Endocrinology | Hypothalamus: Posterior Pituitary Connection

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

Channel: Ninja Nerd

Views: 525,776

Keywords: hypothalamus, hypothalamus-posterior pituitary connection, pituitary gland

Id: 13yGwDAvbQI

Length: 15min 12sec (912 seconds)

Published: Wed May 03 2017