Talk:Action potential

message: The article is extremely confusing, there is a lot of material and definitions which are, however, poorly organized. A lot of repetitions and the flow of argument is completely absent. I'll see what i can do.
It is incredible that it is a FEATURED ARTICLE with so many problemsRvfrolov (talk) 18:32, 2 January 2009 (UTC)
thread_title: Messy article

message: There are three articles now which discuss very much the same things with numerous repetitions and description of the same material in different terms.
*Resting potential
*Membrane potential
*Action potential
As it was already suggested by Methoxyroxy 12:37, 2 November 2006 (UTC)
replies: text: I have replied at Talk:Membrane potential. Looie496 (talk) 22:01, 2 January 2009 (UTC)
replies: text: Hi Rvfrolov. The problem is that explaining an action potential, without first describing what the 'mV' part of membrane potential is, can lead to a whole lot of problems down the road. I'm all for reorganizing it, just very carefully Paskari (talk) 15:41, 24 June 2009 (UTC)
thread_title: Reorganizing the field of MEMBRANE POTENTIALS

message: The current version of the article mixes action potentials with propagation of potentials creating excessive complexity and inaccuracies. 
Potential propagation is not a required property of an action potential.   Most textbooks first define the action potential in an isopotential cell.  In Hodkin and Huxley's experiments, for example, a wire was strung along a squid giant axon to shunt axial currents effectively producing an isopotential membrane compartment.  With this preparation, current-clamp experiments still produce action potentials along the entire fiber, without a "wave of electrochemical activity."      Neither does a cell need to carry APs over a distance to make use of action potentials (e.g. electrocyte action potentials in electric fish, and many other cell types produce action potentials for other reasons than long-distance signaling). 
The current definition is also missing a key defining component: the key role of voltage-sensitive conductances. 
Propagating action potentials may be more consistently described as a continuous succession of local action potentials triggering action potentials in the adjacent sections.  This distinction would help avoid some of the current inaccuracies in the article.  
For example, the current article describes saltatory conduction as follows  "Since the axon is insulated, the action potential can travel through it without significant signal decay."  In reality, myelinated stretches of axons do not produce action potentials and the action potential does not "travel through it."   It would be more accurate to state that depolarization from an action potential at one node propagates passively to the next node and triggers an action potential at the next node.  The signal may decay significantly between nodes and still trigger an action potential at the next node.  The same section seems to imply that the action potential must be generated at the synapse  for the release of neurotransmitter, which is also inaccurate.  Any depolarization of sufficient magnitude (passive or active) will have a similar effect. 
In summary,  to make the article more useful, I recommend providing a complete and general definition of the action potential with minimal extraneous detail.  The adjacent topics such as "Electrotonic propagation of potentials", "Neurotransmitter release",  "Cable theory", "Saltatory conduction", probably belong in separate articles or sections. 
Yatsenko DV (talk) 03:45, 27 July 2009 (UTC)
replies: text: Thank you for your attention to this, and for your very thoughtful analysis. In large part, I agree with you. Your analysis of propagation seems to me to be correct. I have felt for some time that the lead section of the page is too long and rambling, and should be shortened, and I think it would be an improvement to simplify it per WP:LEAD and per your comments. I also think errors in the explanation of action potentials, of the sort you identified, should be corrected as they come up throughout the text. However, I'm not so sure about splitting off separate articles. The topics you list are not all sections in the current page, and the sections related to these topics do begin with main article links already, and it is appropriate to discuss each of those topics in this page (with the possible exception that discussion of the passive propagation of subthreshold graded potentials should be limited to their relevance to action potentials). Therefore, I would tend to favor simplifying the lead, and correcting errors elsewhere, but not necessarily splitting off any new pages or merging material here to other existing pages. --Tryptofish (talk) 15:44, 27 July 2009 (UTC)
replies: text: I'm pretty much in line with that response.  On one side, this article has become much too large and disorganized, probably because of the lack of anybody actively maintaining it.  So simplifying the article would be a good thing.  On the other side, propagation is probably the reason why action potentials exist, so omitting any discussion of it at all would be bad.  Neurotransmitter release, however, might not belong here beyond a brief sentence or two to explain what happens when an action potential arrives. Looie496 (talk) 21:41, 27 July 2009 (UTC)
replies: text: Just to clarify: what both I and Yatsenko agree is that propagation of the action potential, in the sense of an intact action potential just traveling along, is presented misleadingly. On the other hand, propagation in the sense of passive propagation of a depolarization which then brings membrane potential to threshold, activating voltage-sensitive ion channels and regenerating an action potential, is correct, and nobody wants to omit that. (Did that clarify, or make it worse? (smile)) --Tryptofish (talk) 21:51, 27 July 2009 (UTC)

text:  Propagation is not a necessary feature of an action potential and should be relegated to a later section.   Otherwise the definition is simply incorrect because it would not apply to the phenomenon that was described by Hodgkin and Huxley. Action potentials can be and are produced without propagation in many experimental preparations. Voltage-gated channels (active conductances) are a required part of an action potential and should be included in the primary definition.  I would first define the action potential in the case of an isopotential compartment.   Dimitri Yatsenko 00:58, 28 July 2009 (UTC)
replies: text: Although the lead is now more accurate, it is way too long and too technical for a general readership. We need to look at ways to make the wording less technical, and to move parts of the lead into other parts of the page. --Tryptofish (talk) 19:02, 28 July 2009 (UTC)
thread_title:  Propagation is not key to action potentials.  Simplify. 

