CARDIAC-CYCLE
Definition: It is the sequence of events during a cardiac beat various changes that follow during a heart beat undergo cyclic repetition one complete cycle of such cardiac events of a beat is the cardiac cycle
Duration:
Heart beats on an average 72 times per minute in adults while resting hence one beat takes 0.8 sec if the heart beats faster the time is less than 0.8 if slower it would be little more
Events ::
Both atria and ventricles undergo systolic and diastolic phase with every beat Therefore there is an atrial systole and an atrial diastole a ventricular systole and a ventricular diastole these sequences have been illustrated in
Atrial Events::
These include atrial systole and atrial diastole Inner most circle of shows events with time taken for atrial events Atrial systole occurs for 0.1 sec Atrial systole is followed by 0.7 sec of atrial diastole during atrial systole the atria contract pouring their blood into their respective ventricles During atrial diastole i.e 0.7 sec atria relax and the blood from superior and inferior vena cava in the right atrium and the pulmonary veins in the left atrium fill them up After this they again contract to perform atrial systole
Ventricular Events::
The ring outer to atrial events in represents ventricular events As the atrial systole ends the ventricular systole begins this continues for 0.3 sec and is followed by ventricular diastole for 0.5sec
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