(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 ?

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1 Answers

(a) Heart beat: One complete contraction and relaxation of the heart is called a heart beat. The usual heart beat rate at rest is 72 times /minute. 

(b) The heart beats faster when a person runs for a while because the body needs more energy under these conditions.

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