Friday, May 12, 2006

Physical Properties of the Nerve Fibers

Each of the three types of nerve fibers that are in the Vagus nerve have different physical characteristics. The primary differences are in the diameter of the nerve and the presence of myeline. Large diameter nerves transmit signals faster. Nerves with a "coating" of myelin transmit signals faster.

Fiber Types:
- myelinated
- largest diameter axon (5 - 20 micrometers)
- fastest nerve impulse transmission (27 - 280 mph)
- myelinated
- axon diameter is smaller than A fibers (2 - 3 micrometers)
- slower impulse transmission than A fiber (32 mph)
- unmyelinated
- smallest axon diameter (0.5 - 1.5 micrometers)
- slowest impulse transmission (1 - 4 mph)

So... does any of this matter? Not so much. It is enough to understand that the different types of fibers control different types of organs. It is belived that the C-Fibers in the Vagus nerve are responsible for controlling slow things, like the heart. A-Fibers most likely control things like the voice box. B-Fibers... well, I have not come accross research on the B-Fibers (if anyone has any, pls let me know).

Here is the important part: It takes drasticly different VNS settings in order to activate the different types of nerve fibers and cause them to send signals...

You will have to wait till tommorow to learn about that... yes, I can tell the anticipation is killing you. ;)

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