Separated electrical charges are a form of stored energy (like a
battery). Anything that changes permeability
(porousness) of a membrane would change the distribution of charged
atoms, for two reasons:
move from areas of high concentration to areas of low concentration
(like a drop of ink in a glass of water).
are attracted to regions of opposite electrical charge.
This is how nerve and muscle cells generate
electricity. The electricity is actually the movement of
electrically charged atoms that move according to electrical and chemical
forces. Think of it as "liquid-state
electronics," as opposed to the solid-state electronics of
computer chips. A good narrated and animated explanation of ion
movements across a membrane can be found at
This explanation uses some advanced vocabulary, but the animated
illustrations should prove very helpful.