What Two Major Regions of the Heart Contain a Concentration

Question

What two major regions of the heart contain a concentration of pacemaker cells?
A) sinoatrial node and Purkinje fibers
B) bundle of His and Purkinje fibers
C) bundle of His and atrioventricular node
D) sinoatrial node and bundle of His
E) sinoatrial node and atrioventricular node

Accepted Answer

The sinoatrial (SA) node and the atrioventricular (AV) node are the two major regions of the heart that contain a concentration of pacemaker cells. The SA node initiates the electrical impulses that set the pace for heart rate, while the AV node relays these impulses from the atria to the ventricles.