Would we have super reflexes if we had a myelin sheath that could run down our entire axon?

Question

Instead of having the nodes of Ranvier why can't we just have a myelin sheath which speeds up communication between neurons by 20X

Answer 1

Hey, I dont think anyone above has answered your question properly, so heres mine! :) As mentioned before, the myelin sheath is an insulator, and prevents the move of ions across the membrane. Therefore if we had a myelin sheath running down the whole axon you would completely prevent ionic flow, and you would effectively disable the neuron. The reason myelin sheaths work is because the rate limiting step in impulse propagation is the speed at which ionic channels can open on the membrane. At the nodes of ranvier, these ion channels (for sodium) are concentrated, therefore you get a burst of current which quickly diffuses intracellularly to the next node of ranvier. This diffusion chain reaction is much faster than waiting for a string of ion channels to open which locally has a smaller ionic flow.

Now, an interesting thought is what would happen if the nodes of ranvier were further spaced apart, and the ion channels were more concentrated at these locations. Well for there to be any kind of super fast conduction you would have to have a LOT of potential ionic flow extracellularly. I think at this high a concentration, the environment for the neuron would just be too much stress osmotically for the neuron to function as a cell (as apposed to a conducting 'wire'). I think neurons have got it nicely balanced, not too much stress, but fast enough not to get us killed when we walk out onto the road and see a car coming. lol

Nice thought, keep up that inquisitive mind of yours. You'll make a good scientist

Answer 2

Myelinated sheaths don't "speed up" electrical impulses from the brain, they focus them. Myelin is a type of cholesterol produced by specialized neuroglia to prevent the electrical signal running along the neurons from branching off, insulation. Certain lengths of nerve are myelinated for a reason, like along the optic nerve. Besides, the reflexes wouldn't improve all that much, muscles and movements have their own limitations, and reflexes are nearly automatic as it is.

Answer 3

Myelin sheaths slow down impulses, but stop them dissipating out of the sides of the cell. Reflexes generally travel along one nerve cell to to spine, and out again, using saltatory conduction. This would not be possible with total myelination. So, no, we would not have super reflexes. Reflexes are possible because we don't have a total myelin sheath.

Answer 4

In developing mice, the proteins Dlg1 and PTEN were involved in calling a halt to insulation during early development. The balance between not enough and too much myelin insulation is controlled by opposing signals, which together optimize both the myelination and the velocity of nerve conduction.

Answer 5

the nodes of ranvier are what is integral to the entire saltatory conduction....they are the "jumping points" of the charge that propogates down the axon...without them the charge would just dissipate before reaching the output region...

Answer 6

Dammit why in the HELL couldn't we all have ESP then we could react BEFORE we needed to!!

Answer 7

THE ONLY THING THAT WILL HELP IS TO ATTACH A FRAMIS TO YOUR GRIPPLE...WORKS EVERY TIME....