0:08 all engers what we're going to do in
0:10 this video is we're going to talk about
0:12 the hypothalamic and the pituitary axis
0:14 so if you look here at this diagram
0:16 first off let's kind of get some Anatomy
0:18 straightforward here if you look I'm
0:21 taking a piece of the hypothalamus in
0:23 the pituitary gland out of this overall
0:24 diagram here so if you look here I have
0:27 the cerebrum right or the tlon then I
0:31 have the cerebellum midbrain pwn medulla
0:34 spinal cord right what I'm doing is I'm
0:36 taking this piece out right here where
0:37 the hypothalamus and the mammilary
0:39 bodies in the infundibulum and the
0:41 posterior and anterior pituitary gland
0:44 are and we're zooming in on it so again
0:46 this whole chunk of gray matter right
0:47 here is the
0:50 hypothalamus this stalk part here that's
0:51 connecting the hypothalamus to the
0:54 actual pituitary gland is called the
0:57 infundibulum and then again back here is
0:59 going to be the poster pituitary gland
1:01 they also call the neuro hypothesis and
1:03 this one right here is going to be the
1:06 anterior pituitary gland or the adino
1:08 hypothesis all right first off before we
1:10 even get into anything real quick I want
1:12 to make sure that we understand where
1:14 this is actually situated so you know
1:16 this area right here there's a there's a
1:17 bunch of nuclear that are actually kind
1:20 of clustered together here hypothalamus
1:21 then you have What's called the thalamus
1:23 right there and then right back here
1:25 you're actually going to have another
1:27 part of it which is going to be the
1:28 epithalamus which is made up of the
1:31 pineal gland and the habenula and
1:33 habenular commiss and stri medular whole
1:34 bunch of different structures here that
1:38 are making up the diyon so he is the
1:40 hypothalamus is a bunch of gry matter
1:43 nuclei situated anterior to the thalamus
1:45 right anterior and a little bit inferior
1:47 to the thalamus so now we know where the
1:50 hypothalamus is and again the pituitary
1:53 gland is hanging from the hypothalamus
1:56 connected by the infundibulum one more
1:56 thing and then we're going to go ahead
1:59 and Dive Right In if I were to zoom in a
2:01 little bit bit more over here real
2:03 quickly I'm going to say here's the hypothalamus
2:04 hypothalamus
2:06 infundibulum I'm going to draw two
2:08 components here one is actually going to
2:11 be the poster pituitary gland the other
2:13 one I'm going to draw in blue this is
2:15 going to be the anter pituitary gland
2:18 now why am I talking about this really
2:19 quickly and why did I draw out another
2:22 color the poster pituitary gland the one
2:25 in black here that's actually going to
2:27 also be called the neural hypothesis
2:30 it's made up of neural tissue okay they
2:33 also call pites right so again it's made
2:35 up of nervous tissue this blue part
2:37 right here the anterior pituitary or the
2:40 Adeno hypothesis is made up of a
2:42 glandular cuboidal likee epithelial
2:44 tissue and it actually comes from the
2:46 actual ferx so it comes from the mucosa
2:49 of the ferx it's actually derived from a
2:56 Keys
2:58 pouch okay so it actually is derived
3:01 from the actual FX and it actually buds
3:03 off from the ferx and actually combines
3:05 with the posterior pituitary to
3:08 collectively form the anterior posterior
3:11 pituitary gland or together we call the
3:12 pituitary gland or another name for the
3:16 pituitary gland is the hypothesis okay
3:18 so now that we got that straight that's
3:19 good so again we know that the anterior
3:20 pituitary is glandular cuboidal
3:23 epithelia tissue derived from the ferx
3:25 Via what's called wrath Keys pouch and
3:28 we know that the poster pituitary gland
3:30 is actually neural tissue it's made up
3:32 of py so it's not really even considered
3:35 to be um a separate type of gland it's
3:36 not really considered to be an endocrine
3:38 gland it's actually a part of the actual
3:41 brain if you think about it okay now
3:42 that we've done that let's go ahead and
3:45 dive in let's first focus on the poster
3:46 pituitary gland and their hormones and
3:47 then we'll look at the anterior
3:49 pituitary so up here in the hypothalamus
3:52 there's some specific nuclei what is a
3:55 nuclei nuclei are going to be a group of
3:58 cell bodies right so in other words this
3:59 is the cell body here and you might have
4:02 dendrites coming off of it right so the
4:04 group of cell bodies collectively
4:05 together is called a nucleus in the
4:08 central nervous system and then there's
4:10 what's called attract and a tract is a
4:13 bundle of axons grouped together in the
4:16 central nervous system so in the
4:18 hypothalamus I have a bunch of nuclei
4:20 situated all over the hypothalamus we're
4:22 going to focus on very few of them we're
4:23 going to focus on this one specifically
4:26 first so what is this blue nucleus
4:29 called this blue nucleus is actually
4:32 called the Supra
4:35 Supra optic
4:37 optic
4:40 nucleus so it's called the supera optic
4:43 nucleus so the super optic nucleus is is
4:44 again a group of cell bodies
4:47 collectively joined together in a
4:49 specific area which is
4:50 unmyelinated and it's actually going to
