Which of the following terms describes the amount of blood ejected per heartbeat?
Correct Answer: A
Rationale: The correct answer is A: Stroke volume. Stroke volume refers to the amount of blood ejected by the left ventricle in one contraction. Choice B, Cardiac output, is the total volume of blood pumped by the heart per minute and is calculated by multiplying stroke volume by heart rate. Choice C, Ejection fraction, is the percentage of blood pumped out of the left ventricle with each heartbeat. Choice D, Afterload, refers to the pressure or resistance that the ventricles must overcome to eject blood during systole. Therefore, in the context of the question, the term that specifically describes the amount of blood ejected per heartbeat is stroke volume.