Circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment is the movement of blood throughout the body through one continuous circuit of blood vessels. Different organs have unique functions and, therefore, have different requirements, circulatory patterns, and regulatory mechanisms. Several of the most vital organs (including the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification, heart, and kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy) have autoregulatory properties, meaning that they are able to maintain a relatively constant blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure despite fluctuations in mean Mean Mean is the sum of all measurements in a data set divided by the number of measurements in that data set. Measures of Central Tendency and Dispersion arterial pressure (MAP). In other cases, locally produced factors (such as adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs, CO2, or NO) can produce local vasoconstriction Vasoconstriction The physiological narrowing of blood vessels by contraction of the vascular smooth muscle. Vascular Resistance, Flow, and Mean Arterial Pressure or vasodilation Vasodilation The physiological widening of blood vessels by relaxing the underlying vascular smooth muscle. Pulmonary Hypertension Drugs, regulating blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure under specific physiologic conditions.
Last updated: 2 May, 2022
Blood flows through the heart 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 in one direction, sequentially through the following structures:
Circulation
Circulation
The movement of the blood as it is pumped through the cardiovascular system.
ABCDE Assessment of blood through the body:
Deoxygenated blood enters the right side of the heart and passes through the
pulmonary trunk
Pulmonary Trunk
Truncus Arteriosus to the
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, where it is oxygenated. The blood then returns to the left side of the heart via the
pulmonary veins
Pulmonary veins
The veins that return the oxygenated blood from the lungs to the left atrium of the heart.
Lungs: Anatomy, where it is pumped into the
aorta
Aorta
The main trunk of the systemic arteries.
Mediastinum and Great Vessels: Anatomy and distributed throughout the body. The blood travels through systemic
capillaries
Capillaries
Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time.
Capillaries: Histology, where it is deoxygenated again, and travels back to the heart via the superior and
inferior vena cava
Inferior vena cava
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy.
LA: left atrium
LV: left ventricle
RA: right atrium
RV: right ventricle
Distribution of blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure at rest
Image by Lecturio.Changes in blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure to the systemic organs during maximal vasodilation Vasodilation The physiological widening of blood vessels by relaxing the underlying vascular smooth muscle. Pulmonary Hypertension Drugs
Image by Lecturio.Capillary bed demonstrating arteriole, metarteriole, precapillary sphincters Precapillary Sphincters Capillaries: Histology, thoroughfare channel Thoroughfare Channel Capillaries: Histology, and venule
Image: “Capillary bed” by OpenStax College. License: CC BY 3.0Functions:
Starling forces Starling Forces Capillaries: Histology applied to capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology:
Clinical relevance of increased hydrostatic pressure Hydrostatic pressure The pressure due to the weight of fluid. Edema within capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology:
Starling forces
Starling Forces
Capillaries: Histology:
Starling forces
Starling Forces
Capillaries: Histology within a capillary determine the
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure of molecules into and out of the vessel.
The portal vein Portal vein A short thick vein formed by union of the superior mesenteric vein and the splenic vein. Liver: Anatomy carries deoxygenated blood from the abdominal organs to the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy for 1st-pass metabolism of everything absorbed from the GI tract.
Anatomy of a hepatic lobule:
Blood to be filtered enters through the portal
venules
Venules
The minute vessels that collect blood from the capillary plexuses and join together to form veins.
Veins: Histology and flows through the
sinusoids
Sinusoids
Liver: Anatomy and into the central vein. From there, the blood flows out through the hepatic
veins
Veins
Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia.
Veins: Histology and into the
inferior vena cava
Inferior vena cava
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy.
Portosystemic anastomoses are points where 2 veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology connect with one another; in these cases, blood from 1 vein normally drains into the portal system, while blood from the other vein normally drains into systemic venous circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment (i.e., the IVC IVC The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels: Anatomy).
