0:00 Whatever is happening in your body is being controlled by these two systems together. One is your nervous system, neural system, the other is your endocrine system. Ma'am why were two systems needed? Was not one system sufficient? That means there are two types of cells in the nervous system. One is your neuron which is the main cell and one is the supporting housekeeping cells which we call neuroglial cells. The membrane is completely impermeable to negative charge. The membrane is saying I will not let negativity come and go. The forebrain includes our cerebrum, diencephalon and your olfactory lobe. Now some kids will say the diencephalon is not the olfactory lobe. Son is confused, please understand it a little. The limbic system along with the hypothalamus is your emotional brain. Son, the limbic system is here on the sides. Surrounds the temporal lobe. Hello kids, I am Tulika Jha. Your Zoology
0:45 Educator and I welcome you all to the Quick Reviews Podcast Series of Zoology. Today we are going to revise neural control and coordination. Now the system of your body is jointly coordinating anything and everything is happening. That means whatever is happening in your body is being controlled by these two systems together. One is your nervous system, neural system, the other is your endocrine system. So in this chapter we will talk about the nervous system. In the next chapter we will talk about the endocrine i.e. hormonal system. What you are doing, what you are feeling, how you are doing, what you are thinking, everything is under the control of these two systems. Now the name of the chapter is Neural Control and Coordination. So what is the difference between control and coordination ? Let us understand in Laman's language. If I am in class. I said students take out your pens, students
1:31 start writing, students get up, students say down. So, I am controlling each child alone. That is controlling the entire class. But if I step out of the class and I tell children to maintain the decorum of the class. Now you all will coordinate with each other. One will speak and he will silence me; that one will speak and this one will silence me. That is, how your systems in your body are jointly cooperating with each other to make a work done. We call this coordination. That means if an activity takes place in our body then all the systems together start helping it. They start complimenting. For example, if you need to do any stressful exercise, your oxygen requirement will increase. So only the breathing rate will not increase. Heart rate will also increase. Because if breathing rate increases then
2:16 more oxygen will reach our lungs. But who will take it from the lungs to the organs? He will take the blood. So the heart rate will also have to increase. So that's why both systems will work together. Similarly, what did the elders say ? One should not suddenly exercise after eating food, like eat food and then start exercising. Why? Because after eating food, our body requires that all the blood be diverted to the alimentary canal so that absorption can take place. If you do stressful exercises after that, then the body will have another need to send all the blood to the muscles so that the muscles get oxygen and produce ATP. Now the body got confused whether we should go to the alimentary canal or we should go to your muscles. That is why it is said so. So you understand how our bodies coordinate with each other. Now the second question which
3:02 must be arising in your brain is that ma'am why was there a need for two systems? Was not one system sufficient? There was a need for two systems because the mode of action of both is very different. So let us give it a difference and differentiate it. The nervous system controls your body point to point via nerves. That is, if I have to send a signal here. My nerve will go directly. Neurot will release the transmitter and the job will be done. But our endocrine system is not controlling point to point. He is putting the hormone into the blood, and then the blood is circulating and reaching every organ. Ultimately the work is being done on the organ which has the receptor. That means it is not point to point. It is via blood. Blood is going everywhere. So this is point to point. This is via blood. Now its action will be fast. The neurotransmitter will go away with a click. But this one will keep going around and around. So this is fast. Its
3:49 action is slow. But this action of this, that is, the action of the nervous system, that is a short lift. Neurite transmitter bind done, work finished. But the action of the hormone is that yours is long lasting. This is the difference between both of us. That is why there is a requirement for two systems. Now let's take a look at the animal kingdom and see how our nervous system works in the different phyla that we're looking at in each chapter. So the nervous system is also showing a very good evolution. For that matter what is main in our human evolution also? Increase in brain capacity. Evolution of the nervous system. So the first phylum which is your Porifera. The nervous system is absent in Porifera. The next phylum is your Nerea Coelenterata which includes Hydra. Neurons came into it. Neurons i.e. cells of the nervous system and they formed a network. We can also use the word Plexis for networks. Now when we
