Phases of the Cardiac Cycle
1) Atrial Diastole (Atria fill with blood)
2) Ventricular Diastole (Blood is pumpled from the Atria into the ventricles though the AV valves.
3) Atrial Systole (The AV valves close)
4) Ventricular Systole (semilunar valves open and the ventricles contract. Blood is forced from the right ventricle into the pulmonary artery and from the left ventricle into the Aorta. Finally, the semilunar valves close and the cycle is completed.