This content explains the physiological pathway of growth hormone (GH) release, its primary target organs, and its downstream effects, particularly through insulin-like growth factor 1 (IGF-1), on muscle, bone, and cartilage growth, as well as metabolic functions.
Mind Map
Click to expand
Click to explore the full interactive mind map • Zoom, pan, and navigate
all right Engineers what we're going to
do in this video is we're going to talk
about growth hormone so growth hormone
we discussed a little bit about um we
haven't really got to the complete
detail of it yet but we know
specifically in the hypothalamus there's
some specific hormones that are being
made right so for example if we look
here in the hypothalamus here's the
hypothalamus and the hypothalamus has a
specific nucleus situated in there
that's actually releasing this really
really really potent and Powerful
hormone and this hormone is called
growth hormone releasing hormone and if
you remember what was the growth hormone
releasing hormone do uh doing it was
actually circulating through the hypoy
portal system which is this circulatory
vascular connection between the
hypothalamus and the anterior pituitary
or we can call it the Adeno hypothesis
right so it circulates down through the
primary capillary plexus through the
intermediate hypophysial portal vein and
then out through the secondary capillary
plexus and then what it'll stimulate
what what's this actual green cell right
here called what is this green cell here
called this green cell here is actually
called a
somatrope somatotrope a somatotrope when
it responds to the growth hormone
releasing hormone will secrete out into
the bloodstream this very very very
important hormone that we're going to
spend most of our time you're talking
about and that is growth hormone so this
is actually growth hormone now real
quick ghr because it's actually being
released what's some of the secondary
triggers that can cause ghr to be
released so what are some other things
here that are causing this actual
release so you know growth hormone it's
actually stimulated by a couple
different things let's actually note
them so let's say here let's actually
number them so let's say what's
stimulating it so let's say here in this
these actual black column we're going to
say the things that are stimulating it
so one of the stimuli is actually going
to be um we could actually say high
amino acid
levels in the blood in the blood that's
one and I'll explain why that's a strong
stimulus another stimulus here is
actually going to be low glucose levels
in the blood okay so we could say hypo
glycemia right that's another word for
this low glucose in the blood another
stimulus is low fatty acid levels in the
blood okay so low fatty acids in the
blood another very very potent stimulus
of the growth hormone is going to be
exercise that's a huge one exercise is a
very strong stimulus and even we can say
certain types of healthy stressors right
so certain types of healthy
stressors okay because not all stress is
a bad thing so certain types of healthy
stressors okay these things right here
could be the very driving force to start
causing this growth hormone releasing
hormone how they could be utilizing this
mechanism by what stimulating this
nucleus here which we haven't even said
what this nucleus is this nucleus is a
very very potent nucleus and it's
actually releasing other hormones
besides growth hormone releasing hormone
so that's why it's important to know
what are the primary
stimuli um and these triggers that can
actually cause growth hormone release
well the
actual nucleus here is actually called the
the arcu
arcu
nucleus it's called the arcu nucleus
okay so this nucleus right here is
called the arcuate nucleus and again
what's stimulating it high amino acid
levels in the blood hypoglycemia
hypolipidemia EX exercise and certain
types of healthy stressors and it's
causing ghrh release which is
stimulating the somatotropes to produce
GH Okay now what's the function of
GH well growth hormone is actually going
to have a specific organ a Target organ
that it's going to go to first okay so
some of it will actually come to this
target organ some of it will actually go
into the blood triom so let's show it
bifurcating so it's like I'm going to go
this way and then the other way can
actually go and it can actually bind
right into this receptor right here so
let's say it binds into this receptor
right here so let's say here's the
growth hormone we'll draw it as a actual
green circle here let's say it's this
green circle and it binds on to this
receptor and actually this is a h
specific type of receptor um it actually
is going to activate a like kind of like
a tyrosine kinas receptor it's kind of
like a tyrosine kyes receptor and what
it does is there's a specific part
whenever growth hormone binds onto this
receptor it activates this
phosphorilation of specific types of
amino acids on this inner part of this
receptor and what it does is there's
this this enzyme that's activated here
and it's called jonis kyes but we just
actually denote it as Jack so jonis kyes
is Jack and he's the one that's
undergoing this phosphorilation right
and when Jack causes this
phosphorilation another thing that he
can do is he can phosphorate this uh
specific type of U transcription factor
and that transcription factor is actually
actually
called stat so here we got Jack this
Jack is activated and what does Jack do
so let's say here we we Square we we
kind of saw this is stat Jack actually
come over comes over here as a jonis
kyes and he can add phosphates onto stat
what is stat stand for it stands for
Signal transducer activator of
transcription so what do you think he's
going to do he's going to come in here
and he's going to bind onto a specific
sequence of DNA a gene sequence of DNA
right and when he binds onto the
