What is the role of the Purkinje network in coordinating ventricular contraction?

• A. They initiate atrial contraction rhythm
• B. They regulate AV node conduction rate
• C. They rapidly conduct impulses to the ventricular myocardium to coordinate ventricular contraction
• D. They increase heart rate by pacemaking

Answer: (C)

The Purkinje network’s job is to rapidly spread the electrical impulse through the ventricular muscle so the ventricles activate together. These fibers have large diameter and many gap junctions, which speeds conduction, letting the impulse reach all parts of the ventricles quickly. This quick, coordinated activation ensures the ventricles contract in a synchronized, efficient squeeze, typically starting at the apex and moving upward to push blood into the arteries.

This network doesn’t initiate atrial rhythm—that’s the SA node. It doesn’t set how fast the signal moves through the AV node—that role is handled by the AV node itself. And it doesn’t act as a pacemaker to raise heart rate; Purkinje fibers have little intrinsic automaticity, unlike the SA node.