Chapter 18 - Cardiovascular System: The Heart

f. heart relaxed – av valves hang down into ventricular chamber-ventricles contract-blood forced up against valve flaps closing them. 2. two semilunar valves. a. between ventricles and arteries. b. prevent backflow of blood into ventricles when ventricles relax. c. aortic semilunar valve … ................
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