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 don’t move and stay absolutely still, blood will not go to brain, and you will faint....
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- Spring '08
- Blood vessel, return= larger veins, osmotic pressure C.O, fenestrations