Fatty Acids and Lipids

Fatty Acids

Structure

• Characterized by a carboxyl group (COOH) and an aliphatic chain of carbon atoms, which ends with a methyl group (CH₃).
• Amphiphilic (amphipathic) molecules, which are made up of 2 portions: polar (interacts with water) and nonpolar (does not interact with water) 
• Categorized based on saturation (number of double bonds between carbons): 
  • Saturated:
    • The most common fatty acids in cells
    • Do not have carbon-to-carbon double bonds (all carbons are “fully saturated” with hydrogens → results in “straight” chains)
    • Straight chains easily pack together → solid at room temperature
    • ↑ Length → ↑ melting point
    • Examples include lauric acid, myristic acid, stearic acid, palmitic acid, and arachidic acid.
  • Unsaturated:
    • Monounsaturated→ 1 double bond (e.g., oleic acid)
    • Polyunsaturated→ 2 or more double bonds (e.g., essential fatty acids like linoleic acid and linolenic acid)
    • Double bonds cause “kinks” in the carbon chain.
    • Kinked chains do not pack together as easily → ↑ desaturation → ↓ melting point
• Categorized based on length:
  • Short-chain fatty acid (SCFA): ≤ 5 carbons
  • Medium-chain fatty acid (MCFA): 6‒12 carbons
  • Long-chain fatty acid (LCFA): 13‒21 carbons
  • Very-long-chain fatty acid (VLCFA): ≥ 22 carbons
• Configuration:
  • cis: if the 2 R groups are on the same side of the carbon-to-carbon double bond
  • trans: if the 2 R groups are on opposite sides of the carbon-to-carbon double bond 
  • Most naturally occurring unsaturated fatty acids have double bonds in the cis configuration.
• Trans fats: 
  • Contain double bonds in the trans configuration 
  • Produced after a chemical alteration of food, during hydrogenation, or “hardening,” of natural oils in the manufacture of margarine
  • Consumption is associated with ↑ risk of diseases, including cardiovascular disease and diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus.

Nomenclature of fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance

• Based on functional aspects and the nature of the backbones. Common examples include:
  • Glycerol is a tertiary alcohol.
  • Sphingosine is an unsaturated amino alcohol.
  • Isoprene is an unsaturated hydrocarbon.
• Genevan system suffixes:
  • Saturated fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance: -anoic
  • Unsaturated fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance: -enoic
• Delta numbering system: Carbons are counted from the COOH towards the CH₃ (left → right).
• Omega numbering system: Carbons are counted from the CH₃ towards the COOH (right → left) → gives rise to omega (ω) fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance

Functions

• A building block found in other types of lipids, including:
  • Fats Fats The glyceryl esters of a fatty acid, or of a mixture of fatty acids. They are generally odorless, colorless, and tasteless if pure, but they may be flavored according to origin. Fats are insoluble in water, soluble in most organic solvents. They occur in animal and vegetable tissue and are generally obtained by boiling or by extraction under pressure. They are important in the diet (dietary fats) as a source of energy. Energy Homeostasis/oils 
  • Glycerophospholipids
  • Sphingolipids
  • Membrane anchors for other biomolecules (e.g., proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis)
• Energy storage
• Membrane structure

Essential versus nonessential

• Nonessential FAs: can be synthesized by humans
• Essential FAs: cannot be synthesized by humans and must be obtained in the diet:
  • Humans lack desaturase, the enzyme required to make double bonds past Δ⁹
  • The 2 major essential FAs are linoleic acid and α-linolenic acid (ALA).
• ALA can be (inefficiently) converted into eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) → EPA/DHA are technically nonessential (they become essential with inadequate ALA in the diet (which is common))

Glycerolipids and Glycerophospholipids

Glycerolipids and glycerophospholipids are glycerol-based lipids ubiquitous in human cells. They function as structural components of plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products membranes and as storage for energy.