specific Gene sequence it's going to
undergo transcription and it's going to
produce what mRNA then after the MRNA
it'll actually go to a what a ribosome
and then that ribosome will do what with
the protein I me with the actual Mna
it'll translate the MRNA when it
translates the MRNA it actually gets
converted into a protein and then it can
go through multiple different types of
other processes so again what is this
right here this is our
protein and it'll undergo some
modifications in the rough VR and the
GOI but eventually it'll be pushed out
into the
circulation what is this protein that we
actually secreted this protein is
actually going to be
called insulin
like growth factor so we got insulin
like growth factor type
one okay so it's making insulin like
growth factor type one okay why am I
mentioning this because I showed you
here right growth hormones kind of
making a little detour here so let's say
you know he's he's he has this little
fork in the road here so what's this
fork in the road right so he has a
little Fork on the road and he's some of
him is actually going to go this way so
a certain percentage of him is actually
going going to go into the bloodstream
and go exert its effects on target
organs some percentage of them is
actually going to go over here on the
liver and activate what's called this
Jack stat Pathway to lead to the
production of insulin like growth
factors okay what's going to happen now
so let's say here we have our growth
hormone let's focus on the effects of
insulin light growth factor
first okay insulin light growth factor
can do a lot of different things okay
one of the big things he's going to do
is he's actually going to go and promote
a lot of protein synthesis how so you
see this muscle cell right here what
he's going to do is he's going to come
out here he's going to come out of the
bloodstream so let's say here he comes
out of the
bloodstream and he comes over here and
he binds on to this receptor right here
let's actually draw him as um let's draw
him as green again let's say he's the
green molecule right so let say here we
have insulin light growth factor one he
binds onto this receptor present on the
muscle cells skeletal muscle right what
does he do he activates specific
signaling Pathways so he'll activate
specific signaling Pathways and let's
say inside here the muscle cell here's
the actual nucleus it activates specific
genes and produces specific types of
proteins and what are these proteins
going to do these proteins are going to
come over here and maybe phosphorate or
do some specific type of mechanisms to
these channels right here these green
channels guess what these green channels
are for they're for amino
acids what do we say was really high in
the blood in order for the stimulus to
occur we said that there was elevated
levels of amino
amino
acids well what are we going to do with
these amino acids well growth hormone is
stimulating what he's stimulating these
channels to open and guess who these
channels are specific for amino acids
and guess what's going to happen with
these amino acids they're going to get
taken into this muscle cell another
thing that's going to do is this isn't
the only pathway it can stimulate it can
stimulate another pathway it's going to
stimulate another pathway here which is
it's going to take these amino acids and
it's going to convert these amino
acids and cause them to get linked up
and when it links up a lot of these amino
amino
acids it's going to link these amino
acids together and produce what's called
proteins so what are we going to get out
of this we're also going to get proteins
and what kind of proteins could be many
many different types of proteins it
might be proteins that are going to be
like myofibrils like actin and myosin
and other different types of
cytoskeletal proteins and what is that
going to do to the overall size of the
muscle it's going to increase the muscle
size right so what's the overall result
of this The increased amino acid uptake
and increased protein synthesis can lead to
to
increase muscle size right so might te
lead to hypertrophy of the muscles so
it's going to increase the overall
muscle size and muscle function that's
that's a beautiful thing there there
okay so it's going to stimulate amino
acid uptake and increase protein
synthesis which can increase the muscle
size and function that's one thing that
this guy can do what's another thing you
can do so let's say that I take a look
here at the bone so let's say insulite
growth factor comes over here also okay
so Insite growth factor also decides
okay I'm going to come through this way
also so I'm going to come through here
and I'm going to exert my effects on
some specific parts of the bone all
right so what was this insulite growth
factor doing it was coming over here
here and on the bone you know you have a
bunch of different cells within the bone
what are these cells that we're going to
focus on specifically in the bone
there's going to be what's called
called
class what this actual growth I'm sorry
this insulin light growth factor is
going to do is it's going to be able to
work to regulate the activity of these
two cells so what it's actually going to
do is it's going going to be weird it's
actually going to increase the activity
of both of these cells so it's going to
increase osteoblastic activity and it's
going to increase osteoclastic activity
so it's going to increase bone
deposition and Bone resorption and
what's the overall result it's going to
play a very very crucial role within
bone growth but it also we could
actually even be more specific within
the bone not only does it increase
osteoplastic activity and increase
osteoplastic activity is it plays a very
endochondral
oifc okay so it plays a very very
important role with Endo condr
acific so one of the things that you're
