CNS / Central Nervous System
Synonyms
Brain, spinal cord, meninges
English: CNS, Central Nervous System
definition
The CNS (Central Nervous System) consists of the brain (cerebrum, encephalon) and the spinal cord (medulla spinalisIn its entirety, it is probably the most complex organ known to man.
It contains more than 100,000,000,000 (100 billion) nerve cells (Neurons) and at least twice as many special connective tissue cells (Glia).
This enormous number of cells communicate with one another in a wide variety of ways in order to guarantee that the organism can cope with its complex way of life.
As an overall product, amazing capabilities such as:
- logical thinking
- the own Awareness
- Emotions/ Feelings
- and diverse Learning processes.
Precise is also of the utmost practical importance Movement coordination of the body (Motor skills) and the associated recognition of one's own body (sensitivity) in a constantly changing environment, which is captured by sensory impressions.
All of this ultimately requires the regulation of all bodily functions in order to maintain our internal conditions (Homeostasis).
So far, no machine has succeeded in imitating the aforementioned services that we take for granted.
Communication of nerves
When one speaks of the fact that nerve cells communicate with one another, this essentially happens through the release of chemical messenger substances (transmitters, Neurotransmitters) near another Nerve cell (Neuron).
The process is similar to a simple conversation between two people. One pours out words that the other processes. Such a small functional unit is called a synapse. Most neurons have thousands of them Information interfaces (synapses) per se!
Illustration of nerve endings / synapse
- Nerve ending (Axon)
- Messenger substances, e.g. Dopamine
- other nerve endings (Dendrite)
So the incoming information (Afference) mostly on tree-like protuberances of the nerve cell (Dendrites) offset and by a leading away cell extension (Axon) to the efference!
Within a single nerve cell, the information is not transmitted through a transmitter, but rather electrically via a Current flow forwarded (Action potential).
Figure nerve cell
- Nerve cell
- Dendrite
A nerve cell has many dendrites, which act as a kind of connecting cable to other nerve cells in order to communicate with them.
Microscopic anatomy
Basically one differentiates in the CNS one gray tissue substance (Substantia grisea) of one white tissue substance (stoffia alba).
This classification relates to which part of the nerve cells in which part of the body is viewed.
They are in the gray matter Nerve cell bodies (Perikaryen, Soma), a seemingly confused mass of nerve processes (Neuropil) and above all astrocytes (connective tissue cells), which belong to the so-called glial cells.
The appendages of the annoy (Connecting lines) are often not encased in the gray matter by oligodendrocytes with their cell extensions and thus not myelenized (see Myelenization, nerve sheaths), that means they don't have a nerve sheath.
On the other hand, the white matter bundles of nerve cell fibers (Connecting lines), which are usually myelenized by oligodendrocytes, i.e. have a cervical sheath.
This is where the white substance got its name: the myelin sheath contains plenty of fats, so that it shimmers whitish and contrasts with the surrounding tissues in color.
Macroscopic anatomy
The CNS is in the area of the head by the skull bones and on the back by the Vertebral bodies protected, which form a vertebral canal inside.
It is placed in the so-called "Peripheral nervous system ” which emerges with its more or less long nerve fibers from the bony sheaths of the CNS. Both systems are functionally inseparable; the division is made for reasons of clarity.
The brain and spinal cord can in turn be broken down into numerous subunits:
the brain contains:
- Cerebrum (telencephalon)
- the diencephalon (Diencephalon)
- and on the brain stem that Midbrain (mesencephalon)
- the bridge (Pons)
- as well as the direct transition from the spinal cord to the brain, the elongated medulla (medulla oblongata).
- Behind the bridge sits the cerebellum on the brain stem (Cerebellum) on.
- After all, they are also called medulla oblongata, pons and cerebellum Hindbrain (rhombencephalon).
Illustration brain
- Cerebrum
- Cerebellum (Cerebellum)
- Spinal cord
- Pituitary gland (Pituitary gland)
The gray matter, i.e. the cell bodies (perikaryen) of the nerve cells, is in the brain, both in the cortex and in the subcortical core areas below. The subcortical nuclei form a medullary bed, which is embedded in white matter.
The spinal cord extends from the occiput to the 1st or 2nd lumbar vertebrae and experiences different characteristics during the passage in the spinal canal.
In cross-section, it reveals its internal structure: gray matter in the center, which is reminiscent of a butterfly in shape. This is surrounded at the front, back and sides by several bundles of white matter, which, depending on their location, are referred to as the front strand (funiculus anterior), side strand (funiculus lateralis) and rear strand (funiculus posterior).
It is characteristic of the CNS (Central Nervous System) that each section has cavities (inner and outer liquor spaces on the brain, only one channel in the spinal cord), which are filled with a clear, colorless liquid (liquor cerebrospinalis, "nerve water"):
The liquor (nerve water) is a well-controlled filtrate from the cells of the choroid plexus (singular choroid plexus) with several functions:
Upholstery by significantly lowering the effective weight of the brain and cushioning vibrations like a pillow.
Liquor works as a shock absorber
The brain and spinal cord swim in water (liquor = brain water) and are thus well protected against impacts.
Communication between nerve cells and in the sense of informing the nerve cells about the composition of the blood as well as the control of the environment (extracellular fluid) of nerve cells and glial cells are also part of the tasks of the CSF (Nerve water).
