Markless nerve fibers
Markless nerve fibers can be found mainly where information does not have to be passed on so quickly. For example, pain nerve fibers that transmit information about pain sensation to the brain are partially markless. This is important because, for example, there is pain that has to last a long time. In the CNS, non-markless nerve fibers are not covered at all, whereas in the PNS, the nerve fibers are partly covered with Schwann cells.
Function
A nerve fiber has the function of transmitting information that arrives at the axon hill of the nerve cell to the end buttons, which then form a synaptic connection with another nerve cell or directly with a muscle or gland cell. A nerve fiber can transmit the information from the brain to the periphery of the body, for example to the skin. In this case it is called an efferent nerve fiber.
An afferent nerve fiber, on the other hand, carries the information from the skin or organs to the brain or spinal cord, for example. To illustrate this, one must imagine that if you touch the pen and feel with your fingers, this happens via the afferent nerve fibers. This tactile information from the skin is transmitted to the brain.
On the other hand, if we want to write something with the ballpoint pen, our brain must first control the movement. This movement plan is then passed on to the efferent nerve fibers, which then transmit the information to our hand muscles. Now we can grasp the ballpoint pen and start writing.
All this happens within a few milliseconds. In order to maximize the speed of information transmission, there are particularly thick nerve fibers. These transmit information particularly fast.
The so-called Aalpha-fibers conduct information fastest with a line speed of up to 120m/sec.Thin and non-markless C-fibers conduct most slowly at a speed of less than 2m/sec. They provide information about dull feelings of pain. In addition to the thickness of the nerve fiber, the length is also a decisive criterion. There are nerves that are only a few millimeters long and therefore only have to transport the information over a very short distance. Other nerve fibers, on the other hand, can be up to one meter long and therefore have a very long distance over which the action potential and thus the information must be passed on.
