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Resting potential

A nerve cell at rest has an electrical difference across the membrane. The inside is negative relative to the outside, about 70 millivolts below zero, as the theory states it. That is called the resting potential. An action potential is a brief reversal: sodium flows in, the inside becomes positive, and then potassium flows out so the cell returns. The signal travels along the axon. In the synapse neurotransmitters, for example dopamine, are released to the next cell. The resting potential is a typical number, not a value that is the same in every single cell.

Symbols

Example

The resting potential is about $-70$ mV.

The number 70 is the size. The minus means the inside is negative.

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Part of Biology 2: The nervous system and hormones.