End-systolic volume (ESV) is defined as the volume of blood remaining in the ventricle after contraction.

• A. The volume of blood ejected during systole
• B. The volume of blood in the ventricle at the end of diastole
• C. The total blood volume in the ventricle during the cardiac cycle
• D. The volume of blood remaining in the ventricle after contraction

Answer: (D)

End-systolic volume is the amount of blood left in the ventricle after it finishes contracting. During systole, the ventricle ejects part of its blood into the circulation, and the remainder stays behind as the end-systolic volume. This is different from the end-diastolic volume, which is the ventricle’s volume at the end of filling, just before contraction. The stroke volume, or the amount ejected per beat, equals EDV minus ESV, so ESV reflects how effectively the ventricle pumps blood. ESV increases when afterload is high or contractility is reduced, and it decreases when the heart contracts more forcefully.