message: I am removing "nerve spikes" from the first sentence.
I do not believe that the term "nerve spike" could be generally applied to all action potentials.  Action potentials are transient membrane voltage events in individual cells or their compartments.  They happen in many cell types.  Nerves are bundles of axons in the peripheral nervous system  (no nerves in the brain or spinal cord).  Thus "nerve spikes" are but one specific manifestation of action potentials.  The same could be said about MUAPs (motor unit action potentials), for example.  This does not make them synonymous with action potentials.  Dimitri Yatsenko 01:25, 28 July 2009 (UTC)
replies: text: I don't have much of an objection to removing the mention of spikes, which is a bit colloquial. However, I reverted your deletion of "nerve impulse." I did that because, first, it is a widely-used synonym (even though not all action potentials are in neurons), and secondly, because nerve impulse is an existing redirect to this page, and therefore the phrase needs to be bolded in the lead sentence. --Tryptofish (talk) 19:00, 28 July 2009 (UTC)
replies: text:  I have not seen the term "nerve spike" or "nerve impulse" used as a general synonym for action potentials in any modern scientific literature.  An axon is not a nerve. Neurons are sometimes called nerve cells in less technical usage, but this is inaccurate and would not pass in a scientific paper.  So I am conflicted between being precise or catering to general nontechnical usage of terms.  I think we should strive to be technically accurate and, in so doing, influence the popular understanding of these natural phenomena. Dimitri Yatsenko 19:23, 28 July 2009 (UTC)
replies: text: I wasn't disagreeing with you about spikes. Impulse is used widely in English. Besides: WP:R#PLA and number 7 of WP:NOTGUIDE. --Tryptofish (talk) 19:32, 28 July 2009 (UTC)

text:  What if we separate the article for "nerve spike" and "nerve impulse" and explain that it is but one special case of action potential that is recorded from nerves in the PNS?  Dimitri Yatsenko 19:31, 28 July 2009 (UTC)
replies: text: No, not needed, and WP:CFORK. --Tryptofish (talk) 19:34, 28 July 2009 (UTC)

text:  I defined "spikes" and "impulses" in separate sentences in the first section.  What do you think? Dimitri Yatsenko 20:36, 28 July 2009 (UTC)
thread_title:  "Nerve spikes"?  

message: The current wording in the second paragraph states that depolarization "increases both the inward sodium current (depolarization) and the balancing outward potassium current (repolarization/hyperpolarization)".    I question the accuracy of that statement.
As the membrane depolarizes, the membrane potential moves toward the reversal potential for sodium.  This reduces the electrochemical driving force for sodium. Unless the sodium conductance increases by a greater factor to compensate, the sodium current will decrease, not increase.  So the statement is not generally accurate.  I propose rewording it to state that both conductances increase and only when the net current is negative and leads to further depolarization, a positive feedback loop is generated to precipitate the action potential.  Dimitri Yatsenko 21:07, 28 July 2009 (UTC)
replies: text: Sorry to disagree, but the present text you quoted is accurate, and the changes you propose are way too technical for this project. --Tryptofish (talk) 21:35, 28 July 2009 (UTC)
replies: text:  Fair enough.  I agree that this simplification is accurate for relevant time scales, membrane potential ranges, and channel types. Dimitri Yatsenko 22:05, 28 July 2009 (UTC)
replies: text: Thank you for understanding. A lot of this is just a matter that we (Wikipedia) are writing for a general audience, and that puts limits on how technical or scholarly we can get. --Tryptofish (talk) 22:56, 28 July 2009 (UTC)
thread_title:  "Depolarization increases sodium current"? 

message: In the "Quantitative models" section there are many references to things being simple or a simplification.   While this section does have many references attached to it, there is no mention in the article of what these things are simpler than.   That is, why are these things simple, and compared to what, and what would be more complex.
:Reply to unsigned comment: What it means is that mathematical equations do not capture all the complexity of a living cell. I've tried to make it a little clearer, but I'm not sure whether there is any way of saying it better. --Tryptofish (talk) 23:25, 3 September 2009 (UTC)
thread_title: Simplification

message: The refractory period section seems like it was copy pasted from a text book which was written by a high school teach held at gun point. Perhaps we should consider updating it Paskari (talk) 23:30, 6 October 2009 (UTC)
replies: text: I've taken a shot at rewriting it.  Cellular stuff is not really my strength, so if I got anything wrong, I hope somebody will correct it. Looie496 (talk) 00:10, 7 October 2009 (UTC)
replies: text: I'm just about to sign off, but I'll take a look at it tomorrow. --Tryptofish (talk) 00:14, 7 October 2009 (UTC)

text: That is much better, great job. Paskari (talk) 11:02, 7 October 2009 (UTC)

text: Yes, much better, thanks. I tweaked it a little further, not much. --Tryptofish (talk) 18:34, 7 October 2009 (UTC)
thread_title:  Refractory Period Section Poorly written 

message: I've just attempted a pretty major rewrite of the lead, which I hope won't offend anybody.  I thought the existing version was too hard for readers to understand -- it also contained a couple of minor errors.  I also added a paragraph about the distinction between sodium and calcium spikes, which seems to me to be a very important point.  Regards, Looie496 (talk) 20:08, 23 February 2010 (UTC)
replies: text: I note that the lead from the last FAR was moved some time ago to the overview section. If this persists, we should justify the need for both a lead and overview section, and ensure that they are not redundant to each other. Geometry guy 20:39, 23 February 2010 (UTC)
replies: text: The Overview section needs revision too, but it seemed to me that these changes to the lead were sufficiently "bold" that it would be better not to pile other changes on top of them before discussion. Looie496 (talk) 20:48, 23 February 2010 (UTC)
thread_title:  Concerning the lead 

