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PPonte
May18-06, 12:34 PM
Some axons are wrapped in a myelin sheath formed from the plasma membranes of specialized glial cells known as Schwann cells. Schwann cells serve as supportive, nutritive, and service facilities for neurons. The gap between Schwann cells is known as the node of Ranvier, and serves as points along the neuron for generating a signal. Signals jumping from node to node travel hundreds of times faster than signals traveling along the surface of the axon. This allows your brain to communicate with your toes in a few thousandths of a second.


Would someone explain me, please, the sentence in bold?
My doubt is why signals jumping from node to node travel hundreds of times faster than signals traveling along the surface of the axon.

vitaly
May23-06, 12:42 PM
Okay, the fatty myelin sheaths that wrap around axons do not allow the sodium ions to diffuse into the neuron, thus inhibiting a neural response. But, there is a way to get around that. The gaps, or nodes of Ranvier, allow the impulse to travel hundreds of times faster because many parts of the neuron that are myelinated can be bypassed. This means that the signal literally jumps from node to node, and it is faster than having an action potential travel along the entire axon.

Does that help? If you look at a diagram of a myelinated axon, you may see it more clearly.

PPonte
May23-06, 04:12 PM
Thank you vitaly for your explanation, altough I did already understand it by information colected in a search. I should had advised, sorry.