Which of the following correctly gives the orders of events in a cardiac cycle?
A) atria contract, ventricles contract, AV valves close, ventricles relax, semilunar valves close
B) ventricles contract, AV valves close, atria contract, ventricles relax, semilunar valves close
C) ventricles relax, atria contract, ventricles relax, AV valves close, semilunar valves close
D) AV valves close, ventricles relax, atria contract, semilunar valves close, ventricles contract
E) ventricles contract, atria contract, AV valves close, ventricles relax, semilunar valves close

Question

Quizplus · Accepted Answer

The correct sequence of events in a cardiac cycle starts with the atria contracting, which is followed by the ventricles contracting. This causes the atrioventricular (AV) valves to close to prevent backflow into the atria. After the ventricles contract, they begin to relax, leading to the closure of the semilunar valves to prevent backflow from the arteries into the ventricles. This sequence ensures efficient blood flow through the heart and into the systemic and pulmonary circulations.

Which of the Following Correctly Gives the Orders of Events