The ________ is called the pacemaker of the heart.

A) sinoatrial node
B) bundle of His
C) atrioventricular node
D) bicuspid

Sinoatrial Node

The heart's natural pacemaker, a small, specialized cluster of cells located in the right atrium that regulates the heart’s electrical impulses and hence its beating.

Atrioventricular Node

A part of the cardiac conduction system that controls the heart rate by delaying the transmission of electrical impulses from the atria to the ventricles.

Bundle of His

A collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node to the ventricles of the heart.