead to either acute or chronic beryllium disease, also known as berylliosis. It can affect genetically susceptible individuals or workers exposed to the fumes or vapors of the metal. It was first described by Hardy and Tabershaw in 1946. Beryllium can cause either an immediate acute form of illness or insidious chronic berylliosis.

Stable and Unstable Angina Pectoris — Symptoms and Diagnosis

The main symptom of coronary heart disease is angina pectoris, which can be divided into a stable and an unstable form.

Anticholinergic Drugs — Definiton and Classification

In this article, we will study the important pharmacological aspects of anticholinergic drugs such as classification, pharmacokinetics, mechanism of action, important actions on various organ systems, clinical uses, drug interactions, adverse effects and toxicity.

Anatomy and Diseases of the Vertebral Artery

The vertebral artery (VA) arises from the first part of the subclavian artery and ascends in the neck to supply the posterior fossa and occipital lobes. It also provides segmental vertebral and spinal column blood supply. The vertebral artery is normally 3-5 mm in diameter. Ostium is the most common site of stenosis.

Genomics: Mapping and Sequencing Genomes

Genomics is the study of what the genome does. In this article, we include the topics of distinguishing between genetic and physical maps, describing the process of DNA sequencing and characterizing two different methods for sequencing genomes— the clone-by-clone vs. shotgun sequencing.

Human Genetics & Inheritance

Chromosomes are the cellular carriers of genes and are the functional unit of heredity. First described by Mendel in 1865, each gene can exist in an array of different forms called alleles. Hereditary traits are passed to offspring through alleles each given by the parents. The distribution of homologous chromosomes during meiosis, of which one of each pair is randomly chosen, is conveyed to each haploid cell. Genes are passed to the offspring, and each time that the genome is replicated, transcribed, and translated, proteins that reflect the combination of hereditary traits is reflected in the phenotype.

Anaphylactic Shock (Anaphylaxis) — Symptoms and Treatment

The typical situation of an anaphylactic emergency: as an emergency physician you are called to a child who was stung by a wasp while playing in a swimming pool. When you arrive, the little patient is barely conscious, the skin is red and covered with welts. The carotid pulse is barely palpable. The connected ECG shows a tachycardia of 180/min. In addition, you recognize a strong wheezing and humming in all lung sections. The diagnosis of anaphylactic shock is made quickly. But how do you react properly in this situation? And what are the causes of this disease? Answers can be found here.

Skin Cancer: Basal Cell Cancer (BCC) and Melanoma (Malignant Melanoma)

Neoplasms of the skin can be hard to differentiate clinically, but nevertheless they can result in entirely different consequences. While the colloquially called “white skin cancer” describes rather harmless changes of the skin, the “black skin” cancer is feared. As other doctors from different specialties, other than dermatologist, are also consulted when discussing diagnostic findings of their patients’ skins, it pays off to know the most common types of skin cancer.

Appendicitis — Definition and Surgery

Appendicitis is a common and serious gastrointestinal disease that affects many people every year. It can be very acute and painful and, if it is not treated quickly, it can be fatal. We will explore the mechanics behind appendicitis; the causes, treatments and complications that can arise. Appendicitis is commonly examined as it is fairly prevalent, acute and can be very serious.

Vitiligo — Symptoms and Treatment

Vitiligo is a skin condition that is quite common. This is why you should be able to recognize it in clinical practice. Due to its association with other autoimmune disorders, vitiligo is also a frequently examined topic. This article explains the most relevant information for purposes of clinical practice and medical examination.

Nucleotide Metabolism – Purines and Pyrimidines

Nucleotide metabolism results in the synthesis of the four nucleotides that form DNA. These are further divided in two categories: purines and pyrimidines. Their construction and degradation takes place in a progression of single steps, while different enzymes and cofactors are involved in the process. Beside degradation, there is also a form of reprocessing purine and pyrimidine nucleotides, defined as Salvage-pathways.

Bacterial, Viral and Fungal Infections of the Central Nervous System

If a patient suffers from neurological symptoms, lots of differential diagnoses have to be considered. The following article is organized according to the different pathogens: bacteria, viruses, protozoa and fungi. Learn and repeat everything from the approach from acute bacterial meningitis to virally-triggered CNS infections with HSV, ESME, VZV and CMV, and to opportunistic infections in immunodeficient patients. This way, no neurological question in the second state examination concerning infectious diseases of the CNS remains unclear!

Biochemical Pathways: The Pentose Phosphate Pathway

Both glycolysis and its parallel metabolic, the pentose phosphate pathway, start with the breakdown of glucose, i.e. glucose-6-phosphate. Divided into two distinct phases, the pentose phosphate pathway generates NADPH and pentoses, which can be used in other metabolic pathways. The pentose phosphate pathway is a small, but very important biochemical pathway physicians should be aware of, as, for instance, the metabolic disorder glucose-6-phosphate dehydrogenase deficiency (G6PD) may impart a distinct selective advantage against malaria.

Pheochromocytoma (PCC) — Diagnosis and Surgery

There are two types of catecholamine secreting tumors: pheochromocytomas which arise from the chromaffin cells of the adrenal medulla and paragangliomas which arise from the sympathetic ganglia or other cells derived from the neural crest. Catecholamines include epinephrine and norepinephrine, and both are released upon the stimulation of the sympathetic preganglionic nerve fibers during times of stress or sympathetic activation.

Bilirubin and Biliverdin Reductase

Bilirubin is a yellow compound that is the product of the catabolism of ageing heme. It can be used to determine abnormality in liver functions as characterized by the yellowing of skin and mucous membranes such as sclera of the eyes and dorsum of the tongue. In this article, we will discuss about the biochemistry of bilirubin; specifically, the synthesis of the compound and the important enzymes used in the synthesis of this biomolecule.

