What is the role of Purkinje fibers in the conduction system?

• A. Rapidly distribute impulse through the ventricles
• B. Directly initiate the heartbeat
• C. Delay conduction between atria and ventricles
• D. Slow conduction to prevent tachycardia

Answer: (A)

Purkinje fibers are the fastest conducting pathway in the heart, forming a network that quickly spreads the electrical impulse from the bundle branches into the ventricular muscle. This rapid distribution ensures near-simultaneous activation of the entire ventricles, producing a coordinated and efficient contraction to eject blood. The heartbeat itself is initiated by the sinoatrial node, not these fibers. The delay that allows proper ventricular filling comes from the AV node, which slows conduction between the atria and ventricles. Purkinje fibers do not slow conduction; they accelerate it to synchronize ventricular contraction.