An Introduction to the Brain

hi everyone its mr. senti and today I have the pleasure that's right I really do have the pleasure of discussing one of the most important organs in the entire body most complex organs of the entire body and you might have guessed it by the the title of the video this is going to be a conversation about the brain hopefully you'll enjoy it you know the brain is so amazingly complex and intricate that I don't know that it could be discussed in a protein in one video and so this is just an introduction to it and I hope to look at some of the more important regions of the brain talk a little bit about the anatomy and physiology of the brain maybe you can kick around some of the developmental aspects of the brain going from an embryo to an adult brain talk about some of the protective layers that surround the brain and and some of the ventricles or chambers that are found inside the brain so hopefully you'll find it intriguing fun fact right out the start is that 97 97 % of all the body's neural tissue is inside this three-pound structure known as the human brain pretty incredible now it's large it's delicate it contains all kinds of passageways between the neurons and all kinds of information is being shared and networked inside the brain and as I mentioned before that it weighs 3 pounds the truth is inside the body it's less than that significantly less because it's floating and CSF which is cerebral spinal fluid and so that helps to not only cushion and protect the brain but it also lightens the load and so each of the major regions that are going to discuss kind of going from an inferior location down here in the medulla all the way up to the the cerebral cortex right on the very superior aspect of the brain you're moving from what are more although important simple functions to more complex functions as you move up and they become more variable as well and so that's sort of the the basic principle now talk about complexity back up over here in the in the cerebral cortex right up here on the very top of the brain that's where our consciousness is that's where our thought and decision-making comes from our intelligence compassion love the care for individuals our science comes from this particular area you know all of these are produced in the cerebral hemispheres of the brain and it's quite remarkable and what the brain is capable of and likewise on the lower area of the brain which is referred to as the brainstem anything inferior to the brainstem is the spinal cord and so but this is not insignificant either though that's the cool thing the brain stem controls basic functions like which are crucial like breathing and heart rate and respiratory rate and all kinds of things like that and so in addition to that it also is where the messages that flow between the brain and the rest of the body are going through the brainstem so that's that's significant as well so speaking of that brain stem the brain stem is is sort of considered in three parts you have this midbrain right here you have an area called the pons and the medulla I refer to before but it's technically the medulla oblongata kind of a cool name and those are really important those are our essential features like again breathing respiratory rate circulation blood pressure digestion is all being controlled in this most inferior and most fundamental portion of the brain that sort of occurs automatically okay now in addition to those crucial functions it's also the place where sensory neurons are travelling and it's all it's that the place where in other words where we're feeling things in our peripheral nerves there these things need to travel up through the brainstem up to the cortex and then likewise the cortex is then sending down information through the brainstem commands to move muscles so those are our neurons are being relayed as well so the brain stem pretty important cool stuff going on and so the brain stem again is you know located here this purple is this mid in this midbrain area this is a ventral view of the of the brain sheep brain I should add in case you're wondering about its size and so this is the midbrain there this is the pons which is again a little bit more inferior to also a ventral view inferior to the to the midbrain and then there's the module which is the last region of the brain right there and so those three make up the brainstem okay and then we have this interesting structure over here the cerebellum and that you may be familiar with it's one of the more conspicuous regions of the brain it's sort of like a little tiny mini brain if you will its posterior this is interior this is posterior toward the back right here and what it does is it basically controls your coordinated movements like for example when you're playing sports body control it's sort of your muscle memory if you will like for example if you if you when you're a young when you learned how to to ride a bike and you hadn't been riding in a long time that muscle memory is stored here in the cerebellum so it controls movement this sort of middle area referred to as the thalamus and actually below the thalamus is the hypothalamus and the hypothalamus actually proceeds all the way down on this little stalk to the pituitary gland you have an anterior lobe or I'm pointing in a posterior lobe technically the posterior lobe of the pituitary gland it's all part of the