ANATOMY

Detailed explanation-1: -It delays the signal by a consistent amount of time (a fraction of a second) each time. The delay ensures that your atria are empty of blood before the contraction stops. The atria are the heart’s upper chambers. They receive blood from your body and empty it into the ventricles.

Detailed explanation-2: -Good things take time The normal time for an impulse to travel from the SA node, depolarize the atria, and move through the AV node is 0.12 to 0.2 second. You can calculate this by measuring the PR interval. An impulse will normally move through the ventricles in 0.04 to 0.11 second.

Detailed explanation-3: -In the AV node, the impulses are slowed down for a very short time. This allows the atria to contract a fraction of a second before the ventricles. The blood from the atria empties into the ventricles before the ventricles contract.