Adrenal Gland (Adrenal Cortex) Explained Clearly

By Adem Lewis / in , , , , , , , , , , , , , , , , , , , , , , , , , , /

well welcome to another MedCram video
we’re going to talk about the adrenal cortex today and the first thing we’ve
got to learn about is the anatomy general cortex is part of the adrenal
gland which sits right on top of the kidney and you know you’ve got two
kidneys one on each side of your body and right above the kidney is this
little triangular shaped organ called the adrenal gland and it’s got two areas
it’s got a medulla which is in the middle and it’s got a cortex and that’s
what we’re going to talk about today is this cortex this outer portion of the
adrenal gland so let’s zoom in a little bit on that and talk about it okay so
the adrenal cortex is a big triangle if you will and we’re just going to sort of
ignore the middle portion which is the medulla the adrenal cortex is divided
into three layers there’s the outer layer okay and then there’s an inner
layer and the part that gets left over is the middle layer so there’s three
layers basically and those three layers of course has a name and the first layer
the or the outermost layer is known as the zona glomerulosa the middle layer is the zona gesticulate
and the last layer is the zona reticularis so from outer to inner it’s
G F R it’s nice way to remember it zona glomerulosa zona fasciculata zona
reticularis we’ll talk about each of these three layers the other thing I
want to that I want you to know is the type of hormones which is what the
adrenal cortex secretes what type of hormones they secrete they secrete
steroid hormones and that’s important to know that because there are some
hormones that are proteins or peptides so why is it important to know that this
secretes steroid hormones you can take a look at the structure of the type of
hormone that it secretes they’re all derived from cholesterol and the reason
why that’s important is because these hormones are a lipid soluble because
there are steroid now because of that they’re able to go in through the cell
into the cell’s nucleus now why is that important it’s because these hormones
affect transcription of proteins in the nucleus and that causes proteins to be
made that can then be exported now why that why that’s important is because
normally when you have hormones that are proteins those proteins that are
secreted into the blood will hit a receptor on the surface of the cell
which will cause something to happen almost immediately so proteins protein
hormones cause changes that happen very quickly whereas steroid hormones which
is what we’re going to talk about here cause changes that will happen slowly
more slowly maybe over days or even longer because these hormones actually
go into your cell’s nucleus they cause transcription of different
proteins which takes a long time as you recall you have to have transcription
then it goes to the rough endoplasmic reticulum Golgi apparatus and then gets
exported so we’ll talk a little bit more about that so if you remember our three
layers we’ll just call them here the zona glomerulosa the zona reticularis and the zona actually zona fasciculata and the zona
reticularis now if you’re actually to look at this linearly take a slice of
the adrenal cortex you would see that the bulk of the general cortex is
actually made up of the zona fasciculata about 10% up here and the other 10% down
here okay so the fascicular da makes it the major portion so what are the major
hormones that are coming out of this the major hormone out of the zona
glomerulus or sorry the zona glomerulosa is aldosterone we’ll talk about that
the major hormone out of the zona fasciculata is cortisol and the major
hormone coming out of the zona reticularis are androgens the biggest
one is testosterone okay so aldosterone is what’s known as eye mineral corticoid
and cortisol is what’s known as a glucocorticoid okay
so there you have it so the zona glomerulosa makes mineral corticoids
specifically aldosterone the zona fasciculata makes glucocorticoids mainly
cortisol and the zona reticularis makes androgens primarily testosterone the way
I like to look at and this kind of brings up a nice point here with
problems with these and we’ll talk a little bit all G in a little bit but let
me sort of talk about what these do so what does aldosterone do aldosterone
works primarily at the distal convoluted tubules so it’s right there and what does it do
there it causes reabsorption of sodium and dumping of potassium and protons
that’s what it does what does glucocorticoids do or a cortisol
cortisol basically is a hormone that signals to the body that we need to
increase glucose without cortisol you would be dead basically you need to have
cortisol it just sort of makes the whole body run smoothly one of the primary
functions is to increase glucose in the body and it can do that through
gluconeogenesis or glyco general lysis ok androgens
what do androgens do basically it’s the male secondary characteristics it’s also
responsible for sex drive in women this is in fact woman’s only source of
