Pacemaker cells are located in which heart structures?

Pacemaker cells are located in which heart structures?

• A. Sinoatrial node and atrioventricular node
• B. Bundle of His
• C. Purkinje fibers
• D. Atrial appendages

Answer: (A)

Pacemaker cells are specialized autorhythmic heart cells that generate rhythmic impulses to set the heartbeat. They are located in the Sinoatrial node, which sits in the upper right atrium near the entry of the superior vena cava, and in the Atrioventricular node, located at the floor of the right atrium near the tricuspid valve. The SA node acts as the primary pacemaker, setting the normal heart rate, while the AV node can take over if the SA node fails, though at a slower rate. The bundle of His and Purkinje fibers mainly serve to rapidly conduct impulses through the ventricles and do not set the pace under normal conditions. The atrial appendages are simply parts of the atrial wall and do not house the primary pacemaker tissue.

Pacemaker cells are specialized autorhythmic heart cells that generate rhythmic impulses to set the heartbeat. They are located in the Sinoatrial node, which sits in the upper right atrium near the entry of the superior vena cava, and in the Atrioventricular node, located at the floor of the right atrium near the tricuspid valve. The SA node acts as the primary pacemaker, setting the normal heart rate, while the AV node can take over if the SA node fails, though at a slower rate. The bundle of His and Purkinje fibers mainly serve to rapidly conduct impulses through the ventricles and do not set the pace under normal conditions. The atrial appendages are simply parts of the atrial wall and do not house the primary pacemaker tissue.