Overview of Immunity and Its Components

I haven't made the test yet, but I'll work on that soon and I'll let you test it. Any questions? How are we feeling about it? How are we feeling about it? That's a great question. Like, is it going to be, like, pretty easy? This is not, this one is not as... bad as test for usually is usually people do a little bit better on this one yeah okay so let's go ahead and get started we left off talking about these different components of the innate immune system remember we're talking about immunity and innate immunity is what kind of immunity Natural, okay. Is it specific? No. No, okay. That means that you're going to have the same response no matter what type of pathogen it is, okay. And we've been going through, we've been talking about these different components, we've talked about the barrier. which is the skin, the chemical components. We've talked about some of the cells. You remember we talked about neutrophils and basophils and their presence within the blood. And we're going to talk about some of the cells that are present in the blood. So, we're going to talk about some of the more cells and some chemical mediators as well and so these two right here these make up the second line of defense so remember the first line of defense is those barriers those primary barriers and those secondary barriers gonna be things like the skin the chemicals that are secreted the mucous membrane stuff like this and the second line of defense is made up of a bunch of cells and proteins that we're going to discuss in just a second but But the main thing of what the second line of defense does is this list right here. This is what all it's composed of, okay? And one of the first things that it does is it acts as a recognition type of defense for the immune system. So the first type of, they're not really cells, okay, but the first thing that are present on cells that help with recognition for the immune system is something called a toll-like receptor, okay? So have any of you ever gone somewhere where you had to go through a toll booth? Okay. This little toll-like receptor basically just goes through and it's what recognizes the pathogen. Okay. So we've got our macrophage, which is one of those types of cells we talked about. And on the surface is a receptor. And what that receptor does is it goes through the body and it just kind of feels for stuff. And when it finds a foreign molecule, it binds that. And so these... Toll-like receptors act in recognition, okay? And when they recognize a foreign molecule, that will start an inflammatory response, and then it can also promote those lymphocytes to become activated, those B and T cells to become activated. The second line of defense is also important in inflammation, okay? So we've already talked about the inflammatory response briefly when we talked about signs and symptoms, but the classic signs and symptoms... characterized by this inflammatory response is the redness, the warmth, swelling, pain, and even possible loss of function. So we gave the example of if you step on a nail or you stick yourself with a splinter, what starts to happen after that. That inflammatory process is part of your immune system. It's part of your immune system and that helps to contain that pathogen within that area so that it doesn't doesn't follow through anywhere. else. So the redness, the swelling, that's due to the fact that all of these immune cells are rushing to that area. And then the warmth is because of the increased blood flow and it starts to swell because not only are all of those immune cells rushing to the area to help protect, but it's also trying to keep that pathogen right there in that specific area. Okay, so this is an example of kind of what's going on. This is actually, I showed this to my seniors for the immune system, but I like the picture because the book is like almost like an immunology for dummies book, but they use it at the med school too, so I really like it. But this is what's going on. We've got our skin layer. We've got our bloodstream right here, okay? And we see we've got red blood cells. We've got these other types of immune cells floating through the bloodstream. And some of these immune cells are within our tissues, like within our skin. And so you may cut yourself. may accidentally stab yourself with, you know, a splinter or something like that, and you get dirt, grit, stuff inside of the skin, and you've got these little red bacteria. And so what happens is this neutrophil or this macrophage or whatever this yellow immune cell is, it recognizes the bacteria with those toll-like receptors. And it secretes these molecules called cytokines, which we'll talk about. And what these cytokines do is they're kind of alert signals. And so when they are secreted, that causes all these other immune cells that are in the bloodstream to come to the area of infection. and it starts to fight off the bacteria that are there. And so once those immune cells start to migrate, you'll notice that the