going to see out of this is that there's
going to be an increase in like the bone
mass right so the Bone's going to be a
little bit thicker it's going to be
bigger you're going to have this an
increased endochondral oifc process
another thing that it's going to do
what's other components of the bone it's
also going to stimulate protein
synthesis what is it going to stimulate
the protein synthesis of what's the type
of collagen that's present inside of our
bone collagen type one okay so you can
actually have a lot of collagen type one
in here so let's say here we can
actually put here in red we're going to
have a lot of collagen production and
again what type of collagen is actually
being produced here collagen type one so
we're going to be producing a lot of
collagen type one so that's going to
increase okay so that's that part so
what's the process of bone uh working on
the bone it's going to increase the
collagen type one it's going to increase
osteoblastic activity it's going to
increase osteoclastic activity but
they're going to be highly regulated
which is going to enhance the endoc
condr oifc response what's another thing
that this is actually going to do
there's not just that proteins you know
there's other things there's what's
called proteoglycans so it's going to
increase the production of what's called
proteo glycans and these are also
extremely important in bone also okay so
let's just remember that overall in the
bone what's the overall effect in the
bone it's going to increase the overall
production of type 1 collagen increase
proteoglycans highly regulate and
increase the activity of both of your
osteoclast and osteoblast to where they
okay let's say here again we have the
bone and then what part of the bone are
we looking at specifically for this part
here we're looking at the what is this
part here this is called the epiphysial
plates right so this is your epiphysial
plates okay because you have your
diaphysis then you have your epiphyses
and this is the epiphysial plate here on
the ends what is this insulin like
growth factor doing here insulin like
growth factor one is also acting on on
this right here what is it doing here
you know what's actually going to be
some of the main cells inside of this is
actually cartilage here you're going to
have a lot of condra sites so you're
going to have a lot of condr sites guess
what this actual insulin like growth
factor is going to be doing to these
condra sites it's going to be increasing the
the
differentiation the size the hypertrophy
proliferation of all of these condra
sites so what is it doing it's
increasing the let's actually write this
down what is it doing it's increasing the
differentiation okay it's increasing the
size okay and it's in it's causing
increase in
proliferation why are we doing this
because you know what's called
interstitial growth you have what's called
called inter
inter
stitial growth of the bone right where
it's increasing in in length because you
have appositional which is increasing in
width and you have interal which is
increasing in length what growth hormone
is doing is it's causing these actual
condra sites or condra blasts really to
start proliferating right so they start
proliferating well actually they get
bigger in size they hypertrophy all
right so they get bigger in size they
start proliferating excessively and then
what happens is these layers let's say
here's this is this is the part of the
bone down here let's say down here is
the bone and up here is the part of the bone
bone
right what's going to happen is there's
actually going to be osteoblasts which
are going to be chasing this cartilage
right so as we continue to keep
proliferating these guys and getting
them bigger and bigger and
hypertrophying and stuff like that down
here is where they're differentiating so
this is actually going to get turned
into bone and Bone and to bone into bone
so what is it helping the actual bone to
do to increase in length so it enhances
the interstitial growth right at the
epiphysial plates so it's increasing the
actual condr blasts proliferation their
hypertrophy they're increasing in size
and also it's causing them to
differentiate into certain types of bone
tissue okay so what do we have here for
cartilage it's increasing interstitial
growth what is it doing for bone it's
increasing the osteoblastic activity
osteoclastic activity which is enhancing
the endochondral oifc response is making
more proteins like collagen type 1 more
proteoglycans which is being able to
increase the actual density of the bone
and helping to have more thick bones
right and then what else is it doing
here in the muscle it's increasing amino
acid uptake into the muscle cells and
it's activating genes to uh trigger the
protein synthesis process okay now that
we've done that we've looked at the
effects of insulin like growth factor
one it's causing a lot of effects
specifically on the bones the muscles
and the
cartilage now it also does have some
extraskeletal effects but let's look at
the growth hormone real quick you know
growth hormone he loves to act on the
liver so he also has other you know not
only does he actually work through this
Pathway to stimulate the production of
insulin like growth factor one but you
know he also can act let's actually show
it over here here this is also going to
act to be able to do some specific
process what is this process that he's
also going to stimulate here he can also
stimulate what's called gluco
gluco
neo genesis what's the overall effect of
glucon neogenesis it helps to be able to
increase the blood glucose levels how
are you making this glucose from
non-carbohydrate sources where's those
non-carbohydrate sources coming from
let's let's track this growth hormone
all the way over here to the adapost
tissue so this is our adapost tissue
right here
