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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.
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大腦 (The Brain)

2475 分類 收藏
Hhart Budha 發佈於 2014 年 6 月 12 日
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