4:36 go beyond this, things like nerves, ganglions come into play which I will explain to you further down. If we talk of Arthropoda i.e. insects, then the brain is also included, and after that there will be brain, spinal cord and a lot of evolution takes place. Now we are basically going to focus on the human nervous system. So let's talk about the human neural system. The human neural system has been divided into two portions. One being your central nervous system, one is your peripheral nervous system. Now the central nervous system is the main decision making body which will process the induction. It will take the induction of the whole body, process it and decide it. And this includes our brain and spinal cord. The peripheral nervous system is on the other hand. How will the signal reach our central nervous system ? I told you that the central nervous system will take signals from the entire body. It will disassemble the whole body and
5:23 then send the signal. So, how is this signal intake and signal output happening? It is happening due to nerves. That means the collection of all the nerves of your body is your peripheral nervous system. All the nerves together are called PNS. Ok? Now nerves will fall into two categories. One that will carry the signal and deliver it to the central nervous system. That is your sensory nerve also known as afferent nerve. The second one is the one which will take signals from the central nervous system and give it to the organs, that is our motor nerve i.e. the efferent nerve. Now the peripheral nervous system has been divided into two parts. We divided it into two parts. One is the somatic nervous system, one is the autonomic nervous system. The somatic nervous system includes those nerves that go to our voluntary organs. Now you
6:09 cannot control every organ with your will. Can you move your kidney? Can you move your heart? Can you move your intestines? No, all this cannot happen. But can you move your legs? Yes. Can you move your hands? Yes. Can you move your neck? Yes. That means there are only two things under our control – voluntary control. The muscle attached to the bonus and bonus i.e. skeletal muscle. That means, whatever nerves go to these two, we combine them and call them somatic nervous system. Now autonomic nervous system which is not under our control. Meaning, our involuntary control happens automatically. So all the nerves that go to the involuntary organs, that is, the internal organs, we collected them and called them autonomic nervous system. The autonomic nervous system runs in pairs, meaning there will be two types of nerves. Sympathetic and parasynthetic. And the function of both these nerves is agonist, that is, opposite to each other. If one is getting the
6:57 work done then the other will stop it. If this one is getting it done then the first one will stop it. But earlier we used to also tell who was getting which organ operated and who was stopping it. But now we don't ask you so much and we have to focus on NCERT. So let us take a general rule. The sympathetic nervous system makes us alert, makes work done. The parasynthetic nervous system comes down or relaxes us. Now there are exceptions in this like the digestive system. But for now just remember that the sympathetic will alert you and get the work done. It will reduce parasynthetic and make us relaxed. Now a separate paragraph is written about the visceral nervous system. This is very simple. What does visceral mean son? Internal organs. Which nerves go to internal organs? The autonomic nervous system goes, right? ANS. And what is the autonomic nervous system a part of? It
7:43 is part of PNS. So what actually happens? There are some internal organs on which when the nerves go, son, open your eyes and look once. When the nerves go there, let's assume that it is the stomach, then it is an internal organ. When the nerve went to this, the nerve moved around it like this and created some network, created some ganglion and then started supplying it. So it looks like that this organ has its own nervous system. This vast organ has its own nervous system. But it is not like that. This is a part of our PNS. The nerve of PNS is affected. And if we become more specific then it is from ANS only. That is, visceral nervous system is a part of ANS and PNS where no organ has complex network, plexes, ganglion nerves around the organ, that is what we call it, son, visceral nervous system is
