Is there an optimal lenght for myelin sheats to be effective and lead potential across the nerve cell? This has always bugged me.
1 Answer
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The nodes of Ranvier (the gaps between myelin sheath segments) speed up the action potential because the electric current can jump from node to node (or gap to gap). If the myelin covered the entire axon, the signal wouldn't have the gaps to speed up the signal. As for optimal length, the gap is 1μm long, but can be longer, on the order of millimeters depending on the type of cell. The length of the myelin doesn't matter so much as the length of the nodes of Ranvier because they are where the Na+/K+ channels are found so the ion exchange can occur. This is how an action potetial can occur, so the myelin not covering the entire axon is crucial for the ability of neurons to propagate a signal.
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$\begingroup$ Yeah I wanted to know if there was an optimal lenght for myelin coverage. I was thinking that probably with a too long myelin cover the jump of potential couldnt occur. Is that right? $\endgroup$– LivNov 16, 2017 at 14:34
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$\begingroup$ Yes, so longer myelin as in a longer distance between nodes, would likely affect the efficiency of the current jumping from node to node . $\endgroup$– KelseyNov 16, 2017 at 19:21
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$\begingroup$ Can you link me to some original research paper or review about this particular topic? I couldnt be able to find anything about. Probably I'm using the wrong keywords. $\endgroup$– LivNov 17, 2017 at 7:38
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1$\begingroup$ jnnp.bmj.com/content/40/8/769.short This paper talks about it! :) $\endgroup$– KelseyNov 17, 2017 at 20:31