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Cells, Immunology & MSK - PreClinEazy

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Summary

This on-demand session is an excellent opportunity for medical professionals to learn about cells. Starting from the basics of cell formation and hierarchy, the session then dives into four types of tissue; epithelial, connective, muscle and nervous. It covers what shapes and layers of these can be found in various parts of the body and how these were designed for specific functions. Attendees will also receive weekly promotions from Medical Protection Service and MDU Medical Difference Union for free membership. Slides and a feedback form will be distributed at the end of the session and members will also get the chance to join the skilled Easy mailing list for regular updates.

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Learning objectives

Learning Objectives:

  1. Identify and distinguish 4 categories of tissue types (epithelium, connective tissue, muscles, nerves).
  2. Understand the three shapes of epithelial cells (flat cells, cube shape cells, rectangular cuboid shape cells).
  3. Explain the difference between simple and stratified tissue types.
  4. Utilize strategies for memorizing the location of different tissue types in the body (based on function).
  5. Explain the characteristics of transitional and pseudostratified epithelium.
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Computer generated transcript

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The following transcript was generated automatically from the content and has not been checked or corrected manually.

um so yeah, we'll just come to your question in a bit. It's It's in the introduction. So hi, everyone will ask Easy. Um, if you haven't attended one of our sessions before, um, we have been presenting previously on the different name called Revising Recap. But today we're presenting for the first time in this name, which is preclinical just a heads up. This is for this is pitched that preclinical students. So in medical school year once in your toes, if you can see the state, If you're not a pre clinical student, we encourage it, actually. But if you want more clinical, relevant knowledge, do join our finance easy sessions, which are going on a almost a daily basis. Tomorrow we have a session and the next week, Tuesdays, the next session. We're happy to be sponsored by this sponsors. Medical Protection Service is a A protect all medical students and healthcare professionals against medical lawsuits. They have a weekly promotion of 183 lbs. Eso please to sign up to medical protection service. Similarly, MDU Medical Difference Union also protect against medical lawsuits and other malpractice is that you could encounter both the memberships are free. Um, as a medical student and as a first year junior doctor, Um so consider if you want to join both, go in and join both, but we're happy to be sponsored by them. Metal are an amazing platform that help us in many ways. They keep the content, the recordings, the feedback forms a swell as the slides. Although the slides will be sent to you also, so do you check them out, create a A create an account on their on their platform so that you can join us? I say, as remember, um, and a quick shot at the anastomosis also. So we're happy to be sponsored by Quest meant, uh, quest matter. An amazing question, bank. We all use them on. They provide good questions as well as very induct explanation to the questions for clinical medicine. So pleased to use our Pulmicort ask Easy 20 for 20% off their question. Bank, that's not easy. 20 for 20% off. We also have one more, uh, kind of society that way created a community which is the Oscars. The community. Um, if anyone off you guys, the organizer's have the Oscar, the community Lincoln contagious posted in the chat. We provide questions there, and you can ask naturally, any questions that off your sock it doesn't have to be medicine related. It can be anything related and where the it means I'm more than happy to kind of created discussion, going. We post regular day, almost daily questions. They're so do join and engage in the surveys and stuff so that it helps your learning, too. I'll just skip this. So just a few general rules, please keep him microphone and camera on mute. Ask questions, interact on the chat. We're here to answer them. Engage in the polls. I'll be respectful on the chart. The session is recorded. So any anyone who turns on your microphone on camera, uh, by attending the sessions, your permitting us to upload this on to meddle. If you have any problems with this, please let us know and we will try to remove that particular bit from the recording. Feedback forms will be sent at the end of the session. Close to the end of the session. On the slides will be sent. All those filling the feedback form if you have any email if you have any queries. Please email us as at most easier. Don't look dot com. It's also easier look dot com and to receive the slides, please check a junky mail because it tends to go there. So once you remove from your junk emails, hour emails will come regularly to you. And please, if you're enjoying Harrison the social because we do this for free a smart The more publicity we get, the more we can continue doing this. So thank you so much. Megan has a, um um was a mailing list form that she wants to advertise. A few guys are happy to join the mailing list for regular updates on when our pre clinical and clinical sessions are gonna be. Please consider joining the mailing list. We have about 200 people already on there and they slowly building up. We started yesterday, so yeah, join meaningless to receive updates. Uh, today's presenters are mega in Savannah. Uh, would be taking you through the relevant content that you require for the topic today. Um, so I'll pass it over to Americans 100 karat radiant. Thanks for just for everyone. In response to the main list. Also now at the end of the first presentation. So don't worry is coming, but I just want a crackle, so we'll get started so I hopefully everyone conceive my screen. So today, I'm just going to start off by going through a presentation on cells for you. Um, and just before I start, we just wanted to talk a little about a bit about our upcoming frequent easy events. So as a front said, you'll be seeing us about this year we put on here just a few dates that coming up soon for your diaries. It's all on Facebook, so check out the different Facebook event that available. These are some of the ones coming up. Eso We've got embryology, some basic clinical sciences things you learn when you start medical school and some pregnancy and birth topics. Viral immunology. Lots coming up. So I would just say Keep up to date with socials and you'll see it on there. But we'll remind you of these at the end. So as I said, Hello, My name's Megan on one of the pre clinical leads off skis. See, this is basically part of a massive back to school Siris that we're doing is part previously, which is aiming to make your pre clinical years of medical school a lot easier. So in this presentation, I'm going to be going through some cell biology today. I just want a big thank you Becky for preparing this presentation. She was hoping to present today that said, We can't so big. Thank you. Thank you for that. So starting off with themselves when it comes to cells, we focused on some five really high your sub topics that we're going to talk for you today that you can see here. So we'll crack on with the first topic, which is tissue types. So we're going to start off by looking at four different types of tissues. But just so we're in context and we know where we are, let's go back to basics. So cells are basic unit of life there. The smallest unit that you can get to in terms of living things on a collection of cells come together, um, performance set function on when cells do that, then know there's a tissue on that hierarchy continues upsets collection of tissues that performance set function, makeup on organ on a collection off organs that former set function come together to make an organ system. So we're going to start off by focusing on tissue types. As I said on specifically, there are four different types that you need to know about that we're gonna work through today. So we got epithelium, connective tissue muscles and nerves. So we're going to start off with epithelium. But first, I'm going to do a single best answer question. Eso Hopefully if one of guys could put Papa presume pole for me, I'll just give you guys some time to read this question. And then if you could just answer with your and what you think is the correct answer, then we'll go through it. I mean, that's eight. About 10 more seconds. It was only reason pretty more in the cold air. So, uh, well done, everybody. I can see most people got the correct answer. Um, so the correct answer was date sites like Auntie trying going to next light. But someone just cancel the pole for me. Sorry, guys. Piece refrain from drawing on the screen as well Does disrupt a presenters. Well, please. So well done, everyone. That what day That was the correct answer. Eso the arts was day pseudostratified today to that pretty, um, which ones? The respect to checked, and I'll explain a bit more about that in the next flight. So, as I say, starting up with the theory. Um, so there's three different shapes of epithelium, which you can see on the left hand side of this table that you guys need to know about. So there are flat cells, which alone a squamous cells, their cube shape cells, which you noticed cuboid or cells. And there are also rectangular of cuboid shape cells that are no no's kilometer cells. And that's one way of different changing your COPD. Um, um, however, as well a shape, a peculiar tissue can also be described by how many layers there are. So all of these different shapes cells can either be simple, meaning that there's just one layer of thumb. Or they could be stratified, which, as the main suggest, suggest that there's more than one that yourselves. Um, generally you find stratified squamous cells and, uh, um, non crash in izing internally, for example, in your mouth, Um, but you may find stratified squamous cells on external surface of your body and they tend to be crashing eyes ing on when I say crossed my zing. All that means is it just refers to the cells producing or changing to come. Carotene on Garreton is just a protein that makes services dry and impermeable on. We need that character in in our skin, in the soles of our feet. So if you imagine the correct in izing stratified squamous cells are found externally, we've also listed some examples of what particular field, um, could be found within the best with in different parts of the body. I think my best tip remembering these what epithelial type is where in the body is just to think about the tissues function quite logically. So, for example, the lining of the albuterol lie in the lungs needs to be