Patient Care Technician (PCT) AAH Practice Exam

Which part of the heart is known as the pacemaker?

1. AV node

2. QT node

3. SA node

4. All are pacemakers of the heart

The correct answer is: SA node

The SA node, or sinoatrial node, is known as the primary pacemaker of the heart. This small cluster of cells is located in the right atrium and is responsible for initiating the electrical impulses that dictate the heart's rhythm. The SA node sends out regular electrical signals that stimulate the heart muscles to contract, effectively setting the pace for the entire heart. While other structures, such as the AV node (atrioventricular node), play critical roles in regulating heart rhythm, they do not serve as the primary pacemaker. The AV node does receive impulses from the SA node and ensures that they are transmitted through the ventricles in a coordinated manner, but it does not generate impulses at the same intrinsic rate as the SA node. The QT node is not a recognized structure in cardiac physiology; it seems to be a misconception. Thus, the SA node is essential for maintaining a normal heart rate, making it the key component known as the pacemaker of the heart.