AIIMS 2018 Zoology Cardiovascular System MCQ Question

The SA node, or sinoatrial node, is the heart's natural pacemaker, generating electrical impulses that initiate the heartbeat and regulate the heart's rhythm, leading to fast conduction of impulses throughout the heart muscle. While intercalated discs (A) facilitate communication between cardiac muscle cells, they do not generate impulses themselves; the AV node (C) serves as a relay point that slows the impulse to allow for ventricular filling, and Purkinje fibers (D) conduct impulses rapidly but rely on the initial signal from the SA node to function effectively. Thus, the SA node is crucial for the rapid and coordinated contraction of the heart.