 Yes, everyone. Am I what able to you? Am I am I able to you all? Yes. What are we discussing in the previous class? What are we discussing in the previous class? Please let me know which topic was there that is going on. We finished myosin filament agreed. No issues. Screen is visible. Screen is visible or not? Yes, sir. Yes, we have discussed till now the myosin or thick filament. Tell me the myosin or thick filament. This is myosin or thick filament. Now you see how it is going to be arranged. First, we will see the NCRT diagram only. After that, I will discuss few more. Okay, how the arrangement is going to be there. Let's see over here. This is myosin filament. This is myosin filament. This is myosin filament. Agreed? Let's see. This is actin filament. Yes or no? See, actin filament is there on this side also and on this side also. It is on both the sides. Okay, so can you people observe in the center of actin filament what is passing? In the center of actin filament, the z line is passing. Yes or no? In the center of actin filament, the z line is passing. Yes or no? Tell me. Yes, sir. Yes. And m line will be there in the center of myosin filament. This is going to be the m line. That I have already told you it is due to change in orientation of meromysin filament. Yes or no? Let's see over here, dear. Please observe this region. This region. This region. What you can observe at some places actin and myosin both are there. And at some places only myosin filaments are there. At some places actin as well as myosin filament is there. And at some places myosin filament is there. Agreed? Agreed? Tell me. At some places actin as well as myosin. Both the filaments are there. In this area, you people can observe. At some places actin is there, myosin is there. Actin is there, myosin is there. At some places only myosin filament is there. Agreed? Tell me. Tell me. Yes, sir. Say yes or no? Now, can you see this kind of arrangement is known as isotropic or anisotropic? If things are not in a regular pattern, that condition will be isotropic band or anisotropic band. Anisotropic. Anisotropic. So, starting from A, it is known as A band. A band means anisotropic band. And what is this? I band. That is isotropic band. Yes or no? A band and I band. Both are there. Both are there. Then, tell me. In this area, the orientation is anisotropic, hence A band. And in this area, this area from here to here, only actin filament is there. So, it will look isotropic or not? Say yes or no? Yes, sir. Not getting? Others? Others also? Are you people getting this thing? Yes, sir. Let's see. So, this is A band and I band. In the center of I band, Z line is there. And in the center of A band, M line is there. What? M line is there. Yes. Now, please observe this A band. It is having two kinds of area. It is having two kinds of area. In one area, only myosin filament is present. I mean, actin is not covering myosin. In this area, actin is not going to cover the myosin filament. This is known as H zone. What? H zone. So, H zone is where myosin is not covered by actin filament. Agreed? Tell me. Yes, sir. H zone is where myosin is not covered by actin filament. Now, this area. What about this area? Can you see here, actin is overlapping the myosin. So, that will be known as overlapping zone. And in short, I will write this as O zone. Everyone. So, can I say that A band is divided into two areas, that is O zone and H zone. Can I say that? Tell me. Say yes or no. If you will say it is not, you people are not getting, I will repeat or I will discuss further. So, please tell me yes or no. Can I say A band is divided into H zone and O zone. Two zones are there. Yes, sir. Now, you see the area between two z line is known as sarcomere. Area between two z line is known as sarcomere. And what is sarcomere? It is present between two z line. It is the functional unit of contraction of muscle. It is the functional unit of contraction of muscle. Yes or no? Yes, sir. Yes or no? So, you can see A band having two kinds of zone. It is H zone and O zone. And if you will talk about z line, the area between two consecutive z line is known as sarcomere. Z line. I will write over here the consecutive z line. What? Area present between two consecutive z line is known as sarcomere. It is the functional unit of muscle contraction. Do you people agree with all these definitions? A band, I band, z line, sarcomere as well as H zone. Do you people agree? Say yes or no? Yes, sir. Yes. Let's see. So, one important thing. I will like to tell you people regarding the, this diagram you people can see in a bit realistic diagram. Can you observe over here? This diagram? Yes, sir. Please observe what all you people can see. After that I will discuss. I band is present over here. Okay. And from here to here it is A band. Okay. This area is H zone. This area is O zone. Here you people can observe the M line. Here you people can observe the M line. Agreed? Apart from all these things, you people can also see a titan filament. See, what is the function of a titan filament? You people can observe over here. You people can observe over here. Done everyone? Sir. Yes. Sir, the titan filament does it act like a spring during the contraction and relaxation process? Actually, it is going to give you a stability. Agreed? You can see over here. It can give you stability. Okay. Something is there that is connecting one jet disk to another jet disk. Yes or no? Yes, sir. Yes. Because if contraction is not going to be stabilized, that is not going to take place in a great way. Yes or no? Yes, sir. Yes. Anybody else? Anybody else? Anybody else? Zone of overlap is being shown over here. You people can observe and I hope you people have read your CRT well. Isn't it? See, now I will move to one important thing that is sarcoplasmic reticulum. Sarcoplasmic reticulum. Actually, if you will see the endoplasmic reticulum of muscle fiber is there, no? It is having two kind of tubules. Getting my point, rather I will say over here, the tubular system will be the better word. Tubular system. Why it is so? There are two kind of tubules that are present. One is T-tubule, another is L-tubule. Everyone, tell me, dear. One is T-tubule, another is L-tubule. Yes or no? Tell me. Yes or no? You see. In this diagram, a few people will see the T-tubule is going to dip like this. You can say it is formed because of folding of sarcolemma only. Let's see. This is the nerve fiber that is going to attach to the neuromuscular junction. This is the nerve fiber that is going to form neuromuscular junction over here. Any stimulus will come, will be given to sarcolemma, that is the plasma membrane of muscle fiber. Through that only, the impulse goes and it will be transferred to L-tubule and from L-tubule, calcium ions are going to be released. From the L-tubule, the calcium ions are going to be released. Yes or no? Agreed, dear? Now, this calcium ion been bind to troponin C and all and muscle contraction will take place. So, the storage of calcium ion is done by L-tubule and what is the function of T-tubule here? It is transferring the exon potential to L-tubule. Yes or no? The L-tubule is only known as the classical sarcoplasmic reticulum. Agreed, everyone? Yes, sir. Agreed, everyone? To my point, say yes or no? Yes, sir. You all can write. You people have written all these things that you want to write over here? Could you show the tubular system? Yes. Done? Just a second. Done. Done. No issues? Everyone? Yes, sir. Now, one thing is there. Arrangement