Single Gene Disorders: Fragile X Syndrome (FXS, Martin-Bell Syndrome) — CGG Expanding Repeat

Single gene disorders are caused by defects in a single gene. Although they are rare, they affect approximately 1% of the population. These can be dominant, recessive or X-linked. On the other hand, trinucleotide repeat or CGG expanding repeat disorders are characterized by the repetition of the trinucleotide sequence in certain genes leading to gene defects and disorders. Examples of trinucleotide repeat disorders include Fragile X syndrome, Huntington’s disorder, and Spinocerebellar ataxia.

Erythema Multiforme — Definition and Treatment

Erythema multiforme (EM) is a type of cytotoxic dermatitis, which can be triggered by many factors; mainly herpes simplex infection and drugs being the implicating factors. Although it is self-limiting, recurrences are common. In this article, definition, epidemiology, aetiology, pathology, pathophysiology, symptoms, diagnosis, differential diagnosis, therapy, prognosis and progression of EM will be discussed.

Alopecia Areata (AA, Patchy Hair Loss) — Causes and Treatment

Alopecia areata is an autoimmune disease of unknown etiology characterized by recurrent non-scarring hair loss in hair bearing areas, ranging from a small patch to complete loss of hair. It is a benign condition occurs usually without symptoms. Burning sensation and pruritus in affected area can be present in rare cases. Other autoimmune diseases maybe associated such as thyroid diseases and vitiligo. A scalp biopsy may be required for diagnosis in some cases. Treatment is based on the type of alopecia which includes topical minoxidil, corticosteroids (topical, intralesional, or oral), or anti-androgens.

Erythema Nodosum — Differential Diagnosis and Treatment

Erythema nodosum (EN) is a reactive process of the skin which can be triggered by a number of factors. EN is an acute, but self-limiting disease with preponderance for females in 20 to 40 years of age. In this article, epidemiology, etiology, pathophysiology, symptoms, diagnosis, differential diagnosis and therapy of EN will be discussed.

Traumatic Brain Injury: Management of Increased Intracranial Pressure (ICP)

Traumatic injuries due to traffic accidents, sports or violence induced incidents, represent one of the major causes of morbidity and mortality nowadays. Significant portion of all trauma cases include head trauma, which can be divided into fractures, brain traumatic injuries, hematomas (both extra axial and parenchymal) and diffuse axonal injuries (DAI). Recognition of the signs and symptoms is of uttermost importance, for head trauma can be as mild as every day bruises and bumps to the head, or severe and life threatening. Rapid recognition, dedicated diagnosis and adequate imaging which lead to proper treatment - both conservative and surgical - are essential for the best possible, complication- and sequel-free, outcome.

Increased Intracranial Pressure (ICP) — Diagnosis and Treatment

This article provides a clinical run through increased intracranial pressure for the USMLE step 2 examination. It defines raised ICP, goes through its pathophysiology, progression and special forms, diagnosis, differential diagnosis and treatment (management, including patient monitoring). References for the work are included at the bottom.

Thoracic Trauma: Management of Tension Pneumothorax, Rib Fracture, Pulmonary Contusion

Thoracic traumatic injuries can be generally classified according to the mechanism of injury as blunt or penetrating chest injuries. Chest injuries can be also classified according to the site of injury as chest wall, lung, heart, major blood vessel, and esophageal injuries. The extent and specific type of thoracic traumatic injury can be identified by a proper history and physical examination that is supported by adequate imaging studies. The treatment includes fluid therapy and oxygen supplementation in addition to specific treatments depending on the specific type of injury.

Segregation of Chromosomes with Inversions

Inversion is a type of chromosomal mutation which involves breakage and subsequent reunion of the same chromosomal segment, but in a reverse order. This article encompasses basics of inversion and concludes with segregation characteristics and clinical implications of the same.

Immunofluorescence Diagnosis in Vesiculobullous Dermatitis

Learn more about the use of immunofluorescence to differentiate between Bullous Pemphigoid and Memphis Vulgaris.

Urticaria (Hives) — Definition and Treatment

Urticaria is a very common dermatological condition, which is classified into acute urticaria and chronic urticaria based on the duration of the symptoms. The etiology is different for acute and chronic urticaria. Diagnosis requires a thorough history-taking and physical examination, and a laboratory evaluation may be helpful depending upon the underlying etiology. In this article, etiology, pathophysiology, clinical features, diagnosis, differential diagnosis, and management of urticaria will be discussed.

Polyneuropathies — Duchenne Muscular Dystrophy, Limb Girdle Muscular Dystrophies, Channelopathy

This article deals with a number of polyneuropathies. It includes the myopathy junction and dystrophinopathies (Duchenne muscular dystrophy and Becker muscular dystrophy), as well as Limb-Girdle muscular dystrophies and channelopathies, mitochondrial, inflammatory, endocrine and drug induced myopathies. It runs through each disease associated with these pathologies, their etiology/pathophysiology, and diagnosis including history, examination and investigation, and the treatment of the diseases where appropriate.

Polyneuropathies — Myasthenia Gravis, Peripheral Neuropathy, Entrapment and More

This article deals with a number of polyneuropathies. It includes entrapment, compressive and peripheral neuropathy. It also includes information on the neuromuscular junction and myasthenic gravis, Lambert-Eaton Myasthenic syndrome and Botulinum toxin. It runs through each disease associated with these pathologies, their etiology/pathophysiology, and diagnosis including history, examination and investigation and the treatment of diseases where appropriate.

Sex Chromosome Disorders

Sex chromosomes have a pivotal role in sex determination. Aberrations of sex chromosomes in diverse ways at different stages of development of an individual result in disorders of sex development (DSD); the understanding of which is often garbled. With a brief introduction to sex determination and sex chromosomes, this article aims to simplify the concept of DSDs.

Goldilocks Principle and Monoallelic Expression

Monoallelic gene expression refers to the allele-specific expression of genes. Only one allele of the gene is actively transcribed. It can occur in different ways, such as genomic imprinting, random choice of one allele, and X-inactivation. Other allele expressions are balanced and unbalanced expressions. Balanced expressions have both alleles equally expressed, whereas unbalanced ones do not express each allele equally. Goldilocks principle states that everything should fit in a certain margin; neither too much nor too less. When the amount of gene product changes, it no longer follows the “just right” principle of Goldilocks.

