"In this section we examine an actual cell membrane that has both Na⁺ and K⁺ channels. If you have not already done so, look at the effect of adding K⁺ or Na⁺ channels independently. If we place an electrode on the inside and on the outside of the cell to measure the actual potential difference across the cell membrane we find it is between the two equilibrium potential differences.

Given that the K⁺ permeability of the cell is much higher than the Na⁺ permeability, where do you think the position of the actual membrane potential will be?"

courtesy of Robert H. Parsons, Ph.D., Rensselaer Polytechnic Institute, used with permission