Term
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Definition
| arteries-arterioles-capillaries-venules-veins |
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Term
| what are the walls composed of three layer? |
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Definition
endothelium: innermost layer, very smooth
smooth muscle: middle layer, sympathetic innervation produces vasoconstriction(lack of symp. act produces vasodilation), thickest in arteries; elastin fibers also found btwn muscle cells
collagen fibers: outer layer, also contains nerves fibers |
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Term
| what are the three arteries? |
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Definition
| elastic arteries, muscular arteries, and arterioles |
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Term
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Definition
| aorta & its major branches, pulmonary trunk; large diameter, elastic fibers > smooth muscle; "smooth out" or reduce fluctuation in pressure when ventricles contract not responsive to vasoconstriction(why is this important) |
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Term
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Definition
| deliver blood to specific organs & muscles(carotids, brachial) elastic fibers=smooth muscle |
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Term
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Definition
small diameter
elastic fibers < smooth muscle
important in regulating blood pressure & capillary blood flow |
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Term
| what are the walls of the capillaries like? |
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Definition
walls are single layer of endothelial cells w/ small gaps btwn cells
-gas exchange & diffusion of nutrients occurs through gaps |
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Term
| what's the blood-brain barrier in the capillaries? |
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Definition
| brain capilaries have no gaps so diffusion can only occur across endothelial cell membrane that forms networks called capillary beds |
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Term
| what do the precapillary sphincters do in the capillaries? |
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Definition
| controls flow through capillaries, determined by tissue needs(ex: muscles, GI tract) |
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Term
| what does the vascular shunt vessel do in the capillaries? |
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Definition
| directs connection of arteriole & venule, used when capillary bed in closed |
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