Synonyms
Medical: Neuron, ganglion cell Greek: Ganglion = node brain, CNS (central nervous system), nerves, nerve fibers
Declaration
Ganglia are nodular accumulations of nerve cell bodies outside the central nervous system (= brain and spinal cord). They therefore belong to the peripheral nervous system. A ganglion usually serves as the last switch point before the respective organs to which nerve processes are to be sent or as the first switch point for nerve processes that are to be sent from organs to the brain.
It is therefore also an intermediate switching station, where incoming impulses are not only transmitted but can also be “moderated” by other incoming signals. Accordingly, there are motor ganglia for fibers that mediate movement information, sensitive ganglia for the transmission of sensory impressions and other sensitive information (pain, tactile sensitivity, depth sensitivity) as well as vegetative ganglia serving the sympathetic and parasympathetic nervous system. General information can be found under: Ganglion of the nervous system and cell nucleus
- Dendrites
- Cell Body
- Axon
- Nucleus
A nerve cell has many dendrites, which are a kind of connecting cable to other nerve cells to communicate with them.
- Nerve cell
- Dendrite
Tasks
Most ganglia have proper names. Only the segmentally arranged ganglia such as the sensitive dorsal ganglia, which are located at the level of each vertebra in the intervertebral space, and the sympathetic ganglia of the border strand are not all given names. According to the number of extensions there are
- Pseudounipolar,
- Bipolar and
- Multipolar ganglion cells.
- Nerve ending (Axon, Neurit)
- Messenger substances, e.g. dopamine
- Other nerve ending (dendrite)
In pseudounipolar ganglion cells, the impulse-transmitting extension (axon, neurite) and the impulse-applying extension (dendrite) are directly attached to each other, so that only a single extension is visible under the microscope.
Pseudounipolar ganglion cells are found in the spinal ganglia, which transmit sensitive and sensory stimuli from the body to the spinal cord and brain. Bipolar ganglion cells have only two cell extensions: a dendrite and a neurite, which are often approximately opposite each other. Multipolar ganglion cells have, in addition to an impulse transmitting extension (axon), at least two, but usually considerably more impulse receiving extensions (dendrites), often hundreds or thousands.
They are typical for vegetative ganglia, e.g. in the sympathetic nervous system, which is active during stress. As a rule, all ganglion cells are surrounded by mantle cells (glial cells), which nourish and electrically insulate them. The spinal ganglia in particular are in close proximity to the central nervous system because they are located in the course of the posterior (sensitive) spinal nerve roots.
They are enclosed by a bulge of the spinal cord skin like a capsule. The tissue of the spinal ganglion contains the nerve cell bodies (somata) and extensions of the sensitive nerve cells, but also some blood vessels. 80% of the nerve cell bodies are large (about 100 μm) and belong to fast-conducting “mechanoreceptive” fibers, i.e. fibers that transmit mechanical influences such as pressure, tension, bending, etc. The smaller ones (20%) are mostly pain fibers.