Glycerolipids (triacylglycerols/triglycerides)

• 1 molecule of glycerol (polarized) + 3 fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance
• Linked by ester bonds (between a -OH and a COOH group)
• Degree of unsaturation determines if fat or oil:
  • Fats Fats The glyceryl esters of a fatty acid, or of a mixture of fatty acids. They are generally odorless, colorless, and tasteless if pure, but they may be flavored according to origin. Fats are insoluble in water, soluble in most organic solvents. They occur in animal and vegetable tissue and are generally obtained by boiling or by extraction under pressure. They are important in the diet (dietary fats) as a source of energy. Energy Homeostasis are solid at room temperature (more saturated).
  • Oils are liquid at room temperature (more unsaturated).
• Provides thermal insulation
• The main storage forms of fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance (in adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology)

Glycerophospholipids (phosphoglycerides)

• A glycerol backbone (polarized) + 2 fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance + 1 phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes group (PO₄)
• Major components (and the main lipid constituents) of the plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products membrane (lipid bilayer)
• Possess a hydrophobic tail (the fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance) and a hydrophilic Hydrophilic Aminoglycosides head (the phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes group)
• The phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes group typically binds an additional molecule (e.g., choline, serine Serine A non-essential amino acid occurring in natural form as the l-isomer. It is synthesized from glycine or threonine. It is involved in the biosynthesis of purines; pyrimidines; and other amino acids. Synthesis of Nonessential Amino Acids, inositol)
• Lecithins are examples of glycerophospholipids:
  • Amphiphilic
  • Includes phosphatidylcholine, and phosphatidylethanolamine
  • The most abundant phosphoglycerides in the body
  • Represent a large store of choline for other physiologic functions (e.g., acetylcholine Acetylcholine A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system. Receptors and Neurotransmitters of the CNS)
  • Constitute the lipidic component of pulmonary surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS)

Eicosanoids Eicosanoids Eicosanoids are cell-signaling molecules produced from arachidonic acid. With the action of phospholipase A2, arachidonic acid is released from the plasma membrane. The different families of eicosanoids, which are prostaglandins (PGs), thromboxanes (TXA2s), prostacyclin (PGI2), lipoxins (LXs), and leukotrienes (LTs), emerge from a series of reactions catalyzed by different enzymes. Eicosanoids

• A class of biologically important 20-carbon containing compounds (“eicosa” = 20)
• Derived from the oxidation of several key omega-6 and omega-3 polyunsaturated fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance, including:
  • Arachidonic acid Arachidonic Acid An unsaturated, essential fatty acid. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides. It is formed by the synthesis from dietary linoleic acid and is a precursor in the biosynthesis of prostaglandins, thromboxanes, and leukotrienes. Nonsteroidal Antiinflammatory Drugs (NSAIDs) (most important)
  • EPA
  • Gamma-linolenic acid
• Eicosanoid subclasses:
  • Prostaglandins Prostaglandins A group of compounds derived from unsaturated 20-carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase pathway. They are extremely potent mediators of a diverse group of physiological processes. Eicosanoids
  • Prostacyclins
  • Thromboxanes Thromboxanes Physiologically active compounds found in many organs of the body. They are formed in vivo from the prostaglandin endoperoxides and cause platelet aggregation, contraction of arteries, and other biological effects. Thromboxanes are important mediators of the actions of polyunsaturated fatty acids transformed by cyclooxygenase. Eicosanoids
  • Lipoxins Lipoxins Trihydroxy derivatives of eicosanoic acids. They are primarily derived from arachidonic acid, however eicosapentaenoic acid derivatives also exist. Many of them are naturally occurring mediators of immune regulation. Eicosanoids
  • Leukotrienes Leukotrienes A family of biologically active compounds derived from arachidonic acid by oxidative metabolism through the 5-lipoxygenase pathway. They participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. They have potent actions on many essential organs and systems, including the cardiovascular, pulmonary, and central nervous system as well as the gastrointestinal tract and the immune system. Eicosanoids
  • Endocannabinoids Endocannabinoids Fatty acid derivatives that have specificity for cannabinoid receptors. They are structurally distinct from cannabinoids and were originally discovered as a group of endogenous cannabinoid receptor agonists. Cannabinoids
• Functions:
  • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation
  • Immunity
  • Vasoactivity (i.e., vasoconstriction Vasoconstriction The physiological narrowing of blood vessels by contraction of the vascular smooth muscle. Vascular Resistance, Flow, and Mean Arterial Pressure and dilation)
  • Influence mood and behavior