Movement Disorders: Progressive Supranuclear Palsy, Corticobasal Degeneration and Multiple System Atrophy

There are many parkinsonian disorders that present similarly, but are not Idiopathic Parkinson's disease. These include Progressive Supranuclear Palsy, Multiple System Atrophy and Corticobasal degeneration. This article outlines the definition, epidemiology, pathophysiology, diagnosis management and prognosis of these conditions.

Melasma (Chloasma) — Definition and Treatment

Amongst the most common hyperpigmentation conditions, melasma affects a large number of women, especially during pregnancy. Read on to find out more about its causes and the various modalities of treatment that exists for its alleviation.

Nutritional Considerations for Older Adults

With the advancement of age, older adults go through changes that have an impact on their nutrition. Changes can be physical, psychological, health-related or social. Their extent varies among different individuals. Senior citizens can enjoy a quality of life despite these changes, given that they are healthy. Malnutrition is a result of not getting adequate caloric intake and nutrients. Older people are at a greater risk of developing malnutrition. Moreover, if this is combined with disease, it would lead to the spiral of dependence and hospitalization.

Introduction to Vitamins

Vitamins are the organic compounds which are required in small quantities for normal growth, reproduction and maintenance of the human body. They are different from other organic food stuff because they do not go through the degradation processes to provide energy, and do not enter the tissue structure. Moreover, several B vitamins act as a coenzyme in various metabolic reactions of the body. Vitamins are also different from hormones as they are not produced by the body and have to be taken through diet. They are classified on the basis of their biological and chemical activity.

Brain Herniation — Types, Symptoms and Radiology

Brain herniation is a potentially fatal condition that may present as a rise in intracranial pressure. The following text describes the various clinical signs to recognize this condition and the possible measures one can take to treat it.

Aging: Mitochondrial Dysfunction and Telomere Attrition

Ageing is a genetic but environmentally modulated process that one becomes older. There are various theories hypothesized to elucidate aging, such as loss of telomere length (telomere attrition), increase in p13 expression and mitochondrial dysfunction which arises from errors in replication and mutations. The three pathways culminate into accumulation of reactive oxygen species and onset of age related diseases such as cancer and degenerative diseases.

Biochemistry for Physicians: Cholesterol Metabolism

Cholesterol (Greek for: ‘gall’ and ‘solid’) is a media star: For decades, no other biochemical substrate draws as much attention as cholesterol has. But what are the hard pre-clinical facts? How is cholesterol synthesized and degraded in the human body? How is cholesterol metabolism regulated? The following article presents you with useful information that will aid you in your exam preparation.

Membrane Lipid Metabolism

Lipids are a large and diverse group of naturally occurring organic compounds that have relatively very low solubility in water and higher solubility in non-polar organic solvents. Different types of lipid molecules include fatty acids, fats, oils, waxes, phospholipids, eicosanoids, steroids etc. The focus of this article is on two types of lipids, namely glycerophospholipids and sphingolipids. Specifically, the article emphasizes on the synthesis of these two types of lipids.

Cryptococcosis — Symptoms and Diagnosis

Cryptococcosis is a fungal infection caused by Cryptococcus neoformans and Cryptococcus gandii. The encapsulated organisms are inhaled and survive in the respiratory tract without causing any harm. However, depending upon the immunity of the individual, it may result in several clinical diseases. Cryptococcosis is therefore known as an opportunistic infection. Patients with immune deficiency such as HIV, corticosteroid therapy or reticulo-endothelial malignancy may suffer from the additional debilitating effects of the disease.

Arteries of the Upper Limb

The arteries of the upper limb such as brachial and radial arteries are often palpable clinically and used in measuring blood pressure, pulse rate and drawing blood samples for arterial blood gases analysis (ABG).

Steroids and Bile Acids: Mevalonate Pathway and Receptor-mediated Endocytosis

Lipid is one of the biomolecules important to humans. They serve a number of purposes in human metabolism. In the absence of carbohydrates, acetyl CoA does not enter the TCA cycle, instead, are processed to form ketone bodies, cholesterol, steroid hormones, and bile acids. This article focuses on the metabolism of these four compounds.

Proximal Convoluted Tubule (PCT): Clinical Effects of Fanconi Syndrome and Hartnup Disease

Proximal tubule is divided into proximal convoluted tubule (PCT) and proximal straight tubule (PST). The proximal convoluted tubule is the convoluted portion of the nephron that extends between the Bowman’s capsule and the loop of Henle. Its main function is to reabsorb salt and water, organic solutes like sugar and amino acids, potassium, urea, and phosphate. It also secretes ammonium in the urine.

Coronary Steal Syndrome — Definition and Symptoms

An incongruous alteration in the flow of blood in the form of steal syndromes is a well-known complication of coronary artery bypass grafting (CABG). It might be discovered incidentally, that is during an ultrasonographic or angiographic examination performed for any other indications, or during the clinical examination, finding of reduced blood pressure or unilateral upper-limb pulse. Treatment mostly comprises of open subclavian artery revascularization, normally via carotid-subclavian bypass or subclavian artery transposition, and new less invasive options which are endovascular intervention with recanalization, angioplasty with stenting if needed.

Connective Tissue Diseases Associated With Restrictive Lung Disease: Nonspecific Interstitial Pneumonia (NSIP), Scleroderma, Dermatomyositis and Polymyositis

Diseases of the lung are classified as obstructive lung diseases like chronic obstructive pulmonary disease or cystic fibrosis, and restrictive lung diseases.

Tubulointerstitial Disease — Phases and Algorithm of Acute Kidney Injury

These are kidney diseases that involve structures outside the glomerulus. The causative agents incite a hypersensitivity reaction that leads to an inflammatory infiltrate seeding into the kidneys interstitium and irreversible features of fibrosis and sclerosis. This leads to the diseases presenting as an acute kidney injury that may end up as an end stage renal disease. Management is per the acute renal injury algorithms that advocate for identification of the inciting agent and its discontinuation alongside watching out for end stage renal disease and timely institution of renal replacement therapy.

