The Hypothalamus and Pituitary Gland - Video Tutorials & Practice Problems
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1
concept
Hypothalamus & Pituitary Gland
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As you learn about the endocrine system, almost certainly, you're gonna be responsible for the names and locations of specific glands. You're gonna need to know some of the hormones they produce and specifically what some of those hormones do in the body. So to start talking about that, we are gonna start with the hypothalamus and the pituitary gland. And we're starting here because while the endocrine system, a lot of these glands are well, they're distributed throughout the body and they kind of act on their own without any control. If there is something in control of the endocrine system, it's the hypothalamus and pituitary gland. And we'll explain how that works now. So we're gonna start just by saying that this is the connection or the link between the nervous and endocrine systems and right, the nervous system and endocrine systems. Those are your two major body communication systems. So it makes sense that there's this place that they talk to each other and understand how this works. First, we'll look at our image here. We have an image of the brain and pulled out here. We have this part of the brain, the hypothalamus. That's right. Down there and then right under the hypothalamus, we have what I always think looks like sort of this double punching bag hanging off the brain. That's the pituitary gland. All right. So we'll start talking about the hypothalamus again. The hypothalamus is part of the brain and its real main job is that it maintains homeostasis and controls autonomic, those sort of automatic functions of the body and autonomic functions. Those are largely in charge of homeostasis. But the endocrine system also is in charge of many homeostatic variables. So this is where they talk to each other. Hypothalamus is gonna measure a lot of those sort of variables in the body. And then based on what needs to happen, it's gonna tell the endocrine system what to do. And it's gonna do that by controlling the release of hormones from the pituitary gland. All right, as we go down, you'll see, we have this structure that we haven't talked about yet in yellow. The infundibulum, the infundibulum is what connects the hypothalamus and the pituitary gland right there. And it's often described as this sort of funnel like structure connecting the hypothalamus and pituitary gland. Now, functionally, there isn't much to know about the infundibulum. It's just that sort of funnel like connector of the two, but there is a good chance you're gonna have to label it on a, a diagram or at least be able to describe where it is. So as we move down. Now we reach the Pituitary Gland. What I again, often think of this sort of double punching bag right there. And you'll note here in par parentheses, we have the second name, the hypothesis. Now, almost certainly you're not gonna call it the hypothesis and you won't hear people refer to it as the hypothesis. But if it's used as an adjective, you'll use the term hypo physio. So for example, this is something we're gonna learn about in more detail in a future video. But there is this group of blood vessels right here called the hypo physio portal system. That term hypo physio comes from that other name for the pituitary, the hypothesis. All right. So the pituitary, we're gonna say here, its major job is that it communicates with other endocrine glance. Now, the pituitary does release hormones that don't communicate with other endocrine glands that just sort of have more direct physiological function. But here in understanding the system, we wanna think about the pituitary gland in its role of controlling the function of other glands. Now, we're just gonna say sort of structurally it is inferior to the hypothalamus. So again, we can see it right here. It's just under the hypothalamus hanging down there off the brain. And we're gonna say that it's, I've said that it's sort of this double punching bag. So that's because it has two lobes. It has the anterior lobe and the posterior lobe that you can see here in the diagram, these are gonna function differently. The anterior pituitary is gonna be stimulated by hormones from the hypothalamus. So again, we're gonna go into this in more detail coming up. But for now, just to understand that the hypothalamus is largely in control of what's happening here, the way it controls it is that it's gonna release its own hormones. They're gonna go through this little blood vessel system. And that's how the hypothalamus talks to the pituitary gland that anterior pituitary gland, the posterior pituitary is gonna work differently. The posterior pituitary is made of neurons extending from the hypothalamus. So it's actually made of nervous tissue. The hypothalamus, these neurons start here and their axons come down and the axons in the posterior pituitary sort of act both as nervous and endocrine glandular tissue. All right. Now, to really understand how this connection between the hypothalamus, the pituitary and other glands work. We just need to knock off one more vocab word and that's gonna be tropic hormones. A tropic hormone is a hormone that will trigger the release of other i. So, a tropic hormone has target cells in other glands and the response when those target cells recognize the hormone is to release more hormones. So we're gonna say here that tropic hormones from the hypothalamus are gonna act on the anterior pituitary, right? We said it's gonna release some hormones, they're gonna come down and that's what stimulates the anterior pituitary. Again, we'll deal with this in more detail coming up. But that's different from the posterior pituitary. Remember, the posterior pituitary is its own neurons extending down. But these tropic hormones from the hypothalamus act on the anterior pituitary. And then since they're a tropic hormone, that means that the anterior pituitary is gonna release specific hormones at that signal and it's gonna release more tropic hormones. Tropic hormones from the anterior pituitary are gonna act on other lands. And so that's when we say that this is, if anything is in charge of the endocrine system, it's the hypothalamus and the pituitary. That's why. Now because of that function, sometimes you may hear the pituitary gland being called the master gland. Now, for several reasons, some people don't like to call it that anymore. One reason is that the pituitary, well, now we know the hypothalamus is really controlling most of what's going on in the pituitary gland. So it's not really in charge itself regardless. I'm probably not gonna call it that you should be familiar with that term though just because you may see it. Ok. Like I said, we're gonna break down the function of the posterior and the anterior pituitary talk about the specific hormones they release and a lot more detail coming up. I'll see you there.
