NEET BIOLOGY

Detailed explanation-1: -A healthy human heart beats 72 times per minute which states that there are 72 cardiac cycles per minute. The cardiac cycle involves a complete contraction and relaxation of both the atria and ventricles and the cycle last approximately 0.8 seconds.

Detailed explanation-2: -The heart beats 72 times per minute, i.e., that many cardiac cycles are performed per minute. From this it could be deduced that the duration of a cardiac cycle is 0.8 seconds. During a cardiac cycle, each ventricle pumps out approximately 70 mL of blood, which is called the stroke volume.

Detailed explanation-3: -The total period of the cardiac cycle is 0.8 seconds which includes a cardiac diastole of 0.4 seconds, a ventricular systole of 0.3 seconds and an atrial systole of 0.1 seconds.

Detailed explanation-4: -The normal duration of the cardiac cycle is 0.8 second.

Detailed explanation-5: -There is an inverse relationship between the duration of cardiac cycle and heart rate. Hence when the heart rate is increased to 120 beats per minute, the cardiac cycle duration will be about 0.5 sec.