message: I have removed a reference from the lede that was to:
* 
Alphascript Publishing republished Wikipedia content. And the book in question republishes this article. The cover of the book can be seen on Amazon. This article is named on the front cover. (The format for Alphascript books is to list the WP articles contained therein on the front cover as part of the name.)
The person who owns the book can verify that this is republished Wikipedia content by looking at the copyright information inside the book itself. -- RA (talk) 13:16, 28 February 2010 (UTC)
replies: text: The other danger is Alphascript also publishes academics' thesis if they convince them to sign their terms. Was the source republishing of wiki article or a thesis. So always double check before removing any references about whether they are wikipedia article or a thesis. Generally a quick way to check is searching  product description in wikipedia. Kasaalan (talk) 13:29, 28 February 2010 (UTC)
replies: text: It is VDM that also publishes academics' thesis if they convince them to sign their terms. All alphascript titles are wikipedia articles. My mistake. Kasaalan (talk) 19:14, 5 March 2010 (UTC)
replies: text: Note:  I have edited the previous comment, because it was added by altering the comment above it in a way that made this section impossible to understand without going back through the history.  I hope that my revision has not changed the message. Looie496 (talk) 19:26, 5 March 2010 (UTC)
thread_title:  Reference removed: Alphascript Publishing 

message: The inward movement of sodium ions and the outward movement of potassium ions are passive
Let's describe all the events that happen simultaneously:
1/ Sodium movement balanced with chloride
sodium is inward and Na ions stick to the internal membrane,
chloride ions stay out, and balance the Na charge, across the external membrane
2/ Potassium movement balanced with chloride
potassium is outward and K ions stick to the external membrane,
chloride ions stay in, and balance the K charge, across the internal membrane
Now let's see what happens on each side:
1/ Internal side:
sodium is inward and Na ions stick to the internal membrane,
chloride ions stay in, and balance the K charge, across the internal membrane
2/ External side
chloride ions stay out, and balance the Na charge, across the external membrane,
potassium is outward and K ions stick to the external membrane
Result: a membrane voltage that is... quite null.
Osmosis:
Since there are concentrations changes there is water flux through aquaporins:
1/ from int to ext for sodium
2/ from ext to int for potassium
Result : How is it possible to make a bidirectional and simultaneous water movement in aquaporins? Somasimple (talk) 05:57, 5 June 2010 (UTC)
replies: text: Sorry, but you misunderstand. Ion channels are not aquaporins, and they are not permeable to water molecules. In vertebrate animals, aquaporins are mainly expressed in the kidneys, and there is relatively little water transport during an action potential. Ion channels are selectively permeable to ions, so chloride does not move together with cations; also there is a differential distribution across the membrane of impermeable anions. The reason there is a membrane potential at all, is that there is a separation of charge. If you continue to disagree about all of this, please cite sources. --Tryptofish (talk) 14:21, 5 June 2010 (UTC)
replies: text:  Ions channels are not permeable to water molecules? Really? Molecular dynamics of the KcsA K(+) channel in a bilayer membrane Somasimple (talk) 10:22, 7 June 2010 (UTC)
thread_title:  passive movements of positive ions? 

message: About this section Myelin and saltatory conduction
It is said:
# "The evolutionary need for the fast and efficient transduction of electrical signals in nervous system resulted in appearance of myelin sheaths around neuronal axons."
# "Myelin prevents ions from entering or leaving the axon along myelinated segments."
The first assertion is false since every axon is covered by myelin; compact or not, leaving no room (<20 nm) around the axon.
See the excellent book, page 128 Neurocytology: Fine Structure of Neurons, Nerve Processes and Neuroglial Cells
The second becomes, in that case, not true since it assumes that unmyelinated axons are bare. --Somasimple (talk) 05:43, 9 June 2010 (UTC)
replies: text: Well, this topic I do know about.  Myelin appears only in vertebrates (although some other groups have similar substances), and even in vertebrates only a subset of axons are myelin-coated.  I don't have that specific book on hand, but every basic neuroscience book covers this point very thoroughly. Looie496 (talk) 06:44, 9 June 2010 (UTC)
replies: text: Here is a link to the book Ennio Pannese Google book There are citations on page 119 and following ones about evolutionary aspects. On page 128, if vertebrates have always axons that are insulated, how do they function since the ions exchanges can't happen? --Somasimple (talk) 07:28, 9 June 2010 (UTC)

text:  From this one The Biology of Schwann Cells The Biology of Schwann Cells: Development, Differentiation and Immunomodulation Edited by Patricia Armati: "All neurons in the PNS are in intimate physical contact with Schwann and satellite cells, regardless of whether they are myelinated or unmyelinated, sensory or autonomic. All axons of the peripheral nerves are ensheathed by rows of Schwann cells, in the form of either one Schwann cell to each axonal length, or in Remak bundles, formed when an individual Schwann cell envelopes lengths of multiple unmyelinated axons (Figures 1.2, 1.3 and 1.4b). There is now a large body of evidence that defines a multitude of Schwann cell functions that are not related to myelination (Lemke 2001). This uncoupling of myelin-associated functions from other Schwann cell roles emphasises the essentially symbiotic relationship between nerve cells and Schwann cells, where each is dependent on the other for normal development, function and maintenance." Here is the link to the excerpt --Somasimple (talk) 10:07, 9 June 2010 (UTC)
replies: text: You raised a lot of points that need to be addressed so I'll try to hit them all, in no particular order. I must have missed your quotes above (#1 & #2) in the original wikipedia article as number 2 is incorrect (it's mostly due to capacitance changes, there would have been other ways of just removing channels from the membrane to minimize ionic current...but then there's still all that capacitative loss with no regenerative ionic current). Regarding number 1, this is true, though as mentioned in the book to which you linked other organisms have attained similar sorts of results in other ways (e.g. the squid giant axon). I should note that being in intimate contact and being ensheathed are VERY different (and really when we say myelinated what's meant is compact ensheathment, which is somewhat different still). Regarding ion movement, see the discussion of the Node of Ranvier. I don't work on invertabrates, so I don't know how they deal with such things, presumably there's either enough space (This is the case for skeletal muscle, where the fibers are packed like sardines but there's still enough space for things to work. There are some computational modeling studies of these sorts of things on pubmed.) or there are random holes/gaps similar to nodes of Ranvier. The important points from that is that the picture of unensheathed axons in a swimming pool of ions of constant concentration isn't really correct (but normally a close enough approximation) and Schwann cells aren't a one-hit wonder. --Dpryan (talk) 20:56, 10 June 2010 (UTC)
replies: text:  From the excerpt: "In a mixed peripheral nerve unmyelinated fibres outnumber myelinated fibres by a ratio of three or four to one (Jacobs and Love 1985). For example, a transverse section of a human sural nerve contains approximately 8000 myelinated fibres per mm2, whereas the unmyelinated axons number 30 000 per mm2". I think that the approximation you made about the pool is quite far from the reality of anatomy? The constant concentration is perhaps not achieved at all! --Somasimple (talk) 06:28, 11 June 2010 (UTC)
replies: text: For comparison, a t-tubule is often 20-40nm in diameter and even then the ion concentrations don't change that much (you'll get a plateau after a few stimulations in a prolonged train, and the change will only be a few mM). You really don't need a lot of ions to move for an AP to occur, otherwise we would have very different anatomy! So, as I said, the approximation usually works for non-extreme cases (a square mm is a fair bit of space). --Dpryan (talk) 17:43, 11 June 2010 (UTC)
replies: text:  I TOTALLY agree with you. Saying that concentrations remain unchanged may be reformulated that way; Only, a tiny fraction, acts and creates all the effects. It may be refined in another way; The unchanged big portion isn't involved in any manner in the process. --Somasimple (talk) 05:18, 12 June 2010 (UTC)
thread_title:  Myelin and saltatory conduction 

