The Cardiac Cycle Quiz

See Stroke Volume. Stroke volume (B) is the volume of blood ejected by one ventricle during one heartbeat. The ventricle fills during diastole and ejects part of that blood during systole. Subtract the end-systolic volume, the blood left after ejection, from the end-diastolic volume, the blood present before contraction, to calculate it. Stroke volume is therefore an absolute volume, usually expressed in millilitres per beat. Multiplying it by heart rate gives cardiac output, the volume pumped per minute.

E describes the starting filled volume, not the amount that leaves during contraction. D is the residual volume after ejection, so it must be subtracted from the starting volume. The time unit distinguishes C: cardiac output measures flow per minute and combines stroke volume with heart rate. A is ejection fraction, the proportion of the filled volume expelled; it compares the ejected amount with the starting volume instead of reporting that amount alone.