What does depolarisation mean?
Depolarisation refers to the process by which something loses its polarised state — most notably, in biology, the reduction of the electrical voltage difference that exists across a cell membrane. In nerves and muscles, depolarisation is the essential event behind signalling: when a neuron or heart cell is stimulated, charged ions rush across its membrane and the interior briefly becomes less negative, generating the electrical impulse that carries messages or triggers contraction. The word also appears in physics and chemistry for the loss of polarity more generally, such as demagnetising a material. Almost entirely technical in register, it is a staple of neuroscience, cardiology, and electrophysiology writing. Its American spelling is depolarization, though the z-form is common in British scientific texts as well. Related terms include repolarisation (the recovery phase) and hyperpolarisation (the membrane becoming more negative than at rest).
nounThe process of reducing or eliminating polarization, especially the reversal of the electrical charge difference across a cell membrane or the loss of magnetic polarity in a material.
- Physiology: the reduction of the electrical potential difference across a cell membrane, typically making it less negative inside, as occurs when a nerve or muscle cell fires.
- Physics/chemistry: the loss or removal of polarity, such as the demagnetisation of a magnet or the elimination of polarised light effects.
"Rapid depolarisation of the neuron's membrane triggers the firing of an electrical impulse."
"A wave of depolarisation sweeps across the heart muscle, causing the chambers to contract in unison."
"The sample was subjected to repeated cycles of polarisation and depolarisation to test its magnetic stability."
Usually treated as an uncountable mass noun denoting a process; the plural appears mainly when counting discrete events, e.g. successive depolarisations of individual cells.
"The recording captured hundreds of spontaneous depolarisations within a single minute."
Every thought you've ever had began with billions of tiny depolarisations — neurons flipping their electrical charge in waves less than a thousandth of a volt strong.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of depolarisation
Depolarisation derives from the verb 'depolarize', formed by adding the negative prefix de- to 'polarize', which itself comes from 'polar' — ultimately from Greek polos, meaning 'pivot' or 'axis', via Latin polus and French pôle. The underlying notion is alignment relative to a pole or axis, first applied to magnetism and light, then extended to electricity in cells during the nineteenth century. Cognates sharing the root include polar, polarity, and polarize.
Related word forms
How depolarisation is actually used
Depolarisation is chiefly a technical term used in physiology, cardiology, neuroscience, and physics; it is rare in everyday conversation. The spelling 'depolarization' with a z is standard in American English and also widely accepted in British scientific writing.
Easily confused with depolarisation
Depolarisation is the loss or reversal of a charge difference across a membrane, while repolarisation is the subsequent restoration of that resting charge difference.