message: In this article [Cable Theory] the conduction velocity depends greatly of the time constant that is result of τm=Cm*Rm
It is said that myelin decreases the membrance capacitance. That's seems OK but what happens to the membrane resistance in case of myelinization?
Computation of the the time constant with reasonable values leads to an increase of the time constant:
You may see a discussion about this problem.--Somasimple (talk) 10:55, 11 June 2010 (UTC)
replies: text: The discussion you linked to sets it clearly: membrane capacitance decreases while membrane resistance increases, so there is no charge dispersed through the membrane. Think of a capacitor - the plates have their charged particles line up on each end which drops the voltage through the circuit, so to maximize voltage propagation we need to maximize the time constant *across the membrane* and minimize the time constant *through the axon*. That's probably where your confusion lies - you need variables for each direction. Each node can change direction of propagation by depolarizing sequentially, with the potential difference propagating along a straight line each time. SamuelRiv (talk) 23:06, 13 June 2010 (UTC)
replies: text: Vey!!! My confusion comes from the book of Koch. pages 10 and 167. The text is clearly speaking of the τm=Cm*Rm, nothing else. BTW, your comment contradicts the comments below (next section) where internal current becomes negligible... --Somasimple (talk) 05:15, 14 June 2010 (UTC)

text: Okay, I might have gotten confused, but here's what I was saying before (hopefully clearer): there are two R-C-I's here: one for the current between the inside of the axon and the salt medium outside the cell (across the membrane), and the other through the axon from one node to the next. In the first case (across the cell membrane), R is big, C is small, and I is minimal. In the second case (through the axon between nodes), R is small, C is big-to-infinite (as a wire), and I is V/R from the depolarization. Note that charge carriers do not actually flow with appreciable speed through the axon, the same as in electric conductivity through a wire where electrons flow at about 0.1mm/s - rather, the current propagates as a potential difference from one node to the next (as a big capacitor with the dielectric having conductive properties in the cations that I don't know of and should look up). SamuelRiv (talk) 08:20, 14 June 2010 (UTC)
replies: text: That's NOT OK at all: Please give a reference about this second internal capacity. How is it connected with the internal R? In parallel or serial?. Here is mine; Koch circuit Secondly, if you exchange electrons then you have an electric current that travels at light-speed even if the electrons themselves don't (Electric circuit). The internal resistance is BTW higher than you tell us... --Somasimple (talk) 10:11, 14 June 2010 (UTC)

text: In the Koch pdf (I have the same book btw, though in a box somewhere), there are two separable circuits. One is bracketed and labeled "node", while the other lies over the internode and none of the circuit elements are labeled. The first one represents the membrane potential between the inside of the axon and the outside cations, while the other models the internal resistance through the myelinated portion of the axon between nodes. Those are what I was referring to before as "two separate R-C-I's", the first being across the membrane and the second being through the axon. Yes, the current does effectively travel at light-speed as it simply is electric polarization between two points, same as a metal wire (which I used as an example to illustrate that electrons move extremely slowly compared to light-speed current). Another illustration similar to Koch is in this review (section: Active properties of nerve fibers) where Ra is the resistance of the "wire" that is the myelinated internode portion of the axon. So I think we're just mixed up here - it's the difference between resistance through the metal wire and the resistance of the rubber insulation - membrane resistance increases with myelination allowing effective axon "wire" resistance to decrease. SamuelRiv (talk) 16:48, 14 June 2010 (UTC)
replies: text: Are you saying that Sodium current intake (physical displacement) is followed by an electronic exchange (No displacement) with the next node? If so, then you have some problems: 1/ The next node becomes positive with this exchange and the sodium intake at this site will do not happen. 2/ The electric current you create with this electronic exchange has not the good direction. 3/ If an electronic exchange exists, when does it start and when/where does it stop? 4/ The worst problem remains the law of the least resistance. An electric current flows following mostly the least resistance and because AP uses only a very tiny quantity of ions in presence then there is not enough current that flows to the next node triggering another AP. --Somasimple (talk) 05:04, 15 June 2010 (UTC)
thread_title:  Myelin and cable theory 

