Glial

Glial cells, also known as glia, are non-neuronal cells in the central nervous system (CNS) and the peripheral nervous system (PNS). They maintain homeostasis, form myelin, and provide support and protection for neurons. In the CNS, glial cells include oligodendrocytes, astrocytes, ependymal cells, and microglia, and in the PNS, Schwann cells and satellite cells.

Function

Glial cells perform many important functions, including:

• Biochemical support of endothelial cells: Glial cells provide nutrients to nervous tissue and also play a key role in the Blood–brain barrier (BBB).
• Provision of support and insulation: Glial cells are crucial in the physical structuring of the brain. They are the glue that holds the neurons in place.
• Maintenance of homeostasis: Glial cells are responsible for maintaining the balance of ions in the extracellular environment, removing excess ions and neurotransmitters around neurons.
• Formation of myelin: In the PNS, Schwann cells wrap around the axons of neurons to form a myelin sheath. In the CNS, this job is performed by oligodendrocytes.

Types of Glial Cells

There are several types of glial cells in the CNS and PNS:

• Oligodendrocytes: These cells produce the myelin sheath in the CNS.
• Astrocytes: These are star-shaped cells that provide physical and nutritional support for neurons.
• Microglia: These cells act as the first line of immune defense in the CNS.
• Ependymal Cells: These cells line the ventricles of the brain and the central canal of the spinal cord.
• Schwann Cells: These cells produce the myelin sheath in the PNS.
• Satellite Cells: These cells provide physical support to neurons in the PNS.

Diseases Related to Glial Cells

Dysfunction or death of glial cells can cause a variety of diseases, including:

• Multiple sclerosis: This is a demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged.
• Alzheimer's disease: This is a chronic neurodegenerative disease that usually starts slowly and worsens over time. It is thought to involve an increase in the production of certain proteins by astrocytes and microglia.
• Parkinson's disease: This is a long-term degenerative disorder of the nervous system that mainly affects the motor system. The role of glial cells in its pathology is still being researched.

See Also

• Neuron
• Nervous system
• Neuroglia

Glial Resources
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