Cardiac Cycle Vs Atrial Contraction

The most important muscle, the heart, is responsible for allowing us to continue experiencing the simple, yet beautiful things in life. For example, waking up or enjoying a beautiful sunset, other things like swimming and running. To maintain a healthy heart health care givers properly examine this muscle, one component that allows this examination is the cardiac cycle. The cardiac cycle involves a sequence of events affiliated with the flow of blood within the heart during a complete heartbeat, which include atrial systole and diastole followed by ventricular systole and diastole. Systole indicates contraction whereas diastole indicates relaxation. The first phase of the cardiac cycle is Atrial systole, or Atrial contraction in which contraction of the atria tops off the ventricles, filling them to
As the ventricles become full the contractions of the ventricles begin. The second part of the cardiac cycle represents Isovulometric contraction in which the pressure in the ventricles rises forcing the AV valves to close but does not open the semilunar valves, leaving a constant volume of blood within the ventricles. The third phase of the cardiac cycle begins as the ventricles contract and the blood pressure increases, forcing the semilunar valves to open. This rushes blood from the ventricles into the pulmonary trunk and aorta, this phase is known as Ventricular Ejection. As blood begins to leave the ventricles the ventricular volume decreases until it reaches a point called end systolic volume (ESV). No change in ventricular volume is present. The fourth phase of the cardiac cycle is known as Isovulometric