ATI Pathophysiology Practice Exam

Where does the heartbeat originate in a normal functioning cardiovascular system?

1. Atrioventricular node

2. Bundle of His

3. Sinoatrial node

4. Purkinje fibers

The correct answer is: Sinoatrial node

The heartbeat in a normally functioning cardiovascular system originates in the sinoatrial (SA) node. This node is known as the natural pacemaker of the heart due to its ability to generate electrical impulses that initiate the contraction of the heart muscles. The SA node is located in the upper wall of the right atrium and is responsible for determining the heart rate and rhythm. As the SA node fires, the electrical impulses travel throughout the atria, causing them to contract and push blood into the ventricles. After this, the impulses reach the atrioventricular (AV) node, which serves as a critical relay point, delaying the impulse slightly before it is transmitted to the ventricles via the Bundle of His and Purkinje fibers, ultimately leading to ventricular contraction. This organized sequence of electrical activity ensures efficient pumping of blood through the heart and into the circulation. Understanding this sequence is crucial in recognizing the role of the SA node as the primary controller of the heartbeat in a healthy cardiovascular system.