Which of the following statements about the cardiac cycle is TRUE?

Question

Quizplus · Accepted Answer

During ventricular systole, the ventricles contract and increase in pressure, causing the atrioventricular (AV) valves to close to prevent blood from flowing back into the atria. This closure produces the first heart sound, or "lub." Therefore, choice C is the true statement. A is false because diastole is longer than systole at rest. B is false because during isovolumetric ventricular relaxation, both the AV and semilunar valves are closed, and no blood is flowing into or out of the ventricles. D is false because the QRS complex corresponds to the depolarization of the ventricles, while the closure of the semilunar valves occurs later during ventricular diastole. E is false because the atrioventricular valves are already open during atrial contraction (i.e. atrial kick), and they do not need to go from closed to open.

Which of the Following Statements About the Cardiac Cycle Is