hypothalamus and so this thalamus region is sort of a it does a lot but it it basically sends signals from messages coming from your ear ears in your eyes and your mouth and your skin and or relays that sort of like a a router that that distributes that information to particular regions in the cerebral cortex in order to make decisions it sort of diagnosis the situation it sort of assesses that sensory information and then sends it above so it sort of sorts the data and sends it above for decision-making on that that's kind of a cool aspect and then the cerebrum which which makes up the the bulk of the volume of the brain is where a lot of this integration takes place a lot of the decision-making the thinking and all of that goes on and I was mentioning before they go back to it here this right below the thalamus is the hypothalamus right in this area right in here where the arrow is pointing and again the function of that is body temperature regulating body temperature just all kinds of really important but fundamental things it helps to control circadian rhythm osmotic regulation is is controlled there in addition to that if that wasn't enough it does produce a few hormones which are then transmitted via neurosecretory cells into the posterior lobe as I was mentioned before and then are secreted into the blood hormones that are produced in the hypothalamus that are secreted from the posterior lobe or antidiuretic hormone which helps it you to hold on to water and not urinate as much of water and also a hormone called oxytocin which is involved in labor okay and all of those those two hormones are secreted from the posterior lobe okay so the cerebrum is again this location in the body where all kinds of cool stuff is happening and so ultimately it's where all of these messages are being integrated and so it's it's all this thinking going on on the upper part of the brain and so for literally decades scientists have been trying to figure out what is happening and in terms of different locations of the cerebrum and so one of the one of the major breakthroughs in this field of study is the use of functional Nicorette residents imaging or MRI but the this is different from a regular MRI that that uses magnetic imaging for for taking still shots functioning magnetic resonance imaging is a continuous so it's it's sort of like a film and it can last the patient can go inside of this and for maybe 3 to 5 minutes and pictures are taken every few seconds and so it sort of is in real-time and what it does is it's able to measure the brains activity while doing a variety of functions and so well the patient is inside let me show you inside the functioning MRI and again that I need to point out the fact that this is decorated like like a coral reef because again if you're in there for a prolonged period of time it's it's kind of intense and so for kids some hospital facilities have decorations like this which i think is kind of a cool thing I personally I would like to go into one of these myself it's a little scary that might ease the tension and so when you're inside the machine with what's happening is you're able to do certain things like that you're asked to listen to if something or to see something or listen to or to smell something and so what can happen is areas in the the cerebral cortex in other words the upper part of the brain there's going to be increased blood flow to that area that in the particular region that that activity is responding to or thinking about and so the fact that and it's kind of complicated but basically when blood flow increases oxygen is then delivered to that area through oxyhemoglobin and what's interesting is there's a difference between oxyhemoglobin and deoxy haemoglobin and so the make the functioning MRI is able to detect those differences in magnetic field when therefore it's able to take images such that do you notice here this is the posterior of the brain this is the cerebral cortex the outer part of the brain notice how this area is highlighted right here so this is a patient that was asked to look at something and so back here in the occipital lobe of the cerebral cortex we now know that this is the area of the cerebrum that is responsible for vision as a result of that it's totally interesting ok so again we're gonna take you on a little walk and look at these particular regions like the the cerebrum I was just referring to we talked a little bit about the cerebellum the diencephalon the midbrain we talked about some of these before pons and medulla so we're gonna go on a little journey here so the cerebrum again that's what we were just talking about it's the largest part of the brain 80% of the breadth and the brain is the cerebrum so it's divided in a left side and a right side or two different hemispheres right there and there's a fissure that separates the two hemispheres and the two hemispheres are able to communicate and there's like a little bridge right there that allows communication between the two hemispheres it's referred as the corpus which is a word that means body corpus callosum okay so that's responsible for transmitting neural messages between the both the left and right hemispheres of the brain you can see here this is a sagittal cut so this would be mid sagittal cut this is showing only one hemisphere but when you look at a frontal view like this yells and you'll notice that