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  • Hi. It's Mr. Andersen and in this video I'm going to talk about the brain structure and

  • function. Remember structure is what it's made up of. And function is what does it do.

  • We sometimes refer to this as the anatomy or structure and physiology or the function.

  • And so the cool thing is that we're going to go through seventeen different structures

  • in the brain, kind of lay out the basic plan of the brain. But you are using your brain

  • to process it. And if you do a good job when we get to the end and I review all the parts,

  • you should be able to tell me what their structure is and what their function is. And so what

  • type of organisms have brains? It's the animals. Animals use nerves. They have muscles to move

  • around. And so they have to organize that movement. And so they use a brain. And so

  • if we look at the two basic body plans of animals, some are radially symmetrical. In

  • other words they're built around almost a tire. And then some are bilaterally symmetrical.

  • In other words a tiger you could draw a line right down the middle. There's going to be

  • a clear right side and a left side. There's going to be a clear front and end. And as

  • we became bilaterally symmetrical we had to organize that movement. And so this is a simple

  • animal body plan. And so this animal is going to move towards the right. And as it does

  • so it has to take in information. We call that sensory information using neurons. And

  • so right now you're taking in sensory information from your eyes, from your ears. And then inside

  • your brain you're going to integrate that information. You're going to make sense of

  • it. And then you're going to figure out what you want to do. How you're going to act dependent

  • upon that. And so then we have this loop of motor neurons out. Or motor nerves. And so

  • this loop in simple animals is also important in understanding how our brain works. But

  • if we look at these real primitive brains we find that they have a real common structure.

  • They have these four humps. And we call those, well the first one is not a hump, but the

  • spinal cord. We then have the hindbrain, the midbrain and then we finally have the forebrain.

  • And we find this consistent throughout all animals. And if we look at something like

  • a shark, it pretty much looks just like that primitive brain. You can see down here we've

  • got the spinal cord that's bringing information in. We then have the hindbrain, the midbrain

  • and the forebrain. And so one thing you should remember is that the closer we are to that

  • spinal cord, the more basic the functions are. And so we're right down in this hindbrain.

  • It's going to be basically keeping the heart beating. Keep the circulation going. Digestion

  • in the shark. But when a shark decides to attack you or it has some kind of an emotional

  • response, that's going to be way up here in the forebrain. Now if we look at you when

  • you were really little, when you were an embryo, you had a brain that looked very similar.

  • You had a spinal cord. You then had a hindbrain. You had a midbrain. And then you had a forebrain.

  • But during development that brain changes radically. And so this is what an adult brain

  • looks like. So we still see that spinal cord. We then have the hindbrain. We have the midbrain.

  • But look how large that forebrain is going to be. So that's where all of those emotions

  • and memories and all of that thinking, we generally attribute to the brain is going

  • to be in the forebrain. And so let's get to the actual anatomy. And so there are going

  • to be 17 parts that we're going to go through. So you should always be thinking what's the

  • name of the structure? Where is it? And then what's the function, what does it do? So if

  • we look at a basic brain plan we find these four things jump out right away. We're going

  • to see the brainstem. We then see a cerebellum on the back of the brain So again to get yourself

  • oriented right the eyes are going to be right up here. So this would be towards the back

  • of the head. So that's going to be the cerebellum. We then have the area of the thalamus hypothalamus.

  • And then finally we have the cerebrum which is going to be that dominant upper portion

  • of the brain. And so let's begin with the brainstem. The brainstem is broken down into

  • three individual structures. So if we start at the bottom we've got the medulla oblangata,

  • the pons and then we finally have the midbrain. And so those three things, medulla oblangata,

  • pons and midbrain make up what we call the brainstem. So that the structure. What's the

  • function? Well it really does two things. The first thing it's going to do are these

  • more basic needs. It's going to keep yourself breathing, keep circulation going, digestion,

  • swallowing. All of that is going to be controlled by the brainstem. If there's any damage to

  • the brainstem it's going to be catastrophic. What else does it do? Then we have information

  • coming in. So we have sensory information, just like that worm did, coming up to the

  • brain. And then we have motor nerves going out. And so the brainstem is important in

  • routing that information and filtering that information, sending it where it needs to

  • go. What's behind that? We have the cerebellum The cerebellum, and the function of that is

