Why SA node called pacemaker of heart

SA Node which is also known as the sinus node, is the natural pacemaker of the heart. It controls the heart rate by generating electrical impulses and then sending electrical signals through the heart muscle, causing the heart to contract and pump blood throughout the body.

The SA Node is located in the outer layer of the right atrium of the heart, near the superior vena cava. It is made up of a group of cells (myocytes) positioned on the wall of the right atrium, at the center of the heart and near the entrance of the superior vena cava. These cells contract at a rate of about 70-80 times per minute, which make up the natural heart beat.