The Brain

Summary

Mr. Andersen's video offers an insightful exploration of the brain's structure and function, highlighting the anatomy and physiology of its 17 key components. Starting from the brainstem's vital role in basic life functions to the cerebrum's complex integration of sensory input, the video simplifies complex neurological concepts. It also delves into the significance of the cerebellum for motor control, the thalamus as a data router, and the hypothalamus for homeostasis, culminating in a comprehensive review of brain functions.

Takeaways

• 🧠 The brain's structure and function are crucial to understand, with structure referring to its composition and function to what it does.
• 🐠 Animals, especially those with bilateral symmetry, use brains to organize movement and process sensory information.
• 🦈 Primitive brains, like those of a shark, have a consistent structure with four main parts: the spinal cord, hindbrain, midbrain, and forebrain.
• 👶 Human brains start with a similar structure during embryonic development but undergo significant changes, with the forebrain expanding to accommodate higher functions.
• 🌟 The brainstem, consisting of the medulla oblongata, pons, and midbrain, is essential for basic life functions and information routing.
• 🤸‍♂️ The cerebellum is responsible for motor control, coordination, and motor memory, playing a key role in physical activities.
• 🔄 The thalamus acts as a router, sorting and directing sensory and motor information to the appropriate parts of the brain.
• 🌡️ The hypothalamus is critical for maintaining homeostasis, regulating body temperature, osmolarity, and circadian rhythms.
• 💧 The posterior pituitary, part of the brain, controls the release of hormones like antidiuretic hormone and oxytocin.
• 🧠 The cerebrum is the largest part of the brain, responsible for the integration and interpretation of sensory information.
• 🔄 The cerebral cortex, making up 80% of the brain, is divided into four lobes, each with specific functions related to executive control, sensation, vision, and language.

Q & A

What is the distinction between 'structure' and 'function' in the context of the brain?

In the context of the brain, 'structure' refers to the physical makeup or anatomy of the brain, which includes its different parts and how they are organized. 'Function', on the other hand, refers to what these parts do, essentially the physiological processes they are involved in.

Which organisms have brains and why?

Animals have brains because they use nerves and muscles to move around, and they need to organize that movement. Brains are responsible for processing sensory information and coordinating responses to stimuli.

What are the two basic body plans of animals and how does this relate to the brain's function?

The two basic body plans of animals are radially symmetrical, where the body parts are arranged around a central axis like a tire, and bilaterally symmetrical, where the body can be divided into mirror-image halves. As animals became bilaterally symmetrical, they needed a more organized system to control movement, which is where the brain comes into play.

What are the four basic humps or structures found in primitive brains?

The four basic structures found in primitive brains are the spinal cord, hindbrain, midbrain, and forebrain. These structures are consistent across all animals and are responsible for basic to complex functions, respectively.

How does the brain of a shark compare to the primitive brain structure?

The brain of a shark is very similar to the primitive brain structure, with identifiable spinal cord, hindbrain, midbrain, and forebrain. This indicates that the basic organizational pattern of the brain has been conserved across different species.

What is the significance of the forebrain in human development?

During human development, the forebrain expands significantly in size compared to its initial embryonic state. It is responsible for higher cognitive functions such as emotions, memories, and complex thinking.

What are the three main parts of the brainstem and what are their functions?

The brainstem is composed of the medulla oblongata, pons, and midbrain. It is responsible for maintaining basic life functions like breathing, circulation, digestion, and swallowing, as well as routing and filtering sensory and motor information.

What is the primary function of the cerebellum?

The cerebellum is primarily responsible for motor control, providing coordination and motor memory, which allows us to perform actions like riding a bicycle without consciously thinking about it.

What does the thalamus do and how is it likened to in the script?

The thalamus acts as a router, sorting and sending sensory and motor information to the appropriate parts of the brain for further processing.

What is the role of the hypothalamus in maintaining homeostasis?

The hypothalamus is responsible for maintaining homeostasis by regulating body temperature, osmolarity, and other internal states. It also plays a role in circadian rhythms and hormone release.

What is the function of the cerebrum and how is it divided?

The cerebrum is responsible for the integration and interpretation of sensory information. It is divided into two hemispheres connected by the corpus callosum, each with specialized functions and showing lateralization in tasks like mathematical reasoning and facial recognition.

What are the four lobes of the cerebral cortex and their respective functions?

