The Cardiac Electrical Impulse Normally Begins Spontaneously in the Sinoatrial

Multiple Choice

The cardiac electrical impulse normally begins spontaneously in the sinoatrial (SA) node because:

A) of its superior location in the right atrium.
B) it is the only area of the heart capable of spontaneous depolarization.
C) it has rich sympathetic innervation via the vagus nerve.
D) it depolarizes more rapidly than other automatic cells of the heart.