simple. So one layer and it was the needs to be squamous that fought in order to make sure that the gas is pass across it. So if it was Columbus so she ate or it was stratified than the diffusion distance but increase and then the rate of diffusion will go down, which impedes the function of the tissue. So we don't want that so simple. Squamous kind of make sense. Similarly, if you're in the gastrointestinal tract, lots of intermediate molecules are stored in those cells, finding the tract as our food is absorbed. So you kind of need the larger columnar cells for those molecules to be there. So that kind of also makes sense. So my best is just to think for. It's logically as you can and you'll you'll get most of the way there. And this is another note. There are two more types of epithelial that you need to remember that don't fit into this really neat model. So firstly, there a traditional traditional epithelium, which is found in the urological tract. Eso when relax the bladder is lining, has multiple layers of cuboid or epithelium. But when the epithelia is stretched, when the bladder increase, the the urine inside the bladder increases in volume. Then that turns into a stratified squamous epithelium. Another one that you guys need to know is pseudostratified epithelium. Eso basically pseudostratified just means that it looks stratified. It looks like there's multiple layers, but it's just a single layer. Often pseudostratified Colombia is the one that you see the most often, so it's just a single layer of Columbus cells. But the nuclear just a different heights in those cells. Eso It kind of looks like multiple layers, but it's no has mentioned in the previous SBA. This is the type of epithelium that lines the respiratory tract. Um, Ciliated Epithelia is also a common characteristic to be aware off. It's often found in areas where movement needs to a current attract. So, for example, in the respect to tract, you need to walk mucus up up the track to be swallowed or statin when that mucus contains pathogens. But you might also find inside the uterine tracks where, um, that you need to walk on egg towards the spelling drinks that showing two or so you might see ciliated exteriors. Well, corpora. So that's mainly apathy, um, for you. So the second tissue type we're going to look into now is connected tissue, which I would probably say is the hardest one stands. I hopefully try make sense of it for you. So let's say this is the second of all for tissue types on. There are three components that come together to form connected to shoot on. These are cells, fibers and ground substance and each of these components. So your cells, your fire business, brown substance. They differ in their amounts, and they're composition between different connective tissues, a different connective tissues of different amounts on different types of cells and fibers on dumb from ground substance on. That's what gives each specific connected tissue its own qualities. So I'm just going to talk about those three components in a bit more detail. Um, so starting off with cells, depending on as a safe, depending on the different type of connective tissue, different types of cells will be present. So, for example, fat cells, blood cells, etcetera. Another key concept to understand is that fiberglass cells, which are found in these connective tissues to create something called extracellular matrix, which is often you'll see abbreviated TCM on be important thing about that is that the next two components. So the fibers in the ground substance together make up that ECM collectively? Um, no, just focusing on the middle box. Now there are three types of five is that you need to remember. So firstly, you have articular fibers, and these are thin fibrillar strands that supply. Neurovascular networks in the bodies are nerves now, but vessels on what they do is that supports thesis later e and the neurological systems of our body. Um, secondly, you have collagen, which is maker them particular fibers on. It's often used to provide tensile strength between structures, so delving into college in a bit more on those fibers there four types that you need to remember on. We have some new Monix for you to help eso type Type one collagen. It's found in bone, and you remember this because the word one. So for type one collagen is found within the word bone. You then have Type two collagen, which is found in cartilage, which you feel kind of remember His car to. Lunch is kind of got two in the middle, um, type floor. A tight for it runs. Type four is found on the floor, so that's because type for is mainly found in Be basil lemon. A. On the basal lemonade is a layer of fiber in the extracellular matrix, on which epithelium said, so you can have a layer of epithelium, some connective tissue. Blow it, um, and that that connective tissue often as it's fiber contains that type for collagen. Type three is just the Opana. It doesn't really have a cap. Rephrase that we could think off. So you just need to remember that it doesn't do any of those functions. It's actually involved in something called the particular Lemon A, which is a very similar role. It's basically below the basil lemon? A. So you have, like your CD, um, your basal lemonade. And then you were taking lemonade. Elastin is another type of fiber, which you need to know about on this has the ability to stretch and retiling branch on it. It's a lot think it's a lot of, um, um, it's more than them. It branches a lot more men. Collagen does. And then, finally, just the last compound of connective tissue is ground substance. On what grounds substances is. It's a semi solid, same side liquidy substance, which contains a lot of something called great blocker mean a great cans or some days call GI Tracts for sure, and these are basically just short carpet holds a carbohydrate molecules that are found within these connective tissues. So we've got another SBA, so if I could get someone just to reset the pole for me now that you want. So this one of 10 more seconds, we'll close the pole. Million. So this one was quite split, which is very interesting, but that's okay. So the correct answer for this one is easier. Well done. To those of you that put elastic cost is that is the correct answer. So elastic cartilage is cartilage that is found in like the epiglottis in the throat on the larynx and the picture of the year on it come with a complete stand, a lot of bending. I can see why people, but see, because of the kind of round shapes, Um, but hopefully the next little clear that up for you. So this side includes lots of images of other connective tissue type's help me differentiate between and identify the different tissues. So let's just break break or connective tissue down. So connected tissue can be divided into two main groups. You have connective tissue proper and connect tissue that is special. So starting in the left hand side, you have a connective tissue. Papa can then be further subdivided into loose and dents, so loose cut, loose connected tissue is also known as areola um, connective tissue, and it's found under the epithelium and around organs on blood vessels. From that is to say, you have the dense connective tissue, um, which has three subtypes. So firstly, you have regular, which is found in tendons. Ligaments on, um, a neuro. See. So those are the white connective tissues that ankle muscles as they move. So, for example, the afternoon Racists that you have in the six pack, for example, in the abdomen. Um, and characteristically, these things. Regular, dense connective tissue has fiber glass between each of the parallel rows of coral collagen, which gives it it's dense regular structure. Secondly, you have irregular connected to shoot. This histologically, as you can see, looks a lot more messy as the collision is arranged. Really regularly is the name suggests on it's found in the Dermasil the skin, and lastly, you have, um, elastic dense connective tissue proper, which is sounding but vessel, walls, ligaments, vertebrae, Septra, now just focusing on the right hand side of the slide. The second main classifications of connected to shoot is special connective tissue, and once again this could be further subdivided into cartilage, blood bone and adipose eso starting off the castle it once can. Further subdivided. There's three subtypes, so fasting, the most column common type is highly in which you often find in the trachea and any articular ends of any joints. Then you have elastic cartilage, which we outlined in the previous questions, um, on. But it has the most chondrocytes of all of the cartilage types and chondrocytes, or just the cells that form cartilage. Um, then you have proper cartilage. This contains think collagen fibers on. It's often found in a tendon insertions, the pubic symphysis in the pelvis on, also in vertical discs. And as I said, the other type of special connective tissue we're gonna look up be looking at today is adipose, which could be found in around the kidneys and the breasts on in this image on the right is clear that the nucleus of the adipocyte has been pushed peripherally so Upton sides of the cell because there's a large fat droplet store within that. So so hopefully that made sense for everybody. So the for tissue type that we're now going to go on to his muscle so muscle there are three types. They can either be a little cardiac or sues on both. Scalito on Cardiac are striated, but smooth muscle is not so striatum. Muscle is just where the contractile units units are aligned in parallel with each other on, so they perform a contraction, a very specific in a very set direction. Hopefully, that's quite evident from the images on the slide, so you can see on the two on the left hand side. They look almost ropey. They have really clear defined lines on, but it's a bit harder to see those on the smooth muscle image on the right. There's lots of areas I could explore this topic, but today I just wanted to go through the sock. Um, is on also the sliding filament hypothesis particularly risky to muscle. But first, another SBA. So if we could get someone to reset the pole for me, but I'll give you 30 40 seconds, wants this brilliant, and if we could end the pole back, But I think you guys almost unanimously have slashed that one well done. So yes, the correct answer was he so well done to those of you that shows up to me which was the I band s. Oh, I like to remember this by looking at the second letter of the word light, which is an eye so that, like the like region, is the I band, the same process Surprised with the dark region. When you look at cell, come here a second after of dog today. So that's the a band of that represents a dot region. Um, yes. So let's go into that a little bit more detail. So when we're looking at Sarcomere, there are five definitions that you need to know. Eso. The deadline is made from the thin, thin filament acting only on it represents the's start in the end of this all come here on. I remember this because that is a the end of the outfit. Bet so it's