message: From the Peak and Falling Phase" section:
However, the same raised voltage that opened the sodium channels initially also slowly shuts them off, by closing their pores; the sodium channels become inactivated. This lowers the membrane's permeability to sodium, driving the membrane voltage back down.
How? If some sodium is still flowing into the cell, the membrane voltage would continue to go up. Wouldn't it be the rate of increase that goes down?... And if the sodium flow is blocked completely, then how does this change the voltage at all? If the only thing driving down the voltage is the potassium outflow, then the last part of the quoted statement is misleading and needs to be fixed.
Thanks.
184.96.106.141 (talk) 04:56, 12 January 2011 (UTC)
replies: text: The relationship between ion movement and voltage is not as direct as you apparently think.  It is possible to have ion flow without any change in membrane potential, and it is possible to have a change in membrane potential without any ion movement.  The rules that govern membrane potential are outlined in the membrane potential article -- this is complicated stuff, though, and it might be better to consult a textbook. Looie496 (talk) 06:37, 12 January 2011 (UTC)
replies: text: Agreed, it's a complicated subject and perhaps there is a critical concept I have yet to understand. But just for the record, if you got the impression that I was equating sodium flow with membrane potential, that's incorrect. I was only talking about sodium flow's individual contribution to membrane potential. Thanks for your input though. I'll check that link out. 184.96.106.141 (talk) 22:10, 12 January 2011 (UTC)

text: 184, I think you raise a valid point. The problem is with the imprecise "up/down" language, and I'll fix it on the page. As Looie said, the information is correct, but I have to admit that it is worded less helpfully than it could have been. Thanks! --Tryptofish (talk) 20:14, 12 January 2011 (UTC)
thread_title:  Potentially confusing statement 

message: I'd like to suggest a reorganization of this article to make it more readable and less repetitive.  I'm prepared to do it over the next few weeks myself or with help, if there are no objections.  In my eyes, there are 3 parts to this article, and most of my suggestions are for the 2nd.
1. The Lead/Overview - a lot of entries in the Talk agree this needs to be changed to be more coherent and accessible to the lay reader. I think we should make the 2nd paragraph of the lead a much shorter description, just the basic idea of what it means for an AP to be an AP (I know, harder than it sounds). The info currently in the 3rd paragraph should be later in the article - in it's place, we could put a paragraph that takes a quick introductory walk through the later sections. The Overview is okay, but I think voltage changes and threshold potential will make more sense if the explanation walks the reader through an image like Figure 1A, although one that is a little clearer. That is usually how the action potential is taught, with constant reference to a graph.
2. Current sections 2 through 6 - Here's where the article is a bit messy. How I think it could be organized:
::Biophysical basis
:::Phases
::Propagation
::Termination
I think Phases should be included in the Biophysical Basis section. Besides including a lot of similar information, the phases are described using the same mechanisms that are being talked about in 'Biophysics'. And the 'Biophysics' section currently has no structure - going through mechanisms phase-by-phase would give it that. The new section would have general information up front, then subsections for each phase.
The Neurotransmission section should be removed, and its contents sorted into the other sections. First of all, neurotransmission is about the release and reception of neurotransmitters - this is related to APs and should be referred to, but that can go in the 'Termination' section and be primarily links to relevant articles. Second, a lot of what's in this section rambles about things other than neurotransmission anyway. I'm not suggesting any particular content be removed, only moved. Some of that will be clear, some not - I don't know where the bit about sensory neurons and pacemaker potentials should go, though I do agree they should be in the article.
3. The miscellaneous sections - I have no issue with their organization.
So broadly speaking, the changes are to fix the beginning of the article for the lay reader, and then reorganize the middle sections so that they walk through the AP from how it starts, to how it moves, to what it does when it gets where it's going. ~ Twodarts (talk) 02:21, 18 December 2011 (UTC)
replies: text: Go for it!  One of the things I have tried to do, in the limited work I've done on this article, is to leave most of the basic biophysics for the membrane potential article, and focus this article on the biophysics that are specifically relevant to excitability.  But if you're interested in doing major work on the article, you should feel free to do whatever seems appropriate to you.  The article is definitely full of redundancy and extraneous material at the moment, so I think you should feel free to get rid of stuff if you don't think it belongs.  Regards, Looie496 (talk) 17:29, 18 December 2011 (UTC)
thread_title:  Reorganization of the sections, removal of repetition 

message: The article states (emphasis mine):
:"To be specific, myelin wraps multiple times around the axonal segment, forming a thick fatty layer that prevents ions from entering or escaping the axon. This insulation prevents significant signal decay as well as ensuring faster signal speed. This insulation, however, has the restriction that no channels can be present on the surface of the axon. There are, therefore, regularly spaced patches of membrane, which have no insulation. These nodes of ranvier can be considered to be 'mini axon hillocks', as their purpose is to boost the signal in order to prevent significant signal decay."
First it says that the insulation prevents signal decay. Then it says that it's the gaps in the insulation that prevent signal decay (i.e., it's not the insulation itself), which implies to me that the insulation may even contribute to the decay (or why else would there be signal boosters needed?). Could someone do a bit of rewrite to clarify the intended meaning here? DMacks (talk) 06:19, 12 January 2012 (UTC)
thread_title:  Contradictory [[Action potential#Anatomy of a neuron|Anatomy of a neuron]] statements about [[myelin]] 

message: From what I understand, all-or-none signals should be digital. Unless I'm missing something here.--Miracleman123 (talk) 06:58, 4 July 2012 (UTC)
replies: text: I don't think either "digital" or "analog" encompasses the full truth.  The amplitude is essentially all-or-none, but the waveform is smooth and the timing is not discretized. Looie496 (talk) 16:10, 4 July 2012 (UTC)
replies: text: This question has come up before, and I wonder whether we should simply delete the description as "analog" (in other words, say nothing, neither analog nor digital). As Looie correctly says, action potentials are continuous variations in the value of the membrane potential, and therefore, their waveform shapes are analog, rather than digital bits. (In fact, strictly speaking, even their amplitudes can vary, depending on the resting potential that serves as a baseline. But that's not the same thing as graded subthreshold potentials.) What is all-or-none is whether they occur or not. They are nothing like what we generally consider to be digital signals, so I think that it's technically correct to describe them as analog. But it gets real confusing to say that in the same sentence that calls them "all-or-none". I've just moved the link to analog signals to another place on the page. Is this better? --Tryptofish (talk) 19:43, 4 July 2012 (UTC)
replies: text: Also the "purely" digital signals in electronics have a waveform ascending and descending and slight voltage variations,that limit their usability (think of high temperatures where chips start behaving erratically. The notion that an action potential has a definite waveform is irrelevant to it's digtial character. Only the frequency of action potentials passing by contains the relevant information from for instance a sensory organ.Viridiflavus (talk) 13:18, 13 January 2013 (UTC)
thread_title: All-or-none is analog?

