Anterior and Posterior Pituitary

by Jason Amores Sumpter
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Okay, everyone, in this lesson, we're going to be learning about specific glands in the endocrine system, and specifically, we're gonna be talking about the pituitary gland. Okay, so let's get into the lesson, and we're going to talk about the pituitary gland. But it's hard to talk about the pituitary gland without talking about the hypothalamus gland because they are very, very strongly linked. So we have the pituitary gland, and it's going to be composed of two sections. Thean, teary er, pituitary gland and the posterior pituitary gland. Now the hypothalamus, which we learned about in our last lesson, is also going to be part of the indifferent system. But remember, the hypothalamus main job is to connect the nervous system with the endocrine system. The nervous system is going to send the hypothalamus signals about the exterior world, or what the brain is feeling or what the body is feeling, and then the endocrine system. We are sorry the hypothalamus will process those signals and tell the rest of the endocrine system what it needs to dio. So, for example, if the nervous system detects seasonal changes like drops in temperature or less sunlight, then it will tell the hypothalamus that information and perhaps the hypothalamus will tell the rest of the body that it needs to start making sex hormones because perhaps it's breeding season for that particular animal. That's gonna be one way that the hypothalamus is going to work. But the hypothalamus doesn't really send out these hormones on its own. What it does is it tells the pituitary gland to send out these hormones. And there are two parts right, the anterior and the posterior pituitary, and they're going to do different things. So first, let's talk about the anterior pituitary. Now the anterior pituitary is going to secrete Tropic and direct hormones. Trophic hormones are gonna be hormones that affect other indifferent glands. Direct hormones are going to affect other body parts that are not endocrine glands. Maybe it has something to do with hormone signaling thio the muscles or the liver. But if it's a hormone that signals another endocrine gland like perhaps the test ease or the ovaries that do make these different hormones, then it's a tropic hormone. Okay, so tropic hormones signal Thio, other India Quran glands, and the anterior pituitary is going to make these tropic and direct signals and it is going to be linked to the hypothalamus via blood vessels. And that is because the hypothalamus is going to direct what the anterior pituitary is going to do. Theater pituitary is its own gland. It makes its own hormones, but it can't release them or stop releasing them until the hypothalamus tells it that it can. And the way that the hypothalamus does This is the hypothalamus is in the brain, and so is the pituitary gland. And they're very close together, and in fact, they're going to have these blood vessels that connect them. And these air generally called the portal vessels or the portal system. And these were gonna be very short blood vessels that transfer the signals from the hypothalamus to the pituitary gland. And the anterior pituitary is going to get it signals from the portal system. Now, the hypothalamus secretes hormones into this portal system, and they're going to tell the anterior pituitary what to do. Now, This list of hormones F s, H, L H, a, C, T, h, TSH, prolactin and GH are all gonna be the different types of hormones that the interior pituitary makes and can secrete so follicle stimulating hormone and lutin izing hormone are gonna be dealing with sexual reproduction and the producing of GAM. It's You guys will learn more about these hormones whenever we learn about animal reproduction. But I just wanted to put them in here because they are made by the anterior pituitary gland. So the follicle stimulating hormone, or FSH, stimulates follicles and maturation and spur Mata Genesis follicles are going to be things that actually make the gametes. For example, follicles in ovaries make the eggs so follicle stimulating hormone is very important for the production of gametes lutin izing hormone stimulates ovulation and testosterone synthesis. Ovulation is going to be the releasing of the egg from the ovaries into the fallopian tubes and testosterone synthesis is simply the creation of the male sex hormone. So these were going to be mostly important for sexual habits. Okay, now we have these different hormones. We're gonna have the adrenal cortical, a tropic hormone or simply a C T H. And it is going to stimulate the adrenal cortex to secrete other hormones, or glucocorticoids, which is hard to say like cortisol. So this one right here is going to be a tropic hormone because it is going to signal to another indifferent gland to create more hormones, kind of like a stepwise process. And then you're gonna have the thyroid stimulating hormone, which is another tropic hormone, because your thyroid is going to be another endocrine gland. Very important, one which will learn in our next lesson. And the thyroid stimulating hormone does exactly what it sounds like. It's going to stimulate the thyroid to create those thyroid hormones, and then you're gonna have prolactin. Prolactin is very important for the secretion of milk in the mammary glands of mammals, and it is going to be secreted in the production of milk after the baby is born. But I also want you guys to know it is also very important for your immune system, your metabolism and your pancreas actions. Okay, so it does more than just produce milk, but that's its main function. Then you have the human growth hormone or simply growth hormone, and it's going to stimulate the regeneration and the creation off new cells. Now down here is going to be a diagram of how the anterior pituitary and the hypothalamus are going to interact with one another. So these are gonna be the hypothalamic hormones that it creates by the hypothalamus. Okay, and these are going to be delivered via the portal system or the portal vessels to the anterior pituitary. And then these particular hormones or hypothalamic hormones, are going to be telling the anterior