Paraneoplastic Syndromes — Carcinogenesis

Paraneoplastic syndromes are rare disorders caused by a change in immune system response to a neoplasm. It is a disorder that produce a nonmetastic impact on systemic organs due to production of substances by the remote tumor cells in the body. Carcinogenesis, also known as tumorigenesis which stands for the process of transforming a normal cell into a cancerous cell. Strictly defined carcinogenesis represents the initiation of a tumor-forming process, while oncogenesis represents maintenance of the tumorous state in cells that have already changed into a cancerous state. The process is largely dependent on the imbalance between proliferation and programmed cell death (apoptosis) in the cell division pattern.

Renal Diagnostics — Renal Corpuscle, Changes in Glomerular Dynamics, and the Renin Angiotensin Aldosterone System

The kidneys are paired retroperitoneal organs that weigh about 150 grams each. Each kidney is lined by fibrous capsule for protection.

Hematopoiesis and Benign Blood Cell Disorders — Symptoms and Treatment

Hematopoiesis is the process of blood cell formation. It begins in embryogenesis and progresses to adulthood to replenish the cellular component of blood. The sites of hematopoiesis include the yolk sac at the embryological age of 0 - 2 months and the liver and spleen during the embryological age of 2 - 7 months. The bone marrow and thymus are definitive sites of hematopoiesis that take over the function from 8 months to adulthood. Extramedullary hematopoiesis in the spleen and liver can either the bone marrow is destroyed and cannot fulfill the function anymore.

Pituitary Gland Disorders — Hypothalamic–Pituitary–Thyroid Axis (HPT-Axis), Pituitary Sellar Masses, Pituitary Apoplexy and Sheehan’s Syndrome

The pituitary gland/hypophysis is in the Sella turcica/pituitary fossa which is a part of the sphenoid bone and forms the cranial fossa. The gland is divided into the posterior and the anterior pituitary. The most common cause of these disorders is pituitary tumors which are mostly benign (Adenomas) in nature. Diagnosis in most cases is made with MRI, CT imaging and laboratory work-ups. Treatment approaches for pituitary gland disorders involve various methods including medication and surgery. Prognosis depends on the diagnosis.

Intimate Partner Violence (IPV) and Sexual Assault

Physicians, especially family physicians, are often the first contacts for survivors of intimate partner violence and occasionally for sexual assault victims too. Both these problems are prevalent worldwide with both sexes being affected, although women are more affected than men. Besides physical harm and death, intimate partner violence (IPV) and sexual assault can also cause psychological and psychiatric problems. Family physicians should be prepared to identify and provide supportive care to these patients.

Autoimmune Hepatitis — Causes and Diagnosis

Autoimmune hepatitis is a progressive necroinflammatory process leading to chronic hepatitis or cirrhosis. It is characterized by the presence of circulating autoantibodies and high serum globulin concentrations. The pathogenesis of autoimmune hepatitis is unclear; however, a proposed mechanism suggests overactive T cells in genetically susceptible patients. Autoimmune hepatitis is characterized histologically by certain non-specific findings, making the measurement of autoantibodies and gamma globulins essential for diagnosis. It is also essential to differentiate autoimmune hepatitis from other forms of hepatitis.

Defense Mechanisms — Mature Defenses, Neurotic Defenses, and Immature Defenses

When there is a conflict between a person’s subjective moral sense and the person’s thought, feeling, or action, the ego uses defense mechanisms to keep them away from conscious awareness. These subconscious defense mechanisms serve to protect the self from unpleasant feelings, which often including anxiety, shame, and/or guilt. Although these are normal occurrences, used in excess, they can hinder insight or treatment compliance.

Hyperprolactinemia — Symptoms and Treatment

Hyperprolactinemia is defined as a condition of high prolactin levels in the blood. Many factors are attributed to the development of hyperprolactinemia. Bromocriptine or cabergoline are the first line of drugs for the treatment. Refractory cases require a surgery or radiation therapy in case hyperprolactinemia is caused by macroprolactinoma. This article discusses possible causes, diagnosis, treatment and management of hyperprolactinemia.

Types of Fibrocystic Change — Findings and Treatment

Fibrocystic breast changes are considered changes that mimic but do not achieve the threshold to be considered malignant conditions of the breast. They are changes that may be seen even in normal breast tissue. They are common in women of childbearing age 30-50 years old who have had hormonal influence by estrogen, progesterone, and prolactin for years. These changes stop after menopause and thus the occurrence of such changes is rare after menopause. The changes are classified into either non-proliferative change such as cystic lesions or proliferative changes without atypia such as epithelial hyperplasia

Hemoglobin and Movement of Oxygen

Hemoglobin is the iron-containing metalloprotein that is responsible for oxygen transport in vertebrates. It is present in the blood and functions mainly to carry oxygen from the lungs to the other parts of the body, and carbon dioxide from the body to the lungs for eventual elimination. This article will focus on the basic structure and function of hemoglobin.

Female Sexual Dysfunction — Symptoms and Treatment

The female sexual response is non-linear and complex and is intricately associated with feelings of intimacy and satisfaction. Female sexual dysfunction, therefore, can be a result of stresses and interpersonal conflicts, as well as physical illness or medication/substance use. The disorder can be due to lack of (adequate) desire, arousal, or orgasm, or presence of pain. The diagnosis can be tricky as there is frequently an overlap and underlying medical or psychiatric disorders need to be ruled out.

Overview of Personality Disorders: Cluster A, Cluster B and Cluster C Personality Disorders

Personality disorders are a cluster of mental diseases that involve semi-permanent patterns of thoughts and behavior which can be harmful and obstinate. These individuals have difficulties in handling everyday stresses and issues and their behavior can lead to serious issues with relationships and work. It has been seen that this disorder normally starts in the teen years or early adulthood. The clinical signs of personality disorder include emotional dysregulation, impulsive aggression, repeated self-injury, and chronic suicidal tendencies. Identifying this diagnosis is the most important thing for treatment planning.