of actin and myosin is three-dimensional. I am making a dummy diagram over here. You just imagine this molecule. This is a myosin molecule. Okay? The blue one is myosin molecule. You can see. Around this myosin molecule, one, two, three, four, five, six actin filament are surrounding them. There are six actin filament that is going to surround one myosin filament and if you will see, one actin filament is surrounded by one, two, three myosin filaments usually. Okay? I have made only one segment. You can make it like, or you can say make like others also. So, the thing is one actin is surrounding, one myosin is surrounded by six actin filament in a three-debut in cross-section and one actin is surrounded by only three myosin. Yes or no? Tell me. Yes, sir. You all can write these things. Done, everyone? Are we done? Done, dear? Everyone? Am I audible to you? Yes, sir. Done? Now, moving to the next segment, moving to the next segment, I am again taking help from one question. You can say one diagram from NCRT itself, the mechanism of muscle contraction. Okay? It is given, explained by sliding filament theory. Sliding filament theory. You can say in house also, in many cases, sliding doors are present. In many cases, sliding doors are present. Yes or no? In many cases, sliding doors are present. Yes or no? And when you open the door, you just slide that door alongside the wall. Is the length of wall or the door is going to decrease or not? Will it decrease? You are just sliding that door on the wall. Length of none of the thing is going to decrease. Neither the wall nor the door. Okay. Likewise, here acting slides over myosin filament and none of the filament decreases in length. Yes or no? Tell me that or yes or no? Say something, please. Yes, sir. Yes. Now, this is the relaxed state. This is the contracting state. This is the maximally contracted state. You can see in the relaxed state, length of sarcomere is this much. And in contracted and maximally contracted state, is it decreasing or not? Yes, sir. So during muscle contraction, length of sarcomere is going to decrease. Agreed, everyone? During muscle contraction, the length of sarcomere is going to decrease. Yes, everyone? Say yes. Yes, sir. Yeah. Let's see. Sarcomere is decreasing now. What about H-zone? Here the H-zone is that much big. Here, slightly smaller. And here it is not present. So H-zone is decreasing in size or not? Yes, sir. H-zone is going to decrease in size. Now, A-band. A-band. You see, it depends on length of the myosin filament. Length of myosin filament is not changing. So A-band will remain unchanged. Agreed, everyone? So A-band will remain unchanged. Agreed, everyone? Please tell me. Yes, sir. Now, what about I-band? What about I-band? You see, I-band is this much in length. Now, only this much. And here it is almost vanished. So going down, is it increasing or decreasing? Decreasing. Decreasing. So A-band is unchanged. I-band is decreasing now. This is overlapping zone. Is it increasing as we move down? Is it increasing as we move down? Tell me. Increasing, sir. Increasing, sir. So O-zone will increase in length. You people can note it down. We will further discuss formation of cross bridge. We will further discuss formation of cross bridge. Done, everyone? Are we done? Yes, sir. So now you will ask me, sir, how this sliding is happening? Sliding is going to happen by formation of cross bridge. Okay? I am going to let you know how cross bridge is going to be formed. Yes or no? Let's see. This is the myosin filament. It is the main axis of myosin filament, which is formed due to twisting of the tail part. Yes or no? Which is formed due to twisting of tail part? Yes or no? Say yes or no? Yes or no? Agreed? This is the myosin. And this is the cross bridge, the head. Or you can say cross arm part of the myosin. Do you people remember? You people can see over here, no? It's here. The main axis and this is the cross arm. Yes or no? This is the cross arm. Agreed? Yes. Everyone? Let's see. Formation of cross bridge, how myosin joins actin is the part of formation of cross bridge. Here, if I will say this is the actin filament, this is the myosin filament. It is the tail part and this is the cross arm part. Agreed? Myosin. In the head, in this region, actin binding site is present and in this region ATP binding site is present. Yes or no? Here, three blue color ATP. You can say three triangles I have made now that represents ATP. Yes or no? Yes or no? You can see over here from its main axis, the head is at around 120, 130 degree. Yes or no? Yes or no? It is around, that is not a right thing to call like that, but I am just doing it for the sake of understanding. Let's see. Now see, this had happened. What all events are going to take place? The stimulus will arrive to sarcolema at neuromuscular junction. Exon potential will develop in sarcolema. Now that exon potential will be transferred to sarcoplasmic reticulum via which structure? Tritibule. What? Tritibule, yes. As soon as this tritibule is going to, tritibule is going to really you can say convey that stimulus to the altibule what will happen? Release of CA plus 2. And if you people know if CA plus 2 releases, it binds to which part of troponin? Tell me dear. Sir, troponin C? Troponin C, yes. And as and what is the consequence of that? Sir, the binding site is exposed. Binding site of myocin, which is present on actin filament, will be exposed? Yes or no? Yes or no? So that will lead to unmasking of myocin binding site present on actin filament. And as soon as CA plus 2 will be released, this will lead to hydrolysis of ATP2. This will lead to hydrolysis of ATP2. Yes or no? Even ATP will be hydrolyzed. Agreed? And as soon as this will happen, the cross bridge will be formed. The cross bridge will be formed. Agreed dear? Yes. You see how cross bridge is formed? Now you see this is the myocin tail and this is the head. It is now at 90 degree around. This is at around 90 degree at this time. Now here you can clearly see two triangles and one triangle is separated. Two triangle is ADP and one triangle is inorganic phosphate. Agreed dear? Everyone? Agreed? So could you just explain the last part again? What have I told? As soon as CA plus 2 will be released, it will lead to unmasking of myocin binding site present on actin filament. And at the same time hydrolysis of ATP will take place. You see? Here you will see three triangles which is attached to each other. And here is two triangle and one triangle is separated. Yes or no? Two triangle is going to represent ADP and one triangle is going to represent inorganic phosphate. Agreed dear? Yes or no? So you see? It is at 90 degree. It is at 90 degree in this case. So you see? Earlier it was like this. Now it is like this. So not exactly 90 degree. It is something like that. I am just comparing that head is moving in this direction. Yes or no? Head is moving in this direction. Yes or no? Yes. Now you see? Head is further moving in this direction. Head is further moving in this direction. Earlier myocin filament was there. Actin filament was there at this place. Now it is there at this place. Means it has displaced or not? Yes sir. Yes. Now you see? This is the inner stroke. Contraction had happened. Now muscle started relaxing. Now you see? The head started relaxing. But this head is not going to detach from actin filament. Is this detached or not? In this diagram the head is detached or not? Tell me? In this diagram the head is detached from actin filament