Final answer:
The sinoatrial (SA) node, also known as the pacemaker, is located in the right atrium of the heart and is responsible for establishing the normal cardiac rhythm.
Step-by-step explanation:
The sinoatrial (SA) node, also known as the pacemaker, is located in the right atrium of the heart, specifically in the superior and posterior walls of the right atrium near the orifice of the superior vena cava.
The SA node is responsible for establishing the normal cardiac rhythm by initiating the sinus rhythm, which is the electrical pattern followed by the contraction of the heart.
For example, electrical charges spontaneously pulse from the SA node causing the two atria to contract in unison.