8:29 not something different, it is a part of PNS that in some organs the nerve is not enjoying direct supply, it keeps moving like this, forming fibers, forming a network, ganglion and moving around and then working, okay now let's do a little detailing of the cells of the nervous system. Still, we wonder which cells will be there in the nervous system ? So we have a word in our mind called neurons. So neurons are our main functional cells of the nervous system. But friend, when you go to a hospital, you go to meet the doctor. The main work is done by the doctor. But are only doctors available there ? To make sure that the job of the doctor is getting sorted properly. That means the doctor is not facing any shortage? So we also have peens. We also have compounders. We also have people at the reception. There are also nurses. Son, who is there to support the doctor
9:15 in his main job of doing housekeeping ? Doctor or housekeeping staff. Housekeeping staff. That means there are two types of cells in the nervous system. One is your neuron which is the main cell and one is the supporting housekeeping cells which we call neuroglial cells. Now, much detailing of neuroglial cells has not been done in this chapter of nervous system. But I will tell you a little in the end. Let us first talk about neurons. A neuron has three parts. One is the cell body main. One is the dendrite which sends signals to the cell body. One is the axon which carries signals from our cell body. So dendrites are multiple. There is generally only one exon and there is only one cell body. Ok? The cell body to dendrite will send signal toward cell body. That means the dendrite will receive. So where will the receptor for the stimulus be? It will be on the dendrite. It will receive it and
10:01 give information to the cell body. Then Exxon will take him away. The end of the exgon is called the exgon terminal. The end of the exagon is usually branched. Axon terminal ends into bulb or knob like structures. Like a gate knob. Isn't it? Bulb and knob like structures known as synaptic knobs. Which contains small vesicles. Synaptic vesicles inside which neurotransmitters are filled. Now we see small vesicles in the cell body and dendrites. Small granules are visible. Non edge Nissles granules. Well this doesn't happen in Exxon. Occurs only in the cell body and dendrites. What is Nissal granule? Son, this is a fragmented form of rough endoplasmic reticulum i.e. RER. That means our protein synthesis will happen here. Now if we find a dirty sheath surrounding the axon, then
10:49 we say that this neuron is monitored. If we do not find a myelin sheath surrounding our axon, then we say that this neuron is non- innervated. What is Manan Sheet, Ma'am? Now, I talked about house keeping cells, those house keeping cells i.e. neuroglial cells. First of all, there are more than neurons and they are of four types. Shan cell, oligodendrocyte, astrocyte and microglia cell. NCERT has talked about only one cell here, which is your dog cell. So understand that Schwann cell is a supporting cell which remains on the son side of the exon. Now sometimes that Schwann cell extrudes an axon from its plasma membrane. What does a Schwann cell do? Look at this, son. This is your neuron. This is Shan Sale. First of all, there is the present. Shan
11:35 cell is present in surrounding of the excavator. At times he remains quietly present. So we say it is a non-monotonic neuron. Shan cell did not form myelin sheet. But sometimes the Schwann cell extends its plasma membrane and concentrically covers the axon. So the plasma membrane of the white cell becomes your dirty sheet. So what is the composition? It would be phospholipids. Now make a myelin sheet here. Here is the second Shan Sale. A second myelin sheet is formed. The gap between two myelin sheets is called nodes of Runvier. And as we go forward, we'll see all your gates, channels, pumps, they'll all be presented right here at Nudes of Runwear. The color of dirty sheet is beta white. Because off shore cells are made of plasma membrane. The plasma membrane of a human cell is your myelin sheet. What is the plasma membrane made of? Lipid by layer. What is the colour of lipids
12:21 ? White. So what will be the colour of dark winter ? It will be white. That means the myelinated neurons, which we also call medullated, will appear white in colour and those which are non- myelinated, i.e. non-medullated, will appear grey in colour. Why would it look grey ma'am? Because neurons' own color is grey. Ok? Now what are our monitored neurons , monitored neurons are found in our CNS. We have a lot of problems in CNS because why ma'am? Because as we go forward we will see that the dirty cold will increase the speed of conduction. If a neuron has myelin sheath, then the signal will travel quickly in it and if there is no myelin sheath, then it will travel slowly. Now in CNS we cannot afford to have slow decision making. It should be fast. How will you think about NEET exam? So that is why the neurons of the CNS are always
