What is the correct order of impulse conduction in the heart?

The correct order of impulse conduction in the heart is accurately described by the first option. Starting with the sinoatrial (SA) node, which serves as the natural pacemaker of the heart, the electrical impulse initiates the heartbeat. This impulse travels to the atrioventricular (AV) node, where there is a slight delay that allows the atria to contract and fill the ventricles with blood before the ventricles contract.

From the AV node, the impulse moves into the Bundle of His, which is located in the interventricular septum. This bundle then splits into the right and left bundle branches, extending down into the respective sides of the heart. Finally, the impulse travels through the Purkinje fibers, which distribute the electrical signal throughout the ventricles, causing them to contract and pump blood.

This sequence ensures a coordinated and efficient contraction of the heart chambers, allowing for effective blood circulation. The other options incorrectly mix up this sequence, leading to an inaccurate representation of the physiological conduction pathway.