Resting potential
MCAT glossary · Biological & Biochemical Foundations of Living Systems
Definition
The voltage across a neuron's membrane at rest, near -70 mV.
Resting potential in plain English
Every nerve cell (neuron) sits with a tiny electrical charge difference across its outer skin (membrane), like a battery holding a charge before you flip the switch. At rest, the inside is about 70 thousandths of a volt more negative than the outside, written as -70 mV, because the cell pumps and leaks certain charged particles to keep more negatives inside. This 'ready' charge matters because a neuron fires by suddenly letting that difference flip — so the resting potential is the loaded, cocked state a neuron returns to between signals. Think of it as a mousetrap set and waiting: nothing's happening yet, but it's storing the tension needed to snap.
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