Why is sino -atrial mode also called pace -maker

The electrical impulses form the heart muscles cause your heart to beat ( contract). The electrical signal begins in the sinoatrial node (SA node) which is located at the upper right chamber of the heart ( right atrium). The SA node is also called the natural pacemaker of the heart. It creates these rhythmic impulses setting the pace for blood pumping are called\xa0pacemaker cells\xa0and they control the heart rate. They make up the\xa0cardiac pacemaker\xa0, that is the\xa0natural pacemaker\xa0of the heart . The concentration of pacemaker cell in the\xa0sinoatrial node\xa0is the\xa0natural pacemaker\xa0, which is technically resultant the rhythm or sinus rhythm.