NEURITE

definition

In this picture you can see the extensions of the nerve cell (dendrites), the axon with axon mound and a neurite surrounded by a myelin sheath with Ranvier rings (from top to bottom).

A neurite is the term used to describe the cell extension of a nerve cell through which electrical impulses are conducted into its environment. If the neurite is also surrounded by "glial cells" that isolate it, one speaks of an axon.

Function and structure

A neurite is the extension of a nerve cell and conducts its action potentials into the environment. You can think of it as the connecting cable between two computers, where the computers are the nerve cells. So that the transmission between the nerve cells is accelerated, "leap“The electrical impulses that it conducts at certain intervals. Although it is often already isolated by a layer of fat for faster transmission (the so-called myelin sheath, which is produced by the Schwann cells is formed). However, that alone is not enough to achieve the fast impulse line speed of up to 400 km / h (!).

At a distance of 0.2 - 1.5 mm there are also so-called "Ranvier rings" on the neurite, which interrupt the myelin sheath. Between these "jumps“The electrical signal is literally removed, which results in a strong increase in speed.

A neuron usually has only one neurite as an appendage, neurons with two neurites are called bipolar nerve cells designated. The neurite usually ends at another nerve cell, more precisely: at a synapse. There the electrical signal which it conducts is converted into a chemical one and can be amplified or inhibited on the way to the next cell.

A neurite encased in a myelin sheath is also known as an axon, and these can be up to half a meter long, such as in the spinal cord, but also only a few millimeters long.

multiple sclerosis

A well-known disease that its Origin in the nervous system has is the multiple sclerosis. The neurite becomes better isolation and faster signal transmission usually through a Myelin sheath isolated. In multiple sclerosis, this layer of fat gets through for reasons that are not yet clear chronic inflammatory processes destroyed. Hence the name "Demyelinating disease“.

Over time you can Transmitting nerve impulses progressively worse and slower become, leading to the typical symptoms of a MS leads. The decline of the myelin sheath is also visible radiologically and part of the diagnosis.

The MS is currently not curable, but also Well treatable for decades.

Read more on the subject here multiple sclerosis.