- What are the glial cells?
- What function do the glial cells have?
- Where are the glial cells?
- What problems can the glial cells cause?
glial cells or Neuroglia cells form the cellular tissue in the nervous system of the brain. They differ in their structure and function from the other cells in the brain. Glial cells not only form the supporting tissue for the nerve cells, they are also involved in their diet and in the forwarding of information. Read all about the different forms of glial cells such as astrocytes and oligodendrocytes, their tasks and possible diseases.
What are the glial cells?
The glial cells are the cellular tissue that fills the space between the nerve cells of the brain and the blood vessels down to a small gap and which also forms the medullary sheaths around the nerve fibers. The name Glia is derived from the Greek word for glue, because the first assumption in the study of these cells was that they only served as a supportive function for the nerve tissue - the nerve cells would only hold together. Meanwhile, it is known that the glial cells are much more. They separate the nerve tissue from the brain surface and the blood vessels.
There are several types of glial cells in the nervous tissue of the brain, including:
- Astrocytes or astroglia (stellate cells with radial projections): belong to the macroglia (large-celled glia) and form the largest part of the glial cells. Are found mainly in the gray matter of the brain.
- Oligodendrocytes (small, only slightly branched cells): also belong to the macroglia. Found in the gray and white matter of the brain tissue.
- Schwann cells: surround the nerve fibers and form their medullary sheath.
- Microglial cells: have only short processes. Can move in the tissue and absorb foreign bodies and enzymatically digest (phagocytosis).
What function do the glial cells have?
The glial cells create the conditions for the working capacity of the nerve cells. On the one hand they fulfill a supporting function for the nervous tissue of the brain, on the other hand they are also important for its nutrition.
Another function of glial cells is phagocytosis - the uptake of particles into the interior of the cell for food intake or the elimination of foreign bodies.
The transmission of information between the nerve cells is also influenced and guided by the glial cells. During embryonic development of the brain, its growth is structured by the glial cells. When the brain is fully grown, these cells ensure that the environment around the nerve cells and nerve fibers (axons) always remains the same. They regulate the pH, the electrolyte concentration (especially of potassium) and form the sheaths around the axons of the neurons.
Market sheaths are like the insulating layer of an electrical cable. They greatly accelerate the transmission of electrical impulses. Oligodendrocytes form the medullary sheaths in the central nervous system (CNS: brain and spinal cord), Schwann cells form those in the peripheral nervous system.
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Where are the glial cells?
The glial cells are located throughout the brain and fill the space between the nerve cells and the blood vessels. Their numbers are much higher than those of the nerve cells in the brain.
What problems can the glial cells cause?
On glioma is the most common malignant brain tumor. It is formed from glial cells of the nervous tissue. Depending on which type of glial cells the tumor emerges, one distinguishes between different forms:
Astrocytoma (especially in a front brain), a glioblastoma (the most frequent, in all cerebral lobes, subcortical and also in a cerebral cortex), an oligodendroglioma (in hemispheres), an oligoastrocytoma and mixed tumors. An optic glioma forms on the optic nerve, a ponsglioma on the brainstem. All tumors share an uncontrolled proliferation of cells.
Ganglia and Schwann cells may be the outcome of a ganglioglioma, a rare, benign brain tumor.
An epileptic seizure is triggered by massive hyperactivity of the nerve cells of the brain. This overactivity significantly increases the potassium concentration in the extracellular space, because the glial cells can no longer cope with the strong increase and catch it.