Neuroglia: The Little Heroes of the Nervous System

When you hear the term "brain cells", what first comes to mind? Neurons, of course! Well, turns out there are so many other types of cells in your nervous system that have critical roles. Which ones, you ask?

NEUROGLIA! The little heroes of the nervous system!

Of course, neurons play a crucial role in the nervous system. But the functions carried out by the nervous system could not be achieved without neuroglia. The glial cells provide support, nutrition insulation and help with signal transmission. In the central nervous system, the four main types of glial cells are the astrocytes, microglia, ependymal cells and oligodendrocytes.

Astrocytes come from Greek for "star cell", given the name for its star-shaped appearance underneath a microscope. Astrocytes form the cellular glial scars, control the release of ions, form the blood-brain barrier and clear out neurotransmitters from the synapses.

Microglia ("small glue") are specialized macrophages capable of phagocytosis that defend the central nervous system from invading microorganisms. Microglia can display components of debris to other immune cells. These antigens will help other immune cells recognize these invaders.

Ependymal cells create, secrete and circulate cerebrospinal fluid in the spinal cord and brain ventricles.

Oligodendrocytes produce an insulating barrier called the myelin sheath around the axons of neurons in the central nervous system. The myelin sheath increases the speed of signal transmission by wrapping around the axon several times and thus insulating the axon.

In the peripheral nervous system, there are two main types of glial cells: satellite cells and Schwann cells.

Satellite cells surround and support cell bodies in the PNS.

Schwann cells produce an insulation barrier similar to the one formed by oligodendrocytes, but instead found in the peripheral nervous system. However, Schwann cells can form only one segment of myelin, unlike oligodendrocytes which can wrap their processes many times around the axons of several neurons.

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