there's two hemispheres involved in the end the cerebrum okay the upper or most superior part of the cerebrum is made up of gray matter and if you recall you're this in somewhere in your background that the gray matter is a result of a lot of nuclei found in in the some of those neurons and then white matter is suggestive of the fact that there's a lot of fatty myelinated axons in this particular area so as I was saying in this occipital lobe right here vision is is being processed but in these other areas there's other functionalities going on in the truth is you know the the more you get into this this is a sort of a superficial believe it or not coverage of the brain but the more you really study the brain you'll know that that some of the functionality can be shared by different areas just just to be truth be told but we'll look at this kind of simply like vision is occurring mostly here in the occipital lobe that kind of thing and so the the lobes themselves are referred to as the the cranial bones that are protecting them so we have the frontal bone is is protecting the frontal lobe we have the two parietal bones which are protecting the parietal lobes and then we have the temporal lobe right over here and then occipital lobe and then here's the cerebellum right over here okay and so you're welcome to pause this if I go through this a little quickly but this is the the primary functions of those particular areas of the cortex the frontal lobe the parietal lobe occipital lobe that I was mentioning before is is the conscious perception of a visual stimulus this is kind of cool so in other words I not only do I see you but I know who you are or I don't know you are based on that so it's it's perception it's pretty interesting so not only in the temporal lobe were it's the perception of auditory hearing okay so in other words recognizing what I'm saying it's kind of cool all right and so again using that functional MRI you're able to if you looked at this you would say O Hara right over here so this is a person inside the functional MRI that is looking at something here's someone in the in the functional MRI that appears to be listening to something because that's where in the temporal area hearing is being processed right over here so I wanted to point out there's two particular regions right over here do you notice this one area and the more motor cortex of the frontal lobe and then there's this somatosensory area of the cortex and these are two particularly particularly important areas that I just want to touch on just for a second so this primary motor cortex right here which is the back part of the frontal lobe is to generate the nerve impulses that execute movement so that's where the decision-making occurs in order to move these particular areas I find this to be totally fascinating like this is where those parts of the body are asked to move okay and likewise this particular the front area of the parietal lobe which is right there in blue is the somatosensory cortex so this is where the neurons that come up here that sense the feeling in this in these particular areas like the skin or the field pain or information is being brought to that area from sensory neurons and then the perception is occurring in this area and then the decision to move is happening in this area of the brain and so you may have wondered you know how can how can this brain even you know it's so it's large it's three pounds but you know evolutionarily speaking this cerebral cortex has been growing most rapidly in particular it's sort of it's sort of if you will somewhat uniquely large in humans although there are other primates that have large cerebrum but evolutionarily speaking the skull or the cranial bones haven't necessarily been able to maintain the sort of movement towards larger size and so in order to accommodate that increased brain mass the way this cerebrum handles it is that it's very convoluted look at this it's all these folds which increase the surface area is not interesting there's these really prominent ridges known as dark gyri right in here or Jireh so Gyrene are all these like the convoluted worm-like structures and then you have these little shallow depressions known as sulci and right here and then you have larger ones which form deep grooves or fissures all right so that's kind of cool and the cerebellum I was mentioned before is involved in coordinating muscle activity it's really the second largest part of the brain and it and it controls repetitive movements as I was referring to before muscle memory if you want the cerebellum is located beneath it's highlighted here in blue it's located beneath the cerebral cortex and it coordinates all kinds of motion all right and the the diencephalon composes the the thalamus region in particular and the hypothalamus in this particular area right in here so in the middle of the brain and that links with the cerebrum and it also links with the brainstem and so you have a sort of that you know relay system going on both up and down in the diencephalon the thalamus is part of that there's a left and right balanus just staying and as well as the hypothalamus and then connected to the hypothalamus is the pituitary gland on the stalk as you can see right there so the thalamus is this as I was mentioning before is this relay area and processing center for sensory information it sort of takes it up to