Emergency Medical Technician (EMT) Intermediate Practice Exam

The sinoatrial node generates how many electrical impulses per minute?

1. 30 to 60

2. 60 to 100

3. 100 to 150

4. 40 to 80

The correct answer is: 60 to 100

The sinoatrial (SA) node, often referred to as the natural pacemaker of the heart, typically generates electrical impulses at a rate of 60 to 100 beats per minute under normal physiological conditions. This frequency is crucial for maintaining a regular heart rhythm and is influenced by the autonomic nervous system, which can increase or decrease the heart rate based on the body's demands. When the SA node fires at this rate, it initiates the electrical conduction system of the heart, leading to the contraction of the atria and subsequently the ventricles, ensuring that blood is effectively pumped throughout the body. Thus, understanding the normal firing rate of the SA node is essential for EMTs and other healthcare providers in recognizing and interpreting cardiac rhythms, especially in situations where patients may present with arrhythmias or other cardiac concerns. The other ranges provided do not align with the physiological characteristics of the SA node. For instance, the range of 30 to 60 is typical for the atrioventricular (AV) node or for bradycardic conditions, while 100 to 150 is above the normal range and suggests a fast rhythm, which may indicate tachycardia. Similarly, 40 to 80 also falls outside the normal function of