message: I popped in here because this article was in an error category (invalid LCCNs) and one thing I immediately noticed was that the references were /very/ messy. For one thing, only about half the books in the 'bibliography' section were actually cited, and there were a number of books that weren't in that section. I've been doing quite a bit of work on reorganizing how they are laid out, with the goal of trying to get them all into some kind of 'uniform' appearance, and laid out in a way that's actually useful.
Though I am changing the format of the book references to use |ref=harv, it's not out of any intention to violate CITEVAR, or force something like list-defined references on the article...the format as it existed was, like I said, very confused, and moving the books into a separate section and using  and  seemed like the best way to hammer this into something more usable, and less messy.
I would ask, though, that if there is a problem with how I'm doing this, you just poke me and say 'hey dummy', do this instead... I'm not changing the content, but I think where I am now would be a better 'starting point' to get this to something decent that the regular content editors of this can deal with (and that's not ugly) than where it was, even if it means moving in a different direction. If anyone wants to comment, please do so... Reventtalk 11:17, 27 August 2014 (UTC)
replies: text: Just to make it extremely clear, I'm being very careful to not damage the referencing, checking each edit multiple times, every citation 'points' at exactly the same source, it's just the formatting of the reference section (and completing the metadata on all the references) that I'm changing. I am using harvard references for the books, but the same 'visual' change can be done without that if people want me to change it back, it was just easier for sorting out the 'bundling'. Reventtalk 02:26, 28 August 2014 (UTC)

text: Ok, I'm finally done sorting all the books out...this is actually, for the books, more like the 'original' citation format, which was 'manual' short footnotes and a list just now they are actually using the template. I think it would make sense (especially for editability in parts) to also do the same thing with the journals, but I'm not going to do that unless people express that they want me to. If that does turn out to be desirable, please ping me and I will do it. Reventtalk 07:37, 28 August 2014 (UTC)
thread_title:  Reorganizing the references 

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thread_title:  External links modified 

message: I have temporarily reverted a very large addition to the section on plant action potentials. For reference, here it is:
===Plant action potentials===
Plant and fungal cells  are also electrically excitable. The action potential observed in vascular plants is better observed than those of vegetativeHolsinger, Kent E. “Holsinger.” Reproductive Systems and Evolution in Vascular Plants, vol. 97, no. 13, 20 June 2000, pp. 7037–7042. because the diffusion of electrical signals occurs primarily in the phloem sieve tube – a distinctive characteristic of higher plantsHedrich, Rainer, and Erwin Neher. “Venus Flytrap: How an Excitable Carnivorous Plant Works.” Trends in Plant Science, vol. 23, no. 3, Mar. 2018, pp. 220–234., https://doi.org/10.1016/j.tplants.2017.12.004..Hedrich, Rainer. “Ion Channels in Plants.” Physiology, vol. 92, Oct. 2012, pp. 1777–1811., doi:10.1152. 
The general progression of plant action potentials is the same as animal action potentials, however, plants possess alternate mechanisms. 
===== Resting Phase =====
Plant cells are commonly observed to have more negative resting membrane potentials and rising phase membrane potentials. For example, the Dionaea’s resting membrane potential is approximately -120mVHedrich, Rainer, and Erwin Neher. “Venus Flytrap: How an Excitable Carnivorous Plant Works.” Trends in Plant Science, vol. 23, no. 3, Mar. 2018, pp. 220–234., https://doi.org/10.1016/j.tplants.2017.12.004., whereas neurons are regularly between -40mV to -90mVPurves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. Electrical Potentials Across Nerve Cell Membranes.Available from: https://www.ncbi.nlm.nih.gov/books/NBK11069/ .
To attain understanding regarding plant action potentials, Opritov et al. recorded the electric potentials of maize leaves. To do so, they cut the leaf accordingly to allow aphids to attach for a long period to feed in efforts to expose the sieve. Once exposed, the researchers removed the aphids carefully with a laser to access the contents released by the leaf. This liquid-like substance was then measured with a microelectrode that was previously calibrated with a control of water.Opritov, V A, et al. “Direct Coupling of Action Potential Generation in Cells of a Higher Plant (Cucurbita Pepo) with the Operation of an Electrogenic Pump.” Russian Journal of Plant Physiology, vol. 49, no. 1, 2002, pp. 142–147. The recorded values were similar to those that were expected when reviewing a study of Mimosa pudicaFromm, Jörg, et al. “Electrical Signaling along the Phloem and Its Physiological Responses in the Maize Leaf.” Frontiers in Plant Science, vol. 4, no. 239, 4 July 2013, pp. 1–7., doi:10.3389/fpls.2013.00239. which indicated that the resting membrane potential measured was significant.
===== Stimulation and Rising Phase =====
Stimulation also induces action potentials within plant cells, the most commonly mentioned stimulation is touch. Unlike animals, the plant’s action potentials will not register any information regarding the characteristics of the interaction.
Upon stimulation, the depolarization in plant cells is not accomplished by an uptake of positive sodium ions, but but rather the influx of calcium. Logically, one can understand the plant’s lack of dependence on sodium ions to initiate depolarization because too many sodium ions lead to detrimental outcomes.Pardo, Jose M, and Francisco J Quintero. “Plants and Sodium Ions: Keeping Company with the Enemy.” Genome Biology, vol. 3, no. 6, 24 May 2002, pp. 1–4., genomebiology.com/2002/3/6/reviews/1017. Together with the following release of positive potassium ions, which is common to plant and animal action potentials, the action potential in plants infers, therefore, an osmotic loss of salt (KCl), whereas the animal action potential is osmotically neutral, when equal amounts of entering sodium and leaving potassium cancel each other osmotically. The interaction of electrical and osmotic relations in plant cells   indicates an osmotic function of  electrical excitability in the common, unicellular ancestors of plants and animals under changing salinity conditions, whereas the present function of rapid signal transmission is seen as a younger accomplishment of metazoan cells in a more stable osmotic environment.Gradmann, D; Mummert, H in  It must be assumed that the familiar signalling function of action potentials in some vascular plants (e.g. Mimosa pudica) arose independently from that in metazoan excitable cells.
===== Peak =====
As calcium influxes towards the cytoplasm, they activate calcium-dependent anion channels, causing negatively charged ions, like chloride, to flow out of the cell; thus further depolarizing the membrane. Similarly to the resting membrane potentials of plants and animals, the peaks correspond in a similar manner: they are commonly more negative. Dionaea’s action potential usually maximizes at -20mV, approximately 60mV less than an average nerve cell. 
===== Falling Phase and After-hyperpolarization =====
Unlike the rising phase and peak, the falling phase and after-hyperpolarization seem to depend primarily on cations that are not calcium. To initiate repolarization, the cell requires movement of potassium out of the cell through passive transportation on the membrane. This differs from neurons because the movement of potassium does not dominate the decrease in membrane potential; In fact, to fully repolarize, a plant cell requires energy in the form of ATP to assist in the release of hydrogen from the cell – utilizing a transporter commonly known as H+-ATPase. 
Refractory Period
Although there is a lot of debate regarding the refractory period of a plant cell, what is not up to speculation is the fact that their refractory periods are much longer than those in animals, and that in order to fire and action potential again, they require more sources for electrical current. 
Although animals and plants both possess action potentials, those of plants are often overlooked or ignored due to the plants’ lack of nerves and nervous system. The deficiency of a brain or a specified location to integrate information makes it difficult to believe that action potentials of plants create a response; however, plants definitely do perceive stimuli (without information regarding it) that can develop into an (generic) effector response. 
In part, there are formatting problems, but I also am concerned that this material fails WP:DUE. Plants just aren't that big a part of the topic, and it seems to me to be inappropriate to have so many subsections that recapitulate the descriptions of action potential stages higher on the page. --Tryptofish (talk) 22:33, 22 May 2018 (UTC)
replies: text: A lot of it seems to have been reincorporated at Action_potential#Plant_action_potentials, and I added back a bit more. Specifically, the resting potential values for plants vs animals and some more specific info on the role of potassium in the post-peak phases. — Wug·a·po·des​ 00:09, 2 May 2021 (UTC)
thread_title:  Plant action potentials 

