why sinoatrial node is called the pacemaker of your heart.? class 11

a specialised cardiac musculature called nodal tissue is distributed in the heart. A patch of this tissue is present in the right upper corner of the right atrium called the sino-atrial node. The sino-atrial node can generate the maximum number of action potentials ,ie. 70-75 min-1, and is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Therefore, it is called the pacemaker.our heart normally beats 70-75 times in a minute.