2
example
The Hypothalamus and Pituitary Gland Example 1
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Our example tells us that a scientific study demonstrated that studying for exams can lead to an increase in a student's cortisol levels due to stress. Some of the steps of the stress response involving cortisol are shown below. And we wanna circle any steps that involve tropic hormones. So first, let's just remind ourselves of that definition of tropic hormones. A tropic hormone is a hormone that has a target cell in another gland and causes the release of another hormone. So we have this sort of flow chart here showing some hormones and glands and other tissues. We'll start out, we have an image of the hypothalamus and that seems to be releasing this corticotropin releasing hormone that then goes to our next image here of the anterior pituitary, which you see right there, it seems to be releasing adrenocorticotropic hormone. That hormone seems to be going to the adrenal glands, which you see here drawn on top of the kidneys where they are in the body, the adrenal glands seem to be releasing the hormone cortisol and that seems to be going to the liver. All right. So, remembering that definition of a tropic hormone. Well, our first hormone here. Corticotropin releasing hormone. Well, that is going to the anterior pituitary and the release and the, the response seems to be that the anterior pituitary is releasing another hormone. So that seems to me like that's a tropic hormone, it's causing the release of another hormone from another gland. So I'm gonna circle this first hormone here. Next, we have the adrenal corticotropic hormone. Well, again, it's right there in the name tropic adrenal corticotropic hormone. Well, this hormone, what's happening, it's going to the adrenal glands. And how did the adrenal glands respond? They re spawn by releasing another hormone, cortisol. So I am gonna circle adrenal corticotropic hormone. All right. And then finally, we have the hormone cortisol cortisol here is going to the liver and that seems to be where this pathway stops. It looks like from this diagram that the physiological effect from cortisol is going to happen in the liver and there aren't gonna be any more hormones released. That means that cortisol, at least in this diagram is not a tropic hormone. So our first two hormones there, I have circled corticotropic releasing hormone and adrenocorticotropic hormone from this diagram, those look like tropic hormones to me. That's my answer.
3
Problem
Problem
Which of the following describes a tropic hormone?
A
Insulin is a hormone that causes the body to produce glycogen, removing sugar from the bloodstream.
B
Thyroid stimulating hormone signals the thyroid gland to release the hormone thyroxin.
C
Epinephrine is a hormone that leads to many different physiological changes in many different tissues.
D
Estrogen is a lipid soluble hormone, and therefore can pass through the cell membrane.