right this is the atopos what this
growth hormone is going to do is it's
going to bind on to these receptors here
right so here's a receptor here here's a
receptor here what's it going to do it's
going to trigger this intracellular
mechanism right activating an enzyme
called hormone sensitive lipase what's
that hormone sensitive lipase going to
do the hormone sensitive lipase is going
to act as that cutter we talked about
right it's going to start breaking down
what this actual triglycerides when it
starts breaking down these triglycerides
here it's going to break down the
triglycerides into two components what
are those two components one of the
glycerol what's the other component that
we're actually going to make out of it fatty
fatty
acids right so we're making two
components out of this what's that
glycerol actually going to be good for
it's actually going to be good for the
process of gluconeogenesis we actually
use that in order to make glucose so
that's one of the things that growth
hormone can do is it can come over here
act on adapost tissue and increase this
process right here which is called what
is this process called when you break
down triglycerides into glycerol fatty
acids it's
called lipolysis right then what happens
the breakdown products of lipolysis like
glycerol can actually be used in the
liver to make glucose that's called
gluconeogenesis right we said before
that odd chain fatty acids sometimes odd
chain fatty acids can some of them can
also get converted into glucose uh for
glucogenesis but we're like we're saying
here we're going to stick primarily with
talking about uh specifically just the
glycerol for this case but just if you
want to know for your own personal
interest yes odd chain fatty acids can
be converted into
glucose but this is the mechanism that
we're going to talk about so again
glycerol to glucon glucose via
gluconeogenesis is one of the effects of
growth hormone lipolysis is a lipolysis
is an effect of growth hormone also okay
and growth hormone can also activate
amino acid uptake also so we could also
say here if we show with this blue
representing the growth hormone he could
also act on that receptor to increase
the amino acid uptake into the muscle
cells okay so now that we've done that
let's just go over really quickly here
on this board
what's the overall effects of growth
hormone and what's the overall effects
of insulin like growth factor insulin
like growth factor
one and then growth
hormone let's write down their effects
real quick so he was doing what he was
stimulating the muscles right so he was
acting on the muscles he was acting on the
the
bones he was acting on the
cartilage he can also do certain types
of metabolic functions as well but we're
going to stick to this what was he doing
in the muscles he was working working to
be able to do what
increase amino acid
acid
uptake and he also increased protein
synthesis right so he's helping with the
muscle growth right so the muscle
hypertrophy and the muscle growth what
is it doing for the bones doing a lot of
stuff right increasing Osteo I'm going
to put OB for osteoblastic activity it
was also increasing osteoclastic
activity it was increasing collagen type
one production
okay so collagen type one you know how
you can actually remember how collagen
type 1 is actually the main collagen in
the bone you know how you spell bone b o
n e look one okay so collagen type one
is the type of collagen in the bone okay
so collagen type one another thing is
actually going to be besides collagen
type one we also said it could be increased
increased
proteoglycans right so a lot of stuff
like that and then the increase in
osteoblastic and Osteo classtic activity
assisted in what's called Endo condal
oifc okay we're going to put growth
hormone obviously to the left
now all right
now we talk about cartilage what is it
going to do for cartilage we already
said for cartilage it was going to
increase the proliferation right so it's
going to increase the proliferation of
the uh condra blast of the condra
blast it was going to increase the size
blast we said that it was also going to
increase the
differentiation right so in other words
the condra blast would be converted into
specifically um it would actually be
converted the cartilage the tissue would
eventually be converted into bone tissue
so cartilage would eventually get
converted into bone tissue so
differentiation of ctil like we'll say
the condr sites or the condr blast right
so the
condro blast
So eventually this would actually lead
into bone tissue right and what's the
overall result of this an overall result
was an increase in the interstitial growth
interstitial growth which increases the
length of the bone so we could say with
this would increase the length of bone
all right what do we say was the effect
of growth
hormone what we said the effect of
growth hormone was on the
liver and it was on the atap
POS and it was also on the muscles what
is it doing it's working on the liver to
be able to increase what's called gluco neo
neo
genesis it's also working on the liver
to increase the insulin like growth
production it's also going to act on the
atopos tissue and when it works on the
atap post tissue it enhances what's called
called
lipolysis and it's also going to work on
the muscle tissue and in the muscle
tissue it's going to help to be able to
Click on any text or timestamp to jump to that moment in the video
Share:
Most transcripts ready in under 5 seconds
One-Click Copy125+ LanguagesSearch ContentJump to Timestamps
Paste YouTube URL
Enter any YouTube video link to get the full transcript
Transcript Extraction Form
Most transcripts ready in under 5 seconds
Get Our Chrome Extension
Get transcripts instantly without leaving YouTube. Install our Chrome extension for one-click access to any video's transcript directly on the watch page.
