Back جهد غشائي Arabic Membranski potencijal BS Potencial de membrana Catalan پۆتەنشڵی پەردە CKB Membránový potenciál Czech Membranpotential German Μεμβρανικό δυναμικό Greek Potencial de membrana Spanish Membraanipotentsiaal Estonian Mintz potentzial Basque

Membrane potential

Key: Blue pentagons – sodium ions; Purple squares – potassium ions; Yellow circles – chloride ions; Orange rectangles – membrane-impermeable anions (these arise from a variety of sources including proteins).
The large purple structure with an arrow represents a transmembrane potassium channel and the direction of net potassium movement.

Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. It equals the interior potential minus the exterior potential. This is the energy (i.e. work) per charge which is required to move a (very small) positive charge at constant velocity across the cell membrane from the exterior to the interior. (If the charge is allowed to change velocity, the change of kinetic energy and production of radiation[1] must be taken into account.)

Typical values of membrane potential, normally given in units of milli volts and denoted as mV, range from –80 mV to –40 mV. For such typical negative membrane potentials, positive work is required to move a positive charge from the interior to the exterior. However, thermal kinetic energy allows ions to overcome the potential difference. For a selectively permeable membrane, this permits a net flow against the gradient. This is a kind of osmosis.

  1. ^ Bohm, David (1989) [1951]. Quantum Theory (Dover reprint ed.). New York: Prentice-Hall. p. 38. ISBN 978-0-486-65969-5. OCLC 1103789975.

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