or not? So it is still attached. It is detached. It is attached. It is not detached. It will not detach. See this site is now empty as these two ADP and inorganic phosphate they are released. Yes or no? ADP and inorganic phosphates are released. Agreed dear? Yes sir. Noisos? So what happens? You see? This had happened. Now fresh ATP is going to bind to this empty site. This empty site that was there. The fresh ATP has binded to it. Now you see? This will lead to dissolution of cross bridge. Dissolution of cross bridge. Agreed dear? Everyone? Yes sir. Can I say for dissolution of cross bridge binding of fresh ATP to ATP binding site is required? Yes sir. For dissolution of cross bridge binding of ATP to the fresh or you can say empty ATP binding site is required? Tell me? And how formation of cross bridge has taken place? Formation of cross bridge has taken place due to hydrolysis of ATP. Yes or no? Hydrolysis means breakdown of ATP into ADP and inorganic phosphate. Yes or no dear? Tell me? Yes sir. Tell me? Agreed everyone? So I would like to tell you over here. Let's see. For binding of or formation of cross bridge what is required? For formation of cross bridge what is required? Hydrolysis of ATP and for dissolution of cross bridge what is required? Binding of fresh ATP to the ATP binding site is required. Yes or no? Tell me? Yes sir. Yes. Now. Now. Rheigar mortis. What is Rheigar mortis? Rheigar mortis is once a person die after 3 to 4 hour you are going to the body becomes joints become immovable. Yes or no? That is not going to move because any muscle in that state during death will remain in the cell. The same state in which it is there because without binding of fresh ATP the cross bridge is not going to dissolve. Yes or no? Without binding of fresh ATP the cross bridge is not going to dissolve. Agreed? Yes sir. Agreed? This is Rheigar mortis. After death, after death body is going to you can say will remain in the same state. You will try to move the joint you will not be able to do that. Agreed dear? Please note it down and try to understand. If you have any confusion just ask me. So how does the filament relax again? Yes once cross bridge will dissolve filament is going to remain you can say return to its normal site. Yes sir. Got it? Yes. Everyone got it or not? All of you have understood dear? Just take me attendance first. Otherwise I will forget. Yes. Write it down. Excuse me sir. Yes. So Rheigar mortis will set in only in filaments where cross bridge has been formed before death right? See in the body most of the time joints and all you can say those are always moving only. Okay. Getting my point. Either contraction is done or not. Many cross bridge are formed. You can say at every time. That will not dissolve because ATP, fresh ATP is not there. ATP depletion has taken place. So the biosynet is not going to get you can say fresh ATP. So cross bridge will not dissolve. Agreed? Sir will there be cross bridge? Where it is not formed? Where it is not formed? There is no question of dissolution at that place. So will there be Rheigar mortis even if a person passes away in a coma or something? No. In coma only brain is not acting. Rest of the part is acting. ATP is formed during Rheigar. You can say coma also. Getting my point. Brain is not acting. That is something else. Yes sir got it sir. Yeah. Done sir. Done everyone? Now everyone done? Now one disease I would like to define the disease is muscular dystrophy. Okay. Without this diagram you will not be able to understand that. Can you see this protein dystrophy? It is attaching the myofilament to the sarco lemma. Yes or no? Can you see that? Protein dystrophy? Can you see that dystrophy? What? So what does it attach? It is attaching this myofilament to the sarco lemma. Yes or no? Can't you observe this thing? Yes sir. Yes. So if this muscle, you can say protein is there. So there must be some gene which is coding for it. Protein is there. So there must be some gene which is coding for it. Agreed? Yes sir. So if some defect in that gene is going to take place in that clip, in that case will this protein will also get some defect? Yes sir. If gene defect will be there, the protein dystrophy will not be formed as usual. So in that case the force in muscle contraction is not going to be there. So muscular dystrophy is a degenerative disease due to defect in the gene coding for muscle, coding for protein dystrophy which is connecting the myofilament to the plasma membrane. You can observe this disease with the help of this diagram. Yes or no? Sir, is dystrophy responsible for conveying the nerve impulse to the myofilament? No, actually if, like try to understand my point, if dystrophy is not going to attach it to the sarco lemma, in that case what will happen? Like if something is there in your room, okay, in your room and inside the room you are moving that thing. By that the wall of the room is going to move. You have an option. Try to understand my point. You have an option. You have two walls that can be moved. If you will pull, it will move. So if you have to pull that wall, you have to attach things to the wall. If you will not attach and you will start pulling from here, will this effect be transmitted to this wall? No, sir. Yes. Yes, I got it. Done everyone? I think people have, one disease is done. Now I will not discuss this disease in the next segment, okay? Yes. In this segment I will leave it. I will ask you, please see to this. Then, now. Just a second, sir. No issues. Muscular dystrophy. It is a gene defect. Gene coding for protein dystrophy. Dystrophy is a protein. And functions I have told you people. I hope you will understand. Done, sir. Done everyone? Now see. There is a comparison diagram that is there, or you can say table that I have taken from the tortera, one of the great books. So see over here. I have made, you can say, pasted a comparison table over here. You people first observe this thing. Almost all the things we have discussed. Few things you will ask me. I will discuss it to you. You can make this. You can write it down. Okay. You can leave the diagram. I'm going to make that one for you. Few things you will ask me that I'm going to explain. Please write it down. Sir, how could you scroll up a bit? What? Sir, like the first column of the table. Yes, sir, just a minute. Only those things are there that you people have understood. But in a tabulated format. It is a very good table. Many of the questions of need is going to be solved from this table itself. Sir, could you just show the smooth muscle again, please? Done everyone? Sir, just a minute. Done. Once you will be done, please let me know. I have to make you understand few things. Yes, sir. Just a minute. And all those points in which I have ticked it, those are really very important. Done everyone? So the last few headings are just a minute. Yes. Done dear? Just a second, sir. No issues. Done, sir. Done. Let's see. First thing that you people need to know, this thing I'm saying CTM. What is in CTM? See, earlier many cells were like this. After that, what happens? Scepta between them get dissolved. Now it looks like that one cell having many nucleus. One cell having many nucleus. Yes or no, dear? That is in CTM. So skeletal muscle is unbranched. Cardiac muscle is highly branched. A smooth muscle. We are going to discuss that later on. Now see. In a skeletal muscle and cardiac muscle in a skeleton muscle and cardiac muscle. You can say the myofilaments are arranged in the form of