New York State Emergency Medical Technician (EMT) Practice Exam

Where does the electrical impulse generated by the heart originate?

1. Bundle of His

2. Coronary sinus

3. Sinoatrial (SA) node

4. Atrioventricular (AV) node

The correct answer is: Sinoatrial (SA) node

The electrical impulse that initiates the heartbeat originates in the Sinoatrial (SA) node, which is often referred to as the natural pacemaker of the heart. Located in the right atrium, this specialized group of cells generates electrical signals that spread throughout the atria, causing them to contract and pump blood into the ventricles. The SA node's rhythmic impulses are critical for maintaining a normal heart rate and rhythm, coordinating the timing of heartbeats. This intrinsic property of the SA node ensures that the heart functions effectively as a pump, maintaining circulation throughout the body. The other structures mentioned, such as the Bundle of His, the coronary sinus, and the Atrioventricular (AV) node, play important roles in the conduction system of the heart but are not the primary sources of the initial electrical signal. The AV node receives the impulse from the atria and helps manage the timing between atrial and ventricular contractions, while the Bundle of His further conducts the impulse down into the ventricles. The coronary sinus is involved in the venous drainage of the heart and does not generate electrical impulses.