 Hey everybody, Dr. O here. This video we're going to talk about what's called the hypothalamus pituitary complex and we're going to see, this is, I like to call this the bridge between your nervous system and your endocrine system. So why does the endocrine system even exist? Well, the nervous system only can respond to things quickly for short lived responses. So if there's a stimulus received by your nervous system where the response has to be more broad reaching or long term, it's almost like the hypothalamus will take it and translate it into hormones. It's an interesting way to look at it. So let's go ahead and, well, let's talk about the key thing in this video is going to be the three main ways that the hypothalamus controls your endocrine system. So number one, it produces what are called regulatory hormones. There are boatloads of them. I won't ask you to know any of them by name. I'll certainly use their names. I've used them in some of the videos I've already made for this unit. But regulatory hormones are hormones produced by the hypothalamus that control the pituitary gland. So remember the pituitary gland is called the master gland. It's the most important endocrine gland we have, but it listens to the hypothalamus. So that's the number one way the hypothalamus controls your endocrine system. Number two, it actually makes hormones and not just those hormones. It makes the hormones that are stored and released from the posterior pituitary gland. And that would be oxytocin, which plays a role in labor and delivery and the ejection of milk with lactation. And then anti diuretic hormone or ADH, which is an anti diuretic. It causes the reabsorption of more water at the kidneys so that you can keep your blood volume and fluid volume up. So number one, it made the regulatory hormones that control the pituitary gland. Number two, it actually makes the two posterior pituitary hormones and they're just stored and secreted there. And number three, it controls the adrenal medulla, the center of the adrenal medulla. So the adrenal medulla is actually a modified portion of the sympathetic nervous system. So we call it an endocrine gland and it releases hormones, but it is a part of your sympathetic nervous system. So when the fight, flight, or freeze sympathetic response kicks in, your adrenal medulla will dump epinephrine and norepinephrine, so adrenaline, into your bloodstream. So those are going to be the three ways that the hypothalamus controls the pituitary gland. Lastly, I want to talk about what's called the hypophysial portal system or how the hypothalamus actually gets the information to the pituitary gland. So just quickly, what is a portal system? You're going to see it in more than one place, you'll see it in the liver and stuff. Usually blood vessels go, and we haven't learned them yet, but blood vessels go from arteries to arterioles, little baby arteries to capillaries to venules, which are baby veins to veins. That's how your circulatory system works. But a portal system is going to go from an artery to an arterial to a capillary to another capillary bed to a venule to a vein. So when you need to move loads of material in a very small space, you have a portal system, which is going to, since there's more than one capillary bed, you're going to be able to move more and more material. So that's what a portal system is. Why is this important? Well, if the hypothalamus needs to tell the pituitary gland what to do, you don't want to see these chemical messengers, these regulatory hormones, dumped into the circulatory system, travel all the way through the body to come back to the pituitary gland. The pituitary gland is literally a millimeter underneath the hypothalamus. So this portal system allows, so when the hypothalamus releases hormones, it is dumped directly into the pituitary gland. Now when the pituitary gland releases hormones, it's just going to be dumped into circulation and traveled through the body, which is great, because that's where its target is. But that's why the hypofecyl portal system is important. It's a way to quickly get these hypothalamic hormones right to the pituitary gland. And then just keep that in your back pocket for later chapters too though, what a portal system is. Okay, so that is how the hypothalamus is the boss and the control center, command center of the endocrine system. I hope this helped. Have a wonderful day. Be blessed.