What is the End Systolic Volume (ESV)?

End Systolic Volume (ESV) refers to the amount of blood that remains in the ventricles of the heart after it has contracted. During the heart's contraction phase, known as systole, blood is ejected into the arteries. Once this contraction has completed, the volume that remains in the ventricles is termed ESV. This measurement is important for understanding heart function and cardiac output because it helps to assess how effectively the heart is pumping blood.

In contrast to the correct answer, the other choices describe different aspects of cardiac function or volumes. For instance, the volume of blood expelled from the heart during contraction refers to the Stroke Volume (SV), which measures the amount of blood pumped by a ventricle with each heartbeat. The maximum volume of blood in the ventricles before contraction is known as End Diastolic Volume (EDV), which indicates how much blood is present before the heart beats. Lastly, the average volume of blood circulated throughout the body is a different concept related to overall blood volume, which is not specific to the heart's phases of contraction and relaxation. Understanding these differences is crucial for grasping cardiac physiology in relation to conditions and treatments involving the heart.