Stroke volume refers to the ______

Stroke volume is defined as the amount of blood expelled by the left ventricle with each contraction or heartbeat. This measurement is crucial as it reflects the efficiency of the heart in pumping blood during each cycle and significantly influences cardiac output, which is a product of stroke volume and heart rate.

Understanding stroke volume is essential in the context of cardiovascular function and exercise physiology, as it can be affected by factors such as preload (the initial stretching of the cardiac muscle cells), contractility (the force of contraction), and afterload (the resistance the heart must overcome to circulate blood). Thus, option C accurately describes stroke volume as it directly relates to the function of the left ventricle in the cardiac cycle.