the end of the socket. Then you have the end line, which is the thick filament only. So that's the myosin on that's represented by the mid of the software, and similarly, it's M M line three m's EM line Middle. My a sense of Emily Middle licensure only contains my sense is in the middle, and it's the MRI Then, as I said, previously the uh if you look at the second letter of the words dark right, they tell you what bands they correspond to use. The I Band is the light section when you look at a soccer round of microscope. The A band is a dark section, Um, and it's also important to note that in the center or the middle of the A band is that area, which you can see in the top diagram where my sin act and do no overlap when the muscle is not contractive. This is called hate. So on when the muscle contracts, the hate so decreases it shortens. It often goes to nothing if you really contract and what's the I bands or turns as well? And we said, the eye bandage weather's I know acting. So you can imagine that goes down because when you're contracting the muscle, there's the act in on. The Martinez started to overlap more as they come closer, so the area which is active only is gonna go down. But the A band stays the same because the mycin you complete. Imagine the mice. It isn't moving to the A band stays the same thing, so I hate to zone and I been short term, but a band stays the same. So another SBA just about fighting filament Very someone could reset the pole. And if we could just end the pull back Thank you. So, yeah, this one's quite spit again, but that's okay. So the correct answer here was he so the correct up dizzy as the movement of the tropomyosin on active allows those Costcos formations. But I'll go. I'll go through that now. So I think you make sense. So the movement of tropomyosin on act in allows for crossbridge formation because when, uh so when you have muscle contraction as we know calcium is released, we know that calcium is really important for muscle contraction on the calcium does is it binds to monitor who called your pregnancy and I remember as pregnancy. It's got CNN that binds to calcium. And what that does is my calcium binds to troponin. See, it causes a confirmation of change in the trip. My sin to a car and what that does is it exposes the mice in binding sites and it allows those cross bridges two forms. I Hopefully that explains that also SBA. So after that's happened on a DPT and a phosphate is bound to the my sin. But when that for state is lost, so randomly just comes off. That's when the power stroke occurs. So then the muscle moves on. It contracts on. After that power, Stricker's the ATP has lost on a new ATP comes along to replace the ATP on When the ATP binding to that site occurs, it breaks that crossbridge. And then finally, the law step is, um, hydrolysis of ATP back into the ADP and phosphate reverts The massive head back to its original position on the process of doing another power Street can begin again. So the last tissue type, you're going to go on to his nerves. So we have another quick S p a to someone could be seven pohl. Thank you. You just end up old. Uh uh So this one was quite so again, I think the majority is for a B. D. Any quite close pine eso, while done, took all of you that option B. That is the correct answer. Eso The absolute refractory period is when there's insufficient number of sodium channels available for the activation of an actual potential, and that is what is defined as the absolute refractory period. So just to explain the refractory period is the period following a membrane depolarizations. So election potentials come along. It started moving down the nerve after it's gone away. You then about refractory period. First, the first part of that refractory period is called the Absolute refractory appeared, which is what this question was referring to, which is basically when there's two few sodium channel was available for the activation of election potential. So no matter how intense your depo next depolarizations is, so no matter there's a really intense next signal coming along. It won't stimulate another action potential. Um, and you may have potassium channels open on Bring Maybe Hypo Teres Day. But that's not the cause of this part of refractory period. The relative refractory period, on the other hand, describes the state where election potential requires a larger depolarizations stimulus than normal. So if another action said, you came along on, but, um, it was quite a strong one, there was a lot of electrical activity. It could then stimulate another action potential. But if it was like an average sized depolarizations it probably wouldn't cause it. So I'm scared. Talk through compound action potentials. So compound action potentials are known as all or nothing systems on You probably came across this at a level, but basically listen, means is that if the stimulus isn't big enough to generate an actual potential, then election potential will not be made. But once that threshold that you can see the diagram has been met that a lot depolarizations above that voltage will cause the same size actually central. So it doesn't matter if the depolarizations only just cross is that pressure old or it crosses it in leaps and bounds. It doesn't matter. It's all gonna cause the same size at the same leg action potential. So just to quickly run through the cycle of action potential. So you start off with a stimulus and that causes sodium channels open to to that stimulus. Um, if the voltage across the membrane reaches around about minus 55 millivolts, which is the threshold potential, which you can see on the diagram, um, action, potential fire and when it fires consequently, more and more sodium channels in the area begin to open on that depolarizations goes up, up, up as positively charged, sodium ions into south. The cell doesn't like it doesn't like this in a way, if that's how you want to think about it doesn't wanna be unstable. Um, so the cell tries to maintain its that grid every, um So it closes those sodium channels when it gets around, Plus there to your passport E millivolts in his memory potential on at this point the counter early. Sorry, the potassium channels open on potassium irons. You can then move as well, and this causes the report or is a shin off the salmon brain? Um, however, the potassium channels are really slow to close, which is why there's a hyper polarization where you go below the membrane potential that you originally had. Um, and then, after all that's done, a sodium potassium pump takes over, and it restores the potential back to the resting state. So that was all about the different patient types. We got a couple more topics just to cover themselves. So another thing that I think is really important is the South cycle, so or quickly have a with through this. So there are two main stages to the cell cycle that you need to know. So there's interface, which is where a cell spends the majority of its life. On this. It can be thought of a Zaretski state, but in reality there's lots of activity during this phase, and then you have a stage of so division A swell. So, as I say in the first phase into phase, there are three kind of smaller phases within that. So you have G one, which is where the cell is survey. It's internal and external environments. It's beginning preparations to grow in size. It's producing proteins like mRNA, a other proteins that I needed for DNA synthesis and my Tosis. It's also duplicating some of it's constant so that it's ready to divide on this phase lost about 12 to 15 hours. It's important to notice well that you could see on the diagram. There's also an additional Gino very cells can take, and this is often followed by cells such a neurons. Meyer sites eso muscle cells on, but other cells that are really highly differentiated. They can enter this journal on bacon, basically not continue to divide because they're so highly differentiated they don't really need to divide much more. Those cells are probably going to die soon as well. So they enter the gene or phase. But if they were to return back into the cycle, they would do so back into the one. The next favorite phase that you have a last face on s phase is really important phase where DNA replication occurs and it lasts about 6 to 8 hours, which will explore a bit more in a second. You don't have the last phase of interface, which is called Itoh, and this is where preparation from my Tosis is occurring. So that was similar to do. One cell grows a bit more new proteins made organelles a replicated further because if you think with so divides, both cells need lots of organelles. I can't have half the number of organism things about proteins. So you replicates, um, organelles reprehensible proteins on this stage is you lost typically around 3 to 5 hours and then finally is a second cell cycle. Stage two. So division this involves mitosis and cytokinesis, which is in our area. I'll touch punch shortly. So another sp a for you really more. In the poll, there so once again quite split. That's okay. So, Well, don't it will you that chose cyclen or is your answer? That's correct. So I'll go through this now. So the cell cycle, as you can imagine, cells are dividing on that needs to be kept under tight regulation. Eso There's something called Cyclens which I'm gonna go through now, which helps to regulate that. Um and there are lots of different types of Cyclens on these Cyclens peek at different points in the cycle, which is what that question was referring to on It really helps me to remember what Cyclens Pete have peak on concentrations of different times from GI. Want to emphasize by the minimum new Monica deep so DEA be if you want. You kind of think of this as the world debt. But instead of sending it with the day you ended with a B instead, I've had that once right around something, remember it that way and says, I said those the cell cycle has checkpoints in it which need to be monitored really carefully to ensure that cell only divides what it needs to it. That's really important in preventing overgrowth and ultimately ending in cancer. That's how cancers develop. When the cell cycle goes out off. It's normal regulation, so it does this fire. As I said, the generation of different Cyclens that regulate the cycle and certain events need to correctly occur to generate those seconds on down and other events that need to occur to actuate Molecules could cycle independent kind a XYZ, which then allows cells to pass these restriction points. So there are full key checkpoints to remember in the South cycle. So firstly, you have the GI one checkpoint, which is controlled by a tumor suppressor gene called Retin a Blastoma, or B. Normally I'll be is a protein that wraps around proteins called transcription factors, so ah, that transcription factors are basically proteins that allow other proteins to be made from your DNA. Eso normally that retinoblastoma protein, it wraps around those transcription factors, and it kind of covers the Muppet present prevent