Sphingolipids

Sphingolipids are a heterogeneous family of lipids sharing the characteristic sphingoid base backbone:

• Composed of ceramide (sphingosine + fatty acid) + another molecule (“R”) linked to the sphingosine
• Amphipathic and amphiphilic (both hydrophobic and hydrophilic Hydrophilic Aminoglycosides properties)
• A major component of the lipid bilayer
• Several molecules can bind BIND Hyperbilirubinemia of the Newborn to sphingosine producing molecules with different functions:
  • Sphingomyelin Sphingomyelin A class of sphingolipids found largely in the brain and other nervous tissue. They contain phosphocholine or phosphoethanolamine as their polar head group so therefore are the only sphingolipids classified as phospholipids. Neonatal Respiratory Distress Syndrome:
    • Ceramide + a phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes group + choline
    • Found in the myelin sheath of nerve cells
  • Cerebroside:
    • Ceramide + monosaccharide (a single sugar)
    • Important components of nerve cell membranes
  • Ganglioside:
    • Ceramide + complex carbohydrate
    • Important role in modulating membrane proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis, ion channels Channels The Cell: Cell Membrane, and cell signaling

Isoprenoids and Sterols

Sterols and isoprenoids, which form sterols, are an important group of lipids used as part of the cellular plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products membrane, steroid hormones Steroid hormones Steroid hormones produced by the gonads. They stimulate reproductive organs, germ cell maturation, and the secondary sex characteristics in the males and the females. The major sex steroid hormones include estradiol; progesterone; and testosterone. Hormones: Overview and Types, and as bile Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile acids and salts; cholesterol; and electrolytes. It aids digestion of fats in the duodenum. Gallbladder and Biliary Tract: Anatomy acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance, which help absorb fats Fats The glyceryl esters of a fatty acid, or of a mixture of fatty acids. They are generally odorless, colorless, and tasteless if pure, but they may be flavored according to origin. Fats are insoluble in water, soluble in most organic solvents. They occur in animal and vegetable tissue and are generally obtained by boiling or by extraction under pressure. They are important in the diet (dietary fats) as a source of energy. Energy Homeostasis.

Isoprenoids

• Building blocks of sterols 
• Contain 5 carbons
• Examples:
  • Dimethylallyl pyrophosphate Dimethylallyl pyrophosphate Cholesterol Metabolism
  • Isopentenyl pyrophosphate Isopentenyl pyrophosphate Cholesterol Metabolism

Sterols

• A subgroup of steroid molecules derived from the sterol Sterol Steroids with a hydroxyl group at c-3 and most of the skeleton of cholestane. Additional carbon atoms may be present in the side chain. Mycoplasma molecule (a lipid consisting of a 4-ring structure with a single hydroxyl group)
• Phytosterols in plants Plants Cell Types: Eukaryotic versus Prokaryotic (e.g., ergosterol Ergosterol A steroid occurring in fungi. Irradiation with ultraviolet rays results in formation of ergocalciferol (vitamin d2). Azoles)
• Zoosterols in animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic (e.g., cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism)
• Cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism:
  • The most abundant zoosterol
  • Synthesized within cells or obtained from the diet
  • Storage form: 
    • Cholesteryl ester = cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism + fatty acid
    • Allows for storage in or near the cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane
  • Component of:
    • Plasma cell Plasma cell Specialized forms of antibody-producing B-lymphocytes. They synthesize and secrete immunoglobulin. They are found only in lymphoid organs and at sites of immune responses and normally do not circulate in the blood or lymph. Lymphocytes: Histology 
    • Mitochondria Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive ribosomes, transfer RNAs; amino Acyl tRNA synthetases; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs. Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. The Cell: Organelles 
    • Golgi complex Golgi complex A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough endoplasmic reticulum and directing them to secretory vesicles, lysosomes, or the cell membrane. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or golgi apparatus and fuse with the golgi, lysosomes or cell membrane. The Cell: Organelles 
    • Nuclear membranes
• Cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism is the building block for the steroid hormones Steroid hormones Steroid hormones produced by the gonads. They stimulate reproductive organs, germ cell maturation, and the secondary sex characteristics in the males and the females. The major sex steroid hormones include estradiol; progesterone; and testosterone. Hormones: Overview and Types:
  • Glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids (e.g., cortisol Cortisol Glucocorticoids)
  • Mineralocorticoids Mineralocorticoids Mineralocorticoids are a drug class within the corticosteroid family and fludrocortisone is the primary medication within this class. Fludrocortisone is a fluorinated analog of cortisone. The fluorine moiety protects the drug from isoenzyme inactivation in the kidney, allowing it to exert its mineralocorticoid effect. Mineralocorticoids (e.g., aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia)
  • Sex Sex The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism. Gender Dysphoria steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors:
    • Androgens Androgens Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth. Androgens and Antiandrogens (e.g., testosterone Testosterone A potent androgenic steroid and major product secreted by the leydig cells of the testis. Its production is stimulated by luteinizing hormone from the pituitary gland. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to dihydrotestosterone or estradiol. Androgens and Antiandrogens)
    • Estrogens (e.g., estradiol Estradiol The 17-beta-isomer of estradiol, an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position. Estradiol-17-beta is the most potent form of mammalian estrogenic steroids. Noncontraceptive Estrogen and Progestins)
    • Progestogens (e.g., progesterone Progesterone The major progestational steroid that is secreted primarily by the corpus luteum and the placenta. Progesterone acts on the uterus, the mammary glands and the brain. It is required in embryo implantation; pregnancy maintenance, and the development of mammary tissue for milk production. Progesterone, converted from pregnenolone, also serves as an intermediate in the biosynthesis of gonadal steroid hormones and adrenal corticosteroids. Gonadal Hormones)