the cortex and the cortex has to decide and what to do with it so it's pretty pretty cool it relays that the sensory information and decisions to act are created as a result of that and I mentioned this before so a little bit of a review but the heightened hypothalamus sometimes I get excited and get a little head of nice the hypothalamus in addition to producing hormones regulatory hormones which regulate pituitary secretions there's stimulating hormones and regulatory hormones that are produced in the hypothalamus but the motion is is controlled there and some-odd autonomic functions as well as I was mentioning things like osmoregulation body temperature circadian rhythm that sort of thing and then also the pituitary gland which is sitting on a little stalk is it is one of the most though small about the size of a pea is so majorly important it's a major endocrine gland of the body which it the anterior lobe produces a potpourri of enzymes sorts of separate video on that you're welcome to check it out on the pituitary gland but that's connected to the hypothalamus via this invent binge Ilham stalk which is located right there and that's sort of the interface between the nervous system and the endocrine system both are trying to maintain homeostasis and again to review this the the brainstem is made up of the midbrain the pons and the end the medulla this right in here brainstem there okay and then right below that is the cerebellum okay the brainstem Disko a little bit more in detail in that is processes information between the spinal cord which is on the very bottom here right below the medulla and the cerebellum and the cerebrum okay so it's it's a processing area that's sort of sending and receiving information and that includes those three components it also can process sight and sound and the Associated reflexes that are important in reacting very quickly and it maintains consciousness and sleep is also controlled in this particular area it connects this the cerebellum to the brainstem it's involved in both motor and which is so Matic and also some some visceral motor control as well in other words involving the movement of smooth muscle fibers that is the pons so the medulla is connects to the brain and the spinal cord obviously it's going connects upward toward the brain and lower inferior to the spinal cord and that and it relays information and it regulates very important most and crucial things that you're not even thinking about so subconscious autonomic functions like heart rate blood pressure and digestion again here's a nice close-up of these particular structures and again the in order to to go a little fast gonna not mention and read these out but you're welcome to pause and take a look at them if you if you need to so let's get into a quick discussion of embryonic development now embryonic development is it's something that can stand but since we're talking about the brain and how the brain is organized into different regions I thought I would bring in this up because it's it's fairly useful now this upper part of the brain sometimes referred to as the forebrain and then we have this is embryonic speaking we have the the midbrain the hind brain and the spinal cord so there's these four basic regions right here okay and this corresponds inside of the embryo this would be an embryo let's just say at about five weeks of development so just a little over a month you'll notice here that here's the spinal cord you'll notice here is the hind brain right in here and then here's your midbrain and then over here is the forebrain and of course you may know where this is going that though all of these develop it's the forebrain that's really going to develop in the adult brain as you can see here and now look at this look how huge the the forebrain has developed but you could still see the midbrain and the hind brain and the spinal cord here and the adult as well so going all the way back to the beginning right here embryonic lethality brain started off as it as this really thin neural tube the origin of the brain and again here this is a cold scanning electron micrograph of that and what happens is I apologize upfront about the avalanche of terminology but it's fine you know don't don't be intimidated by uh by the anatomy but basically this neural tube can be considered like when you when you break it up into these would are referred to as primary brain vesicles and there'll be more conversation about vesicles shortly but these primary brain vesicles are these interconnected chambers inside the brain and so it starts off here in the forebrain right here in this Pro now Pro means like first like protein or prologue in a book so pros in Cephalon right there are pros and Cephalon then you have this mess and Cephalon which will then manifest into the midbrain then you have this ROM been assessed wrong then sessile Cephalon which is going to refer was going to migrate into the hind brain or develop I should say not migrate develop into those so let's keep these in mind so these there are these basic vesicles these secondary ones and again you can pause this if you need to take some some notes down on this but these are the the the various and Cephalon like the telencephalon the the diencephalon the meso sepal on the meta and cept along the myelin Assefa LAN are the different vesicles brain vesicles that come from those as you can see