Download Glial Cells

Glial Cells
This is a brain. It's grayish, whiteish, and a little bit squishy. It's got a lot of stuff in it, ranging from
the renowned neurons and blood vessels to a special, lesser known assortment of cells called glia. A
human brain is made 65% of glia, and on average, a mammal has 5-10 glia for every neuron.
In the nervous system, there
are glial cells galore. But, what do they do, exactly? The answer is this—a lot.
Glia is really an umbrella term for cells in the nervous system that maintain homeostasis as well as
myelinate, protect, and support neurons. Whether you call them neuroglia, glial cells, or glia, these
cells do everything that neurons can't do for themselves. While neurons are the stars of the show
always in the spotlight, glial cells are their stage crew. The central nervous system and the
peripheral nervous system have a multitude of glia that help the neurons function properly, but
because we don't have much time, we'll just talk about a few of the most prevalent glial cells in the
nervous system.
Firstly, we have microglia. Microglia are specialized macrophages that are capable of phagocytosis.
Basically, they're the nurses of the central nervous system as they constantly check on neurons,
other macroglia, and blood vessels- and eat up infectious agents. Smaller compared to most other
types of glia, microglia have oval nuclei and are usually shifty little things that can change shapes,
but they're important in protecting the nervous system from infection..
Then, we also have astrocytes which are a specific type of macroglia. They're called astrocytes
because they sort of look like stars. Essentially, astrocytes act as the police and garbagemen of the
brain and spinal cord. Not only are they a main component of the blood-brain barrier, but they also
regulate the chemical environment, recycle neurotransmitters, digest dead neuron parts, and anchor
neurons to their blood supply. Astrocytes are the most abundant of glial cells.
Lastly, we have our oligodendrocytes and Schwann cells. Although they have different shapes and
are located in different parts of the nervous system, oligodendrocytes and Schwann cells do
basically the same thing- wrap around and myelinate the axons of neurons to form the nodes
of Ranvier, increasing nerve conduction. Still, there are several differences between these two
types of glia. One - that the oligodendrocytes function in the central nervous system whereas
Schwann cells reside in the peripheral nervous system. And two- oligodendrocytes are also able to
myelinate more than one neuron but Schwann cells can only cover one.
So as you can see, these adorable little glial cells are quite integral to the functioning of the nervous
system and especially the brain. The entirety of their influence is probably most prevalent when
things go wrong. Although microglia are helpful in removing diseased brain cells, they can produce
cytokines that can damage neurons during Alzheimer's disease.
malfunctioning glial cells may contribute to the neurodegeneration of dopamine-producing cells, in
turn leading to Parkinson's disease. But problems with glia are not only associated with
neurodegenerative disorders. Post mortem studies have shown that depression and bipolar disorder
may be linked to reduced glial size and density in the brain. Even chronic pain has been linked to
overactive astrocytes and microglia in the brain and spinal cord.
Now, we can clearly see that glial cells deserve to share the spotlight with our friends the neurons
who seem to push the glia off to the side of the stage. It's strange how glia do just as much for the
brain as neurons do, but the public almost never hears about them. Today, researchers continue to
investigate the functioning of these lesser known neuroglia to better understand the nervous system
because a firmer grasp on how glial cells work would facilitate our struggle to understand the full
capacity and inner workings of the brain.