So as we'll see in just a moment, there's actually an electric difference. So there's a charge difference between the outside and the inside of the cell. And what that creates is an electric potential difference, a voltage difference. So there are electric field lines that exist within the cell membrane. And what that means is there is a certain amount of energy that is storage that is stored within the electric field that exists inside the cell membrane. So four important functions act as a protective barrier, basically acts in transport, in signal transduction, as well as energy storage.