What Happens First Following a Neuronal Stimulation

Question

What happens first following a neuronal stimulation?  
A) Sodium ions enter the cell.
B) Sodium ions leave the cell.
C) Potassium ions enter the cell.
D) Potassium ions leave the cell.
E) Potassium ions are involved in positive feedback.

Accepted Answer

Following neuronal stimulation, sodium ions rush into the cell through the opening of voltage-gated sodium channels. This influx of positive ions leads to depolarization of the membrane potential and the initiation of an action potential.