Windkessel effect in large arteries perform what function –
Correct Answer: Prevent fluctuation in BP
Description: Ans. is 'c' i.e., Prevent fluctuation in BPo All arteries and arterioles have three concentric layers in their wall (from inside out) : Tunica intima (contains endothelium), tunica media (contains smooth muscles) and tunica adventitia (contains fibroblasts and collagen). The tunica intima and tunica media are separated by internal elastic lamina. Tunica media and tunica adventitia are separated by external elastic lamina. Internal and external elastic lamina contain elastic tissue and are responsible for elasticity of vessels, especially large vessels.o The arterial system comprise : -i) Large elastic arteries (windkessel vessels):# These vessels have well developed elastic laminae and therefore a lot of elastic tissue in their wall. The elastic walls prevent abrupt changes in BP a phenomenon called the Windkessel effect.# The walls are stretched during systole, preventing a sudden rise in BP. During diastole, the recoil back, preventing a sudden drop in BP.# Aorta and its immediate braches are windkessel vessels.ii) Large muscular distributing arteries :# These contain less elastic tissue and more muscle fibers than large elastic arteries.# Examples are radial, ulnar, popliteal arteries etc.iii) Arterioles (resistance vessels):# Arterioles contain very less elastic tissue but much more smooth muscle. Arterioles are the major site of vascular resistance.# This is because of two factors : (i) Presence of considerable amounts of smooth muscle in their walls; (ii) By sympathetic (nor-adrenergic) innervation, which constricts the arterioles by producing contraction of smooth muscles.# Beside sympathetic innervation, arteriolar smooth muscle also respond to the products of local metabolism CO2, adenosine, H+ and lactic acid cause arteriolar dilatation.# Distribution of blood flow is mainly regulated by arterioles, by these two mechanisms, i.e., sympathetic innervation and local control by metabolites.# For example, during muscular exercise, strong sympathetic stimulation causes vasoconstriction of the arterioles in the splanchnic area. At the same time, local metabolites cause arteriolar dilatation in the skeletal muscles and myocardium. Therefore, the blood flow is diverted to exercising muscles and the heart.
Category:
Physiology
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