ANP 1105 Lecture Notes - Lecture 9: Tunica Intima, Tunica Externa, Vasa Vasorum
15 Nov 2016
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Document Summary
Delivery system of dynamic structures that begins and ends at heart. Arteries arterioles capillaries enules eins from the heart. Three wall layers (tunics) in arteries & veins. Endothelium: simple squamous epithelium that lines lumen of all vessels. Mostly of smooth muscle and sheets of endothelium. Sympathetic vasomotor nerve fibers innervate this layer (vasoconstriction & vasodilation) Mostly of loose collagen fibers; protect and reinforce wall & anchor it to surrounding structures. Asa vasorum: system of tiny blood vessels found in larger vessels. Thick-walled, large-diameter arteries near heart; highest proportion of elastic fibers. Smooth out pressure fluctuations; recoil helps maintain pressure & flow of blood. Deliver blood to specific organs (0. 3mm-1 cm diameter) Arterioles determine which capillary beds flushed, minute-to-minute. Also called resistance arteries because changing diameters change resistance to blood flow (10 um to 0. 3 mm diameter) Pericytes help stabilize their walls and control permeability. Diameter allows only single rbc to pass at a time.