from functioning, and it prevents the cell generating the proteins that needs in order to get Espace. Um, but when you have a phosphorylation cyclen dependent kind of these exposes the transcription factors, and it enables a cell cycle progression to occur on two essays. So the next checkpoint you have after that is the GI one s phase that monitors DNA damage. So if there's no DNA damage and that's detective, the cell that s l could understand will you be allowed to proceed to its reputation? However, if there is a DNA damage, it can be detected by a Jingle P 53 gene, which becomes activated. This produces a protein called P 21 on what P 21 does is it inhibits a cycle independent crazy once again for the second E. On. Then that cycle, independent kind A Z inhibits that so that no cell cycle progression can occur on the cell on dies by apoptosis. Then you have the two mg checkpoint. This monitors. If there is successful DNA replication has occurred. And if there are no errors, it'll, um, And if there are no I was detected, then the second go into my toast is totally divide. However, however, if there are reputation hours there that are detective, then DNA repair will occur or the cell will be ordered to die upon skin. Where does this and then finally have one more check points? This called the m checkpoint on this basically just checks that all the mycotic spindles that are gonna pull the chromosomes apart during my toe says are fully attached. So that process should go down really well. So that's the point of the M face. So I'm just gonna hurt him now. Eso I talked about the different phases of the one s g two of them. So I'm just gonna holding on that Espace now, which we said was the second stage of into phase, which is my DNA replication. Because so just to talk through the steps of DNA replication or itself, you probably remember these may level, but just add a little bit more detail. So firstly, you have Toprol I summaries, which is basically an enzyme which is really important in this process is that finds to prevent DNA ahead of the fork so you can see in the diagram that little form shape the V shape. Um it binds the data just to avoid the D. A day that's been separated, getting wound and modeled up When DNA here cases the enzyme that why are mines. The DNA spits the DNA. Two strands are at a fork. So the Toprol summarize is just making sure everything doesn't get tangled up basically eso In this image. The top strand is called the leading strand, which is red by DEA claim Aries. So the enzyme, which generates your second strand from the stream it's reading on DNA primaries in this leading strand, reads the delay from 5.2 free Prime on the bottom stone in this image is the liking strand on that's red in three prime to five production. However, the reputation on the leading surrounding the lightning strike a slightly different. So in the leading strand, the replication is continuous, so it just read that long just follows it longer. That's fine, however, in the lagging strand, because the enzyme dealing with the race can only read in a set direction from 5.3 prime. It has to do it in a discontinuous and disruptive freshen, Um, so in the leading strong, where you put a continuous reputation, DNA primaries, it's complementary nucleotides to the one that to the mucus in the leading strand to form a new stranded DNA. And that's fine because it's in the direction they would know me go. However, when you have the discontinuous replication in the liking strand. The DNA primaries can only work 5.3 prime, which isn't the direction The strand. Um So what it does is it makes, um, the replicates, the ads on the complimentary base pads, little fragments called aqua sake fragrance. And then that's fixed up by an enzyme called Know Like a Z, which joins all those little fragments and the backbone of those fragments together to form that second strand on the lagging strand. So then you have, um, the M face. We said, you well, ST twos, this is the emphasis. Um, this is quite a lot. I'm going to leave you guys to read this in your own time and get the slides after you fill in the feedback form. Um, so just a brief summary. My Tosis It could be 75 stages called, Uh oh, that can be broken down to the acronym ppm up eso This is a common name on it. Just used to remember the stages, and it stands for prophase pre metaphase metaphase anaphase and Tina Fey's a said, I'll let you review some urine time, but it's important to recognize that my Tosis is a way of creating deployed cells, though. So in humans, those are cells that have 46 chromosomes. This is different, Teo, my OSIs that produces for half price cells on dumb that's used to produce your game meats on. Those gummies need to have 23 chromosomes in human, so half the amount of normal DNA. So the last subject for this presentation is just chromosome abnormalities. So, um, anatomically chromosomes can be categorized into three different types. So you have medicine trich, which is where The Centrum ear. So the region where the spend a fire was attached during cell division is right in the middle off the chromosome. So the you got the link to the comes out is roughly in the middle. Then you have some messed centric, which is where the Centrum is slightly off to one side of the midline of the chromosomes. Don't buy too much on that. You can also have, um, at her centric, which is where the Centrum is way off to one of the sides of the midline. It is quite close to the crows, owns extremities, and in in circumstances where the Centrum is not directly in the midline. You then need to differentiate the two arms off the cortisone. Um, and the length of the crimson, which is shorter, is they're known as the P arm. On the longer length of the chromosome is the known as the coupon, so you can have some numerical abnormalities of chromosomes this basic acres when there's presence or absence of individual chromosomes. So this collectively so having the wrong number of chromosomes in a cell is known as anybody in the case where there is an absence of a crime zone. This causes a monosomy. So when there's only one set over chromosome and you'd expect have to run from the moment one from that bad, Um, and when there is an extra chromosome present so you would have three copies that's called a tries. Every on um, you're pretty often occurs due to non disjunction mutations during my toe, my OSIs so none Destruction is basically a big fancy work, they're saying. The failure off one or more pairs of homologous propositions, the chromosomes that code for the same information so say to chromosome number four's. So it's the failure when to chromosomes that the same number or sister committed to any on if it's mitosis meiosis on, they don't separate. Normally on that is what causes the imbalance in the numbers of chromosomes in the door to cells that produced. So not only can you get numerical abnormalities, you feel to get structure abnormalities. There's lots of different types. There's really shows duplications, inversions, ring chromosomes. But today I'm just going to be focusing on chromosome translocation on two of those that you really want to be aware of are called reciprocal and Robertsonian transportations. So starting from reciprocal translocation, he's a car due to an exchange of genetic material between two nonhomologous credit zones. So chromosomes that don't go for the same information to, say, chromosome three and a credit for, for example, um, typically, if this exchange is balanced so like the image shown in the on the left, there's no net loss or gain of genetic material. So the effects of quite minimal not harmful because the the genetic material itself is it isn't really changing. It's just in a different order. However, you can get reciprocal transportations, which can be harmful. One famous example is between chromosome nine and creams and 22 which is known as the Philadelphia chromosome when it's formed on this is really harmful, and it could account for 90% of cases of chronic myeloid leukemia, which is a type of cancer. This is because the exchange between the chromosomes, where that exchange occurs on that border, it results in a new gene forming, which is called the BCR able Fusion gene. When the exchange materialist joined back together on this computer, use this sequence of basis. When it's together, it can produce a proton 13. So this is the lip up. Regulate so division. And that is what causes the cancer. Because you produce that pro quo, pro junk gene on, then all of a sudden yourselves want to divide a little, and that leads to the cancer. So secondly, you have a Robert salient translocation, as I mentioned on this involves where too long arms off to act acrocentric chromosomes. So, as I said, the accent, your prednisone is where the Centrum is really close to the end of the crime zone. They're not really new in the middle. It's when to a dental loans and to Crimson's, joined together on the loss of the pr more. The short arm occurs. Usually there's no harmful effects on the vigil individual because such a small amount of genetic material is lost. However, there can be harms. They got meats. So, for example, this can be harmful in when there is a roberts only in translocation between chromosomes 14 and 22. So when they're long arms fused together, the small arms of each of those presents lost on when a parent undergoes my OSIs to produce those gummies, and this occurs 50% of the game, it's a viable on go out of the three viable options that are left one of those resulting down syndrome. So this is one of the common ways in which down syndrome. So thank you for listening. Hopefully, that's made the topic of cells a little bit easier. I'm just gonna pass over to Sahara now. He will teach you a little bit about, you know, J So thanks like those. Really comprehensive. I feel like there's a really good revision of what we learned in the last two years. Gonna quickly show my screen. Yeah. Yeah. Okay. Great. Can you see it? Yep. Oh, good. Okay. College. Thank you. great. Hi, everyone. I'm Sana on going to be going over the immunology bits. I know immunology can be really intimidating because there's so many molecules and cells that are, you know, all involved in the same time. But I'm going to try and break down the basics of it and kind of, um, giving overview of where all starts and, um, where it goes. Basically, you have any questions at all, Please put them in the chat, which I don't answer them for you. So, like I said, going back to the basics. So we're gonna talk about where immune cells come from. We're going to talk about what kind of chemicals the release on do Basically, is it events defense? The body has, um, the enology I'm going to use for today's presentation is if you think of the immune system as the army, the military system off your body, that makes it really easy to understand all the complex process is that happen? So with that analogy, let's just start with hematopoiesis. So hematopoiesis is the process of where all the immune cells are generated and