BIO 3302 Lecture Notes - Lecture 4: Fick'S Laws Of Diffusion, Hydrostatics, Extracellular Fluid
16 Oct 2017
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Document Summary
Walls will expand because of elastic elements during systoli. Wall tension = radius x pressure across wall. Thick, elastic, large radius (2) pre-capillary resistance vessels. Small radius so highest resistance greatest pressure drop is in arteriole. Muscular walls (smooth muscle) to control resistance and provide control over: regional blood flow blood pressure. Smooth muscle in the walls around the vessels. During fight or flight --> constriction near unnecessary parts. Sympathetic nervous system, hormones, local chemical agents, metabolites (3) pre-capillary sphincters. At the smallest part of the arterioles before the capillary bed. Bands of smooth muscle that can regulate blood flow to bed. Low velocity blood flow, long transit time (1-3 s) Venules and small veins r can be adjusted (smooth muscle in wall) Think garden hose, crimp the hose and uncrimp. Drop in resistance--> increase pressure in entering capillary bed. Increase pressure in capillaries and force them to stay there longer.
