NBME 23 Increase in axonal capacitance (NBME Answers)

NBME 23 Answers ↦

nbme23/Block 2/Question#16 (reveal difficulty score)
Which of the following best explains impaired ...
Increase in axonal capacitance🔍,📺
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+18
submitted by ∗seagull(1718),

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"yhw o'tnd yuo tspo thaw 'ryoeu gndio bceeasu 'tsi cliorsu"u.id c-al-tau arnews

+9
submitted by ∗mcl(631),

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In sace yuo naawn go ureps nedr nad daer butao i,mleny enataccaip,c adn sctr,ieaesn shti yug sdeo a doog obj.

nwinkelmann This really helped me, at least the pictures did. Here's my interpretation of the pictures in not super scientific terms: capacitance is like the "capaciy" to keep ions close to the membrane. Myelin puts a barrier between the ions in the conductive environment (ECF or ICF) and the nerve membrane. The higher the capacitance, the closer the ions are to the membrane, so it's like the charge effect is "more potent" so harder to change the membrane potentia, whereas if the ions are farther from the membrane, the charge effect is "less potent" so easier to change the membrane potential and thus easier to depolarize. Thus, with myelin, there is decreased capacity of the ions to be close to the membrane, so in demyelinating conditions, the ions can be really close to the membrane, i.e. higher capacitance. +24

sweetmed this helped a lot! +

roaaaj Well explained! +

euchromatin69 or see u world 917 same concept +1

brise Uworld 1318*** +4

Incase you can't read (like myself), Khan explains this super well in 5mins (at 2x speed) https://www.khanacademy.org/science/health-and-medicine/nervous-system-and-sensory-infor/neuron-membrane-potentials-topic/v/effects-of-axon-diameter-and-myelination

+7/- donttrustmyanswers(65),

+4
submitted by ∗visualninjacontender(17),

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e-imt nnt=tsaco aisneRestc x nteCpicaaac ol wr-e temi tcaostnn = sreaft uticnnoocd e -nyiml oreslw ccniptecaaa - yrbhtee woreingl mtei tnocsnta nad ciiasnrgen ondniccuto sdpee l(wore tiapccya rof neorun to dlho recagh yma olwal teh ehcagr to "mp"uj ofrm odne to dnoe - I amy be gnaikm ttah alts atrp pu tbu that is ohw I tnurddsena ti)

+2
submitted by ∗sympathetikey(1472),

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S:uoecr einM/iywplsg/pkd:ot/iwin.kea/he.rtii

"eimyln edseps teh rasoistnmnis fo reteliaccl umpilses cldeal ncaoit inetapstlo lanog ydealtiemn osaxn by gsntluaiin teh onxa adn endrcgiu axaoln meemnbar entciccaaap"

littletreetrunk I think this makes total sense, but how does it not ALSO stop fast axonal transport? +4

laminin axonal transport is transport of organelles bidirectionally along the axon in the cytoplasm since myelin is on the outside of the axon demyelination doesn't affect this process. source: https://en.wikipedia.org/wiki/Axonal_transport "Axonal transport, also called axoplasmic transport or axoplasmic flow, is a cellular process responsible for movement of mitochondria, lipids, synaptic vesicles, proteins, and other cell parts to and from a neuron's cell body, through the cytoplasm of its axon." +4

yotsubato axonal transport is mediated by kinesin and dynein. Microtubule toxins like vincristine block these +3

drdoom @littletreetrunk "axonal transport" is movement of bulk goods via microtubules (which run from soma to terminus); ions, on the other hand, move in an "electrical wave" that we call an action potential! no axonal (microtubular) transport required! in other words, de-myelination will have no effect on the transport of bulk goods; but it will really mess up how fast "electrical waves" traverse the neuron! +

Do not confuse AXONAL TRANSPORT with ACTION POTENTIALS.

AXONAL TRANSPORT. The directed transport of ORGANELLES and molecules along nerve cell AXONS. Transport can be anterograde (from the cell body) or retrograde (toward the cell body).

https://meshb.nlm.nih.gov/record/ui?ui=D001370

+7/- drdoom(1026),

+1
submitted by hello36654(5),

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os hyw is incsse"tao fo sfta nlaaxo "tnarsport rowgn? t'onD lnedatiyme anso,x by ndoietiifn, evha fats decun?conatc oS eyddamnitlee oxsan wolud eahv ctieno"sas of saft noaalx tot,psrna"r ichwh si the ansewr ,A gitrh?

diabetes i think it slows down ,no cessation . +

gdupgrant Because fast axonal transport refers to the transport of vesicles containing neurotransmitters or some kind of cell product up and down microtubules in the axon. It isn't related to actual electrical signal transduction. +8