The four lobes of the cerebral cortex are the frontal lobe (executive functions and emotional control), parietal lobe (sensation and environmental interaction), occipital lobe (vision), and temporal lobe (language, hearing, and memory).

How does the somatosensory cortex differ from the motor cortex in terms of function?

The somatosensory cortex is responsible for processing sensory information coming into the brain, while the motor cortex is responsible for sending motor commands out of the brain to initiate movement.

Outlines

00:00

🧠 Introduction to Brain Structure and Function

Mr. Andersen introduces the concept of brain structure and function, emphasizing the distinction between what the brain is made of (anatomy/structure) and what it does (physiology/function). He outlines the plan to discuss 17 different brain structures, highlighting their roles in processing sensory information and initiating motor responses. The video aims to educate viewers on the basic organization of the brain and its evolution from a simple to a complex structure, especially in bilaterally symmetrical animals like humans. The script also touches on the importance of the brain in organizing movement and the basic body plans of animals, including radial and bilateral symmetry.

05:02

🐟 Brain Evolution and Basic Anatomy

This paragraph delves into the evolution of the brain, starting from primitive structures with four humps: the spinal cord, hindbrain, midbrain, and forebrain. It explains that these structures are consistent across all animals, using the shark as an example of a simple brain. The script then transitions to human development, comparing the embryonic brain to the adult brain, highlighting the significant growth of the forebrain, which is responsible for higher functions like emotions, memories, and thinking. The paragraph concludes with an overview of the basic anatomy of the brain, including the brainstem, cerebellum, thalamus, hypothalamus, and cerebrum, and their respective roles in basic life functions and sensory-motor integration.

10:05

🔍 Advanced Brain Functions and Lateralization

The script explores the advanced functions of the cerebrum, emphasizing its role in data integration through billions of interconnected neurons and synapses. It describes the use of functional MRI to visualize the brain in action and understand regional functions. The discussion includes the concept of brain lateralization, with the left hemisphere associated with mathematical reasoning and logic, and the right hemisphere with facial recognition. The paragraph also explains the functions of the basal ganglia in motor control and the cerebral cortex, which comprises the frontal, parietal, occipital, and temporal lobes, each with distinct responsibilities for executive functions, sensation, vision, and language/hearing/memory, respectively.

📝 Review of Brain Structures and Functions

In the final paragraph, Mr. Andersen reviews the 17 brain structures and their functions covered in the video. He encourages viewers to recall the parts of the brainstem (medulla oblongata, pons, midbrain), the cerebellum's role in coordination and motor memory, the thalamus's function in information sorting, and the hypothalamus's role in homeostasis. The review also covers the posterior pituitary's hormonal functions, the corpus callosum's connection between brain hemispheres, and the roles of the basal ganglia in motor control. The cerebral cortex's lobes and their associated functions are summarized, along with the somatosensory and motor cortices. The script concludes by suggesting that viewers review the material if they do not remember all the structures and their functions.

Keywords

💡Brain Structure

Brain structure refers to the physical composition and organization of the brain, including its various parts and how they are arranged. In the video, the concept of brain structure is central to understanding how different parts of the brain are responsible for different functions. For example, the script mentions the brainstem, cerebellum, and cerebrum as key structural components, each with distinct roles in the brain's overall function.

💡Function

Function, in the context of the video, pertains to the purpose or activity for which a brain structure is responsible. The script emphasizes the relationship between structure and function, noting that while structure is about composition, function is about what the brain does, such as processing sensory information and controlling movement.

💡Anatomy

Anatomy, as used in the script, is the study of the structure of organisms and their parts. It is closely related to the concept of brain structure, as the video discusses the anatomical layout of the brain, including its different regions and how they are interconnected.

💡Physiology

Physiology is the study of the functions of living organisms and their parts, which in the video, complements the concept of anatomy. The script uses the term to refer to the functional aspect of the brain, such as how different brain regions contribute to processes like sensory integration and motor control.

💡Neurotransmitters

Neurotransmitters are chemical messengers that transmit signals across a synapse from one neuron to another. Although not explicitly mentioned in the script, the concept is fundamental to understanding how the brain processes information, as the script discusses the integration of sensory information and the coordination of movement, both of which involve neurotransmitter activity.

💡Bilateral Symmetry

Bilateral symmetry is a type of body plan in which an organism can be divided into two mirror-image halves along a plane. The script uses the concept of bilateral symmetry to explain how animals, including humans, organize movement and sensory input, with a clear distinction between the right and left sides of the body.

