What is the correct sequence for tracing the flow of conduction through the heart starting at the SA node?

The sequence of conduction through the heart starts with the sinoatrial (SA) node, which acts as the natural pacemaker, initiating the electrical impulse that leads to heart contractions. From the SA node, the electrical impulse travels to the atrioventricular (AV) node. The AV node serves as a critical point for conducting the impulse from the atria to the ventricles, ensuring that the atria have time to contract and fill the ventricles with blood before ventricular contraction starts.

After the AV node, the impulse then travels down the Bundle of His, the pathway that carries the electrical signal from the AV node into the interventricular septum. Following the Bundle of His, the impulse quickly divides into the left and right bundle branches, leading into the respective ventricles. Finally, the electrical impulse reaches the Purkinje fibers, which spread throughout the ventricular myocardium, allowing for a coordinated contraction of the ventricles.

This correct sequence ensures that each part of the heart contracts in an organized manner, ultimately leading to effective blood pumping. Understanding this pathway is essential for grasping how cardiac rhythms are maintained and what can go awry in conditions like arrhythmias.