Final answer:
The process described is known as 'systole,' which is the phase when the ventricles contract and eject blood into circulation. Ventricular systole is one of the two main phases of the cardiac cycle, the other being diastole.
Step-by-step explanation:
The action of the heart by which blood is ejected into circulation as the chambers of the heart become smaller is known as systole. Specifically, this refers to ventricular systole, where the ventricles contract and push blood out of the heart to circulate around the body. This stage is contrasted with diastole, which is when the heart's chambers relax and fill with blood. Both systole and diastole are critical phases of the cardiac cycle, which must be well-coordinated to ensure efficient blood flow.