Final answer:
The term for the volume of blood in the ventricles at the end of diastole is end diastolic volume (EDV) or preload, and it plays a crucial role in determining stroke volume during the cardiac cycle.
Step-by-step explanation:
The volume of blood in each ventricle at the end of diastole, immediately before the ventricles contract at systole, is called the end diastolic volume (EDV) or preload. During the cardiac cycle, the end diastolic volume (EDV) represents the amount of blood collected in each ventricle at the end of the atrial contraction (atrial systole), just before the onset of ventricular systole. It is an important determinant of the stroke volume during the subsequent ventricular ejection phase when the ventricles contract to pump blood out of the heart.
In an average adult at rest, the EDV is typically around 130 mL, indicating how much blood is ready to be ejected. The amount of blood that remains in the ventricle after the blood is ejected is known as the end systolic volume (ESV). These terms are crucial in understanding the mechanics of the heart and the regulation of blood flow through the cardiovascular system, which ensures proper oxygenation and nutrient distribution throughout the body.