PHGY 214 Lecture Notes - Lecture 3: Angiotensin, Autoregulation, Vasoactivity
24 Jan 2017
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Document Summary
Arterioles possess circularly arranged smcs (smooth muscle cells) highly enriched with sympathetic nerves. These smcs are also highly responsive to local chemical changes and some circulating hormones. Normally exhibits a state of partial constriction known as vascular tone. This tone creates a baseline of arteriolar resistance. Two factors that control arteriolar resistance (1) myogenic activity membrane potential fluctuates independently of any neuro or blood born substances. Thus leading to self-induced contractile activity of smooth muscle (2) tonic release of norepinephrine from sympathetic nerves that innervate the arterioles to create the tone. The amount of co received by each organ is determined by the arteriolar distribution and dimension supplying the tissue. Recall key equation driving force for blood flow pressure gradient is identical for each organ. The r in arterioles controls cardiac output moment by moment basis. i. e. pipe/ tube filled with blood with 3 adjustable valves representing arteriole.
