Adrenal Gland (Adrenal Cortex) Anatomy, Physiology, Disorders, and Hormones
28
September

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 renal 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 vesicular de 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 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
that this secretes steroid hormones you could 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
tear 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 and the plastic 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 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 acicular da about 10 percent 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 a
mineral corticoid and cortisol is what’s known as a glucocorticoid 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 with ology 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 okay 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 that’s what does glucocorticoids do or 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 okay 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
Marielle OSA it would then go over to the distal convoluted tubule
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 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 there’s also a little fragment that is made as well
that has as part of it and it’s 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 vesicular de and ACTH also stimulates the reticularis to make
androgens and cortisol if for some reason this is not doing its job you’re
gonna get more ACTH why is that because cortisol is going to back feed on ACTH
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 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 tubule of the nephron the
inner layer the fascicular de is stimulated by ACTH and the outer and
sorry that middle layer that fascicular da is gonna 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 I say the gentleman is 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 gonna see decrease glucose
especially in stressful situations where you need glucose to do flight and fight
you’re not gonna 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 gonna see in Addison’s disease hyperkalemia metabolic acidosis
hyponatremia and hypoglycemia and you also see because of that low sodium
you’re gonna 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 while 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
ACTH syndrome would be just too much steroids maybe you’re getting it
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 hyperglycemia 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 a ACTH then that would
cause everything to be working overtime 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 you


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