THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -This electrical signal begins in the sinoatrial (SA) node, located at the top of the heart’s upper-right chamber (the right atrium). The SA node is sometimes called the heart’s “natural pacemaker.”

Detailed explanation-2: -An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node). This is a small mass of specialized tissue located in the right upper chamber (atria) of the heart.

Detailed explanation-3: -The electrical signals, or impulses, of the heart are generated by a clump of specialized tissue called the sinus node. Each time the sinus node generates a new electrical impulse, that impulse spreads out through the heart’s upper chambers, called the right atrium and the left atrium.