13:06 monitored. Now the neurons of the PNS are also monitored. Some are also non-myelinated. That means if you ask about non-managed then we will say it may be in PNS, ma’am. But there will always be innervated neurons in the CNS. Is it clear? Now NCERT is saying that there are four more types of neurons based on how many processes there are. If a neuron is a round cell like a normal cell, it has neither dendrites nor axon, which means it has no poles. So we call them apolar neurons which occurs during embryonic development. That is, in the beginning, when the neuron of the embryo is being formed, it is a round cell like a normal cell. So there is no polarity, apolar. Then gradually the son becomes an exagon in him. An exagon is formed meaning a polarity comes from one side. If there is one direction then we call it unipolar. That also
13:53 happens in our embryonic development. Then a dendrite comes out from one side. So we say that now that two poles have come, it is bipolar. Bipolar neurons: We have two eyes, so there are two poles in our eyes, that is, inside the retina is our bipolar neuron. It happens at another place. NCERT has not spoken. Ok? Now after that lots of dendrites come out. There is only one exon. When there are many dendrites and one axon then that is your multipolar neuron. Majority of the neurons in our brain and majority of the neurons in our body are multipolar. Now as I told you, let me move ahead. Let me clear two words for you. One is your ganglion one is your nerve. He is saying nerve nerve over and over again. What is Ganglion? Son ganglion is bundle of cell body. One neuron, two neurons, if you imagine adjacent adjacent parallel, then the bundle of
14:40 cell body which forms the bundle, that is your ganglion and the bundle of axon which forms is covered by a sheath of neurolemma, what is neurolemma, it is the same cell, it is covered by its sheath and bundle of axon, that is your nerve and bundle of cell body which is the bundle, that is your ganglion, but we use both these words in PNS. Used in the peripheral nervous system. Son, if your bundle of cell body is in the CNS then we call it Nuclei Eye. Which is written in the hypothalamus in the next chapter chemical coordination and integration that the hypothalamus is newsly. So group of cell body in central nervous system is neural. Similarly, a group of axons in the central nervous system is tracked. As it is written in the corpus callosum, it is a track. I've got it? Otherwise
15:26 listen to it on repeat. Now we will read the most main topic of this chapter which is generation and conduction of action potential. Now before this let us understand the difference between one or two words. Conduction and Transmission. Conduction means with in neuron when your signal is flowing that is called conduction. Going from one neuron to another, that is called transmission. So what are we reading right now? Generation and conduction of nerve impulses. That means we are talking about with these neurons. Two cells in our body are excitable cells. Only two cells are excitable in our body. By excitability I mean if any cell in your body develops charge on both sides of its plasma membrane, one side positive and one side negative, that is, it creates poles across the plasma membrane, then we will call those cells that these are your excitable cells which generate poles
16:13 across their plasma membrane. Now only two cells of our body can do this. One is your neuron, one is your muscle cell. Ok? Now let's talk about neurons. Now how does a neuron generate poles? Let us go into that. First of all, inside your neuron, inside the axon, the most abundant amount of potassium is there and outside the neuron, that is, outside the axon, the most abundant amount of sodium is there. So sodium inside potassium outside sodium outside the exon. Ok? But both have positive charge so there is no problem. Now let's talk about the negative inside and let's talk about the negative outside. Inside there is negatively charged protein and outside there is Cl-, that means positive and negative are outside too. Positive and negative are inside too. Now if we think about diffusion,
17:01 every thing will try to move out because of the concentration gradient, potassium will try to move out and sodium will try to move in. Similarly, the negatively charged proteins inside will try to move out and Cl- will try to move in. It should happen like this only. But the membrane is completely impermeable to negative charge. The membrane is saying I will not let negativity come and go. That means negative charge inside out cannot do anything. Now positive charge remains. Potassium inside, sodium outside. The membrane is freely permeable to potassium. That means potassium will easily go out through diffusion because if there is more of it inside then it will start coming out. But membrane is NCERT saying nearly impermeable to sodium. That means it is almost impermeable for sodium. That means sodium will come in. But