4
concept
Anterior Pituitary
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10m
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The hypothalamus and the pituitary gland serve as the link between the nervous system and the endocrine system. And we also said that if there's anything that's in charge of the endocrine system, it's the hypothalamus in the pituitary gland because specifically this anterior pituitary is gonna release some hormones that affect the release of other hormones throughout the body. Now, before we get going, let's just orient ourselves to our picture here. Here, we have the pituitary gland and you can see sort of in this light brown, we've color coded the anterior pituitary, the front part of the pituitary gland that we're talking about here. And you can see we also have some blood vessels on here and going up. We have the hypothalamus up here in gray. We can also see some neurons here in the hypothalamus, that part of the brain that run down and we'll talk about how those work in just a second. All right, we're gonna start just by saying that the anterior pituitary is stimulated by tropic hormones from the hypothalamus. So, remember a tropic hormone is a hormone that causes the release of other hormones. So the way the hypothalamus tells the anterior pituitary. What to do is it releases its own hormones that have target cells in the anterior pituitary. But this is gonna work differently than how we've been talking about hormones. Generally, normally, when I've said a hormone gets released in the blood and then I say, well, where does the blood go goes everywhere? Not here. Here it gets released into what's called a portal system. Now, to understand what a portal system is, let's look at our drawing here. We have this first capillary bed. This is where these hormones get released. Now, this capillary bed funnels into veins. Well, that's normal, but typically capillaries funnel into veins and then those veins go to the heart and they carry the blood of the heart and then the blood goes everywhere in the body. Not here. Here, these veins go to more capillaries, that's a portal system and there's only a few of them in the body and what a portal system does really well, it takes something from one part of the body carries it through the blood to a very specific other part of the body without having to distribute it everywhere. Now, this one is called the hypothalamic hypo physio portal system because it connects the hypothalamus and remember hypo physio, that was our adjective that refers to the pituitary gland. So we're gonna say here it connects capillaries from the hypothalamus to capillaries of the anterior pituitary. Now, so just look at this one more time. Remember the hypothalamus is nervous tissue. So we see these neurons up here that have axons that run down down to the base of the hypothalamus or the top of the infundibulum here. And then these axons are what actually release these hormones from the hypothalamus. They go into the portal system, the capillaries here, they run down and go directly to the anterior pituitary without having to go out to the entire body. All right, now, what we really wanna focus on here though is we wanna go through this anterior pituitary and think what hormones are, what hormones is it releasing and what do those hormones do? So, we have this table here and it's really this middle column of the table. That's probably the most important. It's very likely that you are going to need to be able to recall the hormones that get released from the anterior pituitary. So here we're gonna go through those and we'll also say just sort of very generally what they do by talking about their target cell location. Now, it's likely you're gonna need to know what some of these do in more detail than we're going over right now. Right now, we just wanna talk about it generally. So we know what hormones are getting released from the anterior pituitary. And again, just generally what they're doing. Now, in this first column, we're gonna look at those hormones that get released by the hypothalamus. And so here, these hormones get released by the hypothalamus and they either stimulate or inhibit the release of hormones from this anterior pituitary. Now, it's less likely that you need to know every one of these hormones off the top of your head. Now, like, always know what you're responsible for it in your class. But again, it's less likely that you need to know these. The good thing is the names, tell you exactly what they do. So it's really easy to figure it out. So let's take a look. Our first one here released by the hypothalamus is going to be growth hormone releasing hormone. Well, it causes the release of something. So it's a tropic hormone. What does it cause the release of growth hormone? So when this gets released, what gets released from the anterior pituitary? I bet you can figure it out. Growth hormone also referred to as GH sometimes now growth hormone. Well, what it does main thing it does is right there in its name in adolescence and youth especially, it's gonna influence the cell division rate, especially in bones and cartilage. It's also gonna have target cells in the liver. All right, our next one down is going to be thyrotropin releasing hormone. Again, that word releasing, tells me that this is a tropic hormone. What's it gonna cause the release of? Well, this thyrotropin? Well, that tells me this is gonna be a tropic hormone tropin and it's a tropic hormone that affects the thyroid gland. All right. So, what is it causing the release of thyroid stimulating hormone? All right. So, this is a tropic hormone that causes the release of thyroid stimulating hormone, which is also a tropic hormone. Thyroid stimulating hormone can also be called TSH. And what is it stimulating where the target cells? The thyroid? All right. So, the thyroid gland that will release thyroid hormone. Now, we go down one more. we have corticotropin releasing hormone. All right. Again, releasing hormone. That means that this is a tropic hormone, it's causing the release of a corticotropin. Well, tropin tells me that the next hormone down the line is also going to be a tropic hormone that affects the cortex of