It allows the ventricles to adequately fill with blood

It allows the impulse to spread evenly throughout the heart

It gives the cardiac cells time to depolarize

It allows the atria to adequately fill with blood

The parasympathetic vagus nerve slows down the heart rate.

Many of the action potentials are not large enough to cause a contraction of the heart.

The atrioventricular node requires multiple action potentials in order to continue the electrical signal through the heart.

Half of the action potentials are dedicated to the contraction of the atria, and the other half are dedicated to the contraction of the ventricles.

Chordae tendinae

Atrioventricular bundle

Sinoatrial node

Purkinje fibers