  • motor control. So as you do sports, for example, it's the cerebellum that's giving you that

  • coordination. And it also gives you motor memory. So as you learn to ride a bicycle

  • and you remember how to ride a bicycle that's going to be thanks to your cerebellum. If

  • we keep moving up we now have the thalamus. The thalamus again sits right on top of the

  • brainstem. And so the best analogy I could come up with is a router. It's basically sorting

  • data and sending it where it needs to go. If we were to look below that there's a little

  • structure here that's incredibly important. It's called the hypothalamus. That's going

  • to be really right above the roof of your mouth. What is that accountable for? It's

  • homeostasis. So it's maintaining body temperature. It's maintaining osmolarity. All of that stuff

  • is contained right up in the hypothalamus. Also important in circadian rhythms. And then

  • if we look right below that you can see a little gland hanging out. And one-half of

  • that pituitary gland, the posterior pituitary, is technically part of the brain. And it's

  • important in basically sending off hormones. And so there are nerves that flow into that

  • pituitary and it's sending out things like antidiuretic hormone. That keeps your water

  • balance the same. Oxytocin would be another important hormone that comes out of there.

  • If we keep moving up then we get to the level of the cerebrum. What's the function of the

  • cerebrum? That is integration. So what we're doing is making sense of all of that data

  • that comes in. Now what makes up that cerebrum are going to be all these neurons. There's

  • tons of neurons that are connected together. Billions of neurons. And billions and billions

  • of synapses or connections between these neurons. And that's where we're making sense of information

  • as it comes in. Now if you were to look at this image right here, so of that brick wall,

  • so take a moment to look at that and I'm going to show you some other images. Now focus on

  • this. And then that. And then that. And what we find is as you look at those images your

  • brain is integrating. It's making sense of all that information. And it used to be a

  • black box. We didn't know really what was going on. But now we can use technology like

  • a functional MRI. A functional magnetic resonance imaging. And what we're looking at here is

  • a brain in action. So this same study was done on females. And what they would show

  • them is something neutral, like a brick wall. And then a kitten. And then something like

  • dirt. And then something like puppies. And so what we're seeing is as those images are

  • switching back and forth we can start to see where blood is flowing around in the brain

  • and we can start to figure out what the different parts of the brain actually do. We're able

  • to figure out their function. So when we're looking at the cerebrum every picture that

  • I've shown you is from the side. So the eye is up here. But if we were to rotate that

  • 90 degrees now were looking at it head on, we'll find that there are two hemispheres.

  • There's going to be a right and a left hemisphere. Now they are connected in the middle using

  • something called the corpus collosum. So that's a connection of nerves in between the two

  • hemispheres. And we do tend to show lateralization. There are going to be certain things that

  • we put kind of on the left side of our brain, like mathematical reasoning and logic. And

  • things that we put on the right side like facial recognition. Now this is plastic. In

  • other words we can move these functions back and forth. And you can even have a radical

  • hemispherectomy, where you're cutting one of these out and you still have a functioning

  • brain. Now if we were to go right below the corpus collosum we get into this area called

  • the basal ganglia. And it's made up of a bunch of nuclei. What are nuclei? Or what is a nucleus

  • in a brain? It's basically a bunch of neurons that are right next to each other that have

  • the same function. And so all of these nuclei together make up what's called the basal ganglia.

  • And you can see this would be the corpus collosum, connecting it together as well. So this is

  • below the cerebral cortex. What's the function of that? Well scientists have been able to

  • figure out there is this complex interaction of inhibition and excitatory response between

  • these neurons. And basically it controls a lot of our motor control. And if you have

  • somebody who has Parkinson's disease then we're having problems in this basal ganglia

  • area. As we move farther up the brain we eventually get to the cerebral cortex. And that's going

  • to make up about 80 percent of the brain. So it's most of the brain itself. And it's

  • broken apart into these four lobes. And so if we start in the front of the brain we have

  • what's called the frontal lobe. What's the function of that? It's mostly executive function.

  • So it's kind of like the boss of your brain. It's emotional control up there. And if we

  • have people who have damage to that frontal lobe they have really huge emotional swings.

  • As we move back towards the back of the brain we get to the parietal lobe. What's the function

  • of that? It basically is sensation. It's you dealing with and reacting to your environment.

