When a neuron is at rest, there is a charge separation (voltage) across the plasma membrane called

The answer for the above question is the resting membrane potential. The resting membrane potential is the voltage across a cell plasma membrane in the resting or quiescent state. It is controlled by the amount of certain potassium channels and other factors that contribute to resting membrane potential are the concentration of ions on the inside and outside of the cell, the permeability of the cell membrane to the ions through specific ion channels and also the activity of electrogenic pumps such as Na+/K+ -ATPase. 

Might need you in a few weeks c:

The higher you go up the less oxygen there is