Which of the following statements concerning the cardiac cycle is true?
A) Blood enters the right and left atria only during diastole.
B) Most ventricular filling occurs before the atria contract.
C) During ventricular systole, the AV valves open.
D) The semilunar valves remain closed throughout ventricular systole.
E) Most of end-diastolic volume comes from active filling.

Question

Quizplus · Accepted Answer

Most of the ventricular filling (about 70-80%) occurs passively before the atrial contraction. The atrial contraction (atrial systole) contributes to the remaining 20-30% of the filling, ensuring complete ventricular filling before ventricular systole begins.

Which of the Following Statements Concerning the Cardiac Cycle Is