  • So we have a lot of neurons coming in here from a sensory input. As we move to the back

  • we have the occipital lobe. The function of that is vision, primarily vision. And then

  • we move on to the side. We have what are called the temporal lobe. Temporal lobe is going

  • to be important in language. It's important in hearing. It's also important in memory.

  • We have a lot of memories in there. And so each of these lobes have different functions

  • that are associated with it. And hopefully those little icons help you remember those

  • functions. Now if we were to go inside the parietal zone we'd find a really important

  • part here. It's called the somatosensory cortex. And that's where sensory information is coming

  • into the brain. And then on the other side of the lobe we have what's called the motor

  • cortex. And so going way back to that worm, we have information coming in, sensory information.

  • And then we have motor output coming out. And so that's going to be a point of integration

  • where we get information in. Decide what we want to do with it. And then send that message

  • back out. Now if we were to look at that somatosensory cortex and map it along the cerebral cortex,

  • we would find that we dedicate huge amounts of that brain surface area to things like

  • your fingers, your tongue, your lips. In other words we have way more neurons and way more

  • sensory information coming in from your fingers as opposed to, for example, your back. We

  • don't have as much of it dedicated to that on the back side. We could also functional

  • MRIs and then even an operation to figure out where a lot of these things are located,

  • like speech and smell and hearing. But over the future we're going to get really really

  • good at figuring out specifically what are all of the different parts of the brain. What

  • are the nuclei? What do they do? And even mapping it down to the level of the neuron.

  • So how did you do? Do you remember those 17 different structures and their functions?

  • Well it's time to review. So let's go through it. What's this one at the bottom? Overall

  • we call that the brainstem. Hopefully you got that. What are the three parts of the

  • brainstem though? Do you remember that? Could you pause the video and then say what they

  • are? Well starting from the bottom remember we have the medulla oblongata. We then have

  • the pons. And then we have the midbrain. So that's going to be the structure and where

  • it's found. Can you remember the two functions of the brainstem? Two big things were, number

  • one is to maintain breathing, heart rate, digestion, swallowing. So these fundamental

  • properties of life. But what's the second one? Remember it's to sort information going

  • up and down. What's behind that? What's that structure called? That is the cerebellum.

  • And so what's the cerebellum do? Remember that's coordination, motor control and also

  • motor memory. Do you remember what sits right up above the brainstem? That is the thalamus.

  • What's the thalamus do? Remember it sorts information as it moves up to the upper parts

  • of the cerebrum. What's below that? That is the hypothalamus. Underneath that. What does

  • that do? Remember that's homeostasis. It's maintaining that internal body state. Do you

  • remember what hangs off the bottom of that? That is the posterior pituitary. Hopefully

  • you're doing well so far. If we keep going then, what is this upper portion of the brain

  • called? We call that the cerebrum. Okay let's keep going into the cerebrum the. So do you

  • remember what's that connection between the two hemispheres of the brain? We call that

  • the corpus callosum. And do you remember what we call those little nuclei that are found

  • below that cerebrum? Those are called the basal ganglia. And they're really important

  • in motor control. And remember the corpus callosum allows our hemispheres to connect.

  • If we were to go up to the upper portion, what do we call this, you know, highly folded

  • upper portion of the cerebrum? That's called the cerebral cortex. Do you remember what

  • the front lobe is called? That was pretty easy. That's called the frontal lobe. What

  • about the yellow lobe right here? That's called the parietal lobe. Do you remember what they

  • do? Frontal lobe remember is executive or boss like functions. And then parietal is

  • going to be sensation of the environment. What about at the end? Do you remember that?

  • That's called the occipital. And then what about the bottom? That's the temporal. Occipital

  • remember is the location where we have vision. And then temporal is going to be more language,

  • hearing, memories are there. Now there are two other parts in our lobe. So what do we

  • call this area right here? And then this area right here? Those are called the somatosensory

  • cortex. Remember that takes in information, makes sense of it. And then we have the motor

  • cortex which is sending information out. So those are those 17 structures. If you don't

  • remember them you may want to watch the video again. Maybe make some flashcards. But that's

  • the brain. And I hope that was helpful.

Hi. It's Mr. Andersen and in this video I'm going to talk about the brain structure and

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大腦 (The Brain)

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    Hhart Budha 發佈於 2021 年 01 月 14 日
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