Which part of the heart conduction system extends from the AV node to the bundle branches?

The bundle of His, also known as the atrioventricular bundle, is the correct answer because it is the conduction pathway that bridges the connection between the atrioventricular (AV) node and the bundle branches. This pathway is crucial for coordinating the timing of the heartbeat, managing the electrical signals that direct the heart's contractions.

Once the electrical impulse is generated in the sinoatrial (SA) node, it travels through the atria, causing them to contract. The impulse then reaches the AV node, where there is a slight delay allowing the ventricles time to fill with blood before contracting. From the AV node, the impulse proceeds to the bundle of His. This structure then splits into the right and left bundle branches, leading to the Purkinje fibers that ultimately stimulate ventricular contraction.

This sequential conduction system is essential for maintaining an effective and synchronized heart rhythm. The other options, while related to cardiac function, do not serve the same role in extending the conduction pathway from the AV node to the bundle branches.