BIOL 1119 Lecture 3: Lecture 3 Circulation Notes
19 Aug 2016
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Thinner walls, less muscular and elastic tissue. Typically 10 mmhg, unlike in large arteries where the bp averages 100 mmhg and surges up to 120 mmhg. Little uctuation in bp in veins unlike bp in arteries, which pulses. 10 x full difference between bp in the arteries and the veins. Post capillary venules are the smallest; more porous than capillaries: uid exchange between post capillary venules and surrounding tissues. Muscular venules receive blood from post capillary venules: not continuous, more bundle like. Tunica media is much thinner than in medium arteries, with bundles of smooth mucsles (unlike arteries) They have internal one way valves in veins, keeps blood moving upward toward the heart rather than dropping down again when muscles relax. The valves lock when blood ows back down onto them. Veins with especially thin walls, large lumens, and no smooth muscle or fat. No vasomotion is possible unlike the other veins.
