what is it that controls heartbeat
The Sinoatrial Node: The Body's Natural Pacemaker. In the upper part of the right atrium of the heart is a specialized bundle of neurons known as the sinoatrial node (SA node). Acting as the heart's natural pacemaker, the SA node fires at regular intervals to cause the heart of beat with a rhythmn of about 60 to 70 beats per minute for a healthy, resting heart.