blood vessel, you see how it dilates from here to there, that allows for things to leak out into that skin area. Okay, so that allows for destruction of the bacterial cells. It becomes red, it becomes inflamed, it becomes swollen, and so on and so forth. So that's kind of the process of what happens with inflammation. And this is just another picture. This one actually comes from your book, but you have a needle or something like that. There's bacteria on that. And so when that penetrates the skin, you get the inflammation process. Bacteria enter into the wound that cause. this pus formation and eventually you have all these immune cells these purple cells here that move to the area and then help to destroy those bacterial cells that were introduced into the skin okay now when these bacteria not these bacterial cells excuse me these immune cells can move from the vessels to outside of the tissue where you were maybe hurt we call this process diapodesis okay Diapodesis, POD, typically means foot, like podiatry, or pedal, if we talk about a bipedal organism, that's somebody that walks on two legs, quadriplegic, you know, anytime you see that word PED or POD, it typically means foot. So, diapodesis is where these immune cells move out of the bloodstream into that tissue, okay? And it's done by the process of chemotaxis, and we've already talked about chemotaxis. about that briefly when we talked about bacteria will move depending on certain chemicals. And so chemotaxis, a lot of these immune cells will move also in attraction to those chemical cells, those chemokines or those cytokines that were secreted at the site of infection. And so I have these videos down here. I want to show you the process of diuresis, what it looks like. At sites of injury, infection, or inflammation, subclinics are released and stimulate endothelial cells that line adjacent blood vessels. The endothelial cells then express surface proteins called selectins. So what happens is the blood vessels bind these adhesions causing them to stick to the walls of the blood vessels. This binding interaction is of sufficiently low affinity that the leukocytes can literally roll along the vessel walls in search for points to enter the vessel. And then they're able to squeeze through. So they're tracked in through the metaxas. squeeze between individual cells without disrupting the vessel walls. Then crawl out of them. So they show a picture, they show like a real-life process at the end. I'm going to move to that. But what happens is you've got these immune cells in the bloodstream and your blood's moving pretty fast and so what happens is these little yellow rectangles are expressed by the blood vessel cells and they will literally kind of like allow for an attachment for these immune cells so that they can bind and kind of roll and move through the area of infection because if not they're just moving through quickly. So you've got this immune cell right here. You can see all the blood cells rushing through. You can see them rolling. So all these little cells that are attached to the bottom that are rolling slowly, those are the immune cells and they're trying to go to the area of infection. So you see it's about to move through the area from the bloodstream into the tissue. Whereas others have already left the vessel and are seen in the surrounding connective tissue. So it'll move through that area. When the blood cell is stopped temporarily by gently clapping the vessels. You see all the red blood cells. How densely both vessels are filled with red blood cells. They're moving through the bowel. So a lot of that you don't have to know the details, but I do want you to just see how that process works, okay? And then let's see, chemotaxis. This is a picture of a video of a macrophage, this big cell right here. Because remember, macrophage means big eater. This is a type of immune cell that destroys pathogens through phagocytosis. And this little black blob right here, that is a bacterial cell. So you see that the neutrophil... this, well excuse me, it's a neutrophil, not a macrophage, but a neutrophil is another type of immune cell and it still eats things by phagocytosis and so it's attracted to this bacteria through chemotaxis. In this spread, a neutrophil is seen in the midst of red blood cells. So neutrophil, staph, red blood cells. Release chemoattractant that is sensed by the neutrophil. So neutrophil basically... Chases it. And starts chasing the bacteria. And that's due to chemotaxis. The bacteria, bounced around by thermal energy, move in a random path, seeming to avoid their predator. Eventually, the neutrophil catches up with the bacteria and engulfs them by phagocytosis. That's what happens. So they consume it and then it's got digestive enzymes in there, it starts to break it down. So that's the process of phagocytosis. And so they phagocytose and they're attracted to that bacteria because the bacteria will secrete these specific chemicals. And that immune cell is attracted to that. okay any questions