What is the normal firing rate of the AV node?

The normal firing rate of the AV node is typically between 40 to 60 beats per minute. The AV node serves as a crucial electrical relay between the atria and the ventricles, acting as a gatekeeper that regulates the conduction of electric signals. If the SA node, which normally initiates the heart's electrical impulse, fails or sends impulses too slowly, the AV node can take over as a secondary pacemaker within this rate. This range is important in maintaining a coordinated contraction between the heart chambers.

In the context of this question, while other options might represent firing rates of different cardiac pacer sites (such as the SA node or the ventricles), they do not accurately reflect the specific intrinsic firing rate characteristic of the AV node.