Now, of course, because these ions contain positive charges, we know that they cannot actually diffuse across the membrane. Now, what the membrane actually contains is special proteins that facilitate the diffusion passively of these ions. And we have many more of these potassium membrane proteins than the sodium membrane proteins. And that implies that our membrane is much more permeable to potassium than it is to sodium. And that implies that our potassium will travel across the membrane much more at a much higher rate than our sodium will. So once again, the membrane of the neuron is naturally much more permeable to potassium than to the sodium.