17:48 slowly the entry will come gradually. That means potassium with one positive charge is moving out at a rapid speed. And sodium with one positive charge is moving inside at a very slow speed. So what will happen? Ma'am, negative charge will come inside and positive charge will go outside. This becomes negative charge inside and positive charge outside polarity. The pole has been developed. The membrane is said to be polarized. And when there is negativity inside, it means the neuron is arresting. Not working. Son, if there is negativity inside you then you will not be able to work. Negativity does n't work. Positivity gets the job done. So what's inside now? Negative charge. Negative charge inside means polarity. The pole has been developed. But it is called resting potential membrane is said to be
18:33 resting polarized state. If we look at the value inside it is -75 millivolts. But that is not in NCERT. But tell me one thing, a time will come when potassium, through diffusion, will become 50-50 on both sides. Now there will be equilibrium. Equilibrium will be achieved. The sodium which was coming slowly. It is possible that it may reach equilibrium after 1, 2, 3, 4, 5 or 6 hours. It is coming slowly but there will come a time when both will be 50-50. As soon as equilibrium is reached this pole disappears. Now we do n't want the polarity to disappear. That means we don't want the membrane to fall into equilibrium. This means we will have to maintain resting potential. The concentration gradient must always be there. Should not be in equilibrium. For this we have sodium potassium pump.
19:20 What does the sodium potassium pump do? It happens occasionally. Whatever belongs to a place, it is sent there. Where does sodium belong? Out. So, every now and then, it throws out the sodium. Where does potassium belong? Inside. In between, it brings in potassium. So equilibrium will never happen. And who is maintaining the resting potential? Which ah what is preventing the membrane to fall into equilibrium. And what is maintaining the concentration gradient of sodium and potassium across the membrane? The sodium potassium pump is removing three sodiums intermittently and in return bringing in only two potassiums. So it is maintaining your resting potential. Ok ? Now if we ask why resting potential developed? Why did negative develop inside and positive outside? If this is asked
20:06 due to differential permeability of membrane to sodium and potassium. At the first place, it became negative inside because the potassium was going freely. Sodium was coming in slowly. That is, the differential permeability of the membrane to sodium and potassium in generating your resting potential. Had it been same? So this cannot happen. When will it come into action? As soon as a stimulus binds to your dendrites. As soon as the stimulus binds to your dendrites. The voltage gated sodium channel of the first node of Ranvier opens. That means before this it was happening through diffused transmission. It was happening through the normal channel. As soon as the stimulus arrives a big gate of which opens? Of sodium. And now sodium will start coming in freely, son. Sodium will
20:53 start coming in freely which was coming slowly. As soon as sodium slowly starts coming in freely , what kind of charge will develop inside? It will become positively charged. As soon as positive signal is detected inside the membrane is said to be in action. We call this depolarization. This is what we call impulse. We call everything signal, this is what we call it. Ma'am why do you say depolarization? I became positive inside. It turned out negative. But the poles are still there. Yes the polls are still there. But if we look at resting, there was a difference of -75. Now when yours comes into action it goes inside + 25. How much was there in resting? -75 and the difference in resting was 75. We are applying the minus for the internal charge. That means the difference in resting was 75. If action potential is
21:38 inside +25 then what is the difference? It is from 25. So compared to before now the polarity has reduced. That is why we say the membrane is said to be depolarized. That is, what is action potential, depolarization, a nerve impulse ? What brought about positivity inside you? This has happened due to entry of sodium influx. So but this entry is a very short lift of sodium. Within a short while, the channel which becomes the voltage gated sodium channel closes and the potassium channel opens. When the potassium channel opens up, potassium starts moving out again and it becomes negative again inside and the same process then jumps to the next node of the receiver. That means where does the next one open? Sodium starts entering the sodium channel. This
