 Hey everybody, Dr. O here. So welcome to the brain. We're going to cover the brain in great detail, but in this video I just want to do a 10,000 foot view of what are all the key things that are happening in all the key areas of the brain. So just a nice introduction. So here we see the brain. It contains 100 billion neurons, 98% of your body's neural tissue is crammed into the brain, which is why it has all those hills and valleys to increase surface area. The average brain weighs somewhere around three pounds, which makes it between two and 3% of your body weight that yet it uses 20 to 25% of your resources. So clearly a very important structure. So I want to start, I like to look at it globally. I always like to start at the bottom and work our way up though, because usually when we talk about the brain, we talk about the cerebrum and our and higher mental functions, functions like our intelligence and all of that. But I actually like to start at the bottom and work our way up. So globally, when I look at the brain, the lower something is it the more important it is for basic survival, basic like life support functions, those kind of things. The higher it is, the more important it is to being a human or a being similar to ours as far as our ability to predict the future and understand the potential outcomes of our actions and recognize beauty. These types of things are going to be these higher order functions. You find them at the top of the brain. We share the bottom of our brain with a lot of other types of animals. The brainstem is called our lizard or reptilian brain for a reason. So basic survival stuff needs to be lower. So that's why I like to start at the bottom and work up. Let's go ahead. We'll start with the brainstem here, which is three parts. The midbrain, also known as the mesencephalon, the pons, and the medulla ablangata, which I love to say. So let's start there. The medulla ablangata is what connects the spinal cord to the brain. So it's the relay center. It carries information to and from the spinal cord to the brain. So the medulla ablangata is where basic life support functions occur. Autonomic control of things like digestion, heart rate, blood pressure control, these types of things. Another key area I like to highlight here is this is where the respiratory rhythmicity centers are. This is the part of the brain that tells you to unconsciously or automatically breathe in, breathe out, breathe in, breathe out. So that's called the respiratory rhythmicity centers. I point that out because as you'll see in a moment, the rate centers are somewhere else. So then we have the pons. The pons is what connects the cerebellum to the rest of your nervous system. So there are fibers and tracks going to and from the cerebellum, the travel up to the cerebrum, across to the brainstem, and down to the rest of the body. So the pons is this relay center between the cerebellum and the rest of your nervous system. Also, you're going to see sub-conscious, motor, somatic, and visceral motor control is going to be here. But the other one that I generally think of with the pons is what I just said, the respiratory rate centers. So the medulla ablongata is what tells you to breathe in and breathe out. The pons is what tells you if you should be breathing faster or slower. And that's primarily controlled by carbon dioxide levels. So if you have too much CO2 in your body, the pons will sense that with chemoreceptors and will tell you to breathe faster to blow it off. If you have too little carbon dioxide, then your breathing will slow. So we cover that a lot more in the respiratory system. That's the pons, the connection to the cerebellum, respiratory rate centers. Then we have the midbrain or the mesencephalon, which means midbrain. This is going to be where the two key things here are visual and auditory reflexes. So we don't see and hear in this area. But if we hear something, we turn towards it, we hear a loud noise, we see something moving, we track it and see what it is. These basic survival instincts that would have helped us find food or not become food are there in the midbrain. So I just can't help it if I'm teaching a class and somebody walks by the window like I have to look. If you hear a loud noise, you might protect yourself or you might look towards it. These are visual and auditory reflexes at the level of the midbrain or mesencephalon. The other thing is inside the midbrain we have the key area of what's called the reticular formation. And the key there is it maintains our consciousness. And so when I say consciousness, I don't mean like conscious like I'm aware of it. I mean like I'm awake and alert. So the maintenance of consciousness. So when you wake up, if you're well rested, this thing's firing right along and you're very conscious. As the day goes on, it gets harder and harder for this part of your brain to keep you awake. And the longer you've been awake, the harder and harder it gets, right? We can try to fool it with things like coffee, but that's just how it is. All right, so the Madhulalangata think basic life support, respiratory rhythmicity centers. Pons, connection between the cerebellum and the rest of your nervous system. And respiratory