Which of the following is true concerning the heart's electrical conduction system?

• A. The bundle of His is located in the right atrium.
• B. The atrioventricular node directly initiates ventricular contraction.
• C. The sinoatrial node acts as the natural pacemaker of the heart.
• D. Purkinje fibers are responsible for initiating the heartbeat.

Answer: (C)

Verified step by step guidance

1. Understand the components of the heart's electrical conduction system: the sinoatrial (SA) node, atrioventricular (AV) node, bundle of His, bundle branches, and Purkinje fibers.
2. Recognize that the sinoatrial (SA) node is located in the right atrium and is known as the heart's natural pacemaker because it initiates the electrical impulses that set the rhythm for the heart.
3. Identify the role of the atrioventricular (AV) node, which receives impulses from the SA node and delays them slightly before passing them to the ventricles, allowing the atria to contract and complete ventricular filling.
4. Understand that the bundle of His is located in the interventricular septum, not the right atrium, and it transmits impulses from the AV node to the bundle branches.
5. Clarify that Purkinje fibers distribute the electrical impulse throughout the ventricles, causing them to contract, but they do not initiate the heartbeat.