In your OWN words, describe the cardiac cycle

The cardiac cycle is defined as a sequence of alternating contraction and relaxation of the atria and ventricles in order to pump blood throughout the body ... In other words, when the atria are in diastole, the ventricles are in systole and vice versa. The cardiac cycle describes all the activities of the heart through one complete heartbeat-that is, through one contraction and relaxation of both the atria and ventricles ... The volume of the ventricles remains unchanged (isovolumetric) during this period.