differenciate to become all the different kinds of white blood cells and red blood cells on bladeless that, you know, I like to think of this as, like, soldier recruitment. So you going to get the right soldiers where the right skills to, like act as a defense for your body. So this all starts in the bone marrow. The bone marrow is a jelly like substance that sits in the center off your bones. So imagine police is usually starts in all the bones in your body. When you're real, it'll your long bones in your shot bones. But as you grow older and want to reach puberty, him out a priest is is quite restricted to the flat bones. So your sternum, your vertebrae and your iliac bone's is usually where him out of places occurs once you hit puberty. So and what exactly happens is that it all starts off with one. Sell this one stem cell that has the multi potent potential to differentiate and specialize into, like many different types of specialized cells. So these is really useful because they start of really flexible, which means you can get a hold variety of different types of white blood cells that can tackle different kinds off infections or trauma that you might encounter throughout your life. So we start with the stem cell and follow it. What exactly happens? Well, first it goes through a round of my Josephs. Obviously, when you go to my Tosis, you get to daughter cells as the product. One daughter cell remains as a stem cell because you wanted to continue as the stem cells. You can get more white blood cells later. But the other daughter cell then differentiates to become more specialized. So you can get a a daughter, Ma, deporting stemcell, differentiating into a my Lloyd progenitor on one that will differentiate into a lymphoid progenitor. So this process keeps happening. My doses keeps happening on you have differentiation happening on from the time from in you from the time when you're in utero to throughout your life. So, my lord cells include megakaryocyte, so that will then go on to become What you may know is platelets or thrombocytes. Platelets are important in blood clotting and in preventing bleeding. You then have every three sites that you might know dried blood cells and these are really important in transporting respiratory gas is my light cells also differentiate into mast cells. Marcel Zar Vital allergic reactions. And finally, you get my low blasts that differentiate into your granulocytes and monocytes. So the first three here basically is neutrophils and a senior. Fields are known as your granulocytes. The notice going, you know, sites because they have these dark staining granule in the cytoplasm that contain chemicals like histamine or so returning, for example. For example, if you look at basophilia, you can see the little dots on the cell, and those are the purple dots. All are Granules that containing history, and therefore it's important for situations where you might encounter, analyze, decree action. Then you have neutrophils that are important in antigen recognition and figure cytosis. It's enough pills also important in allergic reactions and monocytes monocytes were what differentiate to become Macrophages and macrophages are really important, especially in the initial stages off your innate immune response, as well as in initiating the adaptive immune response. But which we'll talk about shortly and then we move on to your lymph or progenitor. You have two main types of cells that arise from this. You have the natural killer cell, which is really important in targeting and killing of I really infected cells and you also have lymphocytes and you have two types of lymphocytes you got to lymphocytes and B lymphocytes on B. Lymphocytes can then differentiate into plasma cells during the adaptive immune response to produce antibodies. We'll talk about all this later in more detail, but this is a review her magic polices and where all the cells exactly come from. But where can this go wrong? So we know the cells are developing. We know you have a huge production off the cells happening throughout your life. But where can this process go along? And where can it's become a disorder? So you may all know of leukemia, which refers to the malignant infiltration of the bone marrow on D. It happens any time during him out of polices, so it can either effect the myeloid development or the lymphoid development, and therefore you can get lymphoblastic leukemia or myeloid leukemia. Depending on what kind of cell types are involved, you can also get myeloproliferative disorders, and basically that's just a fancy way of saying you have the over production off a certain cell type. Most commonly, you get thrombocythemia, which is over production of platelets polycythemia, which is overproduction of red blood cells or my low fibrosis, which is the overproduction of fiber blasts on This is quite dangerous because it can also result in leukemia. So before we go into new, here's your SBA. Someone can watch the pole, please. Thank you. Have you seen your question, Victoria, on the chat about histamine basophil are addressed that in more detail later. But in such a summarize, basically feels mast cells and 18 of those all interrelated. Um, Onda. Yeah, we'll talk about later. More detail. Okay, we can stop the pool. That Great. Yeah. Um, so most of you got it right. Sorry. Um, yeah, most of you got right. Well done. It is histamine. So if you look at a blood smear before and you know what cells look like under a blood smear, the key word here is high density off large blue staining cytoplasmic Granules. That gives you two hints. First, that the cytoplasm contains loss of Granules and that tells you that is either. It's probably a granulocyte. So that already narrows it down to basic fields, seen a fills or neutrophils on, but, um, because it's dark blue staining and because it's a high density as movie later, basic fields have a really high density off these lots of purple dots in there cytoplasm and therefore which contain histamine and allergic reaction. They release these Granules to modulate the reaction. Just explain that in more detail. These are what the different sets look like under the microscope on a blood smear. Black males are really useful because they can tell you if something's wrong with blood cells. And if something is wrong, then they're good indicator of what could be wrong. For example, if you have really high density of platelets, a lot of platelets then possibly could indicate from a safety mia a mile, a political disorder like we discussed earlier. So these are what the cells look like, and I think it's really high year that, you know, on our able to identify what they look like under blood CIA. So if we look at platelets, for example, they appear really small and they stained purple under the microscope. So if you follow these arrows, these little purple dots and the rest are red blood cells on. As I mentioned earlier, the important in blood closing. If we then look at a reader sites that are red blood cells. We know these are buying corn cave discs and don't have nuclei, and this provides a higher surface area for the transport of respect for gases. On day appears Focalin shape with a bit of a dent in the middle of you can see. And then we have masked cells. Mart sells are interrelated to base. It filled in that they have these dark standing pop of Granules in the middle of the cell. However, you can distinguish them from basal fills. Because basophilia, the entire cell is just lots of purple dots. Where's your You can kind of see a bit of a lighter purple area around the dark purple area, if that makes sense on down someone's question, earlier mass cells are involved in the activation of basic fields in the scene of pills. There, for that's how they're interrelated and monocytes, which differentiate into macrophages, are distinguished by the kidney shaped nucleus, and they're involved in a number off processes. But importantly, phagocytosis if we then move onto the granulocytes, the most important in the most abundant white blood cell of neutrophils they are distinguished by having two or more lobes of nuclei that are connected by a thin string that you'll be able to see if you look closer on. But they really are the first line soldiers for urine it immune, response them and macrophages, so they're really in burned in the really important it's enough. Pills are important in your allergic reactions, as mentioned earlier, and you can distinguish them by looking for their buy logs nucleus, which are interrelated on done. They never have more than two nuclear as opposed to neutrophils. And then basophilia like I said earlier, are literally just a bunch of purple dots in one place, and that is the entire cell. And so they're quite usually easy to distinguish on a blood smear. We then move on to our lymphoid descendants, Um, first of all lymphocytes that also usually easy to distinguish because they kind of just have these giant purple blobs off nuclei in them on. They're usually quite big in size as well, on their important in your adaptive immune response. Importantly, and the natural killer cells are also quite big in size, but they're more irregular in shape as compared to lymphocytes, and that's usually how you distinguish them. So now we kind of know who the players in the military, who the Army, who the Army is, who the soldiers are. But we also want to know why we have this in place. Why do we have all these different kinds of soldiers? Andi, How they're going to help us? What is the need for that has specialized in elaborate infrastructure? Well, it may be obvious, but obviously you want to prevent the spread of infection. So if you have an infection in your hand, you want to try as much as possible to prevent the spread of the infection to anywhere else in your body, because that could lead to things like sepsis, which could be lethal. Um, that's really important. And obviously it helps to combat analogic response analogy on do as much. To the extent possible, your body tries to kill these pathogens as much as it can. Obviously, some patterns are more difficult than others, but the end goal is always to get rid of them and possibly arguably. Most importantly, it's really important that your body is able to remember these pathogens so that If you encounter them a second time, you're able to deal with them better, and therefore you won't be as ill as you were. The first time on. This is what the adaptive immune system is all about. So we first talk about the nasal immune system. Um, the main immune system is basically assistant that provides an immediate and non specific first line of defense against pathogens so it develops in you. True on. It's not really acquired like the adaptive immune system is, but it also means that it's non specific because it's never encountered a pathogen before, and therefore it has the same response to any kind of pathogen or infection. Um, and so therefore it's called a non specific immune response, the native mean system. So the 18 system actually has many facets