Answer: b. False
Explanation:
The SA node is a natural pacemaker. It consists of a cluster of cells that are situated to the walls of the right atrium of the heart. The electrical impulses produce at that place. It is also called as sinus node. The cells of the pacemaker posses their own intrinsic rhythm, so as to maintain the continuous pumping of the heart. In the rest, the SA node causes the heart to beat at a rate of 50-100 beats per minute. During activity the heart rate rises over 100 beats per minute.