💡Hindbrain

The hindbrain is a part of the brainstem that includes structures responsible for basic life functions. In the script, the hindbrain is mentioned as being involved in keeping the heart beating, maintaining circulation, and digestion, highlighting its role in vital physiological processes.

💡Forebrain

The forebrain is the anterior part of the brain, involved in higher cognitive functions such as emotions, memories, and thinking. The script emphasizes the large size of the forebrain in the adult human brain, indicating its importance in complex mental activities.

💡Cerebellum

The cerebellum is a region of the brain that plays an important role in motor control, coordination, and motor learning. The script describes the cerebellum as being responsible for coordination during activities like sports and for motor memory, such as learning to ride a bicycle.

💡Thalamus

The thalamus is a structure that acts as a relay station for sensory and motor signals, as well as a router for information going to the cerebral cortex. The script likens the thalamus to a router, sorting and directing sensory and motor information to the appropriate parts of the brain.

💡Hypothalamus

The hypothalamus is a small region of the brain that maintains homeostasis and regulates body temperature, hunger, thirst, and other autonomic functions. The script identifies the hypothalamus as being crucial for maintaining the body's internal balance and its role in circadian rhythms.

💡Cerebrum

The cerebrum is the largest part of the human brain, responsible for higher brain functions, including perception, thought, consciousness, and judgment. The script discusses the cerebrum's role in integrating sensory information and its vast network of neurons and synapses, which facilitate complex cognitive processes.

💡Corpus Callosum

The corpus callosum is a broad band of nerve fibers that connects the left and right hemispheres of the cerebrum, facilitating communication between them. The script mentions the corpus callosum as the connection that allows for the integration of information processed in different parts of the brain.

💡Basal Ganglia

The basal ganglia are a group of nuclei in the brain involved in motor control and learning. The script describes the basal ganglia as being crucial for motor control, with disorders such as Parkinson's disease being linked to dysfunction in this area.

💡Cerebral Cortex

The cerebral cortex is the outer layer of the cerebrum, consisting of gray matter and responsible for higher cognitive functions. The script notes that the cerebral cortex makes up about 80 percent of the brain and is divided into four lobes, each with specific functions related to the brain's overall activity.

💡Lateralization

Lateralization refers to the specialization of function in one cerebral hemisphere over the other. The script discusses lateralization in the context of the brain's hemispheres, noting that certain functions, such as mathematical reasoning and facial recognition, are typically associated with specific hemispheres.

💡Somatosensory Cortex

The somatosensory cortex is an area of the brain involved in processing sensory information from the body, such as touch and temperature. The script describes the somatosensory cortex as a key region for integrating sensory input and highlights the disproportionate representation of different body parts in this area, such as the fingers.

💡Motor Cortex

The motor cortex is a region of the brain that controls muscle movements. The script identifies the motor cortex as the area responsible for sending motor commands from the brain to the rest of the body, illustrating the brain's role in initiating and controlling movement.

Highlights

Introduction to the brain's structure and function, emphasizing the distinction between anatomy and physiology.

Explanation of how animals with nervous systems, especially bilaterally symmetrical ones, use brains to organize movement.

Description of the primitive brain's common structure, including the spinal cord, hindbrain, midbrain, and forebrain.

Comparison of shark's brain to the primitive brain structure, highlighting the consistency across animals.

Discussion on the development of the human brain from embryo to adult, with a focus on the enlargement of the forebrain.

Introduction of the 17 parts of the brain that will be covered in the video.

Detailed anatomy of the brainstem, including the medulla oblongata, pons, and midbrain, and their functions.

Function of the cerebellum in motor control and motor memory.

Role of the thalamus as a router for sensory and motor information in the brain.

Importance of the hypothalamus in maintaining homeostasis and its influence on circadian rhythms.

Explanation of the pituitary gland's role in hormone regulation and its connection to the brain.

Overview of the cerebrum's function in integrating sensory information and higher cognitive processes.

Description of the cerebral cortex's composition, making up about 80% of the brain and its four lobes.

Functions of the frontal lobe in executive functions and emotional control.

Role of the parietal lobe in processing sensory information from the environment.

Importance of the occipital lobe in vision and the temporal lobe in language, hearing, and memory.

Discussion on the somatosensory cortex and motor cortex as key areas for sensory input and motor output integration.

Insight into the brain's plasticity and the possibility of function redistribution after hemispherectomy.

Review of the 17 brain structures and their functions to reinforce learning.

Transcripts

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.