This content explains the function, regulation, and mechanism of action of prolactin, a hormone primarily responsible for milk production (lactation) in the mammary glands.
Mind Map
Click to expand
Click to explore the full interactive mind map • Zoom, pan, and navigate
all right Ninja nerds so what we're
going to do in this video is we're going
to talk about prolactin okay so if you
guys remember from the hypothalamic
pituitary axis video we discussed what
were the stimuli and what were some of
the inhibiting factors for prolactin
we're going to get into a little bit
more detail on that and look at its
effect on target organs all right so
first off what is the function of
prolactin prolactin is designed to be
able to promote what's called lactation
right or milk production so it's working
on the actual mamory gland so if you
look here we have a mamory gland right a
mamory gland is really just a modified
aicr gland which is a type of sweat
gland right so it's a modified aicr
gland and what it's designed to do is
it's designed to be able to produce milk
if you look here at the actual mammory
gland you see these blue tube like
structures right there these are called
your lobules and your lobules are
consisting of these cells which are
called your alveolar cells and those
alveolar cells are the cells that are
making milk and we'll zoom in on one to
look at its action if you look in
between there's all this interlobar
connective tissue and then uh at the end
of the interlobar connective tissue
there's these little ligaments called
suspensories ligaments or Cooper
ligaments and they anchor the breast to
the actual posterior wall right so the
pectoralis Mage and some of the actual
tissue behind that then you got some
superficial fascia and you got these
little tubes draining these actual
glands here what are these tubes here
called these tubes are called the
lactiferous Ducks and then there's
actually a dilation of the lactiferous
ducts just behind the nipple and that's
called the lactiferous sinus and then
again here's the nipple and then there's
a little bit of areola around that okay
so that's our mamry gland and again what
does prolactin do it's going to
stimulate these alveolar glands to start
producing milk and we'll take a look at
that before we do that though let's see
what's the actual stimuli and inhibiting
factors for
prolactin okay so if we look here we
have the hypothalamus right okay and
then right here is going to be your
infundibulum and then here's your poster
pituitary and here's your anti pituitary
right we had some cells before that we
were talking about that release specific
types of chemicals right so these two
guys right here are a group of neurons
right so we're going actually going to
call these as a group here so let's say
I actually group them
together these guys are a bunch of cell
bodies that are collectively in together
in the hypothalamus they're called
nucleus now the aru nucleus is a group
of cell bodies in the central nervous
system right and what happens is their
axons come together and they actually
secrete different types of chemicals but
one of the main chemicals that we're
going to look at here is actually going
to be called
called
prolactin inhibiting hormone and over
here what would be secreted over here
prolactin inhibiting hormone now
prolactin inhibiting hormone let's
actually show that as a black dot here
so let's say there's the black dot right
there there's the black dot right there
I want to define something before I keep
going into showing this axis here I want
to say something about prolactin
inhibiting hormone I know I mentioned it
before but you know there's actually
another name that we can actually give
prolactin inhibiting hormone it's called
dopamine so dopamine is actually just
another name for prolactin inhibiting
hormone now prolactin inhibiting hormone
does what it circulates down through
this actual portal system the
hypophysial portal system right so let's
show it actually circulating down
through the hypo fisal portal system
then what happens it comes out of the
hypohyal portal system into the anterior
pituitary so when it gets out here into
the anterior pituitary look what's going
to happen the prolactin is going to come
over and it's going to act on these
different types of receptors present on
this cell what is this cell here called
lactotrope or sometimes they even call
them lact tropes right but I'm going to
put lacto
Trope what happens is this actual
prolactin inhibiting hormone is going to
act on this receptor and again what's
prolactin inhibiting hormone called it's
called dopamine it actually acts on D2
receptors but neither here nor there
what's the effect it inhibits this cell
from releasing prolactin so prolactin
won't be
released okay well that doesn't help me
how do I know what's going to stimulate
the release of prolactin okay there
there is other nuclei in the vicinity
here so there actually is other nuclei
here one of them that we can take a look at
at
here is actually called look at this guy
he's got a mouth like no other right so
what does he do he secretes certain
types of chemicals what are these
chemicals that he's secreting he's
