What is defined as the amount of blood ejected from the heart in one contraction?

The term that refers to the amount of blood ejected from the heart in one contraction is stroke volume. This measurement specifically quantifies the volume of blood pumped from one ventricle (either the left or right) during a single heartbeat.

To understand stroke volume’s significance, it is important to recognize that it is a key element in determining cardiac output, which is the total volume of blood the heart pumps in a minute. Cardiac output is calculated by multiplying stroke volume by the heart rate. Consequently, while both stroke volume and cardiac output are integral to understanding heart function, stroke volume focuses solely on the volume per contraction rather than the total over time.

Other terms provided, such as blood volume and end-diastolic volume, refer to different concepts in cardiovascular physiology. Blood volume represents the total volume of blood circulating within the body, while end-diastolic volume pertains to the amount of blood in the ventricles at the end of filling (diastole) before the heart contracts. This distinction further clarifies why stroke volume is the correct answer, as it specifically and exclusively identifies the amount ejected per contraction.