What does 'stroke volume' refer to?

Stroke volume is defined as the volume of blood that the heart pumps with each beat. This physiological measurement is crucial for understanding how efficiently the heart is functioning during various levels of activity. It plays a vital role in determining cardiac output, which is the total volume of blood the heart pumps out in a minute.

Measuring stroke volume helps assess cardiovascular health and fitness levels. Increased stroke volume often indicates better heart function, as a more efficient heart can pump a greater volume of blood with fewer beats, ensuring that the body's tissues receive adequate oxygen and nutrients.

The other options focus on different aspects of cardiovascular and respiratory physiology rather than directly measuring blood volume per heartbeat. Therefore, the definition of stroke volume being the volume of blood pumped per heartbeat is the accurate description of this important cardiac parameter.