Veins and Capillaries

Veins and Capillaries - arterioles(small and have smooth...

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BIO 118 Capillaries: -site of exchange for oxygen and carbon dioxide. -Small diameter, very small. Single layer of cells. -Capillaries are permeable; there are fenestrations (pores). Page 433 -Fluid and materials are squeezed out of the fenestrations. -Force that’s pushing fluid out of the capillaries = pressure. -Opposing force= colloid osmotic pressure C.O.P -red blood cells and plasma proteins are too big to squeeze out of fenestrations. -Antagonistic forces working against each other. -Lymphatic system= entire network of vessels that look like veins that drain away extra fluid from capillaries. -All capillary beds; if they were completely filled, it would only take 14% of your total blood volume. -When thinking and being active, your brain needs more blood flow. -Arteries(smooth muscle)
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Unformatted text preview: arterioles(small and have smooth muscles) [There is a pre capillary sphincter ]capillaries rejoining to make venules -Precapillary sphincter is also a smooth muscle , rings of muscles, contract and decrease flow in blood vessel. -VEINS: thin, little to no elastic tissue. -Pressure in venous system is very low (11mm Hg). Tissue is very similar between veins and arteries, but arteries are very very thick. -Venous return= larger veins are equipped with valves(pg 434). -When a person flexes and bulges his muscles, the skeletal tissue will squeeze on your veins, which creates pressure. Veins have one way valves. -Everytime you move, you contribute to blood flow. -If you dont move and stay absolutely still, blood will not go to brain, and you will faint....
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This note was uploaded on 09/29/2011 for the course BIOL 118 taught by Professor Peterson during the Spring '08 term at University of Washington.

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