myofilaments are arranged in the form of what? Sarcomere. Hence, both are going to look astriated. Yes or no? Both are astriated muscles only. Say yes or no? Tell me, dear. But the arrangement, you people are getting or not? Are you people getting? Yes, sir. Yes. Now let's see. One important concept over here is one on. One important concept over here is this is a smooth muscle. It is the plasma membrane of a smooth muscle C. This black line represents actin filament. And this gray line represents myosin filament. Actin filament and myosin filament. And here is the dense bodies. What dense bodies agreed? So the function of, you can say, z line is performed by dense bodies over here. And, and actin and myosin filament are arranged like this. You see almost along the complete length myosin filament is there. So no alternate appearance is there. So it will not look astriated. It is known as striated one. Yes or no? It is known as striated one. Agree, dear? Tell me. Tell me that. Yes, sir. Now, now one is regulatory protein. In case of a striated muscle, what is regulatory protein? Please let me know. In case of a skeletal muscle, what is the name of regulatory protein? Which only regulate, do not contract two kind of proteins I have told you. One is contractile protein and one is regulatory protein. Sir, troponin and tropomyosin. And here that name of that protein is calmodulin. What? Calmodulin. What? What is the name of regulatory protein of a smooth muscle? Calmodulin. Calmodulin. Please see. Here, a smooth muscle having two things. One is single unit. One is multi unit. In single unit, a smooth muscle, all the fibers are joined together. Means they are in here. If you will see, they have written also about gap junction where it is written. Visceral smooth muscle. Okay. It is there because visceral smooth muscle is a single unit of smooth muscle. Means all the muscle fiber will contract together. If you have to perform some work together with your colleagues. Do you need to communicate with them? Do you need to communicate with them? You need to communicate none here. You need to communicate now. Tell me. Yes, you need to communicate now. So in this case, muscle fiber also need to communicate. So they are going to have gap junction. So have you people understood the logic behind visceral a smooth muscle going to have, you can say gap junctions. What is the function of gap junction here? What is the function of gap junction? Please let me know. So connects the sarcoplasm of two different my fibrils. Actually gap junction is going to connect to cells. It helps in cell to cell communication. Yes or no? Yes. So gap junction helps in cells to cell communication. Read everyone. Gap junction helps in cell to cell communication. Isn't it? Isn't it? So if they all the fibers have to contract together in that case, what will happen? They need to have communication or not? Yes, sir. Yes. Then multi unit a smooth muscle. Multi unit a smooth muscle. See, your fibers act independently means one fiber and another fiber. They are contracting differently. Yes or no? So if they are not working together in that case, will they required gap junctions? No, sir. Because they need they do not need communication. So multi unit a smooth muscle do not have gap junction. Here, erector ply muscle and iris muscle. Two muscles are there. Erector ply is there in the roots of air follicles and helps in helps in contraction. Yes or no? Everyone? So muscle, a smooth muscle is fusiform in shape, tapering at both the ends and thick in the middle. It is uni nucleate. Yes or no? It is uni nucleate. Everyone? Sir, can you repeat why the multi unit smooth muscle doesn't require gap junction? Actually, what is muscle? See, many muscle fibers are there. If they are not contracting together in that case, will they require if they do not have to contract together in that case, will they require communication with each other? It is not going to because communication is for what? If cells are working together for that only communication is needed. Tell me. Sir. In multi unit a smooth muscle, the muscle fibers are contracting independently or contracting independently. Yes or no? Everyone? Yes, sir. Then you can see. This is the diagram of multi unit a smooth muscle. Diagram of many things are now one thing is organized into sarcomere. Yes, it is for a skeletal muscle. Yes for cardiac muscle. No for a smooth muscle. I have told you. We'll talk about sarcoplasmic reticulum. It is abundant in a smooth muscle. Some in cardiac and very little in a smooth muscle. So actually, if more sarcoplasmic reticulum is there, in that case, that means they have, you can say, they have stored lots of calcium in this case. They have stored lots of calcium in this case. Not here. Yes, sir. They are going to store lots of calcium in that case. It is the fastest contracting muscle. Speed of contraction is fastest in because for contraction, what do you require? What do you require? Calcium release of calcium only. So if sarcoplasmic reticulum is abundant, it can release calcium very frequently agreed. So which should be the fastest, fastest, fastest contracting muscle? A skeletal muscle should be there. Not here. Yes. Now, regulator proteins, you can see troponin and tropomyosin, troponin and tropomyosin in a skeletal as well as cardiac, because I have told you similar arrangement of, similar arrangement of what? Similar arrangement of what? Sarcomere are there in skeletal as well as cardiac muscle. Agreed, dear? The regulator proteins are troponin and tropomyosin in case of skeletal as well as cardiac muscle. And it is called modeling in case of a smooth muscle. Agreed, everyone? Yes. Tell me, dear. Yes. We'll talk about nervous control. You know that only a skeletal muscle is there in your control. None of other muscle is under your control. Agreed, you people know that. Noisos, now for contraction from where? Calcium is coming. For skeletal muscle, it is sarcoplasmic reticulum. Sarcoplasmic reticulum and interstitial fluid for cardiac as well as a smooth muscle. Agreed? For skeletal muscle, it is entirely sarcoplasmic reticulum. Agreed, dear? Source of calcium. Tell me, are you people getting it or not? Say yes or no? Yes, sir. Yeah. Yes, sir. Now, junctions between fibres, it is none. Here you all can see. Okay. Connective tissue component. All the three covering is there. Only two is there. Epimysium is absent. Here only endomyceum is present. Agreed, dear? Everyone? Yes, sir. Please see to it. So could you scroll down to the diagram of the smooth muscle? Yes. One more thing is there. Let's discuss first. See, this is your cardiac muscle. This is your cardiac muscle. This should be complete first. Just let me take out first. See, this is going to represent junction between two cells. This is known as intercalated disc. Means this is one cell and this is another. I told this is one cell, this is another. It is intercalated disc. Which disc? Intercalated disc. Agreed, dear? Tell me. Yes, sir. Intercalated disc that is there. Now, you can see what is intercalated disc representing? It is the junction between two different cells. And you can see this is the striations that you can see because of that actin and myosin component. This is a striations. Hence it is also a striated muscle. Another thing, this is the branching. And you can see because all the cardiac muscle cells has to contract. All the cardiac muscle cells has to contract together. Hence all the cardiac muscle cells has to contract