Question

Easy definition of heartbeat please, in my book it's too long​

Answer 1

Answer:

The rhythmical contraction and expansion of heart muscles constitute heartbeat.

Explanation:

hope it helps (~‾▿‾)~

Answer 2

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The walls of the chambers of the heart are made up of muscles. These muscles contract and relax rhythmically. This rhythmic contraction followed by its relaxation constitute a heartbeat.