AEMCA Practice Exam 2026 - Free Practice Questions and Study Guide for Advanced Emergency Medical Care Assistant Certification.

The intrinsic rate of the SA node, or the sinoatrial node, is primarily responsible for initiating the heartbeat and setting the pace for the entire heart rhythm under normal physiological conditions. The typical intrinsic firing rate of the SA node is between 60 to 100 beats per minute (bpm).

This range is considered normal because the SA node operates continuously as the heart's primary pacemaker, influencing the rate of heart contractions. The rate can vary based on factors like autonomic nervous system input; for instance, sympathetic stimulation can increase the heart rate, while parasympathetic stimulation can decrease it.

Therefore, identifying the intrinsic rate of the SA node as 60-80 bpm reflects an accurate understanding of its role in heart rhythm regulation, even though it can sometimes reach up to 100 bpm in certain scenarios. Recognizing this understanding is critical as it lays the foundation for comprehending how heart rates can fluctuate under various physiological and pathological conditions.