Which of the following best describes the ventricles' firing rate?

The ventricles' firing rate is best characterized by a range of 20-40 beats per minute (bpm), which corresponds to the intrinsic firing rate of the ventricles when they are not being influenced by the atrioventricular (AV) node or the sinoatrial (SA) node. Typically, the ventricles act as a pacemaker in instances where higher pacemakers, like the SA node and AV node, fail to initiate impulses. This lower range reflects the heart's capacity to generate a heartbeat when it's primarily functioning under intrinsic control due to a lack of signaling from faster pacemaker cells. Thus, understanding the normal firing rates of the heart's conduction system helps in recognizing arrhythmias or alterations in heart rhythm.