about that all right so the third action of the second line of defense is to act as phagocytosis which we just saw this video of how that occurs okay but phagocytosis phago means to eat cyto means cell and so this is where you literally have an internalization of some type of pathogen whether that's bacteria whether it's virus of this immune cell and those immune cells are called phagocytes so that's a phagocyte is an immune cell that participates in phagocytosis. And so what happens is you've got this bacteria and the phagocyte will eat that bacteria and consume it and inside of that it's got all of these hydrogen peroxide and all these granules that will then degrade those bacterial cells and then it'll present it to the B cells and T cells for a more specific response. And so the innate immune system and the adaptive immune system system, even though they are separate immune systems, they do act together to have this common goal to protect the body and to create this immune response to get rid of the pathogen. So the phagocytes, what they do is they go throughout the body and they survey. They survey the tissue. They look for pathogens, okay, dead, injured cells, something like that. They will ingest and eliminate those materials, and then they will take immunogenic material, which means some type of material that the other parts of the immune system will recognize and present it to them. And as we discussed when we talked about the phagocytes on Friday or the different cells, cell types, neutrophils and macrophages, both of these are phagocytes. These are both examples of phagocytic cells. Okay. And remember, neutrophils just kind of have a general purpose. They're usually really early. They have a large amount. Remember, never let monkeys eat bananas. That never stands for neutrophils and they're present in the greatest amount in the body. And macrophages are big eaters and they come from monocytes. And so they also participate. in phagocytosis. So here's just a couple of pictures of how that works. You've got these phagocytes that are in the bloodstream. Some of them are in the tissue. But what happens is when you have a damaged tissue, you've got all these signals being released, some from the skin, some from the phagocytes. And that causes all these other phagocytes to move to the area of infection to help fight off that infection. And so those phagocytes will consume the bacteria and... and basically chop them up inside. And so this is kind of a picture of an electron micrograph that they've colorized to help it be visually more pleasing, but this is kind of the process. The big pink blob, magenta blob, is a phagocyte, and the yellow cells are bacterial cells. And again, this is just another picture. You've got this large cell right here, and it consumes these bacteria, phagocytes. And so upon phagocytosis, it starts to destroy those bacterial cells, and then it just releases the debris into the body. Okay? The next purpose of the second line of defense. This is an interferon response, okay? So interferons are not cells. They are small proteins that are released, okay? So the second line of defense is made up of specific types of cells and specific type of chemicals that are released. An interferon is a protein chemical that is released by certain types of immune cells in response to viruses, okay? Interferon, when you see that word, when you hear that word, you typically associate it with the virus. And so here's a picture of what's happening. When a virus infects a cell, okay, and it goes to the nucleus to start to replicate, the cell recognizes that virus, okay, because it realizes it has been hijacked. And so what it does is it starts to secrete interferon. And it lets the body know, look, I've been infected by a virus. I need some help and so when it secretes that interferon that allows for the immune system to come and attack this virally infected cell Okay, so it binds to the cell surfaces So you see interferon is secreted and it'll bond to the surface of a neighboring cell And so what that neighboring cell does is it starts to secrete these other types of proteins That then can chop up the virus before it allows to infect that next cell Okay And the last purpose of the second line of defense is in complement protein. Okay, so the second line of defense, it plays a role in recognition with those toll-like receptors, plays a role in inflammation, and that allows for that pathogen to be contained in a specific area. The second line of defense also plays a role in phagocytosis, which is where it consumes the bacteria. It secretes interferon, which is a specific type of protein. that helps with virally infected cells and it also helps with the complement system and the complement system is part of the innate immune system so the complement system is made of 26 different proteins that are inactive in the blood rather inactive in the blood but these 26 proteins work together to destroy whatever pathogen is infecting those and so it forms this cascade and that