Detail step of cardiac cycle

 the cardiac cycle include event happen in heart 

one heartbeat to the next

it repeat over and over 

duration of each cycle can be calculated from the heart rate 

e.g if the heart rate is 72bpm 

the length cycle length would be 1 over the heart rte 

one over 72 is 0.013 and that's in minutes 1/72=0.013

 its very small number 

if we multiply with 60 give us the number in seconds 

which is around 0.8 second for each cardiac cycle . 

If the heart rate is increase the cycle length is shorter 

if the heart rate is decrease the cycle length is longer.

during the time there is both contraction and relaxation of the heart

there is atria systole and atria diastole

atrial systole happen before the ventricle systole 

0.8second atria systole would take 0.1 second 

so the rest cycle is 0.7 second the atria spend in diastole

ventricular systole is longer around 0.3 seconds.

the remaining 0.5 second is in diastole

the number would vary depending on the cycle.

but atrial diastole overlaps 

the rest of the cycle is when both atria and ventricle are relaxing in the diastole 

both chamber the duration of diastole is longer than systole 

what exactly need to happen

between heartbeat 

blood from the body and from the lungs reach to atria

this flow into the ventricle 

the ventricles pump out the blood through pulmonary trunk , aorta to reach the lungs and the rest of the body