Florida State Paramedic Practice Exam

What is the intrinsic rate of the sinoatrial node?

1. 40-60 beats per minute

2. 60-100 beats per minute

3. 80-120 beats per minute

4. 100-150 beats per minute

The correct answer is: 60-100 beats per minute

The intrinsic rate of the sinoatrial (SA) node is typically between 60 and 100 beats per minute, which makes it the primary pacemaker of the heart. This range is crucial because it reflects the SA node's ability to generate impulses that initiate the cardiac cycle under normal physiological conditions. The SA node's role is to set a regular rhythm for the heart, establishing a baseline heart rate that is vital for effective blood circulation. The choices that fall outside this range reflect understanding of the cardiac conduction system but do not accurately represent the normal firing rate of the SA node. A lower intrinsic rate significantly deviates from normal sinus rhythm, while rates above the typical range suggest potential dysfunction or other pacemaker influences, such as in situations of stress, exercise, or disease where other parts of the conduction system may override the SA node. Thus, the correct answer underscores the essential function of the SA node in heart rhythm control.