Where can automaticity foci be found in the heart?

Where can automaticity foci be found in the heart?

• A. In the ventricles only
• B. Right atrium and bundle of His
• C. Left atrium and AV node
• D. Only in the SA node

Answer: (B)

Automaticity foci are specialized areas of the heart that can generate electrical impulses independently of the primary pacemaker, which is the sinoatrial (SA) node. These foci can be found in several locations throughout the heart, including the right atrium and the bundle of His. The right atrium contains the SA node, as well as potential automaticity foci that can take over pacing if the SA node fails. Additionally, the bundle of His is part of the conduction pathway and has cells capable of automaticity.

While the SA node is the primary pacemaker, it is not the only site where automaticity can occur. Other areas, such as the atrioventricular (AV) node and ventricles, can also exhibit automaticity, but in this particular case, the presence of automaticity foci specifically in the right atrium and bundle of His is what makes option B the correct answer.