message: Plant and fungal cells  are also electrically excitable. The action potential observed in vascular plants is better observed than those of vegetativeHolsinger, Kent E. “Holsinger.” Reproductive Systems and Evolution in Vascular Plants, vol. 97, no. 13, 20 June 2000, pp. 7037–7042. because the diffusion of electrical signals occurs primarily in the phloem sieve tube – a distinctive characteristic of higher plantsHedrich, Rainer, and Erwin Neher. “Venus Flytrap: How an Excitable Carnivorous Plant Works.” Trends in Plant Science, vol. 23, no. 3, Mar. 2018, pp. 220–234., https://doi.org/10.1016/j.tplants.2017.12.004..Hedrich, Rainer. “Ion Channels in Plants.” Physiology, vol. 92, Oct. 2012, pp. 1777–1811., doi:10.1152. 
The general progression of plant action potentials is the same as animal action potentials, however, plants possess alternate mechanisms. 
===== Resting Phase =====
Plant cells are commonly observed to have more negative resting membrane potentials and rising phase membrane potentials. For example, the Dionaea’s resting membrane potential is approximately -120mVHedrich, Rainer, and Erwin Neher. “Venus Flytrap: How an Excitable Carnivorous Plant Works.” Trends in Plant Science, vol. 23, no. 3, Mar. 2018, pp. 220–234., https://doi.org/10.1016/j.tplants.2017.12.004., whereas neurons are regularly between -40mV to -90mVPurves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. Electrical Potentials Across Nerve Cell Membranes.Available from: https://www.ncbi.nlm.nih.gov/books/NBK11069/ .
To attain understanding regarding plant action potentials, Opritov et al. recorded the electric potentials of maize leaves. To do so, they cut the leaf accordingly to allow aphids to attach for a long period to feed in efforts to expose the sieve. Once exposed, the researchers removed the aphids carefully with a laser to access the contents released by the leaf. This liquid-like substance was then measured with a microelectrode that was previously calibrated with a control of water.Opritov, V A, et al. “Direct Coupling of Action Potential Generation in Cells of a Higher Plant (Cucurbita Pepo) with the Operation of an Electrogenic Pump.” Russian Journal of Plant Physiology, vol. 49, no. 1, 2002, pp. 142–147. The recorded values were similar to those that were expected when reviewing a study of Mimosa pudicaFromm, Jörg, et al. “Electrical Signaling along the Phloem and Its Physiological Responses in the Maize Leaf.” Frontiers in Plant Science, vol. 4, no. 239, 4 July 2013, pp. 1–7., doi:10.3389/fpls.2013.00239. which indicated that the resting membrane potential measured was significant.
===== Stimulation and Rising Phase =====
Stimulation also induces action potentials within plant cells, the most commonly mentioned stimulation is touch. Unlike animals, the plant’s action potentials will not register any information regarding the characteristics of the interaction.
Upon stimulation, the depolarization in plant cells is not accomplished by an uptake of positive sodium ions, but but rather the influx of calcium. Logically, one can understand the plant’s lack of dependence on sodium ions to initiate depolarization because too many sodium ions lead to detrimental outcomes.Pardo, Jose M, and Francisco J Quintero. “Plants and Sodium Ions: Keeping Company with the Enemy.” Genome Biology, vol. 3, no. 6, 24 May 2002, pp. 1–4., genomebiology.com/2002/3/6/reviews/1017. Together with the following release of positive potassium ions, which is common to plant and animal action potentials, the action potential in plants infers, therefore, an osmotic loss of salt (KCl), whereas the animal action potential is osmotically neutral, when equal amounts of entering sodium and leaving potassium cancel each other osmotically. The interaction of electrical and osmotic relations in plant cells   indicates an osmotic function of  electrical excitability in the common, unicellular ancestors of plants and animals under changing salinity conditions, whereas the present function of rapid signal transmission is seen as a younger accomplishment of metazoan cells in a more stable osmotic environment.Gradmann, D; Mummert, H in  It must be assumed that the familiar signalling function of action potentials in some vascular plants (e.g. Mimosa pudica) arose independently from that in metazoan excitable cells.
===== Peak =====
As calcium influxes towards the cytoplasm, they activate calcium-dependent anion channels, causing negatively charged ions, like chloride, to flow out of the cell; thus further depolarizing the membrane. Similarly to the resting membrane potentials of plants and animals, the peaks correspond in a similar manner: they are commonly more negative. Dionaea’s action potential usually maximizes at -20mV, approximately 60mV less than an average nerve cell. 
===== Falling Phase and After-hyperpolarization =====
Unlike the rising phase and peak, the falling phase and after-hyperpolarization seem to depend primarily on cations that are not calcium. To initiate repolarization, the cell requires movement of potassium out of the cell through passive transportation on the membrane. This differs from neurons because the movement of potassium does not dominate the decrease in membrane potential; In fact, to fully repolarize, a plant cell requires energy in the form of ATP to assist in the release of hydrogen from the cell – utilizing a transporter commonly known as H+-ATPase. 
Refractory Period
Although there is a lot of debate regarding the refractory period of a plant cell, what is not up to speculation is the fact that their refractory periods are much longer than those in animals, and that in order to fire and action potential again, they require more sources for electrical current. 
Although animals and plants both possess action potentials, those of plants are often overlooked or ignored due to the plants’ lack of nerves and nervous system. The deficiency of a brain or a specified location to integrate information makes it difficult to believe that action potentials of plants create a response; however, plants definitely do perceive stimuli (without information regarding it) that can develop into an (generic) effector response. 
In part, there are formatting problems, but I also am concerned that this material fails WP:DUE. Plants just aren't that big a part of the topic, and it seems to me to be inappropriate to have so many subsections that recapitulate the descriptions of action potential stages higher on the page. --Tryptofish (talk) 22:33, 22 May 2018 (UTC)
replies: text: A lot of it seems to have been reincorporated at Action_potential#Plant_action_potentials, and I added back a bit more. Specifically, the resting potential values for plants vs animals and some more specific info on the role of potassium in the post-peak phases. — Wug·a·po·des​ 00:09, 2 May 2021 (UTC)
thread_title: Plant action potentials

