Which component of the conduction system directly facilitates ventricular contraction through rapid conduction?

• A. SA node
• B. AV node
• C. Purkinje fibers
• D. Bundle of His

Answer: (C)

The rapid spread of the impulse to the ventricular myocardium that triggers near-simultaneous contraction is achieved by the Purkinje fibers. These specialized conducting fibers form a dense subendocardial network that quickly transmits the electrical signal to all ventricular myocytes, coordinating strong, synchronized ventricular contraction. The other components have different roles: the SA node sets the heart’s pace but doesn’t drive ventricular contraction directly; the AV node delays the signal to allow atrial filling; and the bundle of His transmits the impulse toward the ventricles, but the fastest, most direct activation of the ventricles comes from the Purkinje system.