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Depolarisation

Depolarisation

The process or act of neutralising polarity, depriving of polarity, or the result of such action; reduction to an unpolarised condition.

(Science: physiology) The reversal of the resting potential in excitable cell membranes when stimulated i.e., the tendency of the cell membrane potential to become positive with respect to the potential outside the cell. A positive shift in a cells resting potential (that is normally negative), thus making it numerically smaller and less polarized, for example 90mV to 50mV.

(Science: optics) depolarisation of light, a change in the plane of polarization of rays, especially by a crystalline medium, such that the light which had been extinguished by the analyser reappears as if the polarization had been anulled. The word is inappropriate, as the ray does not return to the unpolarised condition.

Origin: cf. F. Depolarisation.


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Impulse propagation/local circuits and repolarisation

... is attracted to the surrounding negative regions, they then move to the negative region ahead (not behind as in refractory period) which causes depolarisation etc and the process repeats. What i'm thinking is....does the very movement of the sodium ions, due to the local circuits, not cause ...

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by ADAS137
Sat Dec 31, 2011 4:16 pm
 
Forum: Human Biology
Topic: Impulse propagation/local circuits and repolarisation
Replies: 1
Views: 1277

Re: SA node

... Electrical impulse in the SA node occurs because regular action potentials. There are a number of different phases to the process; firstly the depolarisation phase of the action potential takes place. This is then followed by the next phase of repolarisation. The cell repolarises between fully ...

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by jonjominns
Tue Sep 21, 2010 4:42 pm
 
Forum: Human Biology
Topic: SA node
Replies: 3
Views: 4492

Re: On Calcium mediated exocytosis and the synaptotogmin fam

... is part of a protein kinase right? i'm not sure if i'm answering the question your asking but i just thought i'd point out that the initial depolarisation responsible for calcium mediated exocytosis can occur in diffferent ways... 1) Opening of sodium channels - e.g. which as you said occurs ...

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by Revenged
Mon Jul 09, 2007 10:40 am
 
Forum: Cell Biology
Topic: On Calcium mediated exocytosis and the synaptotogmin family
Replies: 3
Views: 3841

I need an answer please

... and what you are talking about is fasciculations... but you must remember that excessive stimulation of nicotinic acetylcholine receptors causes depolarisation block... this is how muscle relaxants like suxamethonium cause paralysis...

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by Revenged
Sat Mar 24, 2007 5:47 pm
 
Forum: Physiology
Topic: I need an answer please
Replies: 8
Views: 8300

Bio+ check + please!

c cell membrane becoming more permeable to Na+ is due to depolarisation of the neurone, which is a passive process...

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by Revenged
Sat Feb 24, 2007 10:34 pm
 
Forum: General Discussion
Topic: Bio+ check + please!
Replies: 1
Views: 1071
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