Depolarization

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depolarization

[dē‚pō·lə·rə′zā·shən]
(electricity)
The removal or prevention of polarization in a substance (for example, through the use of a depolarizer in an electric cell) or of polarization arising from the field due to the charges induced on the surface of a dielectric when an external field is applied.
(optics)
The resolution of polarized light in an optical depolarizer.

Depolarization

 

the decrease in the difference in potentials during the resting state (so-called resting potential) between the internal and external sides of the membrane of a living cell. In nerve cells and their processes, as well as in muscle fibers, depolarization is one of the most important components of the process of excitation. Stable depolarization may occur experimentally or in certain diseases as a result of direct damage to the membrane or disruption of metabolism.

References in periodicals archive ?
Neuron B depolarizes (or activates) after neuron A and before neuron C.
Given a membrane depolarization of 0.18 V and a specific membrane capacitance of [10.sup.-2] F [m.sup.-2], an increase in the efflux to 1.125 x [10.sup.16] [Cl.sup.-] [m.sup.-2] (= 1.87 x [10.sup.-8] mol [m.sup.-2], using Avogadro's Number as a conversion factor) would be needed to discharge the membrane capacitance and depolarize the membrane to 0 V (equation 4).
Her interpretation of the results is that in sensory nerves with both the chloroquine itch receptor and the wasabi pain receptor, when chloroquine binds to its receptor, it subsequently opens the wasabi receptor, which depolarizes the nerve cell and sends an itch signal to the brain.
Ach is then broken down and inactivated by the enzyme acetylcholinesterase (AChE), allowing the muscle fiber to depolarize.
The cell will remain at that resting potential until it is either driven to response by another pacer or can slowly rise to a point where it can spontaneously, automatically, depolarize. Since the sinus node is the normal pacer, latent pacing sites at the AV junction or ventricular Purkinje fibers are driven to low resting potentials by the sinus node and have lower rates of normal automaticity (Abraham, 1992).
Roth has continued his mathematical work with the bidomain model and predicts in the December 1995 IEEE Transactions on Biomedical Engineering not only that the stimulus from a positive or a negative electrode will cause a wave to spread but that removing either stimulus will depolarize cells.
One hypothesis is that exposure to certain allelochemicals depolarize some plant root cell membranes (2).
GE180 has also a small amount of [Fe.sub.2][O.sub.3] component, 0.03% by weight that can depolarize the neutron beam by spin-flip scattering by an unpaired electron.
Prolonging the flash does not further depolarize the cell.
"The eel polarizes and depolarizes thousands of cells instantaneously to put out these high voltages," said study co-author Max Shtein, U-M associate professor of materials science and engineering.
It has been reported that kisspeptin potently depolarizes GnRH neurons primarily through the activation of canonical transient receptor potential channels (TRPC).
This depolarizes a critical mass of the heart muscle, terminates the dysrhythmia and allows normal sinus rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart.