BIO 11 Lecture Notes - Lecture 23: Tunica Externa, Tunica Media, Arteriole
Document Summary
Some arteries have elastic or smooth tissue in the middle. Tunica media smooth muscle inside elastic recoil - stay open even when cut no valves. The arteriole tree; the cross sectional area decreases as less elastic composes the artery total cross sectional area; increases because of the total number of each vessels. Total cross sectional area same as cross sectional diameter. Total cross sectional area; greater than aorta. Muscular arteries ; 50% elastic, 50% smooth muscle. Arterioles ; 20% elastic, 80% smooth muscle. Veins ; all made of the same things, all the same, except veinules are similar to capillaries; all have valves. Follows same pattern as arteries with total cross sectional area. Vessel length: can alter the speed of flow, longer vessels decrease flow speed vessel. Turbulenc e; lamanar flow, low resistance high speed. Turbulent flow, a lot in short branching vessels with direction changing.
