Circulatory System-the Cardiac Cycle, Contraction and Relaxation
The circulatory system consists of the heart and blood vessels. The heart contracts rhythmically to convey blood to all body tissues, through a network of blood vessels. The cardiac cycle includes one systole (heart contraction) and one diastole (heart relaxation). During the cardiac cycle the blood flows through the four heart chambers, and the one-way valves prevent back-flow of blood.
If you would like to find out more about all the physiological and mechanical events occurring during the cardiac cycle, below is the video that I have created.