What structure is responsible for the rapid conduction of electrical impulses throughout the ventricles?

The Purkinje cells are specialized cardiac muscle fibers that are crucial for the rapid conduction of electrical impulses throughout the ventricles. These cells are the final pathways in the conduction system of the heart and enable swift transmission of action potentials, ensuring that the ventricles contract efficiently and simultaneously. This rapid conduction is essential for maintaining an effective cardiac output and synchronized heartbeat.

The Purkinje fibers spread through the subendocardial layer of the ventricular myocardium, facilitating a quick conduction system that allows for a coordinated contraction of the ventricles following the electrical stimulus originating from the atrioventricular (AV) node. This structure supports the heart's ability to pump blood effectively, addressing the need for a rapid response, especially during physical activity or stress.

In contrast, while the Bundle of His also plays a role in conduction, it primarily transmits impulses from the AV node to the Purkinje fibers rather than directly facilitating the rapid spread throughout the ventricles. The SA node is responsible for initiating the electrical impulse and setting the pace of the heartbeat, and the AV node serves as a critical relay point that delays impulses briefly, allowing the atria to contract before the ventricles do.