| Term | Definition |
|---|
| hemodynamics | the forces involved in circulating blood throughout the body |
| artery | a blood vessel that carries blood away from the heart to other organs |
| arteriole | a small, almost microscopic, artery that delivers blood to a capillary |
| capillary | a microscopic blood vessel located between an arteriole and a venule through which materials are exchanged between blood and interstitial fluid |
| venule | a small vein that collects blood from capillaries and delivers it to a vein |
| vein | a blood vessel that conveys blood from tissues back to the heart |
| angiogenesis | the formation and growth of new blood vessels |
| tunica interna (intima) | the deep coat of an artery or vein, consisting of a lining of endothelium, basement membrane, and internal elastic lamina |
| lumen | the interior space of a blood vessel |
| tunica media | the intermediate coat of an artery or vein, composed of smooth muscle and elastic fibers |
| tunica externa | the superficial coat of an artery or vein, composed mainly of elastic and collagen fibers; also called the adventitia |
| vasa vasorum | blood vessels that supply nutrients to the larger arteries and veins |
| vasoconstriction | a decrease in the diameter of the lumen of a blood vessel due to contraction of smooth muscle fibers in the vessel wall |
| vasodilation | an increase in the diameter of the lumen of a blood vessel due to relaxation of smooth muscle fibers in the vessel wall |
| elastic artery | an artery having the largest diameter, but with relatively thin walls, that functions in conducting blood from the heart to muscular arteries during ventricular relaxation (diastole); also called conducting artery |
| pressure reservoir | the brief storage of potential energy by elastic arteries as their walls are stretched by the incoming surge of blood, and the subsequent release of kinetic energy as the vessels recoil, which moves blood through the arteries |
| muscular artery | a medium-sized, thick-walled artery with a thicker tunica media that functions in stronger vasoconstriction and vasodilation to adjust the rate of blood flow to the arterioles; also called distributing artery |
| distributing artery | another name for a muscular artery because of its high degree of branching and transporting blood to each of the body's organs |
| anastomosis | the union of the branches of two or more arteries supplying the same body region, providing alternative routes for blood to reach a tissue or organ |
| collateral circulation | the alternative route of blood flow to a body part through an anastomosis |
| end artery | an artery that does not anastomose |
| metarteriole | the terminal end of an arteriole that tapers toward a capillary junction |
| precapillary sphincter | the distal-most muscle fiber at the metarteriole-capillary junction that regulates blood flow into the capillary |
| microcirculation | the flow of blood from a metarteriole through capillaries and into a postcapillary venule |
| capillary bed | a network of 10-100 capillaries that arises from a single metarteriole |
| vasomotion | the alternating contraction and relaxation of smooth muscle of metarterioles and precapillary sphincters (5-10 times per min) that regulates blood flow through the capillaries |
| thoroughfare channel | the distal end of a metarteriole without smooth muscle, providing a direct route for blood from an arteriole to a venule, thus bypassing capillaries |
| continuous capillary | a capillary with an intact endothelium that forms a tube interrupted only by intercellular clefts; found in the brain, lungs, skeletal and smooth muscle, connective tissues |
| fenestrated capillary | a capillary with small pores in its endothelium; found in the kidneys, villi of the small intestine, choroid plexuses of the ventricles in the brain, endocrine glands |
| intercellular cleft | a gap between neighboring endothelial cells |
| fenestration | the name for the small pores found in the plasma membranes of the endothelial cells of certain capillaries |
| sinusoid | a large, thin-walled, and leaky type of capillary, having large intercellular clefts that may allow proteins and blood cells to pass from a tissue into the bloodstream; in the liver, spleen, anterior pituitary gland, red bone marrow |
| portal system | the circulation of blood from one capillary network into another through a vein |
| postcapillary venule | a blood vessel that receives blood from the capillaries and passes it into muscular venules; permits exchange of nutrients and wastes between blood and interstitial fluid |
| vascular (venous) sinus | a vein with a thin endothelial wall that lacks a tunica media and externa and is supported by surrounding tissue |
| superficial vein | veins that travel through the subcutaneous layer unaccompanied by parallel arteries |
| deep vein | veins that travel between the skeletal muscles |
| varicose vein | a vein that is dilated and twisted in appearance due to leaky venous valves |
| muscular venule | a blood vessel that passes blood into a vein; act as reservoirs for accumulating large volumes of blood |
| blood reservoir | systemic veins and venules that contain large amounts of blood that can be moved quickly to parts of the body requiring the blood |
| capillary exchange | the movement of substances between the blood and interstitial fluid |
| transcytosis | a transport process in which substances in blood plasma become enclosed within tiny vesicles that enter endothelial cells by endocytosis, then move across the cell and exit on the other side by exocytosis; used to transport large, lipid-insoluble molecules that cannot cross capillary walls in any other way (ex: insulin, certain antibodies) |
| bulk flow | a passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction (an area of higher pressure to an area of lower pressure), at rates far greater than can be accounted for by diffusion alone |
| filtration | pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid |
| reabsorption | pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries |
| blood hydrostatic pressure (BHP) | pressure generated by the pumping action of the heart; pushes fluids out of capillaries |
