In the electrical conduction system of the heart, which structure serves as the natural pacemaker by initiating the normal heartbeat?

• A. Sinoatrial (SA) node
• B. Atrioventricular (AV) node
• C. Bundle of His (AV bundle)
• D. Purkinje fibers

Answer: (A)

Verified step by step guidance

1. Understand that the heart's electrical conduction system controls the heartbeat by generating and transmitting electrical impulses.
2. Identify the key structures involved: the Sinoatrial (SA) node, Atrioventricular (AV) node, Bundle of His, and Purkinje fibers.
3. Recognize that the natural pacemaker is the structure that initiates the electrical impulse causing the heart to contract.
4. Recall that the SA node is located in the right atrium and is responsible for starting the heartbeat by generating regular electrical impulses.
5. Conclude that the SA node sets the pace for the heart rate, making it the natural pacemaker of the heart.