PHGY 214 Lecture Notes - Lecture 32: Autoregulation, Shear Stress, Angiotensin
9 Dec 2017
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Document Summary
Radius of diff vessels can be adjusted independently to: distribute cardiac output among organs and tissues depending on needs, help regulate short-term arterial bp. Vasoconstriction: narrowing of a vessel: caused by: increases myogenic activity, endothelin, symp stim (vasopression, angiotensin), o2 and decreases co2. Vasodilation: enlargement in radius and circumference of vessel: relaxation of vascular smooth muscle, decreases resistance and increases blood flow, caused by: decreased myogenic activity, endothelin, symp stim (vasopression, angiotensin), and increased co2. Neuro control mechanism, adds changes at the local level. Decreasing radius by results in a 16-fold increases in resistance. Smaller radius increases surface area that comes w blood. Changes w/n other tissues alter radius of vessels and adjust blood flow to organ. Local chem influences on arteriolar radius: local metabolic change, histamine release. All vessels constricted and one stays unchanged so it would be given much more flow. Local physical influences: local app of heat or cold, myogenic response to stretch.