22:25 one starts out being positive. Then there's the short short lived. It is closed at. The potassium channel opens again. Potassium starts moving out. It becomes negative inside again. Then he jumps. So in this way your sodium channel keeps opening by jumping from note to note. That means positivity keeps moving forward by jumping from note to note. If we look at the NCERT diagram, there is a region A where the entry of sodium is shown. So what happened inside? It became positive. Next region B, right now he is in negative. So if we make a circuit then where will the inside positive charge go next? A to B. If we draw the circuit then sodium has entered at position A. So in region A your exgon is positive inside and on region B it is still negative inside. Ok? But what will happen next, son? will go positive on B. That is,
23:12 if we complete the current circuit. So positive charge will move from A to B inside and positive charge will move from B to A outside. One your current circuit is finished. Son, if the myelin sheet was not present then instead of jumping from node to node, it would have moved forward slowly. That means jumping conduction is taking place due to the myelin sheet. Had the myelin sheet not been there then you would have had continuous but slow conduction. So, we have read this son with these neurons. Now let's talk about transmission. One neuron to the next. Where one neuron meets another neuron. That is called synapse. So the axon terminal of the first neuron will come and the dendrites of the second neuron will come and sometimes there is space in between
23:57 and sometimes there is not. If there is a space present in the middle then we call it synaptic cleft. What is it where two neurons meet? There is synapse. One will have an Exxon terminal. One will have the cell body and the dendrites coming out of it. And if there is no space in between then we call it electrical synapse. And if there is space in between that is fluid field synaptic cleft. If there is a fluid field in between and a space known as synaptic left is present then we call it chemical synapse. Majority of the synapses in our body are chemical synapses. In electrical synapses because there is no space in between the presynaptic neuron and the postsynaptic neuron. Almost all of our axon terminals are connected to each other's dendrites. So what happens in this?
24:44 As soon as the action potential arrives at your axon terminal, the other neuron catches it directly and opens its sodium channel and develops an action potential inside itself. That is, if synapse is of electrical type then transmission is same as conduction and two neurons are somehow behaving like a single neuron. But if you have a chemical synapse then the direct signal will not go. So what happens now? Neurotransmitters are present in the synaptic nub. Your synaptic vesicles fuse with the plasma membrane. Calcium plays a role in this. Actually calcium enters from the synaptic cleft. In which one does the entry take place? at the Exxon Terminal. And that calcium causes the synaptic vesicles to fuse with our axon terminal. Neuron transmitters are released
25:30 into that space. The receptor is present on the dendrite of your next postsynaptic neuron. The neurotransmitter will bind to the receptor and an action potential will be generated inside our postsynaptic neuron. Which one will be fast? Electrical or Chemical? Obviously electrical will be fast. Because all these chemicals are not being released. But these chemicals are majorly present in our body. Electrical signs occur only in our heart. Some bit is not written somewhere but that is yours. Ok? Now this neurotransmitter which is released, it can be of two types, it might be excitatory which we call stimulatory neurotransmitter, it might be inhibitory neurotransmitter, what does it mean ma'am, son, if the neurotransmitter which is getting released, when it is binding to the next neuron and is developing positivity inside,
26:16 that is, it is developing an action potential, then it is a stimulatory neurotransmitter. But if a neurotransmitter, when binding to the next neuron, then instead of opening the sodium channel inside, it is opening a potassium channel and pushing out more potassium and making it more negative inside, then negative, that means it has delayed it further, then it is an inhibitory neurotransmitter. Ok? Now you don't have to remember much but adrenaline, non-adrenaline and acetylcolon are the three excitatory neurotransmitters. Now Acetyl Choline Is the Only Inhibitory in Your Heart. Otherwise acetyl choline is always a stimulatory neurotransmitter. Among these, remember only one thing at this time, Dopamine, because it is written in Cocaine of Human Health and Disease. Otherwise we also have glycine, we have
