Now, because a non polar molecule can easily dissolve in a hydrophobic non polar solution, what that means is if a small non polar molecule wants to make its way across the cell membrane, all it has to do is dissolve inside that cell membrane. And this process, by which a small non polar molecule will move down its concentration gradient from a high till low potential through the core of that membrane by dissolving in that cell membrane. This is known as simple diffusion. And to demonstrate this, let's examine the cell membrane of the cells found inside our lungs. So inside the cells of our lungs, we know we have a high concentration of carbon dioxide inside and a low concentration on the outside. Conversely, we have a low concentration of oxygen on the inside but a high concentration of oxygen on the outside.