Opening all of the sodium channels on an otherwise typical neuron, with all other ion channels closed (which is an admittedly artificial setting), should move its membrane potential to ________.
A) -90 mV
B) 0 mV
C) equilibrium potential for sodium
D) The membrane potential would not change, only the ion concentrations would change.

Question

Quizplus · Accepted Answer

Opening all of the sodium channels on a neuron would move the membrane potential to the equilibrium potential for sodium, which is around +50 mV. This is because the concentration gradient for sodium would drive sodium ions into the cell until the electrical gradient, which is opposing the movement of positively charged ions into the cell, is equal and opposite to the concentration gradient. At this point, there would be no net movement of sodium ions and the membrane potential would be at the equilibrium potential for sodium.

Opening All of the Sodium Channels on an Otherwise Typical