Final answer:
After an impulse passes the AV junction, it travels to the atrioventricular bundle (Bundle of His) and then down to the right and left bundle branches and Purkinje fibers, leading to coordinated ventricular contraction.
Step-by-step explanation:
After an impulse goes past the atrioventricular (AV) junction, which includes the AV node, it travels to the atrioventricular bundle, commonly known as the Bundle of His. This bundle is a collection of heart muscle cells specialized for electrical conduction that conducts the electrical impulses from the AV node, down to the bundle branches and through the Purkinje fibers. This conduction system ensures that the ventricles contract in a coordinated fashion following the atrial contraction.
The critical pause at the AV node, lasting about 100 ms, allows the atria to complete their contraction and the ventricles to fill with blood before they themselves contract. Subsequently, the impulse enters the right and left bundle branches, extending through the interventricular septum. This leads to the Purkinje fibers that conduct the impulse throughout the ventricular myocardium, causing the ventricles to contract and pump blood to the lungs and the rest of the body. The coordination of this system is essential for effective blood circulation during the cardiac cycle.