Which of these events occurs at rapid heart rates
A)The lengths of systole and diastole shorten equally.
B)The length of systole stays almost constant, but the length of diastole shortens considerably.
C)The length of systole increases at the expense of diastolic time shortening.
D)Diastolic time lengthens, and systolic time shortens.

Question

Quizplus · Accepted Answer

At rapid heart rates, the cardiac cycle becomes shorter, and the heart spends less time in diastole. Therefore, the length of diastole shortens considerably, while the length of systole stays almost constant. This is because the ventricles contract more frequently and spend less time relaxing, leading to a shorter filling time for the ventricles.

Which of These Events Occurs at Rapid Heart Rates