EVERYDAY SCIENCE

Detailed explanation-1: -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: -Ventricular systole: lasts about 0.3 seconds-both ventricles contract, blood is forced to the lungs via the pulmonary trunk, and the rest of the body via the aorta. Atrial diastole: lasting about 0.7 seconds-relaxation of the atria, during which the atria fill with blood from the large veins (the vena cavae).

Detailed explanation-3: -The normal duration of the cardiac cycle is 0.8 second.

Detailed explanation-4: -A cardiac cycle is made up of atrial systole and diastole and ventricular systole and diastole. In humans, the heart beats for about 72 times per minute. Hence the time of a cardiac cycle is 60/72=0.860/72=0.8 sec approx. The total time of one cardiac cycle is distributed into atrial systole 0.8 sec.