Multiple choice

Heart beat is initiated in man by __________.

  1. SA node

  2. Purkinje fibres

  3. AV node-adrenaline

  4. Bundle of HIS

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A Correct answer
Explanation

The SA node (sinoatrial node) is the heart's natural pacemaker, located in the right atrium. It spontaneously generates electrical impulses that initiate each heartbeat. These impulses then spread to the AV node, Bundle of His, and Purkinje fibres to coordinate the cardiac cycle.