here the end brain the interview adapter brain the spinal brain and midbrain developed from those particular areas so these are the origin of brain structures come from this these particular areas so that Tallinn South Lawn becomes the cerebrum so meaning sort of the end right there so it becomes the cerebrum the the Met and Cephalon forms the cerebellum and pi and Milan Cephalon becomes the medulla okay so there you have that and I find that this chart right here is is very informative it sort of says what I was trying to say in one nice picture this is a cool picture of a six week old embryo and you can sort of see right in here what we're talking about so this is what you know here here's the beginning of the umbilical cord right here you can see the the heart beating right in here pretty calling the formation of placenta right there but do you notice here so in three weeks you have three basic regions and then after five to six weeks you have this these particular vesicles as I was mentioning these five one two three four five and then those will result at birth to these particular regions of the brain and then these are the vesicles which are chambers more to come and in the brain that are associated with with those particular developmental locations within the embryo okay so here's this conversation about these these vesicles in the brain now these ventricles I should say not vesicles sorry apologize for speaking on that it's a ventricles so maybe most of you are familiar with the the ventricles of the heart which are these chambers of the heart so these are ventricles of the brain sorry about this speaking about that so they're chambers of the brain these chambers of the brain they're there there's a there's a lateral ventricle and there's a and that's made up of a left and right there's there something called third ventricle and a fourth ventricle so those are all lined with these neuroglia cells called in pen the lung cells that secrete secrete CSF fluid though the ventricles and so again this is a really cool picture showing the ventricles here here's the the lateral ventricles right up here and then again I will go through some of the details of this in a moment but this is all of the ventricles shown and so these are basically cavities within the brain and there's there's fluid that flows in there as well and so here's a picture showing the the cerebral Hemisphere that contains this one large lateral ventricle but basically it's there's two sides of it though there's a there's a right side in the left side okay so this is looking at the left side of the of the ventricle right here the lateral ventricle and then I it's separated both the left and right by this sort of partition called the septum Pella you see pellucidum I'm telling you struggling with it with the terminology pellucidum septum pellucidum which is shown right in here right there and so the ventricles are separated left and right and and then this third vesicle ventricle is the ventricle of the diencephalon you can see it here a third ventricle right located right in this region right in here and that is communicates with the lateral vesicle of ventricle via the interventricular foramen and here's a pitcher interior looking in the in the front coronal view and you can notice here there's the third ventricle right in this area right in here that's highlighted in blue so it's a chamber filled with fluid and then right above it you'll notice here is the the lateral Ben ventricles right there in there and there's the third ventricle so those are chambers of the brain chambers of the brain that are containing CSF and then the fourth ventricle extends all the way down here as you can see it in this diagram right in here it's right in front of the cerebellum so it's interior to the cell cerebellum and extends all the way down into the and into the medulla and if you it's continuous I should point this out with the central canal which is right in the center of the spinal cord it's a little little tube in the spinal cord and it connects with the third ventricle as well now this narrow canal that connects the midbrain with that is known as the cerebral aqueduct as you can see right over here in this diagram the cerebral aqueduct this is a midsagittal view by the way right in there so these ventricles are important this way here's a here's a really cool picture of the fourth ventricle right in here which is interior to this cerebellum alright and then again now I come back to this picture because now you might have a better sense of these ventricles as you can see them here and at the extend all the way down I was mentioning into the spinal cord which makes up the central canal and so the cerebral fluid is inside here right inside alright this is also cool this is looking at the ventricles anterior view sort of like the two horns look at this with the lateral ventricles right here not interesting here's the third ventricle in the fourth one which connects down into C this is a nice view connects down into the central canal right there okay now to sort of wrap things up let's talk a little bit about the protection of the brain and I know maybe the most obvious protection of the of the brain is this is the cranium the skull bones but there's some cranial meninges in other words these membranes that are surrounding the brain and there there's three of them the outer and hardest