Glial cells are accessories cells in the nervous system.
So these are not neurons per se
but think of them more as helper cells.
There are gonna be different types
of helper cells in different areas of the body.
So if we look at the peripheral nervous system,
we have something like Schwann cells.
Schwann cells wrap around axons
and form these myelination.
Satellite cells also available in
the peripheral nervous system.
These are primarily in ganglia.
And they help to regulate the
chemical environment of the ganglia.
If we look at the enteric nervous system,
Remember, this is the nervous system
around the GI tract and the gut.
You also have enteric nervous cell, gluteal cells.
These act very much like the satellite cells
and there in ganglia primarily
and they have a number of functions
including regulating the chemical environment.
The central nervous system is more complex.
It’s the brain. It’s the spinal cord.
You know that this is going to be
even more tightly regulated.
Having more tightly regulated something,
you need to have more different service neurons around.
So the first few of these service neurons have to do with
very specific functions in places like the retina,
in white matter, in gray matter, and they involve a lot
of things like nutrient delivery and repair processes.
You also have other ones that help build new neurons.
This is involves synaptic plasticity
to be able to link up various nervous projections.
Once you reach things like oligodendrocytes,
these act a lot like the Schwann cells
did in the peripheral nervous system.
It involves myelination around various axons.
You have microglia that help respond to trauma events,
such as if the cerebral nervous system was damage.
And finally, you have various specialized cells that will
allow for the formation of cerebral spinal fluid.
These ependymal cells are located
along some portions of the ventricles.
And what actually make cerebral spinal fluid
and brain extracellular fluid
that bades all the different cells in the brain.
So let’s talk through ependymal cells and how these
process of cerebral spinal fluid formation occurs.
Astrocytes, and how they help
regulate in terminal environments?
Astrocytes are going to be important processes
to sometimes recycle neurotransmitters.
And what I mean by that, is you have a normal axon
that releases a quanta of neurotransmitter.
And what do you do with that
neurotransmitter once it’s been released?
It often times is broken down into something else.
But, is that axon terminal going
to be able to reabsorb it?
Or does something else surround it help clean it up
and then move it back to the spot
that it needs to be, to be released again?
In this case, astrocytes can serve this function
of helping to clean up a neurotransmitter,
change in it back into its active form, and then
delivering it back to the nerve to be released again.
This example that we have here is about glutamate.
Glutamate is released from post-synaptic nerve terminals.
It is taken up by astrocytes.
You convert to glutamate back into glutamine.
and then you transport glutamine to that axon terminal.
This process allows for the recycling of this neurotransmitter.
So astrocytes do have this capability
of helping to not only deliver nutrients,
to do things like repair processes but even
participate in helping to recycle neurotransmitters.