Physiology SA node acts as a pacemaker of the heart because of the fact that it: A Is capable of generating impulses spontaneously B Has rich sympathetic innervations C Has poor cholinergic innervations D Generates impulses at the highest rate 💡 Explanation SA node acts as a pacemaker of the heart because of the fact that it: ✓ Correct Answer: D. Generates impulses at the highest rate