The cardiac cycle roles describe the sequence of event which takes place in the heart. The heart is pumped with the combination of the systole and diastole chamber. The first stage is ventricular diastole and atrial systole where the both ventricles are relaxed. In the ventricle, the result is low comparing to the atrium above. In the atria due to the increase of a pressure, it is filled. The atrioventricular valves open this allows the blood to pass to the ventricles. The valves in the vena cava and the pulmonary vein is closed which prevents the backflow of blood. The second stage is ventricular systole and atrial diastole where after the atria it relaxes and the both of the ventricles contracts. In the ventricle pressure, the result is higher
