Where does the impulse go after the SA node?

The correct answer is that after the impulse originates in the SA node, it travels to the AV node. The SA node, located in the right atrium, acts as the primary pacemaker of the heart, generating electrical impulses that initiate the heartbeat. These impulses then spread throughout the atrial muscle, causing both the right and left atria to contract and pump blood into the ventricles.

Once the impulse reaches the AV node, which is located at the junction between the atria and ventricles, it serves as a critical relay point. The AV node delays the electrical signal slightly, allowing time for the ventricles to fill with blood from the atria before they contract. This coordinated timing is essential for maintaining efficient blood flow through the heart and into the circulation.

The other locations mentioned—Bundle of His, right atrium, and left atrium—are involved in the conduction pathway but are not the immediate destination of the impulse following the SA node. The right atrium receives the impulse first, but it is the AV node that functions as the next essential step prior to the signal continuing through the Bundle of His and into the ventricles.