| interstitial fluid osmotic pressure (IFOP) | pressure created by proteins present in the interstitial fluid; pulls fluid out of capillaries |
| blood colloid osmotic pressure (BCOP) | force due to presence of plasma proteins; pulls fluid into capillaries from interstitial spaces |
| net filtration pressure (NFP) | balance of pressure; determines whether blood volume and interstitial fluid remain steady or change |
| interstitial fluid hydrostatic pressure (IFHP) | pressure due to fluid in interstitial spaces; pushes fluid back into capillaries |
| Starling's law of the capillaries | describes how the volume of fluid and solutes reabsorbed into the blood is normally almost as large as the volume filtered out of the blood |
| edema | an abnormal increase in interstitial fluid volume that can result from either excess filtration or inadequate reabsoprtion |
| blood flow | the volume of blood that travels through any tissue in a given time period (in mL/min) |
| blood pressure (BP) | the hydrostatic pressure exerted by blood on the walls of a blood vessel (usually the arteries in clinical use), determined by cardiac output, blood volume, and vascular resistance |
| systolic blood pressure | the highest arterial blood pressure during contraction |
| diastolic blood pressure | the lowest arterial blood pressure during relaxation |
| mean arterial pressure (MAP) | the average blood pressure in arteries, roughly one-third of the pressure between the diastolic and systolic pressures |
| vascular resistance | the opposition to blood flow due to friction between blood and the walls of blood vessels |
| systemic vascular resistance (SVR) | all the vascular resistances offered by systemic blood vessels; also called total peripheral resistance (TPR) |
| venous return | the volume of blood flowing back to the heart through the systemic veins |
| skeletal muscle pump | helps move blood from the lower body back to the heart through the contraction and relaxation of leg muscles which alternatingly compress and decompress veins (milking) |
| respiratory pump | the alternating compression and decompression of veins in the thoracic cavity due to the pressure changes generated by breathing that helps bring venous blood back to the heart |
| circulation time | the measure of how long it takes for a drop of blood to pass from the right atrium, through the pulmonary circulation, back to the left atrium, through the systemic circulation down to the foot, and back again to the right atrium; is about 1 minute in a resting person |
| syncope | a suden, temporary loss of consciousness (fainting) that is not due to head trauma, followed by spontaneous recovery; usually due to lack of sufficient blood flow to the brain (cerebral ischemia) |
| vasomotor nerve | carries impulses from the cardiovascular center to smooth muscle in blood vessel walls |
| vasomotor tone | a moderate state of vasoconstriction in a blood vessel that sets the resting level of systemic vascular resistance |
| carotid sinus reflex | baroreceptor stimulation that helps regulate blood pressure in the brain |
| aortic reflex | baroreceptor stimulation that helps maintain normal systemic blood pressure |
| aortic and carotid bodies | structures containing chemoreceptors that detect changes in blood level of oxygen, carbon dioxide, and hydrogen ions |
| renin-angiotensin-aldosterone (RAA) system | a hormonal pathway that works to raise blood pressure if blood volume falls or blood flow to the kidneys decreases |
| angiotensin II | a strong vasoconstrictor hormone that raises blood pressure by increasing systemic vascular resistance |
| aldosterone | hormone that increases reabsorption of sodium ions and water by the kidneys, which increases total blood volume, which increases blood pressure |
| antidiuretic hormone (ADH) | hormone released from the posterior pituitary in response to dehydration or decreased blood volume; increases blood volume, which increases blood pressure; also causes vasoconstriction, which increases blood pressure; also called vasopressin |
| pulse | the traveling pressure wave created by the alternate expansion and recoil of elastic arteries after each systole of the left ventricle |
| sphygmomanometer | the instrument used to measure blood pressure |
| systolic blood pressure (SBP) | the force of blood pressure on arterial walls just after ventricular contraction |
| diastolic blood pressure (DBP) | the force exerted by the blood remaining in arteries during ventricular relaxation |
| Korotkoff sounds | the various sounds heard while taking blood pressure |
| pulse pressure | the difference between systolic and diastolic pressure (normally about 40 mmHg) that provides information about the condition of the cardiovascular system |
| pulse point | a location where the pulse can be felt, such as the common carotid artery, brachial artery, femoral artery, popliteal artery, radial artery, and dorsalis pedis artery |
| shock | a failure of the cardiovascular system to deliver enough oxygen and nutrients to meet cellular metabolic needs; characterized by inadequate blood flow to body tissues |
| hypovolemic shock | shock due to decreased blood volume |
| cardiogenic shock | shock due to poor heart function |
| vascular shock | shock due to inappropriate vasodilation |
| obstructive shock | shock due to obstruction of blood flow |
| systemic circulation | the arteries and arterioles that carry oxygenated blood from the left ventricle to sytemic capillaries, plus the veins and venules that return deoxygenated blood to the right atrium |
| hepatic portal circulation | carries venous blood from the gastrointestinal organs and spleen to the liver |
| portal vein | a vein that carries blood from one capillary network to another |
| pulmonary circulation | carries deoxygenated blood from the right ventricle to the air sacs (alveoli) within the lungs and returns oxygenated blood from the air sacs to the left atrium |
| hypertension | persistently high blood pressure that is the major cause of heart failure, kidney disease, and stroke |
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