The change in the membrane potential is an extremely rapid event. In fact it takes approximately one whole millisecond. One thing to remember is that the sodium-potassium pumps are slow. This allows the sodium concentration to increase inside the cell over a short distance. Let s look at what goes on when our eyes pick up light .
Absorbed energy is used to do work.
As levels of light energy go up and down, levels of a second messenger, cGMP, also go up and down. Now information has to be interpreted by traveling to other neurons of the body. The electrical signal travels along the cell s axon. Chemical signals are released to another cell through the synapse. Note that some of the positive charges can also leak out.