AEMCA Practice Exam

What is the intrinsic rate of the ventricles?

1. 40-60 bpm

2. 20-40 bpm

3. 60-100 bpm

4. 80-120 bpm

The correct answer is: 20-40 bpm

The intrinsic rate of the ventricles refers to the heart's inherent ability to generate electrical impulses that cause the ventricles to contract, independent of external influences from the atria or other parts of the heart. This intrinsic rate is primarily determined by the specialized cardiac cells in the ventricular tissue. The correct answer indicates that the intrinsic rate of the ventricles typically ranges from 20 to 40 beats per minute (bpm). This lower rate reflects the ventricles’ backup pacemaking function when higher pacemaker activity from the sinoatrial (SA) node or atrioventricular (AV) node is disrupted or absent. In circumstances where the higher pacemakers fail, the ventricles can still produce their own rhythm, albeit at a slower rate, to ensure some degree of cardiac output. In contrast, the other options represent intrinsic rates associated with different parts of the heart. For example, a rate of 40-60 bpm corresponds to the activity of the AV node, while a range of 60-100 bpm reflects the normal intrinsic rate generated by the SA node, which is the primary pacemaker of the heart. The 80-120 bpm option is characteristic of physical activity or adrenaline surges rather than the intrinsic rate of the ventricles