In the electrical conduction system of the heart, which structure is considered the pacemaker of the heart?

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

Answer: (D)

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 main components of this system: the Sinoatrial (SA) node, Atrioventricular (AV) node, Bundle of His, and Purkinje fibers.
3. Recognize that the pacemaker of the heart is the structure that initiates the electrical impulse, setting the rhythm for the heart rate.
4. Recall that the SA node, located in the right atrium, is responsible for generating the initial electrical impulse, making it the natural pacemaker.
5. Note that the AV node, Bundle of His, and Purkinje fibers serve to conduct and distribute the impulse but do not initiate it.