Cellular Senescence and Stem Cell Aging

Cellular senescence is the cessation of theprocess of division of the cells. Aging is an insidious definite decline in a cell’s functionality, vigor, and vitality. Recent advances in biomedical research, cytogenetic and molecular studies have brought forth fascinating theories to expatriate aging and, more importantly, to tame aging to modulation by genetic and pharmacological manipulations. This article focuses on the effect of cellular senescence and stem cell exhaustion on aging and the subsequent clinical implications.

Precursor of Thyroid Hormones

Tyrosine is one of the amino acids that play a big role in a number of physiological processes. They are precursors for some hormones and neurotransmitters needed by the body for metabolic functions. In this article, the chemistry of tyrosine will be discussed. The article will answer how it is metabolized to produce the different hormones and neurotransmitters.

Suicide Risk Assessment

Patients with chronic medical conditions, those with psychiatric disorders such as a major depressive disorder, and veterans and those with psychotic disorders are at an increased risk of suicidal ideation, attempt, or death. The assessment of suicide risk in the patient is very important as it can help in preventing a serious suicide attempt that might cause death; therefore, the main purpose of suicidal risk assessment tools is to direct and guide specific suicide prevention interventions.

Schizophrenia

Schizophrenia is a complex, chronic mental health disorder that is characterized by several different symptoms which include delusions, hallucinations, disorganized speech or behavior, and impaired cognitive ability. Schizophrenia has an early onset and a chronic course, making it a disabling disorder for the patient and his or her family. In the following article, you will learn about the pathophysiology, etiology, and treatment of Schizophrenia.

Class 5: Other Antiarrhythmics – Antiarrhythmic Drugs

Miscellaneous antiarrhythmic drugs are those whose mechanism of action cannot be attributed to a single class of effect, and every drug inside the group acts by a different class of actions. This group of drugs isn't always the first line of treatment for many conditions, and their use is limited to few specific conditions.

Mycosis Fungoides (Alibert-Bazin Syndrome, Granuloma Fungoides) — Signs and Symptoms

Skin lesions have a broad range of etiology and can be complex in diagnosis due to their similar appearance on inspection. Cutaneous T-Cell lymphoma is a rare skin disease that presents with several distinct manifestations. Most common of this manifestation is Mycosis Fungoides and Sezary syndrome. Mycosis fungoides is a slow progressing set of mushroom shaped skin lesions, while Sezary syndrome is a rapidly progressing generalized skin disease with a worse prognosis.

Population Genetics — Hardy-Weinberg Principle and Cancer Genetics

Population genetics is the study of the genetic variation in the population. Using mathematical and statistical models, molecular basis of genetics, Mendel’s laws and modern evolution, population genetics determines how the gene and allele frequency changes over time and the factors which influence it. The study helps to determine populations with a large genetic variation (and therefore more likely to adapt), versus populations with lower genetic variability (and therefore with a lesser possibility of adapting) to environmental changes.

Prenatal Diagnosis and Prenatal Screening — Methods and Tests

Prenatal screening is used in clinical practice to detect the necessity for carrying out more detailed and invasive tests for the diagnosis of aneuploidies and congenital or developmental birth anomalies. Ideally prenatal screening should be made available to all pregnant women with more invasive testing being offered to those at increased risk. Ultrasonography is an excellent prenatal screening tool while prenatal diagnosis requires invasive tests like chorionic villus sampling, amniocentesis and fetal blood sampling.

Attention-Deficit/Hyperactivity Disorder (ADHD) in Children

Attention deficit hyperactive disorder is a developmental condition of inattentiveness and easy distractibility with accompanying episodes of hyperactivity. The disease affects about 8–12 % of children in the world, while the worldwide adulthood prevalence is 4–5 %. The disease arises from genetic mutations that may occur due to toxin exposure or hypoxic-ischemic brain injury in the perinatal period. These etiologies cause neurotransmitter deficiencies or structural changes in the brain areas involved in the control of attention and mood.

Delirium, Vascular Dementia, Frontotemporal Dementia and more

Dementia is a syndrome of impairment of cognition and memory accompanied by interference of daily life activities, without a disturbance in consciousness or level of alertness. Dementia should always be differentiated from normal memory loss that occurs with ageing. This change enhanced by old age does not meet the criteria and severity for dementia that limits a person’s physical activity.

Porphyria — Symptoms and Treatment

Porphyria is a group of disorders that arise from a build-up of chemicals that are involved in the production of porphyrin in the human body. The porphyrins are important as these are essential components of the hemoglobin that carries oxygen to the organs and tissues of the body. When there is a high level of porphyrins in the body, different symptoms or manifestations related to porphyria show.

Pediatric Sleep Disorders: Nightmares, Breath-holding Spells and Infant Colic

Infants are likely to undergo sleep problems especially during the first year of life. Nightmares, night terrors, infant colic, and breath-holding spells are common sleep issues. While nightmares may occur at any age, the night terrors, on the other hand, are typically observed during 3—8 years of life. Approximately, 28% of infants are affected by colic. It leads to intense crying episodes in infants who are 1—6 months old. A breath-holding spell is a non-epileptic disorder of benign nature.

Toilet Training in Infants and Enuresis — Causes and Treatment

Toilet training includes training your child to control their bladder and bowels. Girls achieve bladder and bowel control earlier than boys. Enuresis is the voluntary or involuntary voiding of urine during sleep after bladder control is expected to have been achieved. Soiling, also known as encopresis, occurs when the child fails to use the toilet for bowel motions resulting in dirty pants. It is caused by emotional stressor and chronic constipation, resulting in large stool volumes to signal the need to defecate.

Deregulated Nutrient Sensing and Altered Intercellular Communication

Aging is an insidiously progressive deterioration in the physiological integrity of a cell resulting in impaired function . With an impetus to biomedical research and advances, it has come accross a multitude of theories expatiated to reason aging. This article focuses on deregulated nutrient sensing and altered intercellular communication and their potential role in diminution of a cell’s vigor, aging and longevity of life.

