What is known as the volume of blood in a ventricle at the end of filling?

The correct response is based on the definition of End Diastolic Volume (EDV), which represents the amount of blood within a ventricle at the end of the heart's filling phase, known as diastole. During diastole, the ventricles relax and fill with blood from the atria, leading to the highest volume of blood present in the ventricles just before the heart contracts again.

Understanding EDV is crucial in physiology because it directly influences the stroke volume and cardiac output, two vital parameters for assessing heart function. Essentially, a higher EDV can lead to increased preload, which can result in a greater stroke volume due to the Frank-Starling mechanism, where the heart pumps more effectively when filled with more blood.

The other terms, while related to the heart’s function, do not describe the volume of blood at the end of filling. End Systolic Volume refers to the volume of blood remaining in a ventricle after contraction. Stroke Volume is the amount of blood ejected from a ventricle with each heartbeat, calculated as the difference between EDV and End Systolic Volume. Cardiac Output measures the volume of blood the heart pumps per minute and is calculated using heart rate and stroke volume. Thus,