Esophageal varices, splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly, and rectal varices resulting from backup of blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure due to elevated pressures within the portal vein Portal vein A short thick vein formed by union of the superior mesenteric vein and the splenic vein. Liver: Anatomy
Image by Lecturio.Blood flows to and through the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy via the following path:
Renal circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
Image by Lecturio.The kidney has multiple levels of regulatory mechanisms that 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 renal blood flow Renal blood flow The amount of the renal blood flow that is going to the functional renal tissue, i.e., parts of the kidney that are involved in production of urine. Glomerular Filtration (RBF) and the glomerular filtration Glomerular filtration The kidneys are primarily in charge of the maintenance of water and solute homeostasis through the processes of filtration, reabsorption, secretion, and excretion. Glomerular filtration is the process of converting the systemic blood supply into a filtrate, which will ultimately become the urine. Glomerular Filtration rate ( GFR GFR The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance. Kidney Function Tests):
Relative constriction and dilation of the afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology and efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology arterioles Arterioles The smallest divisions of the arteries located between the muscular arteries and the capillaries. Arteries: Histology:
Autoregulation of the renal blood flow Renal blood flow The amount of the renal blood flow that is going to the functional renal tissue, i.e., parts of the kidney that are involved in production of urine. Glomerular Filtration (RBF):
Impact of
mean
Mean
Mean is the sum of all measurements in a data set divided by the number of measurements in that data set.
Measures of Central Tendency and Dispersion arterial blood pressure on the
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure rate of
renal blood flow
Renal blood flow
The amount of the renal blood flow that is going to the functional renal tissue, i.e., parts of the kidney that are involved in production of urine.
Glomerular Filtration (RBF) and
glomerular filtration
Glomerular filtration
The kidneys are primarily in charge of the maintenance of water and solute homeostasis through the processes of filtration, reabsorption, secretion, and excretion. Glomerular filtration is the process of converting the systemic blood supply into a filtrate, which will ultimately become the urine.
Glomerular Filtration rate (
GFR
GFR
The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance.
Kidney Function Tests):
Notice that within the autoregulatory range,
GFR
GFR
The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance.
Kidney Function Tests and RBF remain relatively constant.
Tubuloglomerular feedback Tubuloglomerular feedback Glomerular Filtration:
Macula Macula An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. Eye: Anatomy densa (MD) cells within the tubules can sense tubular flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure and adjust secretion Secretion Coagulation Studies of substances that 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 GFR GFR The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance. Kidney Function Tests:
Fine-tuning mechanisms:
Cerebral circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment is unique because its vessels are protected by a specialized structure called the blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier, and it has the ability to regulate its own blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure.
The blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier
Image by Lecturio.The brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification can regulate its own cerebral blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure (CBF) in response to changes in blood pressure, CO2 levels, and activity levels of different brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification regions.
Blood flow
Blood flow
Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute).
Vascular Resistance, Flow, and Mean Arterial Pressure redistribution in the
brain
Brain
The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem.
Nervous System: Anatomy, Structure, and Classification according to the task being performed:
Redistribution depends heavily on the metabolic activity of the different portions of the cerebral tissue.
The heart does not receive significant O2 and nutrients from the blood flowing through it. Coronary circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment describes the flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure of blood through the vessels supplying the heart muscle itself.
Cardiac
Cardiac
Total Anomalous Pulmonary Venous Return (TAPVR) irrigation during
diastole
Diastole
Post-systolic relaxation of the heart, especially the heart ventricles.
Cardiac Cycle:
During ventricular contraction (
systole
Systole
Period of contraction of the heart, especially of the heart ventricles.
Cardiac Cycle)
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure to
cardiac
Cardiac
Total Anomalous Pulmonary Venous Return (TAPVR) tissue diminishes (down). During ventricular relaxation (
diastole
Diastole
Post-systolic relaxation of the heart, especially the heart ventricles.
Cardiac Cycle),
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure to the heart increases.
Actively contracting muscles increase their own blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure.
Regulating vascular flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure to the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions is critical to thermoregulation Thermoregulation Body temperature can be divided into external temperature, which involves the skin, and core temperature, which involves the CNS and viscera. While external temperature can be variable, the core temperature is maintained within a narrow range of 36.5-37.5ÂşC (97.7-99.5ÂşF). Body Temperature Regulation because heat Heat Inflammation is dissipated as blood flows near the surface of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions.
Nonglabrous skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions is thin skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions with hair on it.
Glabrous skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions is thicker skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions without hair on it (e.g., palms, soles, ear lobes):
Arteriovenous anastomosis in the dermal layers of glabrous
skin
Skin
The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue.
Skin: Structure and Functions, allowing for increased
blood flow
Blood flow
Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute).
Vascular Resistance, Flow, and Mean Arterial Pressure without loss of
heat
Heat
Inflammation in these areas
NE:
norepinephrine
Norepinephrine
Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the locus ceruleus.
Receptors and Neurotransmitters of the CNS