- [Voiceover] The endocrine system has glands
scattered throughout the body.
Alright, so let's look at the endocrine system
of what it really is.
Basically, just a collection of specialized cells.
All of these specialized cells are secreting hormones.
And these hormones, are being secreted
primarily into the blood.
They're called ductless glands.
So secreting into the blood,
sometimes into the fluid around cells,
that's called interstitial fluid,
or sometimes the lymph.
Think of that as part of your immune system.
Hormones themselves,
well you've probably heard of a couple of them.
Might have heard of growth hormone,
thyroid hormone.
So there's many different types of hormones,
but hormones in general
are just chemical messengers.
They're chemical messengers,
that circulate throughout the bloodstream,
and act on a specific cell in the body.
Each hormone has certain target cells.
So here's the basic idea of what the
endocrine system is.
We'll go through the major endocrine glands first,
and then at the end
we'll pick up a few of the more minor ones.
First off, pituitary gland.
Now pituitary is broken up into anterior and posterior.
Well, anterior is front, posterior is back,
but contains hormones like in the anterior side,
adremocortotropic hormone,
thyroid-stimulating hormone,
follicle-stimulating,
lutenizing hormone,
prolactin,
and growth hormone.
While the posterior side of the pituitary,
is the storing,
the antidiuretic hormone,
storing oxytocin.
The hypothalamus is found just above
the pituitary gland.
The hypothalamus,
has a whole bunch of releasing,
or inhibiting hormones.
So pretty much,
the hypothalamus,
will send a hormone to tell the pituitary gland
to release something,
or to inhibit it,
to prevent release.
Pineal gland,
a little bit further back in the brain,
produces melatonin.
Well melatonin is kinda like a sleep wake cycle.
The thyroid gland,
produces thyroxine,
calcitonin here.
Parathyroid?
Well it's just little tiny dots,
on each side of the thyroid gland.
That's your parathyroid hormone, there.
The thymus,
is found just above and in front of the heart.
Tymopoietin, thymosin are two examples.
Now the adrenal glands,
are like two separate glands in one.
You have the cortex,
which is the outside,
and you have medulla,
which is the inside.
So the adrenal gland cortex,
produces things like cortisol, aldosterone,
just a couple of examples.
The medulla, which is the inside,
produces norepinephrine,
and epinephrine.
Now in the case of epinephrine,
think of adrenaline.
Same basic idea.
You may have heard of an epipen before,
that's epinephrine.
Its meant to really get that body going.
Pancreas.
Glucagon, insulin, dealing with sugar regulation
in the blood.
And the gonads.
Obviously male versus female specific.
Female ovaries, estrogen, progesterone.
Male testes, testosterone.
Now those are going to be the major endocrine glands.
But here are a few other glands that also
are going to be having endocrine functionality.
The heart.
You think of it as cardiovascular, pumping blood,
but it actually has a hormone.
Stomach, you think of it holding food,
also contains a hormone.
Intestines, again,
also secretes hormones.
The kidneys.
Usually kidneys are filtering your blood,
creating urine.
They're also creating hormones.
So there's really quite a few different glands in the body
that create hormones.
Now these hormones,
because they're in the blood,
have access to every single cell in the body.
Once you put the hormone in the blood,
it's travelling from head,
all the way down to foot.
But the key thing is,
the hormone only acts
on it's own target cell.
So there might only be target cells
in one organ in the entire body.
That means the rest of the body,
the hormone just keeps on traveling right through.
Doesn't even stop.
Now only very specific cells
have receptors for specific hormones.
So for instance,
thyroid-stimulating hormone.
Just from the name you'd probably guess
that it's going to stimulate the thyroid,
and that's right.
That means the receptors for thyroid-stimulating hormone
are only on the thyroid gland.
But yet you can find
thyroid-stimulating hormone,
in the blood of your hands,
the blood down your feet,
because the hormone goes everywhere.
It can only act at the proper receptor.
Now we have two different control mechanisms listed here.
Endocrine and nervous.
Nervous by far is the faster response,
but endocrine, even though it's slower,
it can be pretty quick, though.
Think about how fast after a very threatening situation,
life threatening situation,
you feel that rush of adrenaline.
Well that's caused by a hormone, epinephrine.
So it can be pretty quick sometimes,
but still slower than nervous.
And both these inner systems,
interact though.
Both endocrine and nervous
have to communicate,
have to work together,
to make sure your body maintains homeostasis.
Now homeostasis is just a proper balance.
So to keep your body healthy and happy,
both the endocrine and nervous systems
must talk,
must work together,
and must keep a constant interaction.