Which term describes the pressure that must be exceeded for blood ejection from the ventricles?

The pressure that must be exceeded for blood ejection from the ventricles is known as afterload. This term refers to the resistance that the heart must overcome in order to pump blood into the systemic circulation. Afterload is primarily determined by the pressure in the aorta and the systemic vascular resistance.

When the ventricles contract during systole, they must generate enough pressure to exceed this afterload in order to effectively eject blood. If the afterload is increased, the heart may need to work harder to achieve this ejection, which can influence cardiac output and overall heart function.

Preload, on the other hand, relates to the volume of blood in the ventricles at the end of diastole, impacting stroke volume but not directly describing the pressure required for ejection. Systole and diastole refer to the phases of the cardiac cycle where the heart contracts and relaxes, respectively, rather than pressure dynamics related to blood ejection from the ventricles.