something. So as we go over what hormone gets released from the uh anterior pituitary is going to be Adreno corticotropic hormone or also sometimes called ac th adrenal corticotropin. Well, this affects the adrenal cortex. So we can write that down adrenal cortex. Now, the adrenal cortex part of the adrenal gland. So this is gonna be another tropic hormone and specifically the adrenal gland will then release cortisol. All right, as we go down our next one, we have gonadotropin releasing hormone, another tropic hormone. What does it cause the release of? Well, tropic hormones that affect the gonads, gonads, the ovaries and the testes, there's actually two hormones that respond to this. We're gonna release luteinizing hormone. And I'll tell you as someone who's mildly dyslexic. Spelling. Luteinizing always scares me the way I remember it. It has this weird E I in the middle of it, luteinizing hormone is a protein hormone. And protein also has that weird E I in the middle of the word luteinizing is spelled similarly to protein and it's a protein hormone. All right. So it's gonna release luteinizing hormone and follicle stimulating hormone. Now, both luteinizing hormone and follicle stimulating hormones are tropic hormones that have target cells in the ovaries and the testes. So they're gonna work a little differently but they will both influence the release of other sex hormones. All right, our final hormone here, prolactin inhibiting hormone. All right, prolactin inhibiting hormone. You're gonna notice this one's different than the other ones. The first four that we did in this left hand column, that word inhibiting prolactin inhibiting hormone isn't a tropic hormone because it doesn't cause the release of a hormone, it actually blocks the release of a hormone. So, when prolactin inhibiting hormone is not released, what gets released from the anterior pituitary is prolactin and prolactin. Sometimes we use just the abbreviation pr L prolactin has target cells in the breasts and we can break down the word and figure out what it means. Latin. Well, that has to do with lactation, production of milk and it is pro Lacin, it's for lactation. So it causes the production of milk in the breasts. All right. So again, it's very important that you remember these hormones and remembering a list like that can be difficult. So we have a memory tool to do it. And this is a memory tool. It's kind of common. You may see at other places, we're gonna see the say that the anterior pituitary hormones are a flat peg f for follicle stimulating hormone, L for luteinizing hormone, A for adrenal corticotropic hormone, T for thyroid stimulating hormone. Now, that first word flat, those four hormones are the tropic hormones that are released from the anterior pituitary. We can keep going through the word though. We have the P for prolactin and we have the G for growth hormone, prolactin and growth hormone. Those are the hormones that have direct action in the body physiologically. All right. That's the anterior pituitary. It's a lot I realize, but we still got to do the posterior pituitary. Now, don't worry, there's less going on there. There's fewer hormones that it releases, but we'll do that next. First though. We have examples and practice problems. You should give him a try.
5
example
The Hypothalamus and Pituitary Gland Example 2
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This example, asks you to imagine that you are a doctor. You have a male patient showing low levels of thyroid hormone or t four, low levels of cortisol producing the adrenal cortex and low levels of testosterone and a male that would be produced in the testes. You believe the cause is a tumor in the hypothalamus. Now, based on your understanding of the role of the hypothalamus in the endocrine system, would you expect the tumor to be blocking the normal function of the hypothalamus or causing overstimulation of the hypothalamus and explain your reasoning. All right, take a second and think that through if you're not producing enough thyroid hormone, cortisol and testosterone and it causes a tumor in the hypothalamus, would you think that's due to blocking the hypothalamus function or overstimulating the hypothalamus? Well, let's think about that. And let's sort of walk this all back. We're talking about thyroid hormone made in the thyroid gland cortisol made in the adrenal cortex and testosterone made in the testes. Now, the release of all those hormones is gonna be influenced by tropic hormones from the anterior pituitary gland, specifically thyroid stimulating hormone will stimulate the release of thyroid hormone, uh adrenal corticotropic hormone will cause, will stimulate the release of cortisol and uh luteinizing and follicle stimulating hormone will influence the release of testosterone. So, if you're not producing enough of those hormones, there's a good chance the pituitary gland is not producing enough of those tropic hormones. But those tropic hormones from the anterior pituitary get released when stimulate, when the pituitary gland is stimulated by tropic hormones from the hypothalamus. So, if the anterior pituitary gland isn't producing enough, there's a good chance it's because the hypothalamus is not producing enough of its tropic hormones. And so if it's not producing enough, that says to me that this would be blocking the function of the hypothalamus. Now, my reasoning, we just sort of gone through now and I'm gonna state it in real simple ways. I would just say that tropic hormones cause the release of other so much. And now, if this were a test, obviously, I would say a lot more than that, I'd start with that. And then I would say how the hypothalamus releases tropic tropic hormones that affect the pituitary gland causes the release of the uh hormones from the pituitary gland. The pituitary gland releases tropic hormones which cause the release of these hormones we're talking about. So, if these hormones are not being released at a high enough level, there's a decent chance that we can follow it all the way back. And the tropic hormones in the hypothalamus are also not being released at a high enough level. That's my answer. We have more practice problems. Follow. I'll see you there.
