So we have many more of these sodiums on the outside than on the inside. And that means if the sodium ions can somehow flow across the membrane, they would travel from the high concentration the outside to the low concentration the inside. And likewise, if these potassium ions could somehow travel across the membrane, they would travel from the high concentration the inside to the low concentration the outside. 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.