Clinical Relevance

• Coagulation: Several of the eicosanoids Eicosanoids Eicosanoids are cell-signaling molecules produced from arachidonic acid. With the action of phospholipase A2, arachidonic acid is released from the plasma membrane. The different families of eicosanoids, which are prostaglandins (PGs), thromboxanes (TXA2s), prostacyclin (PGI2), lipoxins (LXs), and leukotrienes (LTs), emerge from a series of reactions catalyzed by different enzymes. Eicosanoids are important physiologic mediators of coagulation. They can both stimulate and inhibit platelet activity, as well as affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment the activity of endothelial cells in the vessel walls. Thus, the eicosanoids Eicosanoids Eicosanoids are cell-signaling molecules produced from arachidonic acid. With the action of phospholipase A2, arachidonic acid is released from the plasma membrane. The different families of eicosanoids, which are prostaglandins (PGs), thromboxanes (TXA2s), prostacyclin (PGI2), lipoxins (LXs), and leukotrienes (LTs), emerge from a series of reactions catalyzed by different enzymes. Eicosanoids play a critical role in determining the balance between coagulation and bleeding.
• Prostanoids Prostanoids Eicosanoids: can be utilized as pharmaceutical agents. Uses include the prevention of conception, induction of labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor at term, termination of pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care, prevention of gastric ulcers, control of inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and blood pressure, and relief of asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma and nasal congestion. PGD2 promotes sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep. Prostaglandins Prostaglandins A group of compounds derived from unsaturated 20-carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase pathway. They are extremely potent mediators of a diverse group of physiological processes. Eicosanoids increase cyclic adenosine monophosphate Cyclic adenosine monophosphate An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Second Messengers ( cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors) in the thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy, corpus luteum Corpus Luteum The yellow body derived from the ruptured ovarian follicle after ovulation. The process of corpus luteum formation, luteinization, is regulated by luteinizing hormone. Ovaries: Anatomy, fetal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types, adenohypophysis Adenohypophysis The anterior glandular lobe of the pituitary gland, also known as the adenohypophysis. It secretes the adenohypophyseal hormones that regulate vital functions such as growth; metabolism; and reproduction. Pituitary Gland: Anatomy, platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology, and lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy, but reduce cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors in renal tubule cells and adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology.
• Leukotrienes Leukotrienes A family of biologically active compounds derived from arachidonic acid by oxidative metabolism through the 5-lipoxygenase pathway. They participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. They have potent actions on many essential organs and systems, including the cardiovascular, pulmonary, and central nervous system as well as the gastrointestinal tract and the immune system. Eicosanoids and lipoxins Lipoxins Trihydroxy derivatives of eicosanoic acids. They are primarily derived from arachidonic acid, however eicosapentaenoic acid derivatives also exist. Many of them are naturally occurring mediators of immune regulation. Eicosanoids: these eicosanoids Eicosanoids Eicosanoids are cell-signaling molecules produced from arachidonic acid. With the action of phospholipase A2, arachidonic acid is released from the plasma membrane. The different families of eicosanoids, which are prostaglandins (PGs), thromboxanes (TXA2s), prostacyclin (PGI2), lipoxins (LXs), and leukotrienes (LTs), emerge from a series of reactions catalyzed by different enzymes. Eicosanoids regulate many disease processes. Slow-reacting substance of anaphylaxis Anaphylaxis An acute hypersensitivity reaction due to exposure to a previously encountered antigen. The reaction may include rapidly progressing urticaria, respiratory distress, vascular collapse, systemic shock, and death. Type I Hypersensitivity