Genome Instability and Aging

Aging is a complex, mysterious but inevitable end point of a cell’s existence. Numerous theories have been propagated to expound the same; but the unequivocal evidence still eludes us. In this article, after reviewing the basics of aging, we focus on genomic instability and aging.

Adrenal Insufficiency (Addison's Disease, Hypocortisolism) in Children — Symptoms and Treatment

Adrenal insufficiency is defined as inadequate production of adrenocortical hormones (glucocorticoids, mineralocorticoids, and adrenal androgens). Adrenal insufficiency can be primary or secondary. Primary adrenal insufficiency (Addison's disease) is caused by diseases in the gland itself, and the most common cause is autoimmune adrenalitis. Secondary adrenal insufficiency occurs due to decreased production of ACTH either from prolonged glucocorticoid therapy or disease in pituitary/hypothalamic glands. Glucocorticoids therapy is required for both forms of Adrenal insufficiency. Adrenal crisis is a well-recognized life-threatening complication that requires high doses of hydrocortisone and intravenous fluids.

Pediatric Trauma: Primary and Secondary Survey — Checklist

Pediatric trauma is common in children and accounts for most of the deaths in children younger than 1 year of age. While head trauma is the leading cause of death in children, most children with significant traumatic injuries have multiple injuries.

Multifactorial Inheritance

Several inherited disorders occur as a result of defects in one single gene or due to chromosomal abnormalities; however, some disorders can occur due to defects in several genes and these traits or features can be classified as either multifactorial or polygenic. This article will discuss commonly used terminologies, their definitions, different traits, their risk assessment and examples of multifactorial disorders.

Prions and Transmissible Spongiform Encephalopathies (TSEs)

Prions are small proteinacious, infectious particles that causes transmissible spongiform encephalopathies (TSEs). Prions cause a number of diseases in animals that include Mad Cow Disease, Kuru, Fatal familial insomnia, and chronic wasting disease. In this article, prions and diseases associated with them will be discussed. More emphasis will be given to Mad Cow Disease and Chronic Wasting Disease. The history of prion discovery will also be reviewed in this article.

Aging: Epigenetic Alterations and Loss of Proteostasis

Aging is a physiologic process marked by cellular inability to respond adequately to stresses. Epigenetic changes such as reduced histone bulk, abnormal patterns of histone modification as well as abnormalities in DNA formation are some of the causative factors of aging. Another contributory factor to the aging process is the loss of proteostasis which leads to an unstable set of proteins that are toxic to cells and thus trigger the aging process. With the advancement of biomedical science, many new theories have been proposed to decode this mysterious event in a cell’s life.

Nondisjunction — Definition and Examples

Nondisjunction connotes the failure of the separation of homologous chromosomes during cell division. It has significant repercussions and is culpable for a large share of chromosomal anomalies like aneuploidy and various hereditary syndromes. With a brief introduction to the basic structure of a chromosome and characteristics of nondisjunction, this article focuses on clinical implications of the same.

The History of Medical Genetics

Medical genetics involves the application of genetics for the diagnosis and management of hereditary disorders. With the advancement of medical technology, the scope of medical genetics has widened to include the gene interactions, control of gene expressions, gene variations, and environmental interactions. Genetic diseases are now categorized as classical and non-classical. Classical diseases include the chromosomal disorders, Mendelian disorders, and multifactorial disorders. In the non-classical genetic diseases, there is a single gene disorder with an atypical pattern of inheritance. They include the diseases caused by mutations in mitochondrial genes, triplet repeat mutations, genomic imprinting, gonadal mosaicism, and uniparental disomy. Medical genetics differ from human genetics in that human genetics is a field of scientific research that, or may not, apply to medicine, while medical genetics refers to the application of genetics to medical care.

Diabetic Glomerulopathy — Pathogenesis and Management

Diabetic glomerulopathy is the leading cause of chronic renal failure in adults. Long-standing type 1 or type 2 diabetes mellitus is associated with this microvascular complication, along with peripheral neuropathy and retinopathy. The pathology of diabetic glomerulopathy is distinguishable based on certain features, including the presence of pathognomonic Kimmelstiel-Wilson nodules, hence the term Kimmelstiel-Wilson disease. A diagnosis of diabetic glomerulopathy does not require a renal biopsy – rather, it is established based on the presence of significant proteinuria and a history of diabetes for >10 years or diabetic retinopathy. Students should be aware about this important complication of diabetes, including its pathology, pathophysiology, clinical course and management.

Dermatofibroma — Pathology Outlines and Treatment

Dermatofibroma, or benign fibrous histiocytoma, is a common cutaneous nodule that may be superficial or deep. It is the most common painful skin tumor, mostly affecting women. Although, the precise underlying etiology and mechanism for the development of this skin pathology is not well known, it is believed to be a neoplastic process owing to its clonal proliferation growth. While the patients may usually be asymptomatic, the tumor growth may exhibit rapid growth or may remain static for several years. An intervention is not called for unless the patient is symptomatic.

Developmental Milestones: Comparison of Various Ages

Milestones of various ages provide a predictable pattern in infants and children concerning the development of their skills in each age group. Understanding of the normal child development helps clinicians to identify any symptom of delayed child development. Early identification of the developmental delays can prevent future complications, and the child can be timely referred for therapeutic services. The aim is to promote healthy development. Developmental milestones have been established in physical, social, verbal and cognitive domains.

Anticoagulants and Procoagulants: Drugs on Blood Coagulation

Our body employs many mechanisms in order to maintain homeostasis. One particular term that is worth our attention when it comes to tackling homeostasis is hemostasis or the body’s tendency to prevent the contents of our intravascular compartment (blood) to leak into different compartments within the body and into the external environment. This term also refers to the body’s maintenance of the smooth flow of blood within the blood vessels. Hemostasis consists of intricate interdependent mechanisms. These have been the focus of many pharmacological studies that aim to address certain blood disorders. Read everything about it here.

