 Hi everybody, Dr. O here. So in this video we're going to cover the hypothalamus, which is one of the most important structures in the brain. So you see that the thalamus and the hypothalamus are the two key parts of the diencephalon sitting right on top of your brainstem. So the hypothalamus, like the name implies, is going to be beneath or below the thalamus. So you see the hypothalamus there. Key structural areas inside the hypothalamus, this isn't a huge deal to me, but you do have what are called the mammillary bodies. They process a lot of sensor information, but I think the key thing that happens there is they control the reflex movements of the mouth when you're eating. So the fact that you think about how little you have to think about eating, right? As your chewing is very complicated, your teeth, your teeth are moving, your tongue is moving, all sorts of things are happening, and you don't bite your tongue very often, you don't bite your cheek very often. That's because this reflex subconscious control of chewing comes from the hypothalamus here. So that's one of the things that happens there. Number two, as far as structural areas, we have the infundibulum. That's going to be the stalk that connects the hypothalamus to the pituitary gland. So we cover this in way more detail with the endocrine system. But the hypothalamus is that bridge that connects your nervous system to the endocrine system. Both of those systems are responsible for maintaining homeostasis and controlling the body. But the nervous system is really in charge because the nervous system controls things second by second. But also when the nervous system can't do something, it actually tells the endocrine system to do it. The nervous system can't control things like pregnancy and the growth. So it actually gives the task to the endocrine system. So the nervous system is in charge, and the hypothalamus is a key player there. Then we have what are called the tuberous areas of the hypothalamus, which is between the mammillary bodies and the infundibulum. That would be, it helps control the pituitary gland. All right, but the main thing I want to talk about are the eight key functions of the hypothalamus. As you can see, it's very important. In a word, though, or two words, it maintains homeostasis. When I think of the hypothalamus, the first thing I think of is it's trying to help your body maintain a stable internal environment, and you'll see how these things, most of them, tie in. So number one would just be subconscious control of muscle contractions, skeletal muscle contractions. So your cerebrum is responsible for conscious movement. The cerebellum and the hypothalamus play big roles in subconscious movement. But that's not the most important one. Number two, the control of autonomic or subconscious function. Same kind of thing. Remember the word conscious just tells you the cerebrum's involved. Subconscious would be all the structures below the cerebrum. Number three, the first really important one would be the coordination of the activity between your nervous and the nervous system. So I already covered that. So it is that bridge that connects your nervous system to your hormone production, your endocrine system. Number four, actually one of the key reasons that's true is it actually secretes these two hormones. So two of the two hormones that are called posterior pituitary hormones, they're actually only stored there. They're produced by special cells in the hypothalamus and then they're transported to the posterior pituitary gland. And this is not the endocrine system yet, but those two hormones would be anti-diuretic hormone, which plays a role in preserving water, keeping you from losing too much water. It's an anti-diuretic. And oxytocin, which plays a role in labor and delivery, et cetera. So those are the first four major functions. Number five, this is what I want, the one that I think of the most I would say, is this is going to be where a lot of you, it produces emotions. And then this is where your behavioral drive centers are. So the feeding center in the hypothalamus says, I'm hungry. Feed me when our body needs food to maintain homeostasis. The thirst center here says, I'm thirsty. Give me something to drink when we need water to maintain homeostasis. Sexual pursuit area of the brain. All these drives and urges are going to be in here. So I always like to say the hypothalamus doesn't do anything, but it makes you want to do things. So it gives you the urges and the drives to do things. And this can be good and bad, right? Because the hypothalamus urges you to eat all the sugar you can, but that's because our brains evolved in a time when sugar was scarce. So constantly being told by your brain to eat sugar is now a bad idea. Or let's say that you're trying to quit smoking or quit doing drugs or drinking. Well, if your body has developed, you know, the pleasure centers here in the brain are saying, no, we like that it will urge you to keep doing it. So when people talk about willpower, your willpower has to be strong enough to overcome these subconscious urges that come from your hypothalamus and say no to that donut, that cigarette, that heroin, whatever. I don't know whatever your thing is, right? So that's kind of what I think of the hypothalamus and maintaining homeostasis. It urges us to do all types of things that it thinks are a good idea. Obviously heroin, never a good idea, but your brain can't tell the difference, I guess. Number six, we've kind of already covered this, but it coordinates a lot of voluntary and then involuntary or subconscious functions because it's that one of those relay centers between your cerebrum and then the rest of your nervous system. Number seven, another really important one. The last two are both really important. Regulation of body temperature. So there's an area in the hypothalamus called the preoptic area and that's where your body's thermostat is. It's like if you get a fever, it's because chemicals from organisms or your immune system go to this part of the hypothalamus and crank up the heat. So regulation of body temperature and then fever would both be issues here with the hypothalamus. Then lastly, there's a part of the hypothalamus called the suprachiasmatic nucleus and it controls our circadian rhythms. We have special, they just found these several years ago. There's special cells in the retina, these retinal ganglion cells, which don't actually see anything. They don't go to the occipital lobe. They don't tell you what you're seeing. They go to the hypothalamus and say whether it's day or night. They specifically respond to blue light. That's why people talk about you don't need to block all light if you're trying to fall asleep, just blocking blue light, these types of things. Because whenever that blue wavelength of light strikes these retinal ganglion cells, they tell the hypothalamus it's daytime. The sun's out, so don't make melatonin. And then when your brain is not receiving that signal that it believes it's nighttime and it tells your brain to make melatonin. Now the problem with this is that it's eternally noon now. It used to be when the sun went down and was dark and maybe we had fire, but that was it. Now we have so much technology. I could be sitting at this computer at two in the morning. My brain thinks it's noon because my eyes are being bathed with this blue light. Okay, so those are the eight major functions of the hypothalamus. I hope this helps. Have a wonderful day. Be blessed.