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14 Cards in this Set
- Front
- Back
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Structure of a blood vessel
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Inner: tunica intima
Consists of endothelium (simple squamous epithelium), basement membrane, and internal elastic lamina Middle: tunica media Contains circular smooth muscle and elastic and collagen fibers Outer: tunica adventitia connective tissue |
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Arteries
( carry blood away from heart) |
Large elastic arteries
Muscular (distributing) arteries Arterioles Large, Medium, Small |
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Large Elastic Arteries
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Thick-walled with large diameters
Tunica media has many elastic fibers and little smooth muscle |
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Muscular (distributing) Arteries
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Thick-walled with small diameters
Tunica media has abundant smooth muscle and some elastic fibers |
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Arterioles
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Smallest arteries
Tunica media consists of one or two layers of smooth muscle cells and a few elastic fibers |
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Capillaries
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Capillaries consist only of endothelium
Connects arteries to veins |
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Thoroughfare channels
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carry blood from arterioles to venules
(rapidly) |
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Precapillary sphincters
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regulate the flow of blood into capillaries
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Veins
(carry blood back to heart) |
Venules connect to capillaries and are like capillaries, except they are larger in diameter
Large venules and all veins have all three layers Valves prevent the backflow of blood in the veins |
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Valves
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Prevent backflow of blood
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Geneal route of blood from heart and back:
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Moves blood to and from the lungs
Pulmonary trunk arises from the right ventricle and divides to form the pulmonary arteries, which project to the lungs From the lungs, four pulmonary veins return blood to the left atrium |
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Relationship between BP, resistance and flow:
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Blood flow through a blood vessel is determined by two factors:
(1) pressure difference of the blood between the two ends of the vessel, also sometimes called "pressure gradient" along the vessel, which is the force that pushes the blood through the vessel, and (2) the impediment to blood flow through the vessel, which is called vascular resistance |
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three factors that determine the resistance to blood flow:
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vessel diameter
vessel length viscosity of the blood (Of these three factors, the most important quantitatively and physiologically is vessel diameter) |
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Cause of Edema
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If the capillaries (tiny blood vessels) leak fluid into the surrounding tissue the area will start to swell
Leaking capillaries will cause the kidneys to accumulate higher than normal quantities of sodium (salt) and water in order to compensate for the capillary fluid loss. This results in more blood circulating in the body, which in turn causes even more capillary leakage into the surrounding tissue, which produces additional swelling - a vicious cycle |
