Talk:Graded potential
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What determines that a membrane potential is GRADED?[edit]
Is a membrane potential described as 'graded' because:
- the strength of its INPUT can be stronger or weaker (ie, from the number of neurotransmitters and/or of receptors);
- a difference in the NUMBER of inputs will yield a stronger or weaker strength as they summate at the axon hillock;
- the strength of the signal will decrease as it TRAVELS down a dendrite (leakage channels?) and across the soma (the ions SPREAD OUT).
I'm getting the impression that it's the last case, or perhaps the term relates to all those cases?UnderEducatedGeezer (talk) 19:38, 10 March 2016 (UTC)
- @UnderEducatedGeezer: Actually, it's not (3) very much, but pretty much a mixture of (1) and (2), with it being mostly (2) in actual practice. The central point is that it has no single amplitude, but can be either larger or smaller, in contrast to an action potential, that is all-or-none and can have only one amplitude. So there are either action potentials or graded potentials. Should this be made clearer on the page? --Tryptofish (talk) 20:14, 10 March 2016 (UTC)
- @Tryptofish:No, I don't think so, the article does make 1 & 2 clear enough, & I pretty much understood that 'graded' referred to variation, as in 'degraded', & 'graduated'; it's just that it seems to me that the fact that those two, (the number of inputs and their consequent spatial summation, and to some degree the size of an input), are somewhat given to be variant, and the fact that the signal strength, whatever it starts at, will decrease as it traverses the dendrite & particularly the soma isn't so immediately obvious, & is so important to understand, particularly with respect to temporal summation, that it 'deserves' to be labeled graded for emphasis. And I guess I continue to misunderstand and assume that the electrotonic movement of a signal down a dendrite & across the soma is alternatively named as 'graded potential', and I thought I finally understood the nature of the movement of a signal from synapse to hillock by electrotonic potential when I read & consequently visualized that the ions in a neuron spread out as they responded to an input, thus diminishing every local potential of the signal along the way (particularly in the soma). (I hope I'm not now wrong about the signal diminishing because of combo of leakage channels in dendrites & charge spread in soma!) I'll try to make sure to bear in mind that most people apparently apply the term to the first two, thanks. UnderEducatedGeezer (talk) 04:18, 11 March 2016 (UTC)
- Oh, you are very welcome and I'm glad I could help. A lot of what underlies what I said comes from the work of Sir Bernard Katz and his collaborators, who demonstrated that the more synaptic vesicles released presynaptically, the larger the graded potential postsynaptically. More synaptic vesicles of one neurotransmitter, proportionately bigger graded potential. --Tryptofish (talk) 21:21, 11 March 2016 (UTC)
- @Tryptofish:I have to confess that I still think that the term 'graded' should fundamentally refer to any even single input signal (my option #3), because both the variant input strength of a signal (#1) and the number of inputs (#2), each able to cause a sometimes stronger or sometimes weaker signal to reach an axon hillock, are both situational causes, whereas the degrading of any, even single, input, degrades fundamentally, due to the electrotonic spreading of the signal's ions along the neural membrane that inevitably occurs.UnderEducatedGeezer (talk) 12:10, 30 March 2016 (UTC)
- I agree with you that this happens. Most sources that I have read do not treat it as "fundamental". That's because one does not simply consider graded potentials in terms of their summation at an axon hillock. For example, the classic original research on graded potentials was in terms of the end-plate potential. --Tryptofish (talk) 16:14, 30 March 2016 (UTC)
- @Tryptofish:I have to confess that I still think that the term 'graded' should fundamentally refer to any even single input signal (my option #3), because both the variant input strength of a signal (#1) and the number of inputs (#2), each able to cause a sometimes stronger or sometimes weaker signal to reach an axon hillock, are both situational causes, whereas the degrading of any, even single, input, degrades fundamentally, due to the electrotonic spreading of the signal's ions along the neural membrane that inevitably occurs.UnderEducatedGeezer (talk) 12:10, 30 March 2016 (UTC)
- Oh, you are very welcome and I'm glad I could help. A lot of what underlies what I said comes from the work of Sir Bernard Katz and his collaborators, who demonstrated that the more synaptic vesicles released presynaptically, the larger the graded potential postsynaptically. More synaptic vesicles of one neurotransmitter, proportionately bigger graded potential. --Tryptofish (talk) 21:21, 11 March 2016 (UTC)
- @Tryptofish:No, I don't think so, the article does make 1 & 2 clear enough, & I pretty much understood that 'graded' referred to variation, as in 'degraded', & 'graduated'; it's just that it seems to me that the fact that those two, (the number of inputs and their consequent spatial summation, and to some degree the size of an input), are somewhat given to be variant, and the fact that the signal strength, whatever it starts at, will decrease as it traverses the dendrite & particularly the soma isn't so immediately obvious, & is so important to understand, particularly with respect to temporal summation, that it 'deserves' to be labeled graded for emphasis. And I guess I continue to misunderstand and assume that the electrotonic movement of a signal down a dendrite & across the soma is alternatively named as 'graded potential', and I thought I finally understood the nature of the movement of a signal from synapse to hillock by electrotonic potential when I read & consequently visualized that the ions in a neuron spread out as they responded to an input, thus diminishing every local potential of the signal along the way (particularly in the soma). (I hope I'm not now wrong about the signal diminishing because of combo of leakage channels in dendrites & charge spread in soma!) I'll try to make sure to bear in mind that most people apparently apply the term to the first two, thanks. UnderEducatedGeezer (talk) 04:18, 11 March 2016 (UTC)
- @UnderEducatedGeezer: Actually, it's not (3) very much, but pretty much a mixture of (1) and (2), with it being mostly (2) in actual practice. The central point is that it has no single amplitude, but can be either larger or smaller, in contrast to an action potential, that is all-or-none and can have only one amplitude. So there are either action potentials or graded potentials. Should this be made clearer on the page? --Tryptofish (talk) 20:14, 10 March 2016 (UTC)
Wiki Education assignment: Bio 380 Communicating Biology[edit]
This article was the subject of a Wiki Education Foundation-supported course assignment, between 28 August 2023 and 8 December 2023. Further details are available on the course page. Student editor(s): Yeti2021 (article contribs).
— Assignment last updated by Yeti2021 (talk) 23:36, 4 October 2023 (UTC)
This article is written from a neutral point of view, has good links to related entries, and a good overall structure. As part of an educational assignment, I made the following edits to this article: 1. Rearranged sentences in the lead section to go with the flow of the remaining sections that reflect the major points. 2. Added a sentenced on how graded potentials are produced by neurotransmitters which goes along with the new section I added titled "Ligand-gated ion channels" 3. Minor changes to titles to add clarity 4. Added updated references — Preceding unsigned comment added by Yeti2021 (talk • contribs) 03:45, 21 November 2023 (UTC)