one of all the most durable is the dura mater and then just below that is the arachnoid mater and then which is basically like it's sticking to the to the brain is the Pia mater and so so it's the arachnoid mater matter of fact and so these are this is where this the CSF fluid is is bathing the brain as well and that's where that's being controlled and it's also maintaining these meninges are maintaining a biochemical isolation that's fairly complicated concept that I can just throw it out basically is that it's preventing toxic substances and bacterial infections but it's interesting it's you refer to as the blood barrier brain barrier b-b-b but in fact the meninges can get infected and form meningitis which isn't very good so as I mentioned the three layers the dura mater the erector and monitor and the PIA mater that are going from outside to inside and then right below the Pia mater is the brain itself so that these are continuous with the spinal meninges and they protect the brain from physical trauma so that's their function and so here you can see this is looking down at the brain here's the dura mater that surrounds I know the other side has been removed right over here so this is the dura mater you can see how thick it is then you also you can see here in this sort of mid sagittal view of the brain you can emphasizing the dura mater which is on the outside of the cerebrum and then again one last one of the dura mater check that out pretty interesting it's removed on this side okay so it contains epithelial layer it has a an arachnoid space between the arachnoid mater and Pia mater and it sits in that arachnoid space that the CSF fluid is flowing and the PIA mater as I said before is attached to the brain surface directly and it's it's at you know detail but it's a it's a attached through the neuroglia cells known as astrocytes there's star-like cells in the CSF fluid which surrounds and nourishes and cushions the neural structure supports the brain transports nutrients chemical messengers and waste products is very important and in addition keeping the brain life so the blood supply to the brain as one might imagine is most critical the brain is using a tremendous amount of glucose and it needs a lot of oxygen and so there's blood vessels that need to bring the glucose and the oxygen to the brain and so it's delivered to the brain through this internal carotid artery and it's removed by the it's also brought up by the vertebral arteries that are travelling up through the spinal cord for Raymond not the spinal for a vertebral foramen but the the transverse foramen and the and then the deoxygenated blood is removed by the internal jugular veins now and they don't point out since we're discussing blood supply to the brain one of the more devastating things that can happen to a person which can cause paralysis and it can cause death than it can cause all kinds of devastation is cerebral vascular disease and more commonly known as is simply a stroke and so basically when there is a blockage in one of these major blood vessels to the brain obviously Bloods not travelling to this neural tissue and it's going to be deprived of oxygen and nutrients and it's gonna shut off that portion of the brain and the therefore the neurons die and so there's a look there's a few causes you can have a blood clot there you can actually have a hemorrhage you can have trauma occurring in the blood vessels or damaged in a particular way and so stroke can be very very debilitating and then I mentioned before and I thought I'd just touch it on it one more time because it's sort of along the lines of protection of the brain is that this blood bear blood brain barrier or BBB isolates the central nervous system neural tissue from the general circulation and you may be wondering because I'm not going into detail on this on how may occur but I'll say this that in the capillaries that are supplying the neural tissue with with blood those capillaries can actually be less permeable if they're if they contain a lot of tight junctions which are types of proteins in between the endothelial cells of those capillaries and so that in some way protects the diffusion of toxic substances between the general circulation and the brain so in general the meninges they stabilize the brain inside the current the cranial cavity they they carry the cerebral fluid that protects against sudden movements of the brain it also provides nutrients and removes waste and finally the blood-brain barrier in addition to the CSF fluid helps to isolate the brain from unwanted chemicals in the blood that may disrupt neural function so all of that was the introduction to the brain and so if you're still with me I hope in in general that's more and this is the attempt I said this at the top of the video the intention is not to necessarily explain everything but maybe it is to to spark more questions and to provide answers I hope everything that we were discussing so far leads you to further questioning about all of these structures and what they are what they're really up to because again the brain is pretty complicated and so hopefully you learned something and enjoyed it thanks for watching

Channel: Ray Cinti

Views: 14,657

Keywords: brain, brain regions, brain ventricles, cerebrospinal fluid, anatomy of the brain

Id: ZP5RCfegFQ0

Length: 39min 25sec (2365 seconds)

Published: Fri Apr 07 2017