Describe the structure and function
of atrioventricular and semilunar valves:
Atrioventricular Valves (AV) between the atria and the ventricles are controlled by the chordae tendinae and papillary muscles. When the ventricles contract, the pressure of the blood swings teh cusps together, closing the valves to the atria. At the same time, the papillary muscles tense the chordae tendineae and prevent the vales from swinging into the atria.
Semilunar Valves prevent backflow from the pulmonary trunk and aorta into the vetnricles. Semilunar valves have no muscular support; the 3 cusps of the valve support each other like a tripod.