rate centers, midbrain or mesencephalon, visual and auditory reflexes, and the maintenance of consciousness. Next right above that we have the diancephalon. And we'll cover these in great detail later. But the diancephalon is made of three parts. The thalamus, the hypothalamus, and what you can't see here is called the epithalamus. Let's just get that one out of the way. The epithalamus is where the pineal or pineal gland is, which it plays a role in your circadian rhythms. And because of the production of melatonin, we cover that with the endocrine system. Let's talk about the thalamus. When I think of it, the first thing I think of is, yes, it's a relay center. So it relays and processes information. But its primary job is to filter information heading up above it to the cerebrum. So imagine it being like a gatekeeper, about 99% of what you're being stimulated by right now is being filtered out by the thalamus. It determines what's the 1% that I should bother the cerebrum with. So the thalamus is a filter. That's its primary function. The hypothalamus, and we'll do a whole video on the eight major functions of the hypothalamus, but in a word, the hypothalamus maintains homeostasis. So a lot of your emotions come from here. It produces hormones, which we cover with the endocrine system, basic autonomic functions, things like hunger and thirst. These things are all there in the hypothalamus. What I like to say about the hypothalamus is it doesn't make you do anything, it makes you want to do things. This is where like your drives and urges are. So if anything, you all know what the hypothalamus does. It tries to get you to do things that it wants you to do, whether you want to or not, right? So we talk about willpower. So willpower is what's combating the hypothalamus. If you're trying to quit smoking, but the hypothalamus wants you to keep smoking, then you're going to have the urge to smoke. And you can override that, and I hope you do if you're trying to quit. But so you all know what willpower is. I guess this is the opposite of it, right? So it doesn't make you do things. It makes you want to do things. It makes you want to eat that donut and do these types of things. So that is the thalamus and the hypothalamus. You also see on the image here that the pituitary gland. The hypothalamus is connected to the pituitary gland. So the hypothalamus is part of your nervous system. The pituitary gland is part of your endocrine system. It's your master gland when it comes to the endocrine system. So the hypothalamus is the bridge between your nervous system and your endocrine system, but we'll cover that in way more detail in AMP2. Okay, moving up higher, or actually back, now we're at the cerebellum. So three words for the cerebellum. Balance, posture, and coordination. That's the way I look at it. This is the second largest part of your brain. And it basically, the name means small brain. It coordinates like repetitive body movements, posture, the things I just said. So like a test to see if the cerebellum is working is simply just something like this with your hands, repetitive body movements. If you can do that, then your cerebellum is working. If you've ever seen like a field sobriety test to see if someone is intoxicated and they've been driving, what they're basically looking for is cerebellar ataxia, which you basically develop if you're drunk. So you can't walk a straight line, you can't touch your nose because your cerebellum is not functioning properly because you're intoxicated. We'll do a separate video about the cerebellum. But one last thing here is this is kind of where your muscle memory develops. And it does take a lot of trial and error. When you first start to do physical things, like even just sitting up when you're a baby, they're impossible, then they're difficult, then they're easy. Well, the cerebellum can kind of learn as you go. And I find that interesting. So we'll come back to that. And lastly here, we do have the cerebrum. This is going to be the largest part of our brain, a huge part of the brain. Our frontal lobe is basically pound per pound larger than any living thing. It controls what we call your higher mental functions. So thought, memory, conscious movement. All of these things are controlled by the cerebrum. The key word there is conscious. Any conscious thought process that you're aware of, either something I can feel or something I'm doing on purpose. These are things that are either the information's being sent to the cerebrum or sent away from it. The surface area of the brain, we'll cover this more later. But you see that those hills and valleys, so those elevated ridges are called a gyros or gyrie. The shallow depressions there are called a sulcus or a sulci or sulci in pleural. Then you do have a deep groove there called a fissure that longitudinal fissure separates the two cerebral hemispheres. So we'll do a video where we cover that in more detail as well. Okay, I know that's quick, fast, and furious. But that's a big high level overview of the major functions occurring at each part of the brain. We'll do a separate video where we dive into all of them in more detail. I hope this helps. Have a wonderful day. Be blessed.