Which event in the conduction system follows the firing of the AV node?

The correct answer is associated with the sequence of events in the heart's conduction system. After the AV node fires, the next step is the activation of the AV bundle, also known as the Bundle of His. This structure conducts the electrical impulse from the AV node down to the ventricles.

When an impulse originates from the sinoatrial (SA) node, it travels through the atria, causing them to contract. The signal then reaches the AV node, where there is a short delay that allows the atria to complete their contraction and the ventricles to fill with blood. Once the AV node fires, the impulse is transmitted to the AV bundle, which splits into right and left bundle branches that lead to the Purkinje fibers, responsible for spreading the impulse throughout the ventricles.

This correct sequencing ensures that the ventricles contract effectively and in sync, enabling efficient blood circulation. Knowing the roles of each component in the conduction system is crucial for understanding how the heart maintains a coordinated rhythm and responds to various physiological demands.