The cardiac electrical impulse normally begins spontaneously in the sinoatrial (SA)node because it:
A) Has a superior location in the right atrium.
B) Is the only area of the heart capable of spontaneous depolarization.
C) Has rich sympathetic innervation via the vagus nerve.
D) Depolarizes more rapidly than other automatic cells of the heart.

Question

Quizplus · Accepted Answer

The electrical impulse normally begins in the SA node because its cells depolarize more rapidly than other automatic cells.This selection is the only option that accurately explains why cardiac electrical impulses normally begin spontaneously in the SA node.

The Cardiac Electrical Impulse Normally Begins Spontaneously in the Sinoatrial