Question

(a) What is meant by 'heart beat'? What is the usual heart beat rate at rest?
(b) What change occurs in heart beats if a person runs for a while? Why?

Answer 1

(a) Heart beat is the rhythmic contraction and relaxation of the heart, which includes one systole (contraction phase) and one diastole (relaxation phase) of the heart. At rest, human heart usually beats 70 to 72 times per minute.

(b) A person's heart beats faster after running for a while. This is because his body needs more energy after running.
When the heart beats faster, it pumps the oxygenated blood more rapidly to the body organs, thereby providing more oxygen to our cells (for rapid respiration) to produce more energy.