Glia

Glia, also called glial cells or neuroglia, are non-neuronal cells in the central nervous system (the brain and the spinal cord) and in the peripheral nervous system that do not produce electrical impulses. The neuroglia make up more than one half the volume of neural tissue in the human body. They contribute to the maintenance of homeostasis, help form myelin, and provide support and protection for neurons. In the central nervous system, glial cells include oligodendrocytes (that produce myelin), astrocytes, ependymal cells and microglia, and in the peripheral nervous system they include Schwann cells (that produce myelin), and satellite cells.

Function

Glia have four main functions:

to structurally support neurons, holding them in place

to supply nutrients and oxygen to neurons

to insulate one neuron from another

to destroy pathogens and remove dead neurons.

They also play a role in neurotransmission and synaptic connections, and in physiological processes such as breathing. While glia were thought to outnumber neurons by a ratio of 10:1, studies using newer methods and reappraisal of historical quantitative evidence suggests an overall ratio of less than 1:1, with substantial variation between different brain tissues.

Glial cells have far more cellular diversity and functions than neurons, and can respond to and manipulate neurotransmission in multiple ways. Additionally, they can affect both the preservation and consolidation of memories.

Glia were discovered in 1856, by the pathologist Rudolf Virchow in his search for a "connective tissue" in the brain.