to it, because physical and chemical and biological barriers, for example, your skin have see boom like sebaceous glands and swishes fluid that has that has antiseptic properties. Your gastric acid, the pH, is really low, and that's enviroclenz most organisms, and you also have the commence, a log in ISMs or the bacteria in your gut that help to fight any foreign bodies that may enter as well. You also have cellular barriers about the white blood cells we discussed earlier. Granulocytes You're not. You're national killer cells and your mast cells to tackle different kinds of reactions, different kinds of pathologies. And he also humor barriers, which basically refer to things like the complement system, where you have different kinds of chemicals that involved in modulating the immune response. Now let's talk about the really star of the show. In my opinion, I think sentinel cells are macrophages and entered. Excels really are vital in first of all, initiating the in a team you know, response and secondly, initiating the adaptive immune response. So that kind of really important in both senses. And here's why. So, if we go over, the function's off the sentinel cells. Well, the most important thing they dio I think the primary goal is that you should be able to recognize a foreign body when you see one on day. That's what these are primarily really important for. So if a bacteria and does your body, these sentinel cells have these molecules called back to the P R O. C, which are passage in recognition receptors that are able to recognize unique patterns on a specific pathogen. So if this is a bacteria in your body and it has a pathogen associative molecular pattern, which basically means something inside the back here that makes it unique, it could be a protein. It could be a carbohydrate. It could be any molecule in that organism that makes it uniquely recognizable. This part of recognition receptor, which is a protein on the surface of your macrophages 100 XL, is able to recognize that specific PMP and then go and bind to it. So this does two things one. Obviously it alerts the body that Oh my God, there's a foreign body in us and therefore we have to react to it. And second, it makes this pathogen visible to the rest of the use immune system to then come on back. Um, fight your macrophages also really good at phagocytosis. So for less complex pathogens, they're able to just destroy them then and there on the way they do. This is sorry the way they do this is by Pfizer psychosis. So they kind of engulf the pathogen. Put it into this compartment called a faggot lysosome release really like hydrolytic enzymes into that compartment, break down the pathogen and then release the waste products. And that's how they kill less complex pathogens. But for more complex pathogens, in also initiate a in it a inflammatory response. So if you need the help of other immune cells, or you need the help off other chemicals that are useful in killing or targeting an organism, The Sentinel says it really useful in releasing site of kinds and came kinds that are basically proteins that signal to other white blood cells, um, to come to the site of infection and tackle the infection. If that's not enough to kill the organism. If the organisms a bit more complex, if the pathogens being a bit more difficult than this calls for adaptive noon response. In most cases, you always get active, you know, response because your body always wants to make sure that it's not going to encourage her the same illness again on. In this case, the central sounds really important in initiating this process, and it does this by communicating with your lymphocytes by a Mets See molecules, which I'll explain in a second. But before that, I briefly mentioned the word cytokine, and I'd like to talk about that just in case. That's not clear. So what are side to kinds? Cytokine zaching, umbrella term for a family of signalling proteins that modulate the immune response, inflammation on even hematopoiesis is. So they're they're extracellular sibling proteins, and they usually they can be secreted by a variety of white myself to not just 100 XL or central cells. Um, so the way it works is you actually have two kinds of cytokine, so you have a pro inflammatory prevents that supports inflammation and encourage inflammation. And you have those that are anti inflammatory. You must be thinking, Why would you want anti inflammatory side kinds? Do you not want to fight infection? Well, if you think about it, there are certain times in your body where your body goes into inappropriate state of inflammation, where you it's a disorderly state where you have a necessary or inappropriate inflammation, and therefore, this is your body's defense way of kind of combating that, and often times it's strong enough on D, so these main two kinds of side kind that you'll see and with in this family are the two most common ones that you would probably become across the Net school are interleukins and chemo kinds. What are they? It is a long time to realize that interleukins chemo kinds are types of side of kinds and not like different kinds of chemicals in their own interleukins like the word suggests are between leukocytes so into Lukens, and it's secreted by one leukocyte toe. Act on another leukocyte. So I'll one I'll six I'll eight interleukin one interleukin six interleukin eight chemo kinds, like the word suggest is for chemo, kinetics or chemo taxes. So what this means. It's a fancy word of saying if there's a site of infection, you want all the necessary immune cells to come to the site of infection, and you want to release a molecule that they can then follow the track off to get to the site of infection. And that's what Chemotaxis is basically an example of. That is when if there's an infection, then the macrophages will release. I'll eight, interleukin eight and interleukin eight will then be detected by neutrophils, and neutrophils will fall of the path off the interleukin eight to get to the site of infection. If that makes sense that I wasn't really important. That's the main two side of kinds. Like I mentioned earlier. You have I'll eight, which is also known as See X E L. It's you may know you may notice the terms interchangeably, and you also have to Monaco sis Factor alpha. So we first talked about the NFL, for this is really important in your initial stages of the mean in eight immune system. Because water does firstly is it activates the endothelium. When you have an infection in a tissue, you obviously want white blood cells to get to the tissue on, then be able to penetrate the tissue to get into it. And to do that, the TNF Alpha makes it more permeable, such that it allows white blood cells to enter it. Also induce is the acute phase response. What this basically means is that it induces a state. It's a state of inflammation in your body, and what you need for inflammation is first of all, the complement system. Compliment proteins that make up the complement system are produced and sensitized in the liver, and therefore TNF alpha acts on the liver, so up regulate protein expression such a compliment proteins. It also regulates inflammatory markers. Um, such as CRP um, find it also increases body temperature to put, and the use of body temperature is usually a higher temperature is little enough to kill many organisms. TNF Alpha also encourages blood clotting in case there's been wound or trauma that's causing the inflammation. And so these are the most important roles of TNF Alpha. You then look at I'll. It's like I mentioned earlier. It's really important in chemo taxes and attracting white blood cells. The site of infection is also important in degranulation. Granulations is the process by which granulocyte, such as basic filled neutrophils are seen. A fills, um, kind of open up. They're Granules to release chemicals such as histamine or serotonin in response to, um, in in response to a trauma or an allergic reaction or infection. So now we've talked about the united immune system and what the first line defense of the body is. But then now is where it gets a bit more complicated in that you want your body to be able to have some unity long term. How this works is that this sentinel so which could be a macrophage or dendritic. So has a very special protein on its surface and might see molecule MSC Stansel major his the compatibility complex. No one's gonna ask you to say that out loud, but it's just for information. Just a a might see a might see molecules actually coming two types. Um, I'm not gonna go into that today, but you have a messy one, and, um, it seemed to molecules. So what they do is they're able to signal to lymphocytes to initiate it after the immune response that able to signal to tell in four sites on B lymphocytes. Now you may recall that there are two types of the lymphocytes you have CD four Positive T helper cells and see the eight positive T killer cells. Now what's the whole deal about CD four Positive and CD eight Positive? Well, basically, there is there for two receptors on the surface off the T cell. So if a T cell has a CD four receptor, you call it a CD. Four Positive cell. If there. If the T cell has a CD eight Perceptive, you called a CD eight positive cell, and therefore that's a t kill herself. The CD eight positive cells are capable of inducing a pop Tosis in viral infected cells or infected cells. But he help ourselves. Usually you're not involved in doing the killing themselves. They kind of are involved in recruiting other white blood cells such as be lymphocytes to help in generating a memory response as well is killing the organism. So B lymphocytes, Um, during that adaptive immune response, you may remember from a levels when adapted immune response is simulated, the B cell made differentiate into a plasma cell that's then able to produce lots of antigen specific antibodies. That's a brief summary of the doctor, the mean system. Before we carry on his on the SBA, someone be able to start the poor. Please. Yeah. Perfect. Thank you. I'm really loving this. Oh, on the majority. We've got going. Yeah, I think I might stop it there for today. That's okay. Yeah, really Well done is perfect. Yes, So I g antibodies are the antibodies present in breast milk on are really vital to provides. Sorry. Hi. To the wrong answer. But the answer is I g antibodies option sees right. Answer on really important in providing the initial immunity that a child needs when they're first born because they don't really have a very active immune system off their own yet on they need the protection of these IgE antibodies initially before they can start growing their own. Now we've mentioned antibodies immunoglobulins. What exactly are there at? What exactly are they and why do we care? Antibodies are the same as Immunoglobulins. It's a synonym. It's an interest angel term on this is what a very generic one looks like to the green bits are the heavy chains of the antibody, and the yellow bits are the light chain. They're both really important, and we'll go