Assignment # 5 CV Physiology Due Thurs. March 6th Name__________Ilan Leas _____________________ 1. Describe what happens to the AV and Semilunar valves during ventricular systole . Also explain why these valves “behave” (i.e. open or close) this way during this phase of the cardiac cycle (2 pts). During the ventricular systole, the AV valves close because of the rapidly rising pressure. When the pressure in the ventricle exceeds the pressure in the large arteries, the SL valves are forced open and blood is expelled from the ventricles into the aorta and pulmonary trunk. These valves open or close based on pressure. 2. On a normal electrocardiogram, there are visible P, QRS, and T waves. Describe the electrophysiological “events” that cause each. Which normal electrophysiological “event” of the cardiac cycle is not observed/recorded on an electrocardiogram (4)? P wave = Depolarization wave from the SA node through the atria. QRS waves = Results from ventricular depolarization and precedes ventricular
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