eventually leads to lysis of that pathogen, okay, or phagocytosis. So these complement proteins, like I said, it's a cascade. There are about 26 of them, and so you can see here some right here, C5B, C6, C7, C8, that C stands for complement, and they either help to poke holes in the membrane, so like this, all those little dots within the cell, that is due to something called the MAC complex, the membrane attack complex, and this is due to all of these complement proteins. that basically form a pore within the membrane, and that allows for all the contents of the cell to leak out. So it's kind of like those actions of like polymyxins and those cell membrane antibiotics that we talked about, except this is part of the immune system that does that. And complement also helps with a process called opsonization. And opsonization is basically where I call it candy coating. It's where the complement system, these proteins will tag. a bacteria for destruction. And so we see here you've got the bacterial cells seen in green okay and so this C3b anytime you see the C that stands for complement it will tag the bacteria and that allows for a phagocyte to come and consume that bacteria. So candy coating just means that it tags it for phagocytosis. Okay all right and so this picture right here is important. because it just kind of shows you the breakdown of the host defenses. So remember we've got the innate immune system, the acquired immune system. Innate is nonspecific but the acquired or the adaptive, they're interchangeable, are both specific. And there are three lines of defense. The first two, first and second, are part of the innate immune system and the third line of defense is the acquired immune system. And the first line of defense is typically your barriers, whether that's your physical or your chemical barriers, and then the second line... line of defense are all those things that we just discussed. Inflammation, interferons, phagocytosis, complement. Okay and all of this works together to achieve a common goal which is to protect the body. Okay any questions about that PowerPoint? I know spring break is on the mind but... It can be this this can it has the potential to be a hard test if you do not study okay but it is straight up memorization. So I'm gonna call roll real quick, okay? Now that everybody I think has gotten here. Pearl, Liz, Jamaria, Lorelai, Miriam, Emma, Pierce, Kinsley, Aiden, Brecken, Olivia, Ashley. Cole, Vanessa, Liv, Bailey, Desiree, Savannah, Kitler, Brynn, Marlee, Savannah Martin, Maggie, Matthew, Mira, Anderson. Okay, Campbell. She's not here. Okay. Hannah, Pierce, Will, Elizabeth, Anna Claire, Jaden, Carly, Don, Anna, Reagan, and Ava. All right, everybody get up real quick and stretch. Do a minute or so to just stretch, okay? Wake up. Alright, while we're stretching, while we're getting our brain working, what's the first line of defense of the immune system? Barriers. Barriers. What kind of barriers? Skin. Skin, okay. Why is skin important? It's a barrier. Guess what? Germs. Yeah, bacteria, viruses, anything like that, okay? What is another type of barrier? Chemical barriers, where our chemicals are important. Y'all can sit down if you want. Let's get your brain going. Head just stretching. Wake up. So, what is the purpose of these chemical barriers? So, yep, they're secreted by our body and it helps to inhibit the growth or destroy some type of bacterial or viral cell, okay? What is the second line of defense? First of all, is it part of the innate immune system or adaptive? Innate. innate immune system okay so give me some things that the second line of defense does do it yes different types of cells and what are those cells involved in? Vagocytosis. Vagocytosis, which is the process of? Eating. Eating, yep, big eater. Okay, eating the cells. And what does it do when the bacteria is vagocytosed? What does that immune cell do? Inside of the cell. Destroys it. Yep, okay, destroys it. Alright, what's another process besides vagocytosis? Inflammatory response. Inflammatory responses. What's the purpose of that? To alert the body that something's there. Yep, to alert the body that something's there. keep that pathogen contained, and you start to see all the signs and symptoms. Okay? Three more. What else? Identification. Yep, identification. And so those are called toll-like receptors, and they sit on the surface like an antenna, and it recognizes all those foreign materials. And what does that toll-like receptor do? What? It attaches onto it. It attaches onto it, and it takes it to what? It doesn't consume it. It takes it to another cell and usually it turns on the adaptive immune system. Okay. Alright, so that's three. Got two more. Last two we talked about. They're not cells per se, but they're proteins. Interferon. What's the interferon do? It's a protein that does what? When you guys study together, this is how you should be studying. No. It is released by white blood cells. When viruses. Viruses, yes. Virally infected cells. And last one is the