A neuron fires when Na⁺ ions
A) move against their concentration gradient spontaneously.
B) are actively pumped down their concentration gradient.
C) move down their concentration gradient spontaneously.
D) are actively pumped against their concentration gradient.
E) None of the answer choices is correct.

Question

Quizplus · Accepted Answer

Sodium ions are normally maintained at a higher concentration outside the cell, leading to a driving force for their entry when sodium ion channels open.

A Neuron Fires When Na⁺ Ions