6
Problem
Problem
The following hormones are all produced by the pituitary gland. Which hormone is NOT released by the anterior pituitary?
A
Oxytocin.
B
Prolactin (PRL).
C
Adrenocorticotropic Hormone (ACTH).
D
Thyroid Stimulating Hormone (TSH).
7
Problem
Problem
What is the primary function of the hypothalamic-hypophyseal portal system in hormone transport?
A
It transports hormones from the anterior pituitary to the hypothalamus.
B
It allows hormones from the hypothalamus to reach the anterior pituitary directly.
C
It carries hormones from the anterior pituitary to the general circulation.
D
It carries tropic hormones directly from the hypothalamus to the different endocrine glands around the body.
8
concept
Posterior Pituitary
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We want to continue looking at this link between the nervous system and the endocrine system between the hypothalamus and the pituitary gland. And so here we're gonna be talking about the posterior pituitary. And just like when we talked about the anterior pituitary, we're first gonna talk about that link between the hypothalamus and the posterior pituitary. We'll talk about it structurally and how it works. And then we will look at what hormones the posterior pituitary actually releases. So let's get started. All right, we're gonna start just by orienting ourselves to our image. Here. We have the pituitary gland hanging down there. And the posterior part, this rear part, we have color coded in pink. You can see there's some blood vessels on there. And then the other thing you'll notice are these neurons that start up here in the hypothalamus and then run down into the posterior pituitary there. And again, I said they start up here in the hypothalamus, that part of the brain there. All right. So we're gonna start just by saying that the posterior pituitary is this rear portion. That's just what posterior means. It's in the back, this rear portion of the pituitary and it's made largely of nervous tissue and this nervous tissue has a direct connection to the hypothalamus. So, again, that's what we just looked at in this drawing here. These neurons start up in the hypothalamus and they run all the way down and they actually make up the majority of tissue in this pituitary gland. Now, that direct connection is very different from the anterior pituitary gland. Remember the anterior pituitary gland was connected to the hypothalamus through blood vessels and its tropic hormones that sort of instructed the anterior pituitary what to do. Here, we have a direct connection. It's really the same tissue. It's uh cells that start in the hypothalamus and then extend down in and make up the posterior pituitary. So we're gonna say the posterior pituitary really functions as an extension of the hypothalamus. Right. Again, it's the same cells. Now, these cells start in two very specific places. So we wanna call those out and we have them color coded here. They start in the paraventricular and supraoptic nuclei. So, paraventricular nuclei, that's this region sort of here in blue in the hypothalamus and paraventricular pais means like beside and ventricular, it's behi beside the third ventricle in the brain and supra optic nuclei. That's this one color coded in purple. Supra optics means above an optic, it's just above the optic tract. Now, you probably don't need to know, need to break down those words like that. But if you want to know where they come from, that's where they come from. All right. So this paraventricular and super optic N nuclei, these actually make the hormones. So the hormones are gonna be synthesized up here in the hypothalamus. Now, they need to travel down these cells to get to the posterior pituitary. So we're gonna say they travel down the hypothalamic hypo physio tract. Now, that should sound familiar. Remember in the anterior pituitary, we had the hypothalamic hypo physio portal system. Remember, hypothalamic means the hypothalamus, hypo physio is an adjective, that means pituitary gland. And the portal system was this group of blood vessels that connected them in the anterior pituitary gland. But the p posterior pituitary again, it's the same cells. So it travels down a tract and a tract refers to a group of neurons like the optic tract. So we have