complement system. The complement system is composed of what? 26-ish proteins. And they work together to do what? Destroy the bacterial cells. Destroy the bacterial cells how? There's two ways that they can do that. Cascade, okay, and then the two... Two end products of that is what? MAC and candy coating, the opposite of that. Membrane attack, so it can poke holes in the membrane, or it tags the bacteria, okay, and lasts for destruction. This is how you should be firing off questions. What a neutrophil. okay what does this look like what is the monocyte what comes from the monocyte what a basophils do what a eosinophils do which one of these cell types this is how you should be quizzing each other okay this is what helps all right so it on to the adaptive immune system so I thought this was funny in the marrow where I reside this is a hematopoietic stem cell in the marrow where I reside with my progenitors at my side for immunity for blood I will divide divide divide but he's a hematopoietic stem cell because remember these stem cells can either become red blood cells or white blood cells okay when you start getting these that's when you know you've reached nerd status okay when you start laughing at them and y'all will start laughing at them before the end of the class i promise all right so we're talking about adaptive immunity which is a specific type of immunity okay and when we talk about adaptive immunity we get to move into immunization so we're going to talk about vaccines as well and how vaccines actually work okay so this picture right here is just another chart to kind of show you these host defenses remember the innate immune system is non-specific which means you're going to have the same exact response no matter if you come into contact with pollen or the measles same exact response okay it is composed of these physical barriers these chemical mediators and these cells and tissues that all work together in a non-specific fashion to be able to get rid of some type of pathogen now the adaptive immune system or acquired they're used interchangeable so you may see in this book it is a specific specific type of response. And so what that means is it remembers when you come into contact with a pathogen because it creates these memory cells. And that's why we call it specific type of response. Because once you're exposed to something, your body makes cells that will then remember the next time it comes into contact with it. So the adaptive immune system. This is specific immunity, okay? Because it does distinguish between pathogens. So it will recognize if you come into contact with a pathogen that you have come into contact with before. The immune system that is adaptive is less rapid, but it is more targeted. So it is specific, and so it is more targeted. But because it is more targeted, it takes a little bit longer for it to form. So one of my big pet peeves, and I think I've told you guys this before, I can't remember. I tell it to every class probably. three or four times because I can't remember who I tell it to. My biggest pet peeve is when people say, I'm not getting the flu vaccine because I got the flu when I got the flu vaccine, and that is not the case. Most people get the flu vaccine because so-and-so had the flu, and you're trying to protect yourself, but you've already been exposed, and it takes your body about two weeks to make an adaptive immune response against a pathogen, and so what happens is you think you're going to be protected by the flu vaccine but you've already been exposed to the flu and so the flu divides and you get sick from the flu but you blame it on the flu vaccine even though you've already been exposed because it takes your body like I said about two weeks for you to create an adaptive immune response for that vaccine to work against the flu or any type of other pathogen okay so the adaptive immune system is regulated by immune cells the t-cells and the bees cells. Now the innate immune system has a ton of cells. Neutrophils, basophils, eosinophils, macrophages, monocytes, natural killer cells, all of those are innate immune cells. The only two immune cells of the adaptive immune system are T cells and B cells. And so we say that adaptive immunity is divided into a humoral arm and a cellular arm. The humoral immunity is B cell mediated and the cellular immunity is T cell. mediated. So we talk about immoral, we talk about what's in like the bloodstream. And then cellular, what type of cells are typically utilized in this adaptive immune response. So right here, this just shows you've got this phagocyte that consumes an organism. And that phagocyte processes that organism, that pathogen, that virus, that bacteria, and then it's just a bunch of bacteria. and it presents it to the adaptive immune system, the T cells and the B cells. And those T cells and B cells then have a humoral arm of immunity and a cellular arm of immunity. So the B cells, what they do is they create memory B cells, and they also create these plasma cells that then