27:02 GABA, we have serotonin. So you can see that as well. Now we are just ending it. In our central nervous system, we have to study only about the brain. The rest of the portion has been removed. So the covering of the brain, that is triple layered known as meninges. The closest thing to the brain is your found matter, and it is closely investing your brain. That means it is stuck to your neural tissue. Who found the matter? These are basically blood vessels. They are absolutely stuck. Closely associated with your brain. The pia mater which is away from the dura mater. And the one in the middle, that's your aranoid. Now there is not much detailing done on it. Who is made of what. But for now, these three layers protect your brain. And then out of this comes our cranium i.e. brain box. Ok? Son, these meninges of yours are
27:49 protecting both the brain and the spinal cord. But we have to study the brain in this chapter. Now let's talk about the brain. Brain Our brain has been divided into three portions. Fore brain, mid brain and hide brain. The forebrain includes our cerebrum, our thalamus and our hypothalamus. This is all that has been discussed in NCERT. The Moment I Removed My Skull. Take my skull away. What I see is a highly convulated structure, a folded structure known as the cerebrum. Now there's a longitudinal fissure in the middle, look here, which is dividing the cerebrum into two hemispheres, right and left hemispheres. Due to folding, more space is created for our neurons. Now our cerebrum is hollow from inside. It is empty. So I opened my hand like this and I saw that it was empty from inside. There is a ventricle. Ok? The cerebrum from outside is
28:34 grey in color. The outside of your cerebrum is gray in color. And the inside of your cerebrum is white in color. This is so son, because what is the cerebrum made of ? from the neuron. On the outside is the cell body. There will be no action on the cell body. Sorry there will be no myelin sheet on the cell body. So the color of your neuron is grey. Because the cell body is outside, we call it grey color and grey matter and the outer part of your brain is cortex. Inside is the medulla. Our axons are present in the medulla. The myelin layer over the axon is sheathed. The color of dark winter is white. That is why the inside of your cerebrum i.e. medulla is your maintained axon and is white in color. Now no one here likes anything from their home. All the axons of this hemisphere are going this way in bundles. All the axons of this hemisphere are coming here in bundles.
29:22 So the bundle of axon is formed below the longitudinal fissure. Are you getting my point? What do we call the bundle of axon in the central nervous system? They talk about tracts. So what goes down the longitudinal fissure ? Bundle of axons. Manated axon. Tract non edge corpus callosum. Ok? Is it clear? Now there is a sensory area near the cerebrum which will receive signals from the entire body. There is a motor area which will give signals to the entire body. And a large area. Which is neither sensory nor motor nor association area. This is for our intersensory communication like memory, intelligence, creativity, will power etc. Ok? One will take the signal, one will give the signal, and one will be creative in itself. Now when you are overthinking at 3:00 in the night, is
30:09 your body giving signals? Or you are giving signals to your body. When you are in a creative thought, I will do this, I will do it like this. Is your body giving signals? Are you giving signals to the body ? No. So, this area is neither sensory nor motor. Intersensory communication. You are wandering within yourself thinking about yourself. Memory, intelligence, will power, creativity all come under the association area. Now there is a system in the deepest layer of the cerebrum called the non-limbic system. The limbic system along with the hypothalamus is your emotional brain. Son, the limbic system is here on the sides. Surrounds the temporal lobe. Limbic system plus hypothalamus emotional brain. We have three parts in the limbic system. Hippocampus, amygdala and septum. Now their job is sexual pleasure. Anger means fear,
30:55 sorry anger means rage. Fear means anger, rage, motivation, sexual pleasure. Whatever emotions come to your memory, they are all part of the limbic system. Now speaking in summary the limbic system is also involved in all factory responses. That means smell also comes from our limbic system. And many times, son, we associate the person we love with his smell. So when all the emotions are in the limbic system, the child gets connected with the mother's emotional smell. So all the emotions i.e. smell is also a part of our limbic system. Son, are all these emotions under your control? Getting angry at someone or falling in love with someone is not in your control. That means this is autonomic activity. This is the response. This is written in our summary.
