This document discusses the phases of the cardiac cycle:
1) There are seven phases of the cardiac cycle that describe the contraction and relaxation of the atria and ventricles as well as the opening and closing of valves.
2) The phases include atrial contraction, isovolumetric contraction, rapid ejection, reduced ejection, isovolumetric relaxation, rapid filling, and reduced filling.
3) Each phase is characterized by the state of the atrioventricular and semilunar valves as well as the electrical and mechanical events that occur in the atria and ventricles.