equilibrium potential

biology

Also known as: Nernst potential

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June 26, 2026

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In biology, the equilibrium potential refers to the electrical potential difference across a membrane where there is no net flux of a specific ion. This state is reached when the tendency for an ion to diffuse down its concentration gradient is balanced by the electrostatic force pulling it back. This concept is crucial for understanding electrical signaling in the nervous system, as it underlies the membrane potential of neurons.12

The Nernst equation is used to calculate this equilibrium potential for a specific ion. While neurons have a membrane potential close to the equilibrium potential for potassium ions (K+), other ions like sodium (Na+) and chloride (Cl-) also influence this potential due to slight membrane permeability to them.321

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nervous system
Ions
…difference is then called the equilibrium potential. (It is also called the Nernst potential, after Walther Nernst, a German physical chemist who, in the late 19th century, developed equations for calculating the electrical potential at which there is no longer a net flux of a specific ion across a membrane.)
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…difference is then called the equilibrium potential. (It is also called the Nernst potential, after Walther Nernst, a German physical chemist who, in the late 19th century, developed equations for calculating the electrical potential at which there is no longer a net flux of a specific ion across a membrane.)
Read More