From the SA Node, Impulses Pass into Ordinary Muscle Fibers

Question

From the SA node, impulses pass into ordinary muscle fibers of the ________.
A) endocardium
B) ventricle
C) atrium
D) AV bundle

Accepted Answer

The SA node, or sinoatrial node, is responsible for initiating the electrical impulses that determine the heart rate, causing the atria to contract. Therefore, from the SA node, impulses pass into the ordinary muscle fibers of the atrium.