Nervous tissue

Nerve tissue is composed of crosslinked nerve cells ( neurons). In between the blood capillaries connect glial cells with neurons and other glial cells. With this related nerve cells nerve tissue is distinguishable from other types of tissue. Mainly nerve tissue in the brain to find the spinal cord and peripheral nerves, but also in the intestine ( → Enteric nervous system) and in the retina like a net connected nerve cells are present.

In the living organism the nervous tissue has the color pink to white. In the gray matter outweigh nerve cells. The white matter consists of pathways, the myelinated nerve fibers. In the white matter of the cross-linking is low.

Nerve tissue selectively conducts impulses from receptors to the effector organs. The gray matter processed, the white leads. Neural tissue in addition to muscle, epithelial and connective tissue of the four basic types of tissue.

Glial cells and neurons

Nervous tissue is composed of nerve cells ( neurons ) and glial cells. About the neurons pulses are selectively transported ( conduction ). In a gigantic network of connected neurons constantly run countless emotions on pre-marked paths at a speed of about 360 km / h The pulses branch to many other neurons converge on a few neurons or inhibit other neurons. The comparatively smaller and more abundant glial cells fulfill auxiliary tasks. Glial cells can be structurally and functionally divided into astrocytes, oligodendrocytes, Schwann cells, microglia, ependymal cells and satellite cells. Astrocytes have contact points for the bloodstream and to near and distant neurons, but unlike the neurons do not form a global network. In some sources the Glianetze be explained as a syncytium and the connections with gap junctions. The function of glia is only partially understood. At the beginning of the neuro nato mix research was considered glial cells for a pure cement substance ( glia = glue). It was later realized the protection and filter function: Glia holds required for the nerve cells biochemical environment erect, produced for the nerve function required substances disposed of interfering metabolites and fights invading microorganisms. An astrocyte -fed with his cell processes several neurons and one neuron is supplied by several astrocytes. The former creates energy dependencies. The reserves in the astrocyte are low. Consumes a lot of neuron, the other served neurons have less.

In more recent research shows that the glia in not yet known, the activity of neurons organized, the neurons follow the defined patterns of glial cells. The glia are the commands to the formation of synapses and shall interact with the neurons determines the paths, on which flow the emotions through the brain. Repeatedly used paths are solidified, unused paths are resolved. The latter is referred to as " weeding ." Neurons, which do not embed in used paths are eliminated via apoptosis. More and more it becomes clear that glia are no auxiliary cells, but organize the activity of the neurons.

At the single neuron about 20 000 synapses dock. And also Astrozytenkontakte are also anatomically visible, the PAP (peripheral astrocytic process). Many small Astrozytenkontakte form a mound at and around the synapse.

Regeneration

Avoid the age of six months in the human body, the specialized nerve cells, the cell division. During cell division, whose function would be impaired. Nerve cells are extremely specialized. Adjacent cells can not accept failure in their function. But undifferentiated neurons can continue to divide, migrate to the brain regions that fit into the existing network and learn successively. If this fails, these cells are eliminated (apoptosis).

In the peripheral nervous system nerve fibers can regrow after injury ( neurogenesis ).