State all steps of three phases of cardiac cycle.
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Cardiac Cycle Phases
Following are the different phases that occur in a cardiac cycle:
Atrial Diastole: In this stage, chambers of the heart are calmed. That is when the aortic valve and pulmonary artery closes and atrioventricular valves open, thus causing chambers of the heart to relax.
Atrial Systole: At this phase, blood cells flow from atrium to ventricle and at this period, atrium contracts.
Isovolumic Contraction: At this stage, ventricles begin to contract. The atrioventricular valves, valve, and pulmonary artery valves close, but there won’t be any transformation in volume.
Ventricular Ejection: Here ventricles contract and emptying. Pulmonary artery and aortic valve close.
Isovolumic Relaxation: In this phase, no blood enters the ventricles and consequently, pressure decreases, ventricles stop contracting and begin to relax. Now due to the pressure in the aorta – pulmonary artery and aortic valve close.
Ventricular Filling Stage: In this stage, blood flows from atria into the ventricles. It is altogether known as one stage (first and second stage). After that, they are three phases that involve the flow of blood to the pulmonary artery from ventricles.