together. Hence what is there? There should be abundant gap junctions in the intercalated disc. Yes or no, everyone. Because what have I told? If all the cells has to contract together, those cells bound to have gap junctions because they need to contract. They need to communicate. Yes or no? So intercalated disc is rich in gap junction. Is this understood? And what intercalated disc representing for? Is that understood? Yes or no? Others also. You need to take part in the class because in so many classes, I keep on emphasizing because you see we are studying science. Okay. It can never go one way. It cannot happen. You have to explain also. If you are not getting anything you have to ask and you understood if I'm asking a question, you should explain that. Let's see. Draw the diagram and write down what I have written. Done, everyone? Yes, sir. There is a homework. You have to find out the difference between white muscle fiber and red muscle fiber. You have to find a difference between white muscle fiber and red muscle fiber. This is important. Sir, the intercalated disc diagrams are just a minute. No issues. You all can write. Once you will be done, please. You can say let me know. Done. Done, sir. Yes, sir. That t t bill thing I have explained again. You all can see. In each sarcoplasmic reticulum, you can say, sorry, in each sarcomere, there are two t t bills are there. It is situated at the junction of a and I band. Okay, there are two. Okay. Anybody is confusing that it is for anybody is confusing that it is for two year and two year. See, see this diagram. If I will cut it now. I will see to this side and to this side. Yes or no. It is similar. One, two. Let's sit here. Everyone after cutting this, I will see to here and to here. So it will look like it is for agreed. Yes, but actually it is two. It is situated at the junction of what a and I band per sarcomere. It is two. Done. Are we done? Yes, sir. Yes, let's sit here. One is types of muscle contraction. One is types of muscle contraction. And another is neuromuscular junction. Just a minute. I will talking about types of muscle contraction what types of muscle contraction types of muscle contraction one is isotonic contraction. Another is isometric contraction. You can see just to imagine you are put you can say pulling a dumbbell up in the gym. And you can do it now also. Can you see your you can say if weight of the dumbbell is 5 kg in that case, the weight is going to be constant now. If you wait up the dumbbell is 5 kg in that case, bait is going to be constant. Only thing you are doing what means force that your muscle is putting its constant, but length of length of the muscle is decreasing. Muscle tone means the force exerted by muscle muscle tone means the force exerted by the muscle agreed. So what is isotonic contraction. It is the force is constant, but you can say the length is decreasing. Yes or no. The force is constant, but the length is decreasing agreed. Yes, sir. Everyone. Now, in the second case you just you people just imagine you are pushing a car. In that case, you try to increase the force, but length of the muscle is not changing. That is what I saw metric agreed here. What happens over here in isotonic contraction. Let's see. I'm going to write over here. I saw Tony contraction is where I saw Tony contract where the length is decreasing decreasing, but force remains constant. Which force that is exerted by the muscle and in isometric what happens force changes length of muscle. The length of the muscle is constant. Agreed here. Everyone agreed everyone. Yes, sir. Write it down. Done. Are we done? So just a minute. Done. Done. Let's see. One is neuro muscular junction. It is another important fact. You people should be knowing. Neuromuscular junction over here. Neuromuscular junction. It is the junction between neuron and the muscle fiber. It is the junction between neuron muscle fiber. Let's see muscle fiber is one muscle cell. What all components are there? This is the pre synaptic membrane. This one. Just a minute. This is the pre synaptic membrane. Which is the membrane of exon terminal or synaptic knob. Yes or no. This one. Can you observe easily? Or should I make? Let's see. This membrane. This membrane is pre synaptic membrane. This is the sarco lemma known as motor and plate. The part of sarco lemma which is the part of what? Which is the part of neuromuscular junction is known as motor and plate. And you can easily observe there is a space present between pre synaptic membrane and motor and plate known as synaptic cleft. Synaptic cleft. Yes or no? Agreed dear? That is known as synaptic cleft. Say yes or no. Either say yes or say no. Are you people getting me? Am I audible to you? Yes, sir. Yes. So pre synaptic membrane is the membrane of synaptic and bulb or synaptic knob in which neurotransmitters are there. And post synaptic membrane is which is there in the synapse in case of junction between neurons. Here it is motor and plate. That is the sarco lemma only. Yes or no? Now you see. Motor and plate is going to have receptors for a stylocholine. What? Receptors are there. This green color structure. Can you people observe? Can you people observe? Yes, sir. Agreed dear? Yes. Agreed everyone? So that is the motor and plate. And here is the receptor. Once impulse will arrive here from the zone synaptic knob. From the synaptic knob, what is going to happen? The synaptic recycle is going to release the neurotransmitter. That neurotransmitter will be there in the synaptic. Yes or no? And from there it will go to bind to the receptor present on the motor and plate. And from there it will generate exon potential in the muscle fiber. Yes or no? Tell me dear? See all the steps are given. Impulse is arriving. Stylocholine is getting released. Now it is binding. Let's see. Here binding is there. Neurotransmitter you people know, right? What is the neurotransmitter in case of neuromuscular junction? Neurotransmitter is what? Acetylcholine? Yes or no? And in the synaptic left, one enzyme is there. That is acetylcholine s. There is. Agreed dear? Agreed dear? Everyone? I think screen mirroring has stopped. Just give me a minute. Yes. Can you people see? A stylocholine and here is the stylocholine stress. Agreed dear? Everyone? Done? Say yes or no? Yes sir. Yes. Agreed? So neuromuscular junction you people have to understand. And what is this for? A stylocholine stress is enzyme which will dissolve the or digest the stylocholine. Yes or no? It will digest the acetylcholine. Okay. Once conduction is done, the neurotransmitter has to be dissolved or digested. Otherwise what will happen? It will keep on happening and that is not a good thing at all. So in your NCRT, can you people see? One digit is mysthenia gravis. Please take out your NCRT. Please take out your NCRT. One digit is mysthenia gravis. Can you observe and read out the paragraph? Why this disease is there? Read out the paragraph why this disease is there? Done? Agreed everyone? Are we done here? Are we done? Yes sir. In a better way we will understand this again once you will be done with synapse. That is the junction between two different neurons. This is all about the muscular system. Now, locomotion and movement chapter in that skeletal system we are going to study now. Let's see here. Locomotion and movement. What is movement? It is any change from the original position. Movement can be amoeboid. It happens by changing the shape. You can see over here, observe over here. The cell is changing its shape and moving out. That is known as diapetesis in case of WBCs. One is ciliary movement. Continuous or coordinated movement of cilia brings about movement. It is the movement of female gamete in fallopian tube. It is the movement of female gamete in fallopian tube. And one is muscular movement. It is due to contraction of muscles. It is movement at joint. The movement that takes place at joint. Agreed. And another is flagellar movement that is shown by sperm in case of human body. So you people can write this thing first. Movement. Done, everyone? Are we done here? Just a minute, sir. Done. Done, everyone? Amoeboid movement, ciliary movement, muscular movement and flagellar movement. Agreed, dear? Now, what is locomotion? Locomotion is any movement that brings about change in place. Agreed, dear? Hence, I will say over here, all locomotion are movement. Movements are not locomotion. Agreed, dear? Done. We'll talk about skeletal system of human. In adults, it consists of 206 bones. 