this group of neurons, these axons that are running down through the infundibulum. So the hypothalamic hypo physio tract that is gonna allow these hormones to travel down axons through the infundibulum and into the posterior pituitary. Well, then once we're in the posterior pituitary down here, well, this is where these hormones are actually gonna get released from the axon terminals and it's gonna be action potentials that again start up in the hypothalamus that lead to the release of the hormones. So the hormones have to travel down these axons to be released by the axon terminals. But it's the same axons that carry the action potential down and stimulate the release. Now, you may note that's very similar to how a lot of the nervous system works, right? You have an action potential that comes down, that leads to the release of a neurotransmitter, which is a chemical messenger. The key difference, a neurotransmitter travels from one neuron across a synapse to another neuron. But here it, these chemical messengers are released from an axon terminal and into the blood. Well, if you release a chemical messenger into the blood, you call it a hormone. All right. So let's see what hormones are released from this posterior pituitary gland. Now, we've set up this table just like we did for the anterior pituitary. But you'll see there's a lot less going on here. In this case, on the left, it's always gonna be stimulated by hypothalamic neurons. The action potentials are always gonna cause the release of this horm of, of these hormones. There are no tropic hormones. We don't have to worry about those here. All right, the hormones of the posterior pituitary. Again, this is very likely something that you need to know to be able to know what hormones are released by this gland. And then we're also gonna say, say what target cells they affect and just very generally what they do in the body. Now, again, you may need to know what these hormones do in more detail, but we're not talking about that here. Right now, we just wanna talk very generally what they do and associate the correct hormones with the correct gland. All right. So we'll start out the first hormone that we wanna know is called anti diuretic hormone, antidiuretic hormone, also called or abbreviated A DH and also called vasopressin. Now, to know what this does, we can break down the word, well, anti means against or opposite of something like that. And diuretic, you may be familiar with that word diuretic. You may know that things like caffeine or alcohol are diuretics. If you take caffeine or alcohol, that causes you to make more urine. A diuretic is something that causes you to put more water into the urine. So an anti diuretic keeps you from putting water into your urine. It causes you to make less urine urine, thereby sort of increasing your blood volume, putting more water back into the blood. So this helps you keep this uh hormone tells you to keep more water in your blood. And therefore the target cell location is in the kidneys. All right, our next hormone is going to be oxy Tosin. All right. Oxytocin is a hormone with target cells in the uterus and the breasts. And Oxytocin is often associated most closely with uterine contractions. The release of Oxytocin is what con causes contractions during labor. Now, it's also has target cells in the breast because the release of Oxytocin helps the letdown of milk. So, to uh the production of milk and the release of milk during nursing. Now, Oxytocin has been shown to do other stuff as well. It's involved in bonding. It's involved in the mother and baby bond forming. It's also released when you fall in love. But what people usually want you to focus on is again, these target cells in the uterus causing uterine contractions in labor and in the breast uh associated with the release of milk. All right. Now, to remember these hormones, we have another memory tool for you. And our posterior pituitary memory tool is to say powerful antioxidants. Now, to break this down, powerful that po should remind you of the posterior pituitary anti. That refers to the anti diuretic hormone and oxy. Well, oxy refers to Oxytocin. All right. That wraps up the pituitary gland. Like always we have examples and practice problems that follow. I will see you there.