secreting chemicals for example this one
chemical that he secretes is actually called
called
trh you might have heard of that before
remember remember that from thyroid
hormone it's called thyrotropin
releasing hormone this nucleus right
here is called the par
par ventricular
ventricular
nucleus and what does he do he secretes
thyrotropin releasing hormone guess what
thyrotropin releasing hormone does it
can actually circulate down through the
hypo fical portal system and then it can
come out right it can come out here into
the anti pituitary and it can bind on to
some specific receptors present on this
actual lactotrope and look it binds onto
the lactotrope and guess what kind of
signals it gives to this lactotrope it
gives stimulatory signals okay that's another
another
thing other things that can actually
trigger this pathway besides thyrotropin
releasing hormone because we need to
know all the things that are stimulatory
and all the things that are inhibitory
so again what's this inhibitory one here
this black dot right here this is
Prolactin inhibiting hormone and once
this red dot right here this is called
thyrotropin releasing hormone he's one
of the types of prolactin releasing
hormones what are some other things that
can stimulate this prolactin release
okay so let's show him he's giving the
stimulatory signal and now look what
this guy's going to do he's going to
start uh undergoing some specific type
of transcription and translation and
look what he's going to produce out of
this he's going to produce Pro lactin
the hormone that we care about right so
TR is stimulating this path way what are
some other things that can stimulate
prolactin production because we need to
know those you know females they they
usually have a lot of estrogen right so
they make a lot of estrogen where do you
make estrogen from you make it from the
ovaries right so when the estrogen is
produced during the actual uh pregnancy
process and even actually during the
birthing process and after the birthing
process what happens is estrogen levels
are extremely important for prolactin
production so what does it do estrogen
can actually
stimulate prolactin production but you
know what else it can do it can come
over here and act on these neurons right
here you know the arcu nucleus it
actually can come over here and look
what it can
do it actually can inhibit the arcu
nucleus from producing prolactin
inhibiting hormone so what happens if
you produce very little prolactin
inhibiting hormone little prolactin
inhibiting hormone is going to have less
of a negative effect on this lactotrope
and that's going to start producing
prolactin so there's two stimulate
effects of estrogen one is it's going to
stimulate prolactin production directly
as well as inhibit the release of
dopamine okay there's other things that
can also do this too I'm just going to
mention uh one more and that is
breastfeeding okay because there's a lot
of things that we could mention here but
we're just going to mention the most
significant and the most important ones
so breastfeeding also has a direct
stimulus on prolactin production okay so
whenever there's the suckling of the
baby it can act activate mechano
receptors and that can trigger the
production of oxytocin but it also can
stimulate the production of so it also
where else could it work here the
what the pair of ventricular nucleus to
release more thyrotropin releasing
hormone more thyrotropin releasing
hormone will actually stimulate this
lactotrope to make more prolactin okay
now we got that now so we know what
stimulates the release of prolactin we
know what inhibits the releas of
prolactin inhibit inhibitory dopamine
stimulatory is estrogen breastfeeding
and thyroid troping releasing hormone
we're done okay let's come over here to
the mammory gland in the mamory gland
like we said there's a whole bunch of
alveolar cells over here and these
alveolar cells are the ones that are
making the milk what we're going to do
is we're going to zoom in on an alveolar
cell and take a deeper look at how prolactin
prolactin
works okay so if we look over here
prolactin is actually circulating in the
blood now so let's say here this Green
Dot right here is actually going to be
prolactin and prolactin is being
transported in the bloodstream right and
what happens is this prolactin so again
what is this chemical here called called
prolactin what will happen is Prolactin
will act on these alveolar cells which
are part of your mammory glands within
your lobules right what is it going to
do it's going to act on these receptors
because this is an alveolar cell so
again what is this cell here called This
is an
Alvar cell and it's one of the
components of the lobules right so this
is a component of the
lobules now what happens prolactin comes
out of the bloodstream and activates
some specific receptors that are present
on this alviar cell we're not going to
go into detail on it just remember we'll
cover this when we talked about the
receptor pathway but it activates what's
called jonis kinas which is a jack which
then activates what's called stat and
Stat is a signal transducer that
activates transcription transcription