206 bones, 206 bones. Okay? In newborn, more number of bones are there. Okay? We will talk about that later on. Your skeletal system consisting of exgeal skeleton and appendicular skeleton. Exgeal skeleton consists of a skull, ribs, sternum, and vertebral column. A skull, ribs, sternum, and vertebral column. What is appendicular skeleton? It is consisting of girdles and limbs. Girdle. What is the function of girdle? You see, see the diagram. This part is girdle. This part is girdle. It is actually connecting the exgeal skeleton to the limb. Yes or no? So, what is the function of girdle? It connects exgeal skeleton to limbs. Agreed, everyone? It connects exgeal skeleton to limbs. Two kind of girdles are there, dear. One is pectoral girdle. Another is pelvic girdle. One is pectoral girdle. Another is pelvic girdle. Pectoral girdle having two bones. Talk about that later on. And you are having two kind of limbs. Upper limb and lower limb. Okay? After break, we will start with this only. Okay? We'll have a 15 minutes break. We'll be joining you people soon. Okay? Understood? Tell me. Yes, everyone? Am I audible to you? Am I audible to you? Am I audible to you? Say yes or no? Let's see. Exgeal skeleton system is going to have 206 bones. Yes or no? Everyone? Am I audible? You people are back. Say yes or no? Yes, sir. Yes. A skeletal system is going to have 206 bones for adults. It is more in, you can say, infants, because as the age progresses, fusion of many bones are going to take place. It will become, many bones will become one. Here, exgeal skeleton is going to consist of the skull, the ribs, the sternum, and the vertebral column. Exgeal is going to have two kinds of bone. One is cranial bone and one is facial bone. Exgeal is going to have two kinds of bone. One is cranial bone and another is facial bone. And ribs are going to have a true, false, and floating category. Ribs are going to have true, false, and floating category. A sternum having only one bone. And vertebral column having 26 serially arranged vertebra. What? Vertebra. Exgeal is going to be formed of cranial bone and facial bone. But it also contains aerocycle and void bone with it. Yes or no? We are going to discuss one by one. One thing is, exgeal is made up of 22 bones or composed of 22 bones. But exgeal contains 29 bones. Why I am saying so? Because see, inside exgeal only aerocycle is present. But it is not taking part in formation of exgeal. It is only present inside the exgeal because it do not articulate with any of the bone of exgeal. Aerocycle do not articulate with any of the bone of exgeal. And here is the void bone. Having only one bone is there in the neck region. So are you people agree with these two points? In form, like your room is there. Room is there. Wall is there. Okay. Your room is made up of wall. But if table is kept inside room, I cannot say that room is made up of table also. Isn't it? Tell me dear, are you people, you can say able to understand the analogy that I am saying? Yes. Yes. So if somebody will ask you room is made up of, you are going to say wall. Okay. Likewise, exgeal is composed of 22 bones, but it contains 29 bones. Yes or no? Done? Now, all this calculation, we will see one by one in the next part, but we are going to start with the skull. Skull having cranial bones and facial bones. There are eight cranial bones and 14 facial bones that are there. Eight cranial bones and 14 facial bones agreed. Eight cranial bones and 14 facial bone. Let's see how many cranial bones are there? Eight. One is frontal, two are parietal, two are temporal, one is occipital, one is spinoid and one is ethmoid. Agreed? Let's see. Frontal is over here. Okay. There are two parietal bone here. This is for right side and for left side also it will be there. So one frontal, two parietal, one occipital. It is for two temporal, one spinoid bone. Yes or no? Can you people see over here? This bone, that is a spinoid bone. Please see to it. This yellow color bone is a spinoid bone. Can you see a bony cavity inside a spinoid bone? Can you see a bony cavity inside a spinoid bone? That is known as cellar tarsica. That is known as cellar tarsica in which pituitary gland is present. Which gland? Please tell me. Which gland is there? Pituitary gland is present inside the cellar tarsica. Agreed here? Agreed or not? Say yes or no? Either of this. You can say. There are 14 facial bones. Before that eight cranial bones. Can you people observe the spinoid bone? It is attached to the frontal bone also. To the parietal also, to the temporal also. To the occipital also. Yes or no? All the bones. Which are there? So can I say that a spinoid bone is articulating to all the cranial bones? Can I say that? Can I say that? You people can see over here. What all bones are there? Frontal, parietal, temporal occipital. These four bones are there. These four bones are there. Agreed? These are there. It is attached to this also, this also, this also. And this also. So spinoid bone is attached to all the cranial bones. Agreed? Agreed? Now, 14 facial bones. Okay. 14 facial bones are there. Two nasal bone. Two maxilla. Two zygomatic. One mandible. Two lacrimal. Two palletine. Two inferior. Apart from vomer and mandible. All the bones are paired. Agreed? Although I have made a mnemonic in Hindi. Okay. But if it is going to help you people, you can see. See. NJM, MB, IPL. NJM means there is a favorite station in Delhi. You can say a large station that is Nizamuddin. If you would have come over there, you must be knowing otherwise. Nizamuddin. For that NJM is written. MB in Hindi, maybe IPL you know. So you can use this mnemonic in whatever way you people want to use. So apart from vomer and mandible, all the bones are what? All the bones are paired. Agreed here? Agreed? Everyone agreed? Tell me. Yes. You all can observe. Just give me two minutes. I'm just talking to you. Just give me two minutes. I'm coming back. Just a minute. Let's see what I wanted to tell you all. See. I told NJM nasal bone. You can observe over here. Nasal bone. Gigomatic bone is this cheek bone. M. Magillary bone. MB. Mandible is there. And vomer is also there. I'm going to show you people. Vomer. You can see a small bone in the base of the nasal septum. That is vomer. Agreed? MB, IPL. Inferior nasal conca. This one. P for P, palatine is going to be there. Palatine bone is over here. This is palatine bone. L, lacrimal. It is there on the lateral side. It is there on the lateral side. You all can observe. Over here. Getting