BIOL 2060 Chapter Notes - Chapter 13.0: Vasopressin, Pulse Pressure, Hyperaemia
20 Apr 2018
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Factors that determine flow: pressure gradient, radius. During stress, blood loss higher resistance so no flow. During exercise: % of co increases in skeletal, skin, heart (local hyperemia) decrease in digestion, liver kidney (sympathetic control) bones. Arterioles have: endothelium cells (ec) & smooth muscle. Contribute to map & controls individual flow to arteries. Functions of ec: line heart, blood vessels, prevent cells & platelet adherence (thrombosis), control exchange of fluid in capillaries. Mediate new capillary growth (angiogenesis), regulate inflammatory response. In ec: l-arginine converted to no by nos. Acts on smooth muscle to activate guanylate cyclase to activate 2nd messenger cgmp and dilate. Inhibition of pde prevents breakdown of cgmp so dilation continues. Local control of blood flow within organ: active hyperemia/reactive hyperemia. Metabolites include increase adenosine, k+, h+ , co2 decrease o2, increase prostaglandin. During systole: metabolites accumulate in in coronarty due to decrease flow. Dilation: decrease myogenic, decrease o2, increase co2 & metabolites increase no.