secrete antibodies. So antibodies come from B cells, and they are part of the humoral arm of immunity. T cells, on the other hand... T cells also create memory cells, but they create an effector T cell, some type of T cell that does the effect, that does the killing, or something like that. So the host adaptive immune system is the third line of defense. Those T cells, those B cells, those lymphocytes, those are the third line of defense. So when the body comes into contact with a foreign molecule, we call this an antigen. Now an antigen is just a piece of that bacteria or that virus. So a carbohydrate, a protein that's on the surface. You remember how we talked about the bacterial cell can have stuff on the outside? Like the polysaccharide. It has peptidoglycan. It has the capsule. Remember how we talked about all those different things on the surface of the bacteria or the virus? virus, those spike proteins, that is called an antigen. Okay, anything on the surface, a piece of bacteria or virus, a piece of a pathogen on the surface that the immune system recognizes is called an antigen. And when the body comes into contact with an antigen, that is when those B cells and T cells become activated and the B cells start to make antibodies that are specific towards that pathogen. okay now adaptive immunity is specific and it also produces memory these are two hallmarks of adaptive immune immunity okay adaptive immunity is specific it creates antibodies or t cells that are specific against a specific type of pathogen okay so if you had the fluke last year and you had the flu this year i just use fluke because you know we We've had this little endemic going around here at MC. But if you had the flu last year and you had the flu this year, it's two different strains. And your body has created an immune response against each one. So you have cells directed at each one. And that's why the flu changes so much is because it knows that if not, then it doesn't survive because the immune system would attack it. So antibodies are produced that function only against the antigen that were produced in response to. The adaptive immune system is specific. The adaptive immune system also develops memory cells. So the adaptive immune response is specific, and it also produces memory. These lymphocytes, they can remember whatever they come into contact with and then remember it every single time after they come into contact with that. Now, there's different types of adaptive immunities. There's active... immunity there's passive immunity there's natural immunity and there's artificial immunity and all of these are different types of adaptive immunities okay now active immunity what does it mean to be active alert moving yep okay so this is when a person is challenged with an antigen what's an antigen a piece on the bacteria that creates a response exactly okay so when a person is challenged with an antigen and it produces antibodies, okay? It creates memory, it takes time, and is lasting. That is when you are actively producing antibodies on your own because you come into contact with a bacteria or a virus or something else. Now, passive immunity, on the other hand, what is passive? How does passive differ from active? Less harmful. No, not necessarily less harmful, but passive. What does passive mean in general? Not as alert. Yeah, not as alert, okay. So passive, just kind of brushing by, right? Passive immunity is when antibodies are donated to an individual, okay? It doesn't create memory, it acts immediately, and it's short-term. So do you remember during COVID-19, when people would get sick and they would go get monoclonal antibodies that is a passive form of immunity because what's the body creating its own immune cells it was but it takes a while for that to happen remember it's a slow response so People were going to get these preformed immune cells, these preformed antibodies, and that helped to attack the virus quicker, okay? So passive immunity. This means that antibodies are donated to an individual. Yes, ma'am? This is also what happens with breastfeeding? Yes. Yes, it is. Okay. Passive. And I've got a picture that shows that in a second. Now, there's natural and artificial immunity as well. So natural immunity is natural. This is part of life experiences. When you are a small child and you get sent to daycare or kindergarten or whatever else for the first time, you get sick. You always have a snotty nose. That's just what happens in daycare because you're protected in a bubble at home and then you go into the germ factory, which is daycare or preschool. And you come into contact with all kinds of pathogens because kids are nasty. Kids don't wash their hands, they share stuff, which is nice, but they also share germs, which is not so nice. That is natural immunity. You come into contact just in the wild. Artificial immunity is acquired immunity through a medical procedure such as a vaccine. When we get vaccines, that is kind of considered artificial immunity because it's not a natural