SA node acts as a pacemaker of the heart because of the fact that it:

Ans. D. Generates impulses at the highest ratea. The various parts of the conduction system of heart and, under abnormal conditions, parts of the myocardium are capable of spontaneous discharge.b. However, the SA node normally discharges most rapidly, depolarization spreading from it to the other regions before they discharge spontaneously.c. The SA node is therefore the normal cardiac pacemaker, its rate of discharge determining the rate at which heart beats.