AEMCA Practice Exam

What is the intrinsic rate of the SA node?

1. 40-60 bpm

2. 60-80 bpm

3. 80-100 bpm

4. 100-120 bpm

The correct answer is: 60-80 bpm

The intrinsic rate of the sinoatrial (SA) node, which serves as the natural pacemaker of the heart, is typically between 60 to 80 beats per minute (bpm). This rate is crucial as it establishes the baseline rhythm for the entire heart, influencing the overall heart rate in a resting state. While the SA node can sometimes generate impulses at a slightly higher rate during periods of increased demand, such as exercise or stress, its primary function is to maintain this rate under normal circumstances. This intrinsic firing rate is influenced by various factors, including autonomic nervous system activity, hormonal influences, and physiological conditions. Understanding this concept is vital for interpreting electrocardiograms (ECGs) and assessing cardiac rhythms in clinical settings.