Hemorrhoids (Piles) — Symptoms and Treatment

Hemorrhoids cushions are normal structures of the lower rectum. They are very vascular and pathology develops when that vasculature becomes engorged (especially the veins). Itching and pain are common symptoms of hemorrhoid pathology. Hemorrhoids are classified on their origin relative to the dentate line: external (below the dentate line), internal (above the dentate line), and prolapsed internal hemorrhoids. Most hemorrhoids are treated with dietary modification (increase fiber) and stool softeners, but occasionally surgery is required.

Porphyria — Classification and Diagnosis

Porphyrias are a group of metabolic disorders, at the bottom of which lies a disturbance in the synthesis of the heme; thereby, in most cases, it is about a hereditary enzyme defect. The disease patterns differ depending on the affected enzyme; one clinically differentiates between acute and non-acute forms. In particular, a physician should also be aware of the two most common forms of overall rare diseases as an important differential diagnosis. Below is thus an overview of the clinical manifestations, diagnosis and treatment options of the porphyria.

Nerve Tissue: Brain

Thrombosis

The article explains hemostasis, venous and arterial thrombosis, its symptoms, diagnostic tools, causes and treatment options. Learn more about it on Lecturio.

Lower Limb Anatomy

The basis of any surgical discipline and radiological imaging is structural anatomy. This article envisages clarifying the basics of lower limb anatomy with focus on the gluteal region, posterior thigh and the popliteal fossa. The muscles of the gluteal region are specialized to bear weight and maintain the horizontal balance of the pelvis. The posterior thigh muscles are the lateral rotators of the hip and the popliteal fossa is responsible mainly for extension/flexion and adduction.

Screening Tests Sensitivity and Specificity

This article discusses screening tests in detail. Screening tests are conducted in order to find out or identify any disease or calamity in a person before realization of its related symptoms. It is of major importance when it is used to identify diseases which are deadly and are desired to be cured timely to avoid any dangerous consequences. The article discusses various elements of a screening test including sensitivity, specificity, false positive and negative results, positive predictive value (PPV), negative predictive value (NPV) along with examples.

Sex-Linked Genetic Disorders and Chromosome Theory Exceptions, Epigenetic Factors

The Boveri–Sutton chromosome theory states that the chromosomes are the basis of all genetic inheritance. Morgan's work with fruit flies provides a solid evidence associating a specific gene with a specific chromosome. The SRY gene is important in the sex determination of humans. It encodes a SRY protein which is responsible for male sex determination initiation. Certain human genetic disorders are sex-linked, such as color blindness and hemophilia. There are two exceptions to the chromosome theory of inheritance.

Single Nucleotide Polymorphisms and BRCA 2 Gene

Genomics is the study of the genetic material of organisms. It includes the study of methods for knowing the location and sequence of genes. Alternative splicing is a method for gene expression that results in the formation of multiple proteins from a single gene. DNA sequence may include coding and non-coding sequence. BRCA2 gene is an important gene that codes for a protein which helps maintain genetic information by DNA repair.

Cell Cycle and Cell Division P53 Gene, Mutated Genes

Cell cycle refers to the process of division marked by cell growth, DNA replication, distribution of replicated chromosomes to daughter cells, followed by cell division that a cell undergoes proliferation. It consists of different phases, regulated by the cell cycle checkpoints. There are a group of enzymes and proteins that regulate and ensure the replication of DNA and cell division linking to the extracellular signals to control cell proliferation. Any defective DNA is immediately repaired, and, if unrepairable, it leads to programmed cell death (apoptosis). These proteins are, in turn, controlled by proto-oncogenes and oncogenes, whose mutation leads to cancer.

Management of Hyperlipidemia in the Family Medicine Setting

The leading cause of death in the United States is cardiovascular disease, which has been long connected to dyslipidemia in general and hyperlipidemia in particular. Half of the American population are found to have hypercholesterolemia, while one-third of people in the United States have an elevated level of the so-called bad cholesterol known as low-density lipoprotein (LDL) cholesterol. Because of this, a significant number of those who seek medical attention in the primary care setting are expected to have some sort of hyperlipidemia that needs to be corrected.

Treatment of Osteoarthritis in the Family Medicine Setting

Osteoarthritis is a common problem in the general population that seeks medical attention in a primary care setting. The main risk factors for osteoarthritis are a family history of the disease, the female gender, past trauma to the involved joint, aging and obesity. Because of the increasing number of obese people in the United States, family physicians are expected to see more osteoarthritis cases in the coming years.

Bipolar Disorder — Classification and Therapy

Bipolar disorder is a psychiatric illness characterized by periods of depression and mania/hypomania. It affects approximately 1% of the general population. The disease results from genetic mutations precipitated by environmental factors. Clinically, it varies from manic features of hyperactivity and irritability, to depressive episodes with reduced activity, lethargy and loss of interest, and a mixed picture of manic and depressive episode features. Treatment of bipolar disease involves pharmacotherapy with mood stabilizers, behavioral therapy, and electroconvulsive therapy. Mortality and morbidity are mainly due to the associated suicidal and homicidal tendencies.

Research Ethics: Nuremberg Code, Belmont Report, and the Declaration of Helsinki

The article has discussed the history and background of medical and research ethical reforms. The ethical reforms include the Nuremberg Code, the Declaration of Geneva, and the Hippocratic Oath. The reforms also include “The Belmont Report” resulting from the Tuskegee Syphilis Study. The declaration of Helsinki ties together the Nuremberg code and the declaration of Geneva. The article has also discussed pillars of research ethics and the Research Ethics Board in detail.

DNA Structure and Replication Replisome, Monohybrid and Dihybrid Crosses

Deoxyribonucleic acid known as DNA is a structural molecule which carries the genetic information of all organisms. DNA has a helical structure in which two strands of DNA twist around each other. The stability of DNA molecule is assessed by the length of the strand and the melting temperature. There are various enzymes which participate in the replication of the DNA molecule and these enzymes collectively form a complex machine known as the replisome.

