PNB 2265 Lecture 11: Lecture 11
10 Feb 2017
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Document Summary
Three mechanisms: local control, neural (reflex) control, hormonal control. Local control: regulation at arteriole: intrinsic. Blood flow is adjusted to meet needs of the tissue: All tissues can get blood at the same time, but different amounts of blood depending on the tissue. Regulate the radius of the arterioles depending on how much blood each: vasodilation: tissue needs. Decreased blood pressure in organ (flow autoregulation) Neural (reflex) control: innervation by neurons can change radius: sympathetic ns is responsible for vasoconstriction (alpha receptors) and vasodilation (beta receptors, main regulator of map!!! (mean arteriole pressure) Takes average of those two: use neurons to innervate because your tissue knows it needs to adjust and it just won"t. Arteriole only regulated by sympathetic: sympathetic and parasympathetic. Can vasoconstrict and vasodilate, only using (cid:498)gas pedal(cid:499) Will constrict at an alpha adrenergic receptor. Vasodilator for vessels with: angiotensin ii. Goes up with resistance: nitric oxide. Everywhere there are tissues, there are capillary beds to manage exchange.