message: Unlike the rising phase and peak, the falling phase and after-hyperpolarization seem to depend primarily on cations that are not calcium. To initiate repolarization, the cell requires movement of potassium out of the cell through passive transportation on the membrane. This differs from neurons because the movement of potassium does not dominate the decrease in membrane potential; In fact, to fully repolarize, a plant cell requires energy in the form of ATP to assist in the release of hydrogen from the cell – utilizing a transporter commonly known as H+-ATPase. 
Refractory Period
Although there is a lot of debate regarding the refractory period of a plant cell, what is not up to speculation is the fact that their refractory periods are much longer than those in animals, and that in order to fire and action potential again, they require more sources for electrical current. 
Although animals and plants both possess action potentials, those of plants are often overlooked or ignored due to the plants’ lack of nerves and nervous system. The deficiency of a brain or a specified location to integrate information makes it difficult to believe that action potentials of plants create a response; however, plants definitely do perceive stimuli (without information regarding it) that can develop into an (generic) effector response. 
In part, there are formatting problems, but I also am concerned that this material fails WP:DUE. Plants just aren't that big a part of the topic, and it seems to me to be inappropriate to have so many subsections that recapitulate the descriptions of action potential stages higher on the page. --Tryptofish (talk) 22:33, 22 May 2018 (UTC)
replies: text: A lot of it seems to have been reincorporated at Action_potential#Plant_action_potentials, and I added back a bit more. Specifically, the resting potential values for plants vs animals and some more specific info on the role of potassium in the post-peak phases. — Wug·a·po·des​ 00:09, 2 May 2021 (UTC)
thread_title:  '''Falling Phase and After-hyperpolarization''' 

message: The first sentence of the second paragraph is a bit wordy and confusing. I would suggest not mentioning saltatory conduction here. — Preceding unsigned comment added by Mikeyvon (talk • contribs) 21:55, 16 September 2021 (UTC)
thread_title:  second paragraph 

message: "In the Hodgkin–Huxley membrane capacitance model, the speed of transmission of an action potential was undefined and it was assumed that adjacent areas became depolarized due to released ion interference with neighbouring channels. Measurements of ion diffusion and radii have since shown this not to be possible.[citation needed]"
What is "ion interference" here? What radii are we talking about? And where are the citations?  — Preceding unsigned comment added by 89.3.212.183 (talk) 02:20, 3 July 2022 (UTC)
thread_title:  Last paragraph in Biophysical Basis really confusing