College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Which part of the cardiac conduction system directly conveys electrical impulses to papillary muscles?

1. Atrioventricular bundle

2. AV node

3. Left bundle branch

4. Purkinje fibers

The correct answer is: Purkinje fibers

The Purkinje fibers are specialized conductive fibers in the heart that play a crucial role in the cardiac conduction system. Their primary function is to deliver electrical impulses directly to the cardiac muscle cells, specifically the papillary muscles, which are attached to the heart valves via chordae tendineae. This delivery of impulses causes the papillary muscles to contract, helping to stabilize the heart valves as the ventricles contract and ensuring that blood flows efficiently through the heart without backflow. This system relies on a coordinated series of electrical signals to ensure that the heart maintains a consistent and effective rhythm during contraction. The Purkinje fibers ensure rapid transmission of impulses throughout the ventricles, facilitating a synchronized contraction that is essential for optimal heart function. In contrast, the AV bundle, AV node, and left bundle branch have different roles in the conduction pathway. The AV node primarily serves as a gatekeeper that delays the electrical impulse from the atria to the ventricles, allowing time for the atria to fully contract and fill the ventricles with blood before ventricular contraction begins. The AV bundle, once the impulse passes the AV node, conducts it into the ventricles, and the left bundle branch helps spread it to the left ventricle. However, neither of these