it? Getting it? Just a minute here. I'm back here. Understood this thing? This is the cranial and facial bone. That is your complete skull. Okay. Few bones you can see over here also. So for a skull, I'm going to write. Composed of eight bones. Cranial bones and 14. Facial bone. Scal contains 29 bones. Cranial bones are eight. Facial bones are 14. Erocycles are six. And white bone is one. Erocycle is three. Malleus, incus, and STPs. Malleus, incus, and STPs. You can remember it like miss. Yes or no? Agreed everyone? Do you want to write this? Do you want to write this? Say yes or no? Am I audible to you? Yes sir. You can write this. Done everyone? You all can write this down. Are we done? Are we done with this? Let's see. Cranial bone. Cranium or brain box I have told you. I have told you about the spinoid bone. I have told you about the spinoid bone. Now, sutures. This is structure. You see. This thing you can see. How cranial bones are joined to each other. With the help of sutures. Scal bones are joined to each other with the help of sutures. Sutures are fibrous joint. Do not allow any movement. Do not allow any movement. Sutures are fibrous joint. Do not allow any movement. Agreed? And one is fontanel. Fontanel. If you are going to touch the cranium or head of a small child, you are going to get this kind of soft structure. This kind of soft structure. That is known as fontanels. What fontanels? They are the area in a skull where bones are not joined by sutures. Present in early part of life. Because your brain is going to need a space for growth. Your brain is going to need a space for growth. Agreed? And that is known as fontanels. They are the area in a skull where bones are not joined by sutures. Present in early part of life. Helps in growth of brain. Then, dear, now you see. This is your brain. Not brain rather, this is the... We are trying to watch this thing from this side. From the lower side. We are trying to watch this thing from the lower side. Agreed? Lower side. You see, this view is there. Can you see these two structures? Can you see these two structures, dear? They are known as occipital condyle. And this is the structure through which a spinal cord comes out. This is the structure through which a spinal cord comes out. You can see there are two occipital condyle which is going to bind to your first vertebra that is atlas. Your first vertebra that is atlas. Agreed, dear? Agreed? So how many occipital condyle are there in case of human? On either side of forearm and magnum? Through which a spinal cord comes out of the, you can say, cranium. How many occipital condyle you all can observe? How many occipital condyle you all can observe? Two, sir. There are two. So this kind of skull is known as daikondylic skull. Daikondylic skull. Agreed, dear? You all can observe. You can write down the definitions. Write down. How are you? Yes, dear? Am I audible now? Yes, sir. Mystically, I have muted myself and I was speaking constantly. After that, I have seen the, let's see, occipital condyle is two. That kind of skull is known as daikondylic skull. Here is mono-kondylic skull. Only one occipital condyle. It is there in reptiles and apes. Getting my point? Reptiles and apes. Getting my point? Daikondylic skull. Two occipital condyle. Dibia and mammalia. Okay. Facial bone. N-Z-M-I-P-L. And all I have told you already. If we will talk about aerocycles, you can say malleus, incus, and stapes. Malleus, incus, and stapes. Stapes is the smallest bone of your body. Stapes is the smallest bone of your body. Yes or no? Done, dear? Yes, sir. You all can see. You all can write. You all can write these things. Monocondylic, daikondylic skull part. Spinal cord comes out through foramen magnum. That also you can write. Done. Monocondylic, daikondylic skull. You are done. Yes, sir. Now one is hoid bone. You can see the location of hoid bone. You can see. It is a special bone. It is there in the neck. Single U shaped. It do not articulate between any other bone. Okay. But many muscle of the skull region articulate with it. It is the part of the skull bone. Done. Done. Done, sir. Done. A sternum. A sternum is situated in the mid ventral line of thoracic cavity. Okay. Mid ventral in the center here. Okay. It is having three parts. Manobrium body and G fight process. G fight process. Agreed. Manobrium body and G fight process. Okay. It articulates. You can see. It articulates with clavicle. This bone is clavicle. Yes or no. It articulates with clavicle. And ribs. Ribs. Okay. Read. Done here. It articulates with clavicle and ribs. Yes or no. Done. Done here. Yes, sir. Let's see. Ribs. Ribs. There are 12 pairs of rib. Okay. There are 12 pairs of rib. Agreed. Human rib is bicephalic rib. It has two articulation surface on its dorsal side. Okay. Types of ribs, true ribs, false ribs and floating ribs. True ribs, false ribs and floating ribs. True ribs are one. Let's see here. True ribs are one that articulates. Well, Four. To the thoracic vertebra or dorsal it to the thoracic vertebra and what really to the external. With the help of file in cartilage. So behind it is. But the bro external ribs. Behind it is attached to vertebra and in front is attached to. External. vertebral column dorsally and you see hyaline cartilage of seventh rib, seventh rib that is there, okay, means it is it is not directly attaching to sternum rather to the hyaline cartilage of seventh rib, it is vertebrochondral ribs, eight ninth and tenth pair of ribs, floating ribs, they are attached to the vertebral column dorsally and anteriorly they are free, means they are attached to nothing, so only vertebral ribs are there, every deer it is eleventh and twelfth pair, first seven are true vertebro sternal ribs, next three are false ribs only vertebrochondral ribs and last one is floating ribs that is eleventh and twelfth pair, done, we will just write it down, done, so put it scroll down, yes, done, everyone, done, done, everyone, this is the let's see, done, let's see, we will be talking about vertebral column now, we will be talking about vertebral column now, let's see vertebral column, let's see deer, can you people observe this thing, structure of vertebra please observe, what you are able to find in this, done, everyone, let's see deer, you have 26 serially arranged vertebra, can you observe over here, can you observe over here, this is the anterior side, this is the posterior side, yes or no, now, this is the cervical curve, this is the thoracic curve, lumbar curve and sacral curve, let's see, cervical curve is formed by, actually you know, if you will see now, in the uterus of mother the child is like this, this is head, this is tail region, everything is convex, yes or no, first time this is head, first time child want to raise his head and this curve becomes concave from posterior side, concave from posterior side, agreed, concave from, agreed, yes sir, so this curve, cervical curve is present from the beginning or developed after the birth, tell me, in the beginning, yes, it is present from the beginning or once child has started raising his head, then it is formed and this lumbar curve is formed once child is going to, child will start to get up, okay, child will try to get up, agreed dear, tell me, say yes or no, getting or not, please tell me dear, I told cervical curve is formed once child is trying to raise the head, so it is not present from the birth, it is formed later on, agreed and lumbar curve is formed, lumbar curve is formed once, child will start to get