31:41 Now the thalamus. The thalamus is below. Cerebrum This is your longitudinal fissure. There are two wall like structures beneath it. We call this the thalamus. Look in the thalamus there is an M and an S. Thalamus means it will connect motor and sensory together. Thalamus i.e. motor sensory signaling. What was in the association area? Two S. That means it was connecting two sensors. Intersensory communication. An M1S in the thalamus. That is, it is signaling motor sensory signals to each other. Then just below the thalamus comes our hypothalamus. The hypothalamus, this is mainly happening for our homeostasis. One is maintaining a constant environment of our body. 37° temperature is our pH fix. So whatever is the constant, osmolarity is fixed. As osmolarity
32:27 increases, thrush is generated. That means he wants to keep these things fixed. 300 milliosmol osmolarity, 37° temperature keeps all these fixed. Apart from this it will generate desire. Thirst, hunger, and once we had both, our stomachs were full. The thirst was quenched. That is truth. So hunger, thirst and satiety. Apart from this, there is a little bit in cardiovascular but that is not written in NCERT and obviously in emotions because it is involved with the limbic system. The hypothalamus is also controlling your pituitary by a group of 10 hormones. It is controlled by 10 hormones which we will already read about in the next chapter. Now next is your mid brain. The mid-brain is present between the thalamus and hypothalamus of your fore-brain and your medulla. Now whatever comes below us is
33:12 present in between the pons. That means forebrain and hindbrain because I have not told you about the part of the hindbrain. So our mid brain is present between the thalamus and hypothalamus of your fore brain and hidden brain. Now some of the ination is in the text of the mid brain , some is in the summary. There is a cavity in the middle of the midbrain called the non-cerebral aqueduct. The dorsal side which is our mid brain. The dorsal side has just the same function. We have four swellings on the dorsal side. These four swellings we call corpora quadri gemina. Two are above, two are below. Superior by gemina, inferior by gemina. Now the NCERT text is saying that the function of the mid brain is to connect the brain to the fore brain. Which is true. But son, this is the work of the ventral side of the mid brain. There are four swellings on the dorsal side , their function is written in the summary. Auditory, visual and tactile response. It
34:00 does. If my son has to look back and someone calls me and says maam, will I turn my ears or my head too? My head will spin automatically. So coordinated movement of head with ear if I have to look here cheating being an exception. If I have to look here, should I move my eyes like this or should I turn my head too? I will turn my head too. So coordinated movement of head with eyes and ears i.e. visual auditory tactile. This is the function of your corpora quadrigae. Now last is your hind brain. The hyoid brain has three parts. Your cerebellum, your pons, your medulla, oblongata. The cerebellum is like a mini cerebrum. The cerebellum is on the dorsal side. It is a folded highly condulated structure. It is providing additional space for neurons which could not get accommodated in your cerebrum. Those who could not reach the cerebrum, come here. Plus your
34:46 cerebellum is also responsible for your body's balance and posture. Alcohol receptors are present here. Then is your bones. Pons is a Latin word which means bridge. It works as a bridge to connect different parts of your brain. Also, the pons has a pneumotoxic area which controls your breathing rate. Decreases the duration of inspiration. Then is your medulla oblongata. The medulla oblongata controls our initial first, which was the first chapter, that is, the three systems. It controls the digestive, respiratory and circulatory system i.e. gastrointestinal reflex, your breathing and cardiovascular system. The medulla oblongata is directly connected to your spinal cord. Ok? Now brain stem.
35:32 Think of the brain stem as a brain being a cabbage. So cabbage has a stem and cabbage has a flower. So the cerebrum and the cerebellum will look like cauliflower. So what is left for us? So, son, our medulla is oblong. What remained was our pons and our mid-brain. That means mid brain plus pons plus medulla oblongata is your brain stem. Why ma'am you left out the thalamus hypothalamus? So son, the thalamus is completely wrapped by your cerebrum. The cerebrum completely wraps around our thalamus. That is, what is the brain stem? Mid brain for mid brain pons and medulla oblongata or you can say mid brain brain minus cerebellum. With this we are done with this chapter. Till then, tata, bye-bye and namaste.
