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So we are going to talk about brain tumors.
But before we talk about brain tumors, let's talk about the basics of cancer.
In cancer there is a primary tumor.
So let's say that you have a, a tumor in your colon.
That means that a colon cell is dividing, and dividing,
and dividing, and instead of stopping, it keeps on dividing.
It becomes immortal.
It's just going to divide without any limits.
And because it keeps on dividing, it keeps on growing, it gets bigger and bigger.
And if that's all that were going to happen, that would
be okay, because we'd go in, and we'd take it out.
But that's not all that happens.
What happens in cancer is that, that one of those cells decides to
go rogue, or few of those cells decide to go rogue and they travel some place else.
And then they start a new tumor elsewhere.
So they metastasize.
They spread.
So, the cell that or tumor starts in the colon, and then
a few cells float off to some other place, and now all of
a sudden, you've got tumors that are in your bones, or tumors
that are in your lungs, and maybe even a tumor in your brain.
Same thing with breast cancer or lung cancer,
it starts in one place, it starts in
the breast or it starts in the lung, but from there it can spread to other organs.
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So, one source of brain tumors is metastasis spreads from
other or, from other tumors, so for instance lung tumors.
The metastasis are a problem and actually the brain tumors are a problem because
they exist within the cranium, and the cranium is a fixed, bony container.
It can't expand.
And as a tumor expands, the, the cranium is not going to expand.
It's going to increase the pressure and we're going to have a problem.
Okay, so besides having tumors that spread from other
organs, what are the other sources of brain tumors?
Well, one of the very consistent things about neurons is that they don't divide.
They are what's called, they are, they are at the end of their line.
They have no descendants.
Once a neuron is born, it lives and it dies and when it dies, that's the end.
It doesn't, it cannot replace itself, and, and that's the end.
So neurons don't make tumors because they don't divide
at all, and they don't get into this uncontrolled division.
So what makes tumors?
Well, it's other cell types within the brain.
And the primary one that does this are glial cells.
So glial cells don't have the limits on division that neurons do.
So, glial cells can divide and make these tumors.
And and so, glials, gliomas, tumors of glial
cells, are the most common type of brain tumor.
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is the type that comes from a division
of meningeal cells, and these are called meningiomas.
Remember that we have the pia, the arachnoid, and the dura.
These are meningeal cells that cover the brain and if they start to divide
once again they're going to make a space-occupying
tumor that's going to increase pressure within the skull.
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And finally, the other major type of brain tumor
is are tumors that come from glandular cells.
Now, you might think, well, the glandular cells, I've
got glands here, and I've got glands under my armpit.
I've got glands at various places.
But do I really have glands in my head?
Well, it turns out you have two glands in your head.
One is right here, and that one is called the pineal gland.
You may have heard it, heard of it, because it makes melatonin.
Melatonin might help you sleep.
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And this, these glandular cells are not neurons.
They're, they're gland cells, and they can
become, they can divide without, without control.
The other, gland that we have in our head is, is one that sits right here.
It's not actually on this picture, but it's called the pituitary,
and these pituitary cells can also divide and that's called pituitary adenomas.
These pituitary adenomas are fairly common.
They account for about 10 to 25% of inter-cranial tumors.
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Okay, so bottom line is, brain tumors are a problem because they take up space.
Brain tumors are not tumors of neurons, they're
tumors of glial cells, meningeal cells, or glandular
cells, or they are metastasis spread from other
organs such as the colon or the lung.
Peggy MasonProfessor