process. It's not you coming into contact with a virus and your body producing a response to that. So I've got this picture here that kind of shows all these differences. And you are going to have to know a couple. of these okay now acquired immunity can either be natural or artificial what is natural adaptive or acquired immunity what does natural mean happens on its own yep okay part of natural processes and artificial is done through some type of medical procedures not natural right okay now for natural immunity you can have active natural immunity or passive natural immunity okay now active natural immunity this would be you coming into contact with a microbe okay so you go to kindergarten in my case Everybody had the chicken pox in kindergarten. You guys didn't, because you guys had the vaccine. I had the chicken pox. I had polka dots. I had stealth scars all over my body from the chicken pox, okay? So, went to kindergarten, everybody had the chicken pox. I got the chicken pox. That's natural because it was part of the why, okay? And it's active because my body started to form antibodies against the chicken pox, okay? So it's natural because it's happening on its own, and it's active because my body's doing the producing of the antibodies. Now, passive natural immunity is where one person receives preformed immunity by another person. And an example of that is breastfeeding. So when a baby breastfeeds, the mother produces antibodies that pass through the breast milk. Is that a natural thing? Are those natural antibodies? Yes, from the mother. But is it active? Is that baby actively making its own antibodies? Or is it receiving some that are preformed? receiving something so that's considered passive it's being passed along okay it's not a natural process artificial immunity okay you can have active immunity or passive now what is artificial immunity Yes, done by medical procedure. Your body's not doing it on its own, okay? It's not just because you come into contact with a pathogen. Now, active artificial immunity, okay? is vaccination. This is where you guys went before you went to kindergarten and you got your chicken pox shot. Okay, so you didn't get the chicken pox. You weren't covered in polka dots like I was. Okay, so you go you get the chicken pox shot and what happens is that That prevents you from coming into contact with the chickenpox in the wild. So a person develops his own immune response. It's active because that vaccine exposes you to the pathogen, but it's artificial because it's not natural. But you're still making your own antibodies against that pathogen. So it's artificial, but it is active because you're the one that's doing the antibody production. Now, passive artificial immunity... That's like when you go to the doctor and you get antibody therapy. It's artificial because you're getting therapy. It's a medical type of procedure. And it's passive because it's not your own. So active immunity is when you create it your own. Passive is when you get it from another person. So I will give you an example of something, and I'm going to say what type of immunity is this. It's going to be natural or artificial. but notice that active and passive can fall under natural Or active and passive can't fall under artificial, okay? So I would give you an example. A kid goes to kindergarten and gets sick with the flu. What type of immunity would that be? That would be natural and it would be active, okay? So I would say something like you have COVID and you are sick so you go to the doctor and you get monoclonal antibody therapy. What kind of immunity would that be? Artificial. it would be passive okay so I will give you examples you will have to tell me that okay all right so antigens this is the piece on that back to this is perceived as foreign it is not a normal part of the body okay and that's why the immune system recognizes it so microbial cells viruses it could be foreign you think about blood typing okay ADO blood typing you have to have a specific type of blood that's passed on to you before you get a transfusion, things like pollen. All of those are considered foreign to the body and they will amount, they will mount an immune response. Now an epitope, okay, an epitope is a part of an antigen. So an antigen is a piece on a pathogen and an epitope is a specific part of an antigen, okay, and it is recognized by the lymphocytes. So these little pieces right here, this is considered the epitope. of the antigen. It's just a specific piece of an antigen and remember an antigen is a specific piece of a pathogen. Now there are different types of antigens that exist. Antigen is a piece on a bacterial cell or a viral cell that is going to create an immune response. There's something called alloantigens and this is a marker of one individual that are antigens to another of that same species. Allo means same. So an alloantigen would be like if you have type B blood and I have type O blood and they try to give me your blood, my body's gonna mount an immune response