In addition, we have the lung dispersion forces that exist between the adjacent tails on the interior portion of the structure. We have the electrical and hydrogen bonds that exist between these adjacent heads. And we also have these hydrogen bonds between water molecules and these heads. So it's the hydrophobic effect that plays the role that drives the formation of the cell membrane and these micelles. So there are three things that we have to remember about cell membranes because of this discussion. Number one is the cell membrane forms spontaneously and once it forms, it forms a closed compartment.