 Here's my little half head. I always get a little disturbed looking at this picture because it looks like my little small, blondie boys, but that's okay because if I could look inside their heads, I actually would as long as I didn't have to chop their head in half. All right, so take a look at this location. Anatomy students should definitely be aware, what is this structure right here embedded down in the sphenoid bone of the skull? That would be the seletursica of the sphenoid bone, and it's a pituitary gland. And so you can see here, this is sphenoid bone, and you can see that this pituitary gland is nestled down inside that part of the sphenoid bone. If you take the bigger picture, here's pituitary, nicely protected, very important. I have pituitary and hypothalamus split into two sections, but really it's really hard to talk about them separately because they are so intimately connected in structure and function. Superior to the pituitary gland and literally connected to it is the hypothalamus. You can see that this space up here, this area, this is my hypothalamus. And if you take a look at this, it's really significant because the hypothalamus literally reaches down. Doesn't it look like that is hypothalamus that's reaching down into the pituitary gland? And that's not on accident. The pituitary gland has two parts, and the anterior part is endocrine tissue. The posterior part is actually neural tissue. It's actually brain. It's an extension of the hypothalamus. And that structural feature is going to be very significant when we look at the function of these two structures. So the hypothalamus, it's basically considered like the mama, no. The master of all homeostatic responses. The hypothalamus controls the whole thing. And in fact, before we can talk about specific interactions between the hypothalamus and the pituitary and the distinctions between ant pit over here, this is ant pit, and post pit back here, we have to have a little bit more anatomy. This, I don't know, those of you who've had anatomy know that portal systems, I find portal systems fascinating. Portal systems are two adjoining capillary beds. And we're going to talk about portal systems because I just can't help it. Most of the time, in the circulatory system, and relax, don't freak out, this is definitely just diagrammatic and just for illustrational purposes. Most of the time, we have one capillary bed. You have your arteries coming in and feeding a capillary bed where gas exchange and nutrient exchange takes place with all your cells. In fact, all your cells are like some distance, some tiny little distance away from a capillary or they're going to die. So you've got all these capillary beds where exchange happens. And then all the dirty old blood flows back into the veins and head back to the heart. The heart sends them to the lungs. We have capillaries in our lungs. Now we have gas exchange occur there and we get new fresh blood to send to the body. There is no reason to have two capillary beds in sequence because capillary beds are where you get dirty blood. In anatomy, we talked about the hepatic portal system and that was a place where you did see two capillary beds in sequence where all the capillary beds surrounding the digestive tract took all that oxygen-poor but nutrient-rich blood to the liver. And the liver in another capillary bed sorted through the nutrients and made sure that there was nothing poisonous there before dumping all that nutrient-rich blood from the outside world in your intestines into the regular circulation. To me, I look at that portal system and I go, brilliant, what a great idea. Let's have two capillary beds in sequence so that we can filter out the blood. Well, the hepatic, I mean the portal system that exists between the hypothalamus and the pituitary gland is a different kind of portal system. But in this one, this is going to be important because you look at how the hypothalamus communicates with the pituitary gland. And can you see here? I have a capillary bed from the hypothalamus and I have another capillary bed where? With ant pit. So the anterior pituitary actually has its own additional capillary bed. Why? Why would you do this? Well, here's the deal. The hypothalamus produces releasing hormones and there are, I believe, six of them because there are six hormones produced in anterior pituitary. The hypothalamus dumps releasing hormones into this portal system. What? And then those releasing hormones, you don't dump them into the whole circulation, dilute them out there in the madness, dump them into the portal system. And then they go, let's not stay in a capillary bed till we get to ant pit because we can certainly go faster if our vessels get a little bit bigger. So we'll get them a little bit bigger and then we'll branch out again into another capillary bed where now we're going to deliver the hormones to ant pit. The message when those hormones come, the message is you got to release some different hormone out into the bloodstream, out into the general population. In this way, the hypothalamus is able to control the hormones produced or released by ant pit. The hypothalamus is also tightly related to the posterior pituitary gland and that one, dude, this is fantastic. Neurons in the hypothalamus literally pass all the way down into the posterior pituitary and essentially the hormones produced in posterior pituitary actually are made in the hypothalamus and are just stored in post pit. And post pit from a message, no, upon a message from the hypothalamus will release the hormone into the general bloodstream. There isn't a portal system between the hypothalamus and the posterior pituitary. You'll see that that's not necessary. There isn't a releasing hormone for the hormones produced in the posterior pituitary. I guess we've talked about hypothalamus and our pituitaries and how they are unique and different from each other and now in the next section, I'm going to talk about all the different hormones that we're dealing with here.