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Why are there two types of neurones (myelinated and non-myelinated)

Hi guys, I'm just wondering why there are two types of neurones as stated in title.... shouldn't all the neurones in the body be myelinated, seeing as myelinated neurones carry impulses at faster speeds than unmyelinated neurones..?
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mrsd09
Hi the ones that are not myelinated are only found in parts of the body where fast responses are needed mainly in peripheral nervous system, the non myelinated allow for quicker impulses :smile:

Hope that helps


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Reply 2
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F1's Finest
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Original post by mrsd09
Hi the ones that are not myelinated are only found in parts of the body where fast responses are needed mainly in peripheral nervous system, the non myelinated allow for quicker impulses :smile:

Hope that helps


This was posted from The Student Room's iPhone/iPad App



But i thought that the ones that are myelinated conduct impulses faster due to the nodes on Ranvier (saltatory conduction?)
Original post by mrsd09
Hi the ones that are not myelinated are only found in parts of the body where fast responses are needed mainly in peripheral nervous system, the non myelinated allow for quicker impulses :smile:

Hope that helps


This was posted from The Student Room's iPhone/iPad App


Original post by James A
But i thought that the ones that are myelinated conduct impulses faster due to the nodes on Ranvier (saltatory conduction?)


James A is right here: myelinated neurones carry impulses quicker than non-myelinated neurones due to the Nodes of Ranvier and saltatory conduction, as the impulse 'jumps' between the Nodes of Ranvier, meaning that less of the axon membrane has to be depolarised / repolarised / hyperpolarised. :smile:
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tdx
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Original post by James A
Hi guys, I'm just wondering why there are two types of neurones as stated in title.... shouldn't all the neurones in the body be myelinated, seeing as myelinated neurones carry impulses at faster speeds than unmyelinated neurones..?


just a guess, but my thoughts are that it's due to evolution... (as most things commonly are), in some areas, where immediate responses aren't necessary or the distance the impulse travels is small, then having unmyelinated neurones wouldn't be disadvantageous, hence they stuck
Reply 5
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tdx
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this is a useful collection of videos.. keep watching next video untill the nerve ones finish (about 4/5 I think) :smile:

http://www.khanacademy.org/science/biology/v/anatomy-of-a-neuron
Reply 6
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Original post by thegodofgod
James A is right here: myelinated neurones carry impulses quicker than non-myelinated neurones due to the Nodes of Ranvier and saltatory conduction, as the impulse 'jumps' between the Nodes of Ranvier, meaning that less of the axon membrane has to be depolarised / repolarised / hyperpolarised. :smile:



Original post by tdx
this is a useful collection of videos.. keep watching next video untill the nerve ones finish (about 4/5 I think) :smile:

http://www.khanacademy.org/science/biology/v/anatomy-of-a-neuron


Cheers lads, I also realised that myelinated neurones are found in the sensory/motor neurones (because they travel long distances)

Non-myelinated neurones on the other hand are found in the brain where only short distances have to be made...

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