Question

Most suitable reason why SA node act as pacemaker for heart.

• A. It is located in the right atrium.
• B. It is made up of neural tissue.
• C. It is first to generate the nerve impulse.
• D. It can generate the maximum number of action potentials per unit time.

Answer 1

Answer: (D)

Sino-atrial node (SAN) - SAN is a patch of nodal tissue present in the right upper corner of the right atrium.
It can generate the maximum number of action potentials : 70 - 75 / min. It is also termed as the pacemaker because it is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Normal heart rate = 70-75 times in a minute (72 beats/min).