PLN 203 Lecture Notes - Lecture 5: Fibrinolysis, Qrs Complex, Cell Membrane
23 Feb 2017
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Document Summary
Two pairs of one-way valves prevent backflow during contraction. Atrioventricular (av) valves: between atria and ventricles, bp closes valve cusps during ventricular contraction, papillary muscles tense chordae tendineae to prevent valves from swimming into atria. Semilunar valves: pulmonary and aortic tricuspid valves, prevent backflow from pulmonary trunk and aorta into ventricles, have no muscular support, three cusps support like tripod. Sacs that prevent valve cusps from sticking to aorta. Origin of right and left coronary arteries. Connective tissue fibres: physically support cardiac muscle fibres, distribute forces of contraction, add strength and prevent overexpansion of heart, provide elasticity that helps return heart to original size and shape after contraction. Cardiac skeleton: four bands around heart valves and bases of pulmonary trunk and aorta, stabilize valves, electrically insulate ventricular cells from atrial cells. Supplies blood to muscle tissue of heart. High bp, elastic rebound forces blood through coronary arteries between contractions.
