What term describes the amount of resistance the heart must overcome to eject blood?

The term that refers to the amount of resistance the heart must overcome to eject blood is afterload. Afterload is a critical concept in understanding cardiac function, as it represents the pressure the ventricles must generate to open the valves and propel blood into circulation. High afterload can negatively impact the heart's efficiency, making it harder for the heart to pump effectively, which is particularly significant in conditions like heart failure.

Preload, on the other hand, pertains to the initial stretching of the cardiac muscles prior to contraction and is influenced by the volume of blood returning to the heart. Cardiac output refers to the total volume of blood the heart pumps in a minute, which is a product of stroke volume and heart rate. Stroke volume represents the amount of blood ejected by the heart with each contraction, but it does not specifically address resistance. Therefore, afterload is the correct term to describe the resistance that must be overcome for blood ejection.