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Contraction of the ventricle in the heart begins by the command from

1. Chordae tendinae
2. S.A. node
3. Purkinje fibres
4. A. V. node

Correct answer: S.A. node

Solution

The S.A. node is the heart’s primary pacemaker and initiates the electrical impulse that starts each heartbeat. That impulse travels through the conduction system, eventually causing the ventricles to contract.

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