androgens is from the adrenal cortex so knowing these things knowing these
functions and remember these are steroids so they’re going to go into the
cells so how would aldosterone work
aldosterone would be secreted from the zona glomerulosa it would then go over
to the distal convoluted tubule cells it would go into their nuclei and tell the
nuclei to make little sodium potassium pumps that would then be exported to the
surface again these are steroid hormones so what’s telling this this organ to do
all of this well the major one is what’s stimulating the zona
glomerulosa to make aldosterone it’s potassium high potassium so high
potassium tells the zona glomerulosa to make aldosterone
and that’s what happens what’s stimulating this a substance called ACTH
ACTH is a peptide or a amino acid protein hormone that is secreted from
the pituitary okay it also there’s also a little fragment that is made as well
that has as part of it and this become important later something called
melanocytes stimulating hormone we’ll talk about that in a little bit that’s
nothing really need to know too much about at this point what stimulates this
again ACTH okay and there’s a negative
feedback inhibition so ACTH stimulates the oculata and ACTH also stimulates the
reticularis to make androgens and cortisol if for some reason this is not
doing its job you’re going to get more ACTH why is that because cortisol is
going to back feed on AC th to reduce it and androgens the same way on ACTH
obviously if aldosterone is causing the potassium levels to go too low it’s
going to also negatively feedback on it okay so we’ll talk a little bit more
about that in a little bit okay so let’s just review again we’ve got the adrenal
cortex okay it’s made of three layers and we know what they are from the
outside and it’s G F R we know it stimulates the outer layer the thing
that stimulates the outer layer is potassium okay and what does the outer
layer make it makes aldosterone which works at the distal
convoluted tubules of the nephron the inner layer the fascicular de is
stimulated by AC th and the outer end sorry that middle layer that fascicular
lotta is going to make cortisol and the inner layer is also stimulated by ACTH
and it makes testosterone okay now if there’s a problem let’s let’s say that
we could have a problem here with the adrenal gland let’s say the adrenal
glands not working what would it look like say none of the layers are working
since there’s no aldosterone we can’t dump potassium so you would see that
potassium by the way this is called Addison’s disease so in Addison’s
disease this is where you have no adrenal glands working you would see what you would see an
increase in potassium because aldosterone is not working
what else does aldosterone do it causes dumping of protons so you would have a
metabolic acidosis okay because you’re going to not be able to dump that and
you’re also not going to be able to reabsorb sodium so your sodium would be
low what else would you see your cortisol levels not going to be working
so you’re going to see decrease glucose and especially in stressful situations
where you need glucose to do flight and fight you’re not going to have it and
then finally lack of testosterone which really doesn’t cause that much of a
problem at least acutely so what are you going to see in Addison’s disease
hyperkalemia metabolic acidosis hyponatremia and hypoglycemia and you
also see because of that low sodium you’re going to have low blood pressure
that’s the big problem let’s go to the other side what happens if you have too
much of this going on well you could have that from something called
Cushing’s now it’s called Cushing’s syndrome if and sorry this Cushing’s
disease and there’s Cushing’s syndrome what’s the difference between the two
well Cushing’s syndrome would be from any cause Cushing’s disease would be if
there is too much ACTH from the pituitary so disease is if there’s too
much a cth syndrome would be just too much steroids maybe you’re getting
exogenously like someone’s giving a cortisol or prednisone so what are you
get to see there based on this you’re getting a lot of aldosterone so you
could see a low potassium you could see a low proton that would be a metabolic
alkalosis and you would also see an increased sodium which would mean
increase in your blood pressure what about a cortisol you have a lot of
cortisol so you’d also get high or glycaemia as well and you also get a
lot of testosterone so you get secondary male sexual characteristics as well okay
so this is the highs and the lows of it if also because of that if you had a lot
of this stuff function and guess what your ACTH would be it should be low if
you’re not dealing with a Cushing’s disease if you’re dealing with the
Cushing’s syndrome but if in fact the pituitary is over secreting ACTH then
that would cause everything to be working over time and that would give
you these syndromes that I was talking about before
alright so join me for part two of our med cram lecture on the adrenal cortex

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