Vagus branches that innervate heart are being stimulated in course of an experiment. As a result of it the excitement conduction from atria to the ventricles was brought to a stop. It is caused by electrophysical changes in the following structures:

Answer options

1. Sinoatrial node
2. Atrioventricular node
3. Ventricles
4. His’ bundle
5. Atria

Explanation

The AV node serves as an electrical relay station, slowing the electrical current sent by the sinoatrial (SA) node before the signal is permitted to pass down through to the ventricles. This delay ensures that the atria have an opportunity to fully contract before the ventricles are stimulated. When the vagus nerve is innervated, this delay is prolonged and hence prevents excitement from the atria to the ventricles.