Certified Outpatient Coder (COC) Practice Exam

The normal pacemaker of the heart is the sinoatrial (SA) node. This small cluster of specialized cells is located in the right atrium and is responsible for initiating electrical impulses that trigger heartbeats. The SA node generates impulses at a rate of 60 to 100 beats per minute, which sets the rhythm for the rest of the heart.

While the other structures play important roles in the heart's electrical conduction system, they are responsible for different functions. The atrioventricular (AV) node serves as a gateway for impulses to travel from the atria to the ventricles, and it acts as a secondary pacemaker if the SA node fails, but it does not generate impulses as rapidly as the SA node. Purkinje fibers are involved in the rapid conduction of impulses through the ventricles, ensuring synchronized contractions, but they do not initiate the impulse rhythm. The Bundle of His conducts impulses from the AV node to the ventricles but also lacks the primary pacemaker function of the SA node.

Understanding the hierarchy and function of these components is crucial for recognizing how the heart maintains its rhythm and responds to various physiological needs.