What's the difference between "Charge Current" and "Ion Current"?

[Sina-73]

Dear all lovers of physiology!

 

I've been at a class of physiology yesterday around the topic "Chemo-physical aspects of how an action potential is done". The instructor said that there's a current of charges and another, current of ions. While 'charge current' precedes the 'ions current'. I didn't understand the meaning, although I asked him several times, still didn't find out the concept! Is anyone here can help me through this confusion?!

 

Wishes,

Sina

Edited February 21, 2014 by Sina-73

[studiot]

An electric current is what happens when there is a net movement of electric charge in a particular direction.

Charge is regarded as being 'carried' by various bodies, also called charge carriers. It does not exist by itself.

 

Two types of carrier you will encounter in biology are electrons (negative carrier) which are sub atomic particles (smaller than atoms and part of them) and ions which are atoms (or molecules) with an excess of electrons (negative carrier) or a deficiency of them (positive carrier).

 

Positive charges moving in one direction are equivalent to negative charge moving in the opposite direction.

 

Your instructor meant the movement of electrons when referring to charge current and the movement of ions when referrring to ionic current.

Ionic currents normally occur in solution, since ionisation is one way that solutes can dissolve in solvents.

[Lizzie L]

"Charge current" isn't a term I've heard before. Your instruction might have been using it to refer to the flow of electrons, rather than the flow of ions, as in "ionic current". But it's possible s/he was referring to wave of depolarisation that travels down an axon.

 

It's also possible that your instructor was confused!

[Ringer]

The instructor may have also been talking about which factor is causing the movement of the current, meaning whether the movement of ions is being caused by an electrical gradient or a chemical gradient.

[Karim123]

This is a quite dilemma and not only your Instructor faces it. No one can ever find a convincing answer without tracing the origins of these terms. Note that the charge current is a construct of physics and when applied on biological system, by giving electrical stimulation (i.e. electrons) would generate charge current. This charge current would change the depolarization state of the membrane and trigger ionic current, which at threshold value, causes action potential. How such charge current occurs in biology has never been seriously considered although it is conceived that mechanical (e.g. touch), thermal (hot/cold), olfactory, gustatory, etc stimuli can cause conformational changes on their receptors to cause charge current transmitted as ionic current across the axon fibers. I hope I am correct

Edited August 4, 2021 by Karim123
gramatical