How is stroke volume defined in relation to cardiac output?

Stroke volume is defined as the amount of blood ejected per heartbeat from the left ventricle of the heart into the aorta. This measurement is crucial in understanding cardiac function because it directly influences cardiac output, which is the total volume of blood the heart pumps in a minute. Cardiac output is calculated by multiplying stroke volume by heart rate, illustrating how stroke volume plays a significant role in determining overall blood circulation and oxygen delivery throughout the body.

The other choices do not align with the definition of stroke volume. The total volume of blood in the body, for example, is a concept related to blood volume rather than the specific amount pumped by the heart with each beat. Similarly, the blood volume returning to the heart refers to venous return, while the amount of blood pumped per day does not reflect the specific mechanics of the heart's pumping action with each contraction. Thus, understanding stroke volume as the amount of blood ejected per heartbeat is critical for grasping broader concepts in cardiovascular physiology.