Astrocytes: Definition, Function & Types

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson is going to define the term astrocyte. You'll learn what the two main types of astrocytes are and the many functions of astrocytes in general.


Astro-nomy. Astro-physics. Astro-naut. All those well-known words have a prefix of 'astro-', which means star or star-shaped. And this same exact prefix can be found in the word astrocyte, where the suffix of '-cyte' refers to a cell. So what do you think the word astrocyte means literally? Astrocyte means a star-shaped cell. More specifically, these are non-neuronal cells of the nervous system that help to support the neurons (nerve cells).

Let's find out more about the different types of astrocytes and what they do.


There are two main types of astrocytes. The first of them is known as the fibrous astrocyte. Fibrous astrocytes are astrocytes that are mainly found in the white matter of the nervous system. However, some can be found in the gray matter, such as in the thalamus of people. The second major kind is the protoplasmic astrocyte. Protoplasmic astrocytes are mainly found in the gray matter of the nervous system.

Astrocyte (green).
Astrocyte (green).


Astrocytes have numerous functions. If our central nervous system were a city, then some astrocytes work in the public water department. That's because that department is responsible for ensuring that water gets to its citizens in an appropriate manner through the pipes. Well, the central nervous system has pipes of its own, blood vessels, and the astrocytes help regulate the flow of blood through these vessels.

Other astrocytes work in the communication department of our city. This is because they ensure that the spaces between neurons, called synapses, are maintained at optimal levels for the transmission of biochemical information. So astrocytes help to maintain and regulate synapses, and thus, the way our brain cells communicate with one another.

Other astrocytes work in the food and energy department of the city. Why? It's because their job is to take up sugar from blood vessels and store it. Then, when the nerve cells need it, astrocytes can release various nutrients that can be used by the nerve cells for the production of energy. So astrocytes store and release sources of nutrition for the nervous system, especially when the city is starving, so to speak. In other words, when hypoglycemia, or low blood sugar, occurs.

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