4:53 be gray matter this is called the super
4:56 optic nucleus what does the super optic
4:59 nucleus do it makes a specific hormone
5:00 and and that hormone is actually going
5:03 to be carried down this what is this
5:05 this axon right here it's traveled down
5:08 the axon is transported down the axon by
5:10 specific types of motor proteins and as
5:12 you transport the actual vesicles down
5:14 here is these little vesicles containing
5:16 the specific hormone that's already been
5:19 pre-synthesized we're just Wai waiting
5:21 for a stimulus to release it that
5:24 hormone is called the anti dtic hormone
5:26 so okay now that we know we're going to
5:28 secrete what hormone are we making here
5:37 diuretic
5:40 hormone also referred to as short-handed as
5:42 as
5:44 ADH sometimes they even call it another
5:46 name I'll write that one down to it's
5:47 also called Vaso
5:49 Vaso
5:51 pressin so sometimes they also call it
5:54 vasopressin so again super optic nucleus
5:56 is secreting a specific hormone called
5:59 the anti dtic hormone but we said it's
6:00 already been presynthesized it's already
6:02 formed and sitting in these little
6:05 synaptic vesicles what triggers this
6:08 super optic nucleus to produce Action
6:10 potentials that move down the axon and
6:13 Trigger the release of this hormone
6:15 okay one big thing that actually can
6:18 trigger this effect here is is actually
6:22 going to be low blood volume so one of
6:24 the big ones is actually going to be low
6:27 blood volume all right so one big thing
6:29 is going to be low blood volume and if
6:33 you you have low blood volume what else
6:34 does that actually correlate with it
6:36 correlates with low blood pressure
6:39 because volume is a direct indicator of
6:41 pressure so low blood pressure will be a
6:44 very strong stimulus of these super
6:48 optic nucleus here okay what else
6:52 another big big big one is the plasma
6:56 osmolality okay so another one is the
6:59 plasma osmolality and specifically for
7:03 this one high plasma osmolality High plasma
7:06 plasma
7:08 osmolality so what does this mean by
7:11 high plasma osmolality well osmolality
7:13 is referring to basically the
7:15 concentration of solute inside of the
7:17 plasma and water so it's the
7:19 concentration of certain types of
7:21 electrolytes and solutes and water
7:23 inside of our blood plasma the higher
7:26 the plasma osmolality the less water
7:29 there is the more hypertonic it is the
7:32 lower the plasma osmolality what's that
7:33 mean that means that it's actually going
7:36 to be hypotonic so if it's again if it's
7:38 high plasma osmolality that means that
7:40 there's a lot of solutes very little
7:42 water it's hypertonic if it's a low
7:44 plasma osmolality what does that mean
7:46 that means that there's a lot of water
7:48 and less solutes so if there's a high
7:50 plasma osmolality that means that
7:51 there's very
7:54 little low
7:57 water High
8:00 solutes okay
8:02 this super optic nucleus actually has
8:04 specific things called osmo receptors
8:06 that are situated around it we're not
8:08 going to talk about those they that's be
8:11 called the subicular organ and the organ
8:13 vasculosum of lamin terminalis they're
8:15 basically osmo receptors that pick up
8:18 the plasma osmolality whenever it's high
8:19 it's going to stimulate this guy to send
8:22 action potentials down and release ADH
8:23 one other stimulus that's another
8:26 important one is also pain so pain also
8:29 has the ab ability to activate
8:32 the production of anttic hormone now
8:34 once we've produced this anttic hormone
8:35 it's going to go and exert its effects
8:37 on two different Target organs that
8:39 we'll talk about individually in another
8:42 video okay but again one more time pain
8:44 can stimulate the super optic nucleus
8:46 low blood pressure or low blood volume
8:49 and a high plasma osmolality which means
8:51 low water high amounts of solutes right
8:53 and who can pick up that change in
8:55 osmolality The osmo receptors like the
8:58 subicular organ or the Organo vascul
9:00 vasculosum of laminat terminalis and
9:03 where stimulated it sends the action
9:06 potentials down the axon and sends this
9:09 actual release of anttic hormone out all
9:10 right and then it's going to go affect
9:13 its Target organs what can inhibit so we
9:15 know it stimulates it what can inhibit
9:17 it one thing that can inhibit it is the
9:20 opposite effect so if you have what high
9:22 blood pressure if you have low plasma
9:25 osmolality what else is another really
9:28 big one alcohol so another really really
9:32 big effector of this is alcohol alcohol
9:37 actually has a inhibitory effect on ADH
9:38 okay so it has an inhibitory effect on
9:40 ADH and again what other things could
9:42 have an effect here like I said it could
9:45 be high blood pressure so I put High BP
9:49 or low plasma osmolality which I'm
9:51 denoting here as po
9:55 okay so again high blood pressure low
9:57 plasma osmolality and alcohol are some
10:00 very strong Inhibitors of anttic hormone
10:01 okay now that we've done that let's move
10:04 on to the next one what is this nucleus
10:06 that's situated right here called this
10:08 one is called the
10:11 the par
10:17 ventricular