Reaction (SRS-A) is a mixture of leukotrienes Leukotrienes A family of biologically active compounds derived from arachidonic acid by oxidative metabolism through the 5-lipoxygenase pathway. They participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. They have potent actions on many essential organs and systems, including the cardiovascular, pulmonary, and central nervous system as well as the gastrointestinal tract and the immune system. Eicosanoids C4, D4, and E4. Properties include potent constriction of bronchial airways, increased vascular permeability, chemoattraction, and leukocyte activation during hypersensitivity reactions (such as asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma). Lipoxins Lipoxins Trihydroxy derivatives of eicosanoic acids. They are primarily derived from arachidonic acid, however eicosapentaenoic acid derivatives also exist. Many of them are naturally occurring mediators of immune regulation. Eicosanoids are anti-inflammatory/counterregulatory compounds (chalones) of the immune response, and have vasoactive functions.
• Cyclooxygenase Cyclooxygenase Nonsteroidal Antiinflammatory Drugs (NSAIDs) (COX) inhibitors: block the conversion of arachidonic acid Arachidonic Acid An unsaturated, essential fatty acid. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides. It is formed by the synthesis from dietary linoleic acid and is a precursor in the biosynthesis of prostaglandins, thromboxanes, and leukotrienes. Nonsteroidal Antiinflammatory Drugs (NSAIDs) into inflammatory and procoagulant eicosanoids Eicosanoids Eicosanoids are cell-signaling molecules produced from arachidonic acid. With the action of phospholipase A2, arachidonic acid is released from the plasma membrane. The different families of eicosanoids, which are prostaglandins (PGs), thromboxanes (TXA2s), prostacyclin (PGI2), lipoxins (LXs), and leukotrienes (LTs), emerge from a series of reactions catalyzed by different enzymes. Eicosanoids, which include prostaglandins Prostaglandins A group of compounds derived from unsaturated 20-carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase pathway. They are extremely potent mediators of a diverse group of physiological processes. Eicosanoids, prostacyclin Prostacyclin A prostaglandin that is a powerful vasodilator and inhibits platelet aggregation. It is biosynthesized enzymatically from prostaglandin endoperoxides in human vascular tissue. The sodium salt has been also used to treat primary pulmonary hypertension. Eicosanoids, and thromboxane. By inhibiting the inflammatory effects, pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways is reduced. By inhibiting the procoagulant effects, coagulation is slightly inhibited.
• Polyketides: molecules created by organisms in a similar fashion to fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance (utilizing similar enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes and acyl-CoA). These products have a wide array of pharmaceutical properties, and have been used for antibacterial Antibacterial Penicillins, antifungal Antifungal Azoles, immunosuppressive, and antitumor applications. Notable polyketide medications include erythromycin Erythromycin A bacteriostatic antibiotic macrolide produced by streptomyces erythreus. Erythromycin a is considered its major active component. In sensitive organisms, it inhibits protein synthesis by binding to 50s ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins. Macrolides and Ketolides, tetracycline Tetracycline A naphthacene antibiotic that inhibits amino Acyl tRNA binding during protein synthesis. Drug-induced Liver Injury, amphotericin, tacrolimus Tacrolimus A macrolide isolated from the culture broth of a strain of streptomyces tsukubaensis that has strong immunosuppressive activity in vivo and prevents the activation of T-lymphocytes in response to antigenic or mitogenic stimulation in vitro. Immunosuppressants, and anthramycin.