for what multiple different types of
things so what is this going to activate
it's going to activate genes to make
mRNA and that mRNA is then going to get
what translated into proteins via the
ribosomes and what are these proteins
going to do they can do so many
different things some of these proteins
might be milk proteins so for example we
might actually do what we might actually
excrete these proteins out into the
Lumen what kind of proteins could this
be this could be things like casine this
could be things like lacto Farin lot of
different types of proteins right what
else can it do you know these proteins
can also come over here and maybe
phosphorate specific types of channels
what type of channels maybe channels for
certain types of uh ions so maybe this
one could be for certain types of ions
so what could this one be for ions maybe
this channels for other different types
of proteins let's say that this channel
is opening up for uh other different
types of proteins so let's say that this
is like IG antibodies or other different
types of proteins
right and let's say that this one is for
uh cholesterol so let's say that this is
a pathway for cholesterol or different
types of lipids right and really they
don't need a transport receptor uh
really cholesterol and lipid soluble
substances don't really need a
transporter because they can move
through the membrane I'm just showing it
as with respect to the diagram so again
what could be brought in ions what else
could be brought in certain types of
amog globulins like IG GA and certain
types of proteins as well as cholesterol
or different types of lipids as well as
making your own proteins and then what's
going to happen all of these things are
going to get pushed out where out into
the actual Lumen right so again what's
this going to come out here IGA proteins
and other different types of things and
also a lot of lipids and cholesterol
okay all right so again what are these
chemicals that are going to be present
in Lum Lumen a lot of different types of
ions and electrolytes right what else
could be present here bunch of different
types of proteins what kind of proteins
we could have things like casine or
renin or lacto Farin right what else
could you have you could also have other
different types of proteins like IGA
antibodies or as well as plasma proteins
that you filtered out right okay what
else could you have you could also have
a lot of different types of lipids and
cholesterol right so we could also have
a lot of different types of
lipids and
cholesterol as well as vitamins there's
so many different things that are
present within the actual milk that it
would take forever to go through all of
them okay but just know that basically
that's what it's doing it's stimulating
the production of a whole bunch of
different types of proteins some of the
proteins are going to be direct milk
proteins other things are going to
activate certain types of channels or
other different types of Pathways to
bring in substances from the plasma
right like IGA antibodies or certain
types of ions or cholesterol or vitamins
or minerals all these different types of
things to provide nutrient support to
the baby
okay now that we know that we know what
what have we been able to accomplish
throughout this whole thing here we've
been able to say what is the stimulus
for prolactin production what is it what
are the three stimuli for prolactin
production so again if I were to kind of
highlight here the big ones we'd say
estrogen is a very powerful stimulus
what else did we say we also said
stimulus and what else did we say we
also said thyrotropin releasing hormone
is a very positive stimulus so all of
these things are stimulating what
prolactin production what are the things
that are inhibiting prolactin production
this would be
dopamine okay so dopamine is a very very
powerful inhibitor
of prolactin production oh one more
thing that I want to mention here and
that's going to finish up our video here
guys let's come back over here for a
second here um I remember I told you
that estrogen is a very strong
stimulator right well estrogen is a
stimulator of prolactin production but
when estrogen is produced right after
the actual birthing process the estrogen
levels drop a little bit and as the
estrogen levels drop a little bit what
happens is because normally like let's
imagine here's this receptor right
estrogen is going to work through
different types of Pathways to inhibit
the action of prolactin on this alol
cell so even though prolactin levels can
be high it won't be able to exert its
effects inside of the cell because why
the reason why this wouldn't happen is
because of extremely high estrogen
levels so with extremely high estrogen
levels it can stimulate prolactin
production but inhibit the action of
prolactin on the Alvar cells so what has
to happen is is after after the birthing
process the estrogen levels start coming
down a little bit coming down a little
bit coming down a little bit and then
what happens then prolactin can act on
the specifically the Alvar cells to
produce all the different types of
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.