10:19 nucleus okay so what is this one called
10:20 here this is called the par of
10:22 ventricular nucleus and both of these
10:23 are actually PA of ventricular nuclei
10:26 this one is and this one is so again
10:28 this these two could actually be having
10:30 their axons combined so I could actually
10:31 draw from this guy I could actually say
10:33 that these two axons are actually
10:36 combining here and when they combine
10:37 they form again what's that called
10:40 attract okay so these two guys could be
10:42 combining here all right so the
10:44 paraventricular nucleus it has these
10:45 axons that extend all the way from the
10:47 hypothalamus to the actual posterior
10:49 pituitary and it releases a very very
10:51 specific hormone in response that
10:53 because same thing like ADH the hormones
10:55 are stored in the synaptic vesicles in
10:57 the axon terminal so they're already
10:58 pre-formed and synthesized we just need
11:01 to stick stimulus to cause the release
11:02 so again what's this hormone that's
11:11 oxytocin okay so we call it oxytocin so
11:14 oxytocin is a very very important
11:15 hormone that again we'll talk about its
11:17 effects in an individual video and all
11:19 of its T Target organs but let's just
11:23 say what stimulates his release he
11:25 stimulated he stimulates these neurons
11:27 here so let's say what stimulates this
11:30 guy here so what stimulates here let's
11:32 actually do this in green so we can see
11:34 it here so let's say we have here what
11:37 stimulates this nucleus what's a
11:40 stimulator of that nucleus a stimulator
11:42 of this nucleus is usually going to be
11:45 the birthing process so one big thing is
11:48 the birthing process and like I said
11:49 I'll explain this in more detail when we
11:51 talk about in individual video so the
11:53 birthing process is a really really big
11:56 one another really big effector of it is
12:00 actually going to be suckling
12:02 so when the baby is actually suckling on
12:04 the mother's uh mammory glands or
12:05 specifically the areola it's actually
12:08 suckling on the nipple it can activate
12:10 specific receptors that will send the
12:12 actual release of oxytocin another thing
12:14 is actually going to be for the male
12:16 sexual ejaculation response so it's also
12:18 responsible for
12:21 ejaculation so all of these things are
12:26 very very strong stimulators of oxytocin
12:27 and again what are they the birthing
12:30 process suckling and ejaculation again
12:32 we'll talk about these in more detail
12:33 but again what happens stimulates the
12:35 par of ventricular nucleus he sends
12:38 Action potentials down calcium rushes in
12:40 and stimulates the release of oxytocin
12:42 so again posterior pituitary hormones are
12:44 are oxytocin
12:45 oxytocin
12:48 and anttic hormone are also called baso
12:50 press all right now that we've done that
12:52 for the Post tier pituitary let's go
12:54 ahead and look at the actual hormones
12:55 released by the anti pituitary in a
12:57 deeper way so over here you're going to
12:58 notice what do I have here I have I have
13:01 a nice vascul I have a blood vessel a
13:03 blood vessel connection a vascular
13:06 connection between who between the
13:08 hypothalamus and the anterior pituitary
13:11 gland whereas over here in the posterior
13:12 pituitary what was connecting the
13:15 hypothalamus to the posterior pituitary
13:17 these axons so there's a neural
13:20 connection now we need to Define what is
13:22 this neural connection right here that's
13:24 extending all the way from the
13:27 hypothalamus to the
13:31 actual posterior pituitary what is this
13:33 neural connection called this neural
13:35 connection is called the
13:48 fical
13:49 tract okay so let's define that again
13:51 let's basically work these words out
13:53 hypothalamic it's coming from the
13:55 hypothalamus to the hypothal what does
13:58 that mean the hypothesis hypothesis is
14:00 another word for the toer gland right so
14:03 it's going from hypothalamic hypohyal
14:05 it's a tract what is a tract it's a
14:07 bundle of axons in the central nervous
14:10 system so again this connection that's
14:11 connecting the hypothalamus to the
14:13 posterior pituitary gland is called a
14:15 hypothalamic hypop faial tract which is
14:17 a nerve connection all right whereas
14:20 over here if you notice this part of the
14:22 there's like a capillary bed on this
14:24 side there'll be a capillary bed down on
14:26 this side and there's a portal vein
14:29 connecting it we say by definition
14:31 whenever there's two capillary beds
14:33 connected in series between an
14:35 intermediate portal vein this is called
14:37 a portal system well it's a portal
14:40 system for what the hypothesis so this
14:42 right here is called the what's this
14:44 portal system here called This is called the
14:46 the hypo
14:49 hypo fisal
14:51 fisal portal
14:53 portal
14:56 system and again what is the hypop hypop
14:59 faal portal system it is again going to
15:01 be two capillary beds this is the
15:03 primary capillary plexus this one down
15:05 here is the secondary capillary plexus
15:07 and they're connected in series through
15:09 an intermediate portal vein and what's
15:10 that portal vein called the hypop fesial
