Name: 大腦 (The Brain)
Uploaded: 2021-01-14T05:05:27.000Z
Duration: 13 min 56 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

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