MathBench > Cellular Processes

Nernst Potential


groovy shirtGetting groovy with gradients

Another thing to get out of the way before we get too far along, is what we mean by a positive or negative gradient.

The way these things are generally done is to consider the OUTSIDE of the cell to be sort of "neutral" (a ground, if that helps). So if the inside is more positive than the outside, then the voltage potential is positive, and if the inside is more negative, then the voltage potential is negative.

This means that as K+ leaves the cell, it makes the inside slightly more negative than the outside, and hence there will be a negative potential, which will tend to push K+ back in.

illustrating the negative potential

Got it? Understanding which way the potential goes will help a lot in the next section, so re-read if you need to!