KINE 3012 Lecture Notes - Lecture 7: Sympathetic Nervous System, Extracellular Fluid, Endothelium
24 Nov 2014
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Some control of blood flow is local, through smooth muscle and other things. Because blood flow influences mean arterial pressure we also need a way to regulate the whole system all together to make the body parts work nicely together. Sympathetic nervous system supplies arterial smooth muscles everywhere but the brain, certain amount of sympathetic input maintains tone. There is no a1-adrenergic receptor in the brain. Under same sympathetic stimulation, we can get increased blood flow to some areas and decreased to others. Increase in one type of nervous stimulation can have different neural effects on other organs. Capillaries are sights of exchange, two types of passive exchanges, diffusion and bulk flow. Molecules that are diffusing out of capillaries have to diffuse out the cell through interstitial fluid into the tissue. There is some bulk flow in between the gaps of endothelial cells. Capillary beds are perfect examples of form fitting function.
