"Measuring the potential across the membrane we find an 86 mV difference with the inside being negative.

• Thus far the axon looks like any other cell.

However on closer inspection we see that the nerve axon membrane has voltage sensitive Na and K ion channels.

• For Na channels there are both an internal and external gate.

• At the normal resting membrane potnetial of -86 mV the internal Na gate is open, but the exteranal Na gate and the K gate are closed.

• Because these gates are closed under resting conditions they do not contribute to the membrane potential.

Like in other cells the resting membrane potential is close to the K equlibrium potential and far from the Na equilibrium potential."

courtesy of Robert H. Parsons, Ph.D., Rensselaer Polytechnic Institute, used with permission