pituitary what to make. So G N r. H is the gonadotropin releasing hormone, and it's going to tell the anterior pituitary to release the gonad hormones or the FSH and LH hormones, which go to the gonads. So you'll find that the naming of the hormones that come from the hypothalamus are pretty self explanatory because they are the releasing hormone or the inhibiting hormone. Because the I found this comptel, the interior pituitary, to release something or inhibit something. So the gonadotropin releasing hormone tells it to release the gonad hormones. C. R H is gonna be the cortical trope in releasing hormone, telling it to release the cortical trope in hormones and T R H is the dire a trope in releasing hormones, which you're gonna be the thyroid hormones. It's gonna tell the interior pituitary to release those thyroid stimulating hormones. Now the only one that's a little different is gonna be D A d A is gonna be dopamine. So it doesn't really fit its name All that well. Um, but dopamine is actually going to tell Prolactin to stop being released at a particular time. Okay, While the thyroid trope in releasing Hormone is going to tell prolactin to be made now, the G h r h is simply the growth hormone releasing hormone. Pretty self explanatory. It's going to tell the anterior pituitary to release the growth hormone, which you guys can see as the plus. Just you guys know the plus science here are telling the anterior pituitary to secrete that hormone. Now, the minuses are telling the anterior pituitary to stop releasing that hormone. So G h r h is telling the interior pituitary to make growth hormone, but s T is telling it to not make growth hormone. Do you guys know what s T actually is? S t is gonna be somatic toe statin. Do you guys know what this is? Samat, A statin is actually another word for growth hormone. So the growth hormone is actually going to be a negative feedback system whenever there's too much growth hormone or too much so mad a statin it is going to go back to the hypothalamus, and the hypothalamus is going to tell the anterior pituitary to stop making growth hormone. So growth hormone basically tells itself to turn off, which is kind of interesting. So I hope this makes sense. This is going to be how the anterior pituitary interacts with the hypothalamus. The hypothalamus doesn't make any of the anterior pituitary hormones, but it does tell the anterior pituitary to either release or inhibit those hormones that it makes on its own. Put the post eerie pituitary is quite different. The posterior pituitary does not make its own hormones. It is going to release the hormones that the hypothalamus makes. So the hypothalamus is basically going to make these two hormones and those they're going to be the oxytocin hormone and the anti diuretic hormone, and it's going to store them in the posterior pituitary gland. And then it will tell the posterior pituitary gland when it is allowed to actually release these particular hormones. So the posterior pituitary secretes direct hormones, thes air, not going to be hormones that interact with other indifferent glands. they're going to affect tissues directly, and it is linked to the hypothalamus by these neuron ax ons. And these neuron axons are going to be the pathway that oxytocin and a D. H actually travel to get to the posterior pituitary. So the hypothalamus produces these neuron hormones neuro hormones, and it stores them in the neurons that connect the two the posterior pituitary. So simply the posterior pituitary is the storage location. And then the hypothalamic axons synapse on these capillaries and tell the post Terry Pituitary when it is allowed to release oxytocin or a D. H. Okay, guys, you can actually see these structures here. This is gonna be appear in blue. This whole thing right here is the hypothalamus, and it is actually connected to the posterior pituitary via these Exxon's, which you guys can see here. So let me highlight that a little bit better for you guys. These were going to be the ax ons, and they're gonna have or the, um neurons, and they're gonna have their axons. They go all the way down into the posterior pituitary. And then whenever the hypothalamus tells the axons, the axons tell the posterior pituitary to release oxytocin or a D. H. Now, oxytocin and a D. H are very important hormones. Whenever you're talking about the survival of your body, a. D. H. You guys will learn more about whenever we learn about Osma regulation and excretion. But just know that it's used greatly whenever you are dehydrated or you have blood loss. Because A D. H, also called vasopressin, increases your water re absorption in your kidneys, and you don't lose as much water in your urine, so build water back up in your blood. Now oxytocin has a huge range of these different functions that it can dio. It is used in females to signal lactation after the baby's born. It will cause milk to be lactate ID. It also stimulates contractions and labor and really cool this one right here. It plays an important role in social bonding. They have done studies that show that oxytocin is greatly linked to maternal behavior. So whenever a mother has a baby and then she holds the baby, her oxytocin levels go up, her oxytocin levels go up, and she feels more maternal, has more maternal instincts. Also, oxytocin is used when partners interact or loved ones interact your oxytocin levels go up, so it's correlated with bonding. They've even done studies on pets and seeing that animals such as dogs, whenever they interact with you like you pet them, they're oxytocin levels go up, so that's really neat. It's basically the bonding hormone, and it's used for reproduction as well, in the form of labor contractions and lactation. But that's all the information I have for you guys on the pituitary gland. Remember, it has two components. The anterior pituitary gland, which makes a whole bunch of hormones on its own and is told by the hypothalamus, went to release those hormones and the posterior pituitary gland, which is given hormones by the hypothalamus and then secretes those hormones when the hypothalamus tells it to. But in our next lesson, we're going to learn about the thyroid and how it plays a part in the endocrine system.