up, yes or no, so in those animals in which tetrapedial mode of locomotion, this lumbar curve is absent, yes or no, tell me, say yes or no, done, done, yes sir, so here you can see the thoracic curve and the sacral curve is primary curve which is present from the birth itself, it is the primary curve, what all curve, what all curve, what all curve of primary, primary curve is what thoracic and another one is sacral, why it is present from the, agreed and then what is secondary curve, cervical and lumbar because it is formed later on, agreed dear, everyone, done, done dear, yes sir, now your vertebra is going to have following parts, the body, the vertebral arch and processes, there are transverse process, spinous process and superior process, articular process, inferior articular process, you people just observe transverse process and spinous process in this diagram, you see to it, can you observe, can you observe that spinous process is going into some other plane, agreed, done, agreed, let's see, here I will say the vertebral body, okay and then processes, this is the transverse process, you can see, this is the spinous process, you will see that in this view, it is going down, agreed, vertebral body is connected to this, this arch, vertebral arch with the help of this bony structure that is known as pedicel, you can observe and spinous process is connected to this, with this help of this structure that is lamina, done, vertebral body, body is a solid structure and you can see this is vertebral foramen through which spinal cord passes, agreed dear, can you clearly observe, yes sir, done, now superior articular facets, see one vertebra is kept on another, so inferior articular facet of this vertebra will articulate with superior articular facet of this vertebra, yes or no and in between, there is inter-vertebral disc, inter-vertebral disc which is white fibrous cartilage, done, done dear, superior articular facet of this vertebra will join to inferior articular facet of upper vertebra, done, done, done everyone, let's see dear, I have told vertebra having following parts, that is body, the body is a thick disc shaped anterior portion, you can observe, body is there on the anterior side, then vertebral arch, then processes transverse process and a spinous process, they are going to provide attachment to the muscle and you people can observe the role of superior articular process and inferior articular process, I will send this PDF to you, you people can write this thing, done, done, done, done, vertebral arch, vertebral foremen and see, opening of one vertebra is known as vertebral foremen, okay, if they will join, they will form vertebral canal, done dear, done everyone, so this is the vertebral column, see, you can see the first vertebra is known as atlas, second is known as axis, you can write down, done, done sir, let's see dear, you have, you have seven cervical vertebra, twelve thoracic vertebra, five lumbar sacral is one and coxigial is one, but actually it is, but actually it is, if you will talk about this, it is 26 vertebra, but in infants it is, in infants it is 33 vertebra, how it is so, how it is so, tell me, because in infants sacrum is going to fuse, agree dear, in infants sacrum is going to fuse, sacral is five that becomes one and coxigial is four that becomes one, so total number of vertebra in infants is 33, you all can write this, done, so your vertebral formula is C7, T12, L5, S1 and coxigial one, you can write it like C7, T12, L5, S5 in bracket and coxigial four in bracket, so how many will be there, done, dear, tell me, first cervical vertebra is known as atlas and second is known as axis, they form atlantooccipital joint, yes or no, see to it, done, dear, you all can see, are you done with this, done, sir, let's see, one important thing, dear, one important thing, what is the process and what is the fossa, see, this is the process, process means positive, positive elevation and here is behind, this is fossa, what, behind this is fossa, agreed, behind this is fossa, agreed, dear, so what do you think, which vertebra is going to have process and which, which vertebra is going to have fossa, tell me, which vertebra is going to have process and which vertebra is going to have fossa, sir, atlas has a process, atlas having a process and axis is going to have a fossa, you see, what is the meaning of pi board, pi board means a pillar, what a pillar, okay, and this kind of joint is known as pi board joint, so what kind of joint is there, what kind of joint is there between atlas and axis, it is pi board joint, tell me, tell me, dear, understood this thing, this is the pi board joint, everyone, do you, people have any confusion in vertebral arch, vertebral foremine, spinal canal, transverse, spinal process and all, tell me, agreed, agreed, now we'll talk about appendicular skeleton, we'll talk about appendicular skeleton, you see, it consists of 126 bones, how many bones, 126 bones, agreed, and what are they in the, in this, see, I have told how many components that are there in appendicular skeleton, it is girdle and limbs, agreed, agreed, girdle and limbs, girdle is going to have two kind of girdles are there, first we will read this photo only, after that we will go to that, what is pectoral girdle, you can see, this is escapula, what, this is escapula, agreed, this is escapula and this is clavicle, clavicle, agreed, you can easily observe on the back side a spine of escapula, yes or no, yes or no, agreed, you can easily call that as a spine of escapula, what, a spine of escapula, are you people getting me, this is known as a spine of, can you observe this thing or not, yes sir, and this ends into, this ends into acromion process, acromion process, agreed, this ends into acromion process, this is from the backside, if you will see that from the front side, here is your acromion process, here is your acromion process, to this, clavicle is going to join, yes or no, no, so to the acromion process of escapula, which bone is going to join, clavicle on the lateral side, to the sternum, clavicle is going to join to form, to form a sternoclavicular joint, yes or no, tell me dear, to acromion process, clavicle is going to join or not, laterally and medially, clavicle is joining to sternum or not, tell me, yes sir, done, done everyone, so can you observe over here, now just below the acromion process, can you see there is a cavity or fossa over here, to which head of humerus is going to bind, then, can you repeat, below the acromion process, this is the glenoid cavity, to which head of humerus is going to join, you can easily see this, to form gleno-humoral joint, agree dear, so can you see how many bones are there in the pectoral girdle, how many bones are there in the pectoral girdle, one is a scapula and one is clavicle, so to this side and to this side, how many bones are there in total, four and if you will talk about pelvic girdle, one this side and one this side, how many of them are there, two, so total bones in the girdle is done, now see, total number of six bones are there in the girdle, total number of six bones are there in the girdle and 30 in each limb, you have four limbs, 120 in the limbs, it will be 126 and 80 bones are there in the axial skeleton, so in total it is 206, agreed, done, done dear, agreed, we will see in the next class, okay, in the middle I have muted the mic and I keep on speaking, keep on speaking and it happened like that only, no issues, we will see it in the next class, okay, bye dear.