over them and each other because it took me a long time to really understand what this was on. I hope I can help you with the same. So the function of antibody molecule is in host Defense is to recognize on bind its corresponding antigens in, and then to deliver the bone data gyn to other components of the immune system, to then clear it or destroy it. So antibody antigen binding an interaction is carried out by different parts off the immunoglobulin. For example, one pots off the immunoglobulin. Let's look at this red region here. This is called a hyper variable region, and it's also known as the F A A B or fabrication. It's hyper variable because it has. Every single antibody has a different amino acid sequence in that red region, and that's what makes an antibody really specific to a specific antigens. So because this antibody has a really specific hypervariable region, it's able to bind to a really specific pathogens anti gyn, if that makes sense and the reason we want this is because we want to be able to have access to different types of pathogens, not just one. So if you have a collection of antibodies that are really varied and have different types off label regions, that means you're less vulnerable to an infection because you have the resources to tackle it. So this variable region, then, is exactly what determines the idiotype off the antibody. So let's see. This is an eye GI antibody within the class of I G body body's. Every single antibody is different to begin with because of this hyper variable region. What is the constant region this blue bit over here? is called the Constant Region, and this constant region is the same between all I G antibodies. So all I easy antibodies would have identical constant regions, and this is what distinguishes them as I G antibodies. So this part is important for things like finding two other white blood cells are also important for binding to compliment proteins. Teo activate the complement system. This is a brief but hopefully useful summary about antibodies on what they look like and what they use is. But the main function in to go on more detail is this. Firstly, let's look at the variable region. The F A a B bit. The F A A B bit is really important in neutralizing antigen on pathogen cells, so we know that on the surface of pathogenic cells like bacteria, for example, you have antigens. Now, what antibodies are able to do using the highly specific variable region is that they're able to go and bind to the antigens on these pathogens on definitely allies them by neutralizing them. You're making sure that they can no longer a via and bind and penetrate your own body cells that make sense that also really useful an option is a shin optimization means you're making the pathogen more recognizable to the rest of the mean system and the rest of the body. So the antibodies are gonna go and coat the pathogen with themselves, and then the rest of the body is going to be like, Oh, look, there's a cluster of antibodies there that fold must be an infection. The F C region, which is the constant region, see if constant is important in activation of the complement system, which is part of the acute rephrased response that we mentioned earlier. And it's also important in the activation of cytotoxic cells, for example, activation of natural killer cells that are capable of killing virally infected cells. And finally, it's also important in acting on certain receptors around the body that are either pro inflammatory or anti inflammatory. If we then talk about the different types of antibodies, we have I G antibodies, which is the most abundant in your body, and they're also really important in terms off the fact that able to cross the placenta, that the only trouble immunoglobulin that can cross the placenta and therefore they're important for the only stages of immunity in a fetus on the secreted by plasma cells in the blood. IgM antibodies have a unique structure in that bed pen tomatoes and therefore they have five arms and have this star shape and they're responsible for the early stages of immunity. What I mean by that is that initially, in an immune response, a B cell will secrete rgm antibodies and roughly after six months is when they started secrete i G antibodies. I eat. The antibodies are generally better than IgM antibodies for immunity because they have more penetration off pathogens. But idea antibodies are a form of temporary immunity you offered by your plasma cells idea. Antibodies are found in your body secretions, some mucus, saliva tears on breast milk and they provide, um, immunity against pathogens temporarily. IgG IgE Antibodies are important in parasitic infections and allergic reactions, and I g antibodies are part off the beast. A receptor on the surface of the B cells on are important in activating basic filled and Marcelle in the contacts and allergic reaction. So that's a summary of what immunoglobulins are, what their function is and what the classifications of them is on. I'm gonna end this immunology recap there. Thank you so much for listening. If you have any questions, please. With them in the chat on the hand. Back to Megan now. Thank you so much. So now that was really, really comprehensive on D. I wish I could talk a few years ago. That would be super helpful. Um, so I know it's getting on a bit. Boy are in the last session, so I'm just gonna have a quick with through, um sk Can you see that? Okay, Yeah. Pretty. And so, a state last topic of the night is the muscular skeletal system. So in this presentation, I'm just gonna be going through the basic physiology, basically, of the muscular skeletal system. So the alone's once again big thank you to back you for doing these flights. So here's what I'm going to be covering today. That's just cracking to it. So let's start by looking at the muscular skeletal system on a kind of overview level on it's over organization. So there are 206 bones in the typical adult human body on these concussion rise into two groups. These could be actually, if they're on the midline or they can be half indicator if the bones are located in the upper or lower limbs. So some of your axial bones are your skull, the bones in your neck, your ribs, things like that and your appendix, your bones of the bones in your limbs and said it's important to note here that killed in typically have, um, 270 bones on. That's just because as they develop their bones fuse together on subsequently being quantity of bones, the number of months you have decreases as they fuse Sedin. How do we classify all those? So there are five or six different types of bones, depending on who's classifying them on examples have shown in this image here. So I've categorize them into sex. Just couple basis. Eso These six types include short bones on the short bones are approximately the same, which is they are long, and they're generally used to provide support and stability to other structures. There's not usually much movement involved in short bone, so short bones include things like your carpal bones in your wrist, for example, they don't move a lot, but they provide a bit of stability to arrest. You have flat bones, which, as the days yes are very thin, and they're very fact. They tend to act as a protection for important muscles on. They've provide a large surface area for muscle attachments. So one famous example is the scapula. See your shoulder blades that helps to provide extra and protection to rib cage. Then we have long bones. Onda long bone is basically any bone in the body that is longer than it is wide on day. Also have growth plates at either side or either end of these bones, from which, as they grow the bone forms. So when a long bone growth has plates at the end, that's where the new bone forms from. These long bones haven't out a hard surface of compact own on a spongy in a material, which contains bone marrow, which you've probably heard about, um, long bones that they tend to be found in our particular second skeleton. So it's a set of skeleton of our limbs. So, for example, your femur in your leg or the humerus in your upper arm, and then you have sesamoid bones. These are usually very small, irregular shaped bones they usually present in tendons where a tendon past never joined on. The importance of these bones is to protect those tendons and to protect those joints. So the famous obvious one is the patella is the image shows access. Your kneecap is. It's cloak really known eso it. Make sure that you protect your knee joint because it's not the most stable joint in the body. Then you have sexual bones. So these are flat, very small, irregular shaped bones, which I found between the suitors and the skull. So I want to emphasize it's know the skull bones like It's not like your frontal bone. You brought a one C's have bones that are within the suture is you can kind of see it on the diagram. Um, there for a flat, very small irregular. But because they found in the suitors, they're they're Sometimes they're in class. They're called pseudobulbar owns. Then you also have irregular bones. A same name suggests once again, they're non uniformed. Shake their regular on basically any bone that doesn't fit into the other categories. Someone famous. One is thevenet very of the spine, so we'll have a quick SBA. It's that someone could just launch the pole for me, Brean. Thank you. Brilliant. If we could just I'll just end the pole that so I think. Yet the majority did get it right. So well done, everyone that got it right on The answer is a D. So the answer is secondary cartilaginous, which I'm going to explain in the next side. So I'm going to talk about different joints, So joints or articulations, they come in three different types that you need to be aware off. So there's cartilaginous this fibrous in this I know of you so starting off across, imagine it's they could be further divided into primary or secondary primary. Can't imagine's joints are found between the epifix ISS. So when you have a long bone, the wider end where the articulation is that your emphasis on the diagnosis and the diagnosis is is the tubular shaft that runs from the proximal to the distal ends of the bone. Um, and those primary primary constellations joints occur between the two of them on these primary cause. Rashes joints are composed of highland cartilage. Then you have secondary cartilaginous joints. Eso good example of this is that the pubic symphysis on in the international discs where there's fibrocartilage in between two layers of highly cartilage on the articular surfaces of the bone. As the diagram shows, um, then we have fibers, joints s 05 wrist joints are immovable. They're found in the skull. Suture is the tibia fibular interosseous membrane, which is basically remembering that collects the tibia and fibula in the lower leg, preventing them from slipping over each other on also the bony sockets of the teeth as well. So these are really movable tough joints. Lastly, you have sign of your joints. These have many different components to them, including articular