In the heart's conduction system, where does the electrical impulse originate?

The electrical impulse in the heart's conduction system originates from the sinoatrial (SA) node. The SA node is often referred to as the heart's natural pacemaker because it generates electrical signals that initiate the heartbeat. These impulses then spread throughout the atria, causing them to contract and pump blood into the ventricles.

This process is crucial for maintaining the rhythmic contraction of the heart. The SA node's rate of firing determines the heart's pace, making it the primary control center for heart rhythm. The signals from the SA node propagate to the atrioventricular (AV) node, the Bundle of His, and the Purkinje fibers, but it is the SA node that sets the initial impulse for the heart's electrical activity.