• Neonatal Respiratory Distress Syndrome Neonatal Respiratory Distress Syndrome Respiratory distress syndrome (RDS), also known as hyaline membrane disease, is caused by the lack of adequate pulmonary surfactant production in an immature lung. The syndrome is most commonly seen in preterm infants. Neonatal Respiratory Distress Syndrome: In premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis births, a low quantity and quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement of natural surfactants cause the collapse of alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS). Composed of 70% glycerophospholipid (specifically phosphatidylcholine), natural surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) reduces surface tension Surface tension The force acting on the surface of a liquid, tending to minimize the area of the surface. Acute Respiratory Distress Syndrome (ARDS) within the alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS), allowing the alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS) to stay open more easily, which improves oxygen exchange. The early administration of pulmonary surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) is important to prevent respiratory distress syndrome in premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis infants.
• Niemann-Pick disease Niemann-Pick disease Niemann-Pick disease (NPD) is a rare, inherited, lysosomal storage disorder. The disease is classified on the basis of the genetic mutation. Type A and type B result from mutations in the SMPD-1 gene, resulting in acid sphingomyelinase enzyme deficiency. Type C results from NPC1 or NPC2 gene mutations, which are needed for intracellular transport of lipids. Niemann-Pick Disease (also known as sphingomyelin-cholesterol lipidosis): an autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance lysosomal storage disorder characterized by the accumulation of sphingomyelin Sphingomyelin A class of sphingolipids found largely in the brain and other nervous tissue. They contain phosphocholine or phosphoethanolamine as their polar head group so therefore are the only sphingolipids classified as phospholipids. Neonatal Respiratory Distress Syndrome and cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism in cells, most notably neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology.
• Essential fatty acid deficiency Essential fatty acid deficiency Short Bowel Syndrome: linoleic and alpha-linolenic acid are required for prostaglandin, thromboxane, leukotriene Leukotriene Asthma Drugs, and lipoxin formation. Symptoms include dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema), alopecia Alopecia Alopecia is the loss of hair in areas anywhere on the body where hair normally grows. Alopecia may be defined as scarring or non-scarring, localized or diffuse, congenital or acquired, reversible or permanent, or confined to the scalp or universal; however, alopecia is usually classified using the 1st 3 factors. Alopecia, thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia, and (in children) intellectual disability Disability Determination of the degree of a physical, mental, or emotional handicap. The diagnosis is applied to legal qualification for benefits and income under disability insurance and to eligibility for social security and workman’s compensation benefits. ABCDE Assessment. At-risk groups include infants receiving formula diets low in fat and patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship maintained exclusively on intravenous nutrition for long periods of time.
• Abnormal metabolism of essential fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance: can be related to dietary insufficiency, but can occur in multiple diseases. These include cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis, acrodermatitis enteropathica, hepatorenal syndrome Hepatorenal Syndrome Hepatorenal syndrome (HRS) is a potentially reversible cause of acute kidney injury that develops secondary to liver disease. The main cause of HRS is hypovolemia, often as a result of forced diuresis or drainage of ascites. This leads to renal vasoconstriction resulting in hypoperfusion of the kidneys. Hepatorenal Syndrome, Crohn disease, cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis, chronic alcohol-use disorder Alcohol-use disorder A primary, chronic disease with genetic, psychosocial, and environmental factors influencing its development and manifestations. The disease is often progressive and fatal. It is characterized by impaired control over drinking, preoccupation with the drug alcohol, use of alcohol despite adverse consequences, and distortions in thinking, most notably denial. Each of these symptoms may be continuous or periodic. Klebsiella, and Reye syndrome Reye syndrome A form of encephalopathy with fatty infiltration of the liver, characterized by brain edema and vomiting that may rapidly progress to seizures; coma; and death. It is caused by a generalized loss of mitochondrial function leading to disturbances in fatty acid and carnitine metabolism. Varicella-Zoster Virus/Chickenpox.