cartilage disks, which just cover the two ends of the bone. On this axis. Shock absorption often sign of your joints. Also have a labor, um, which is basically a ring of fibrocartilage, which acts to deepen a joint soccer to make the joint more stable. So you might find that in the hip joint is where there's a labrum to make sure that the femur stays in the socket between the two connected bones is a sign of your joint committee on this cavity contained Sign of your fluid, which assists with the movement between the bones, making these joints removable so you'll find these. They're saying, like the knee. There's a sign of your joint. So any joints where you want a lot of range of movement? So then that's kind of the structure of the joints. Joints can also be, um, um, cast by based on their range of movement. There's six million different types of movement, So pivot hinge Saddle plain X Lloyd on ball sac. Stock it. You can review these slides in your own time. Hopefully, these examples are nice and clear. So we have another SBA. I'm just going to read on the pole brilliance. I'm just gonna, in the poll that eso this is not surprising. Really, to me is a big split between osteoblasts on osteoclast to be in day world. Um, to those you that selected option D, that is the correct answer. So it's osteo cross. This is because the hormone P T h. It's secreted in response to low blood serum calcium levels. So when the levels of calcium in the blood of really low on what P. T. H does is it indirectly stimulates osteoclasts on D increases their activity within the bone in order to release more calcium into the blood, to then elevate a low blood serum calcium level. But I'll go into that right now so we can understand that. So I've just talked about osteo class. Those are multi new created, so cells with multiple nuclear bone resulting. So so the cells break down our bone. Um, as I said before, the role of peach age is to raise calcium levels in the blood when they're detected is low. Therefore, it kind of makes sense that the pH will stimulate the osteoclasts a zone osteoclasts or activated. They break down the bone. So when the bone is broken down, it releases that calcium, Which can they go back into the serum back into the blood. I'm raised those calcium levels. There are two other bone cells that you need to be aware of. So there's osteoblasts. These, in contrast, on union and clear a nuclear. It'd so they only have one nucleus. These are the opposite. Their bone forming cells. Eso the cells secrete a substance called osteo it that could be mineralized to produce, um, bone that we have on their four that helps to maintain bone tissue. So the way I like to remember. This is osteo glasses got beings. It builds up bone. Um, another way to remember it. You just gotta be careful that it's not confusing is osteo blast. It blasts bone, but it doesn't do that. You've got to remember it doesn't opposite what you think it does, eh? So it doesn't blast, but it doesn't break it down. That's what lost trust does. So I that builds bone or it doesn't blast it. Whatever way you find easier to remember, then we have also cites These are found in small base small spaces in the bone called lacuna. These different shape into are stable or so and osteocyte becomes an osteo best. So I'm gonna quit. You just go over the origin of the cells. So the bone forming osteoblasts of the cells that build up the bone on bone resort bings of the cells that break down the osteoclasts, they their origins very significantly, but their pathways a quite intimate, so we'll go through them. So in order to produce an osteo cast as a heart attack about you have hemolytic stem cells. So that's an immature stem cell that is able to develop into any type of blood cell on what that does. Is it different gaits into a monocyte Then it different shapes into a Mac rage on there different rates into your osteo cross because, uh, before finally becoming an osteo trust, whereas in order to produce an osteo blast, you have, ah, missing time on cell, which is basically just a different type of stem cell that goes under undergoes differentiation to become an osteoblast on it's the balance between the bone forming and the results Shin, um, that controls how much bone we have. Um, and that could be explained by a couple of products that are produced by the osteoblasts. So, as you can see on the diagram lost, your last produces rank l receptors that buying to a substance called rank on osteoclasts. Progressive cells on produce, um, and produce osteo cross, and they undergo osteo across the genesis. So the production lost a car cells on when osteoclasts Or did you stop? See, this increases bone results in their job, so increases bone destruction. However, osteo blast also produce something called osteo progesterone in which is also knows Oh, PD for short on that can also buy into a rank receptor on that directly inhibits the binding of rank to those rank L receptors. Uh, thus that stops. The bone was option because the osteoclasts aren't being produced. Let's say this this key balance between breaking down bone and forming new bone is really significant. Clinically So. A Z example. If you have post menopausal women, they produce a lot less estrogen when they go into the medicals. Onda estrogen normally promotes this O. P. G production, so this production of osteo pedestrian hence, when women reach the menopause, their estrogen levels decrease. As I said, that causes a decrease in O p. G. Therefore, there's a lack of rank l receptor inhibition essay so it increases, um, rank l receptor activation. And that causes an increase in osteo class and bone results, shins or break breakdown on. That's why women that postmenopausal, they have a decrease in bone health and that increases their bone fragility. Fertility on causes a lot of conditions such as osteoporosis. So quickly do another SBA. I'll just reset the pole. Thank you. Five more seconds. Give it a guess. If you don't know know, probably getting it wrong but, you know, and it there s Oh, yeah, definitely. The majority of you got it, right. Really? Really Well done. Eso The answer was big cortical bone world unto those of you that put that on. So I'm going to talk through the different types of boring histologically on the next line. So histologically there are two types of bone. You have a primary bone, which is known as waving bone, or you have secondary matches is in there is the metal bar on primary bone to start off with is what is formed when there's healing of fractures. Whereas, um, secondary bone is no second, your bone can be and spongy, or it could be cortical, which is also known as compact on as shown in the images. Um, slide spongy bone is present in the medulla, so the middle of a second bone but the come back bone is on the cortex and the outside of the bone, so the most superficial layer of the bone is known as the cortical bone. So looking a bit more closely at primary or waving bone, it has a low density off osteo it. So that said that that substance containing collagen that's laid down by osteoblasts before it's middle of mineralized to produce. A heartburn is broken. Bone is very austere. Site rich Rich makes sense because we said the osteo sites are the initial version of osteoblasts. They go on to become a state lost, um, which lay down the osteo read so in the Proair. And there's lots of immature osteo osteo sites. There's not many osteoblasts because they will say is osteo sites. And so because there's not many osteoblasts, there's not much osteoid, um, and this all has a very irregular arrangement. Um, as I said, Woven permit bone. It plays a really important world in wound healing, especially during the remodeling stage where the waiver bone is remodeled into second bone by osteoblasts. So now, looking at all second, you pardon? Uh, secondary. Um, spongy bone is similarly an irregular arrangement, but what it does is it has a structures called in a trabeculated on deregulation are basically just strands of connective tissue. In this case, bone surrounding spaces, which contain the bone marrow on the bone marrow for which the directory surround, can either be red, which is where active him out of polices president. So where new blood cells have been formed? All yellow marrow which isn't really active, it's mainly got fat in it. So it's not producing those new red blood cells and other blood cells as well. Um, if we were to take a cross section of the trabecular a bone osteoblasts, as you can see in the image, will be aligned across the conference of the TRABECULAR A with the occasional osteoclast. On this conference, however, the osteo sites would be present in smaller spaces. There is, like a day and connected to each other by curricular. So I realized that was a lot of big words at once. We're gonna break it down so a Z can see a second bro. Combat bone has a lot of key structures that you need to remember. So we're gonna break it down into four main definitions that you need to go. So firstly, you have osteo means which are also known as have diversity in systems on these a concentric rings of compact home. Then you have where the osteo sites it in small spaces that I Symbicort look okay, these are between the concentric rings on the cuniculus I into collect the osteo sites to one another. Then you have. The central canal is also known as the Have A have a seizure and canal on. It's the the center, often osteon running long to to diddly so horizontally containing the neurovascular bundles that is needed for the bone. Just a life. So we'll the vascular tests all the bloods that the arteries, the veins and the nerves as well. And lastly, you have Vulcans canals. The's run horizontally on dumb. They connect the heaviest Aryan canals to one another. So I know it was a very, very quick room for, um, SK. I really hope that me tensed everybody, thank you so much for coming tonight. Sorry, it run over a little bit his a little bit of a reminder of what's coming up. Aziz. Pre concessions. We've got some more back to school Siris coming up soon, but one this Saturday, one same time lexical next Wednesday and a Saturday after so it make sure to check Facebook for the events click going so that you get this room links. We hope to see there is well, the as these sessions. And don't forget to fill in the feedback forms and so that you can receive the slides and the recording. Yes. Um, yeah. You received the slides in the recording. Now we have changed it a bit. Um, so the recording will be available on medal for you guys to review as many times. It's possible. So And if you guys have any pre clinical friends, another university, please share our events. Um, we just wanted to make it, uh, kind of public sort of everyone in it and not only kind of students and for those in other university to appreciate it with your friends. Uh, someone's just starting you on a nice. Hopefully that's helped tonight is giving a bit of a head start, but thank you for coming. Oh, uh, polo is here. 100 water. What? I'm joined by the team.