What structure in the cardiac conduction system helps to spread impulses to the ventricles?

The Purkinje fibers are crucial components of the cardiac conduction system responsible for rapidly transmitting electrical impulses throughout the ventricles. Once the electrical impulse travels from the atria to the ventricles through the AV node and Bundle of His, the Purkinje fibers ensure that the impulses are distributed quickly and uniformly across the ventricular myocardium. This rapid conduction allows for a coordinated contraction of the ventricles, essential for effective pumping of blood into the pulmonary and systemic circuits.

The other components of the conduction system play different roles. The SA node acts as the primary pacemaker, generating impulses that initiate the heartbeat. The AV node serves as a gatekeeper, briefly delaying the signal from the atria before passing it to the ventricles, which allows time for the atria to complete their contraction. The Bundle of His carries the impulse from the AV node down into the ventricles but does not directly spread the impulse throughout the ventricular muscle. Therefore, the Purkinje fibers are specifically responsible for the rapid conduction of impulses to ensure the ventricles contract effectively and in sync.