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example
The Hypothalamus and Pituitary Gland Example 3
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Our example wants us to fill in the table below on the differences between the anterior and posterior pituitary glands. So as I look at this table, I have a column for the anterior pituitary column. For the posterior pituitary, there's four cells that we need to fill in there. And in those cells, we need to put the structure that connects those things to the hypothalamus and we need to put the whole hormones that each one releases. Now, we also have this illustration here just as a reminder, we have the pituitary gland shown here. And in brown, we can see the anterior pituitary and in pink, we can see the posterior pituitary in the yellow. We see that infundibulum and the hypothalamus would actually be up here. But it's also showing those blood vessels on the pituitary gland as well. All right. So let's start with this for, for cell, the anterior pituitary, what is the structure that connects it to the hypothalamus? Do you remember? Well, we can remind ourselves by looking at this illustration, this illustration, as we see this anterior pituitary, we have this beta capillaries here all around it and it has a direct connection up to these capillaries that are here at the base of the uh hypothalamus or the top of the infundibulum there. And remember we said that this is kind of like a, a pretty unique structure of blood vessels. There's only a few of these in the body where capillaries empty into veins and then instead of going back to the heart, they go to another capillary system. That means that whatever gets put into that first capillary system gets taken directly to another very specific part of the body. And here we're talking about carrying those tropic hormones from one place to another. So you remember the full name? It was the hypo balm hypothalamic referring to the hypothalamus where the capillaries start. Hypo physio. And I remember hypo physio, that's that word. That's the adjective that refers to the pituitary gland. It's the hypothalamic hypo physio portal system. All right, let's work our way across the posterior pituitary. What is the structure that connects the hypothalamus to the posterior pituitary? All right. Remember the posterior pituitary works. We said almost like a direct extension of the hypothalamus. We had neurons that start up here in the hypothalamus and run all the way straight down through. And those axon terminals are what really make up that posterior pituitary gland and the hormones are synthesized in the hypothalamus and they travel right down. And so do the action potentials. And that's what tells the posterior pituitary gland to release those hormones into these capillaries here. So that group of axons running down through the infundibulum. Do you remember what that is called? Well, the name is very similar to what connects the anterior pituitary to the hypothalamus. But I don't want to write it all out again because that took me a little while. It was again, the hypothalamic, it starts in the hypothalamus. I'm just gonna write each this time the hypothalamus hypo physio hh. Now, it's not a portal system because it's a group of axons. It's a tract. So we have the hypothalamic hypo physio portal system, that group of blood vessels that con connects the hypothalamus to the anterior pituitary. We have the hypothalamic hypos tract that connects the hypothalamus to the posterior pituitary. All right. Now, let's remember our hormones. Now, remember anterior pituitary, there are a number of hormones and we don't actually have a lot of space here in this table. So I'm not gonna write them all out, but I will write out our memory tool and then we'll go over each hormone as we go. So, do you remember the memory tool? And if you remember the memory tool, hopefully, you remember the hormones, the memory tool was flat peg. All right, let's go through these f f stood for follicle stimulating hormone that had target cells in the gonads. L stands for luteinizing hormone also as target cells in the gonads. A stands for adrenal Corticotropic hormone that has target cells in the adrenal gland. T stands for thyroid stimulating hormone, which has target cells in the thyroid gland. Now, that word flat, those hormones, those are the tropic hormones released by the anterior pituitary. Down down here, we have peg, we have PP stood for prolactin prolactin, uh stimulates the production of milk in the breast and we have G for growth hormone, growth hormone influences growth. All right. So those are the six hormones of the anterior pituitary. Let's remember what's in the posterior pituitary. Remember we had a memory tool for that as well. And that memory tool, I said, powerful anti oxidants and that powerful the po reminded me that I'm talking about that posterior pituitary and anti. Well, I can, I got enough room here. So I'll write it all out. That was anti diuretic hormone. Remember that had uh target cells in the kidneys and causes your body to keep more water in the blood, produce less urine. And the ox was for Oxytocin, that hormone that is uh responsible for stimulating labor contractions and also for stimulating the release of milk in the breast. All right. That's the pituitary gland and it's linked to the hypothalamus. Now, I think this is probably the most complex part of the endocrine system that you need to know. And you may need to know some more details than we've gone over here. But if you can fill a table like this out off the top of your head. I'd say you're doing pretty good.
10
Problem
Problem
Which of the following statements about the posterior pituitary is true?
A
The posterior pituitary is connected to the hypothalamus via the hypothalamic-hypophyseal portal system.
B
The posterior pituitary releases hormones that are synthesized in the hypothalamus.
C
The posterior pituitary relies on tropic hormones to signal when to release ADH and oxytocin.
D
The posterior pituitary releases tropic hormones that target other endocrine glands.
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