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