Levels of Measurement and Type I & Type II Errors

This article has explained the concepts of variables and data levels of measurement. There are two types of variables i.e continuous and discrete. The four scales of data measurement used in statistics are nominal, ordinal, internal and ratio measurement. Causality refers to a relation between two variables. The article has also discussed frequency and normal distribution along with examples. Central limit theorem and type I and II errors are also part of this article

10 Important Muscles of the Human Musculoskeletal System

Our musculoskeletal system is a complex machinery of bones, joints, muscles, and their auxiliaries, which serve as the body's supporting structure and give the body the ability to move. Our skeletal muscles provide the moving strength and may be low or high in their muscle tone. They have different courses from origin to insertion and also differ in their function. In the following article, you will receive a concise overview of 10 important muscles of our musculoskeletal system.

Rules of Addition and Multiplication, Prediciting the Outcome of a Cross, Test Cross Uncover Genotypes

Mendel, an Austrian monk, worked on basic concepts in genetics which were not recognized until after his death. Rediscovery of Mendelian genetics paved the path for modern genetics. His concepts heavily relied on test crosses and the rules of probability. The addition and multiplication rules are applied to mutually elusive and independent cases, respectively. However, modern genetics is an exception from Mendel’s genetics. Discovery of multigene inheritance, multiple alleles, dominance variations and epistasis has changed the face of classical genetics to a great deal.

Validity and Reliability, Causality, Causal Relationship Possibilities, External Validity

This article discusses measures of association, causality relationship and different possibilities in a causal relationship. The Bradford Hill criteria comprising nine principles is also being discussed. The possibilities of a causal relationship include four principles. The article also explains reliability, validity, and related characteristics. The major threats to reliability discussed in the article include poor sampling, instability and divergence.

Attributable Risk and Odds Ratio

This article discusses the concept of ‘association’ in biostatistics. Measures of association assume categorical or continuous level of data. The article also discusses in detail three kinds of risks and odd ratio. Attributable risk is also known as excess risk which is calculated when individuals or subjects in a research are assembled on exposure status. Population attributable risk is also discussed which indicates reduction in an incidence which may be observed in case the whole population were completely unexposed.

Ankylosing Spondylitis (Bechterew’s Disease) — Symptoms and Classifications

Ankylosing spondylitis, formerly known as Bechterew’s disease or Marie-Strümpell disease, is a type of inflammatory rheumatic disease which affects mostly the spine. In the end-stage of this disease, patients suffer from complete fusion and rigidity of the spine—the so-called "bamboo spine". Here, you will find all the relevant facts on ankylosing spondylitis (AS) that you need for your rheumatology exams.

Lung Cancer: Invasion and Metastasis, Paraneoplastic Syndromes and Treatment of Mesothelioma, Small-cell Lung Carcinoma (SCLC) and Non-small Cell Lung Cancer (NSCLC)

Lung cancer is notoriously one of the most common lethal tumors in the medical world. It is essential to be accustomed with the basic details about this disease. In this article, you will gain all exam-relevant information about the epidemiology, pathogenesis and clinical recognition of lung cancer.

Anatomy of the Gluteal Region and Posterior Thigh: Popliteal Fossa and Neurovascular Bundle

The gluteal region is located posterior to the pelvic girdle and extends downward on the back of the upper part of the leg as the posterior thigh and then the popliteal fossa. This region consists of the gluteal muscles, the hamstring muscles and several clinically important arteries, veins and nerves. The muscles of the gluteal region help to move the hip joint during walking, standing and sitting.

Unilateral Renal Agenesis (URA) — Diagnosis and Complications

Unilateral agenesis is defined as the complete absence of development of one kidney and ureter. The condition is usually silent and is usually detected on fetal ultrasound scan by the presence of empty renal fossa. The incidence of URA is relatively common and is due to genetic as well as maternal causes. Human renal development is initiated by the 5th week of gestation and renal agenesis occurs when the ureteric bud fails to form the ureter, the renal pelvis, and renal mesenchyme. URA is often associated with anomalies of the contralateral kidney and ureter as well.

Anatomy of the Distal Convoluted Tube and Bartter & Gitelman Syndrome

In this article, you will gain a perfect overview of the distal convoluted tubule, the portion of the nephron of the kidney extending from the loop of Henle up to the collecting duct system. Furthermore, you will learn about the pathophysiology and treatment of the autosomal recessive disorders called Gitelman syndrome and Bartter syndrome for the perfect medical exam preparation.

Potter's Syndrome — Causes and Prognosis

Potter syndrome, also known as the Potter sequence refers to the specific appearance of the baby due to oligohydramnios which is a decrease in amniotic fluid volume which causes deformities in the fetus while in the uterus. These deformities include flattened nasal bridge, epicanthal folds, low set ears and bowed legs. It also leads to pulmonary hypoplasia. The cause has decreased the production of amniotic fluid which is required to cushion the baby against the uterine walls.

Introduction to Rheumatology and Calcium Pyrophosphate Deposition Disease (CPPD, Pseudogout)

In rheumatology, we talk mainly about disorders of the musculoskeletal system, connective tissue diseases, inflammatory disorders, and bone disease. Musculoskeletal pain is a common feature in most rheumatological disorders and might be caused by arthritis or soft tissue inflammation. In this article, you will get an introduction to rheumatology and pseudogout and gain all essential information for your next medical exam.

Sjögren´s Syndrome — Diagnosis and Treatment

Sjogren's syndrome is a systemic chronic inflammatory disease that is characterized by infiltrative lymphocytic inflammation of the exocrine organs. Sjogren's syndrome is more common in women. Most patients are in their 50s to 60 years of age. Patients present with sicca symptoms which include xerophthalmia, xerostomia, and parotid gland enlargement.

Anatomy of the Collecting Duct System and Water Reabsorption

In this article, we will talk about the microscopic anatomy part of the kidney known as the collecting duct system. The collecting duct system consists of a series of tubules and ducts that connect the nephrons to a minor calyx or to the renal pelvis. This collecting duct system, as the name implies, is responsible for the reabsorption and excretion of different electrolytes and for fluid balance in our bodies “collecting”.

Muscle and Connective Tissue Diseases: Lipoma, Fibroids (Uterine Myoma), Duchenne Muscular Dystrophy (DMD, Duchenne Syndrome) and more

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