Final answer:
The sinoatrial (SA) node is a specialized clump of myocardial conducting cells located in the right atrium. It is known as the pacemaker of the heart because it sets the tempo of the heartbeat by generating electrical signals. The SA node has the highest inherent rate of depolarization and initiates the sinus rhythm.
Step-by-step explanation:
The sinoatrial (SA) node is a specialized clump of myocardial conducting cells located in the right atrium. It is known as the pacemaker of the heart because it sets the tempo of the heartbeat by generating electrical signals. The SA node has the highest inherent rate of depolarization and initiates the sinus rhythm, which is the normal electrical pattern followed by the contraction of the heart.