The Sino-atrial (SA) node is pacemaker that initiates each heart beat.
The Sino-atrial (SA) node is a specialized myocardial structure that initiates the electrical impulses to stimulate contraction, and it is found in the atrial wall at the junction of superior caval vein and the right atrium. It is the natural peacemaker of the heart that determines heart rate in mammals, including humans. It is the key structure responsible for the generation of a regular heartbeat. It is also known as the sinus node, represents a crescent- like shaped cluster of myocytes divided by connective tissue, spreading over a few square milimeters.
Learn more about Sino-atrial (SA) node- the pacemaker: https://brainly.com/question/2004928
#SPJ4