against that type B blood because it does not recognize it. So that alloantigen is that type B blood. A superantigen, okay super, think about great. This is something that creates an overwhelming immune response almost. the point to where it can possibly kill you. An allergen is an antigen. Okay, we know what an allergen is. A pet dander, dirt, dust, okay, anything like that. Any type of antigen, remember it's a piece on a bacterial cell or virus cell that provokes an allergy. And then we have an autoantigen. Auto means self, so this is any molecule on self tissues. And autoantigens are typically responsible for autoimmune disorders because the body recognizes itself as foreign and will attack it. Okay so these are just different types of antigens that exist. Okay now let's talk about these lymphocytes for a second. So we talked about these briefly. We talked about the hematopoietic stem cell and we said that it can create either red blood cells or white blood cells. And so we talked about the basophils, the neutrophils, the eosinophils, the monocytes, and then we said the lymphocytes which are created from this hematopoietic stem cell. They are considered cells of the immune system, but they are part of the adaptive immune system. So B cells and T cells are the cells of the adaptive immune response. Now B cells are made in the bone marrow and they stay in the bone marrow. That's where they go through maturity process. T cells on the other hand, T cells migrate to the thymus and the way that you can think about is B and TT. The thymus, not the thyroid, the thymus. The thymus is one of those organs that is a, it's a lymphoid organ, okay? And then afterwards, those T cells and B cells can move to secondary lymphoid tissues, which we talked about on Friday. So everything is made in the bone marrow, okay? The B cells stay in the bone marrow, and the T cells move to the thymus. And when they move to those areas, they go through an education. process, okay? And when they become mature, then they can move to other parts of the body. All right, so this is kind of the process of how that happens. You've got the bone marrow, you've got T cells and B cells that are made. B cells stay in the bone marrow, they become grown up, mature cells, and then they move to secondary lymphoid tissues like the lymph organs, lymph node, the spleen, different things like that. T cells are made in the bone marrow, they move to the thymus, where they become mature. and then they can move to those secondary lymphoid tissues. All right, now T-cells. Let's talk about the specific type of T-cells, okay? T-cells are broken down into two categories. They are called CD4 positive T-cells. and CD8 positive T cells. Now, CD is just a marker that's present on the cell, specific type of marker. CD4 positive T cells, they're called helper T cells. That's what they do. They help. okay they activate B cells to produce antibodies those T cells come along they handshake the B cell and that activates the B cell they help the B cells they're called T helper cells and they're the most common type of T cell that exists the cda-positive T cells they're called the cytotoxic T cells and so they destroy host cells that are affected they are important in destroying abnormal cells like cancer cells and viral infected cells. CD4 positive, CD8 positive. These are the two types of T cells that exist and they have different functions. They have different functions. So we see here this is how the CD8 positive T cell works. This is a T cell. We see these little viruses and what it does is it starts to secrete these molecules that will then... kill that cell. Now it's a very complicated process. You don't have to know this. This does come from your book. This is actually what's going on. Okay. There's a lot that we are not teaching you that's under the surface. Okay. But you've got the CD4 positive T cell and the CD8 and they have a lot of different functions depending on what's being produced. But what you need to know is that the CD4 positive T cells are helper T cells and they activate B cells. CD8 positive T cells. cells they destroyed abnormal cells whether that's a cancer cell or a virally infected cell and that cell dies by a process called apoptosis. Now B cells on the other hand, B cells produce antibodies. That is their job. T cells activate B cells and B cells produce antibodies. Okay that is how that works. So B cells also produce something called a memory cell. This looks like a cigarette. I really that just looking at it briefly but it's actually where they're doing like a handshake okay so you've got a T cell that helper T cell that is activating the B cell and then the B cell once is activated can produce antibodies against a specific pathogen okay now it's a big long complicated process you do not have to know this picture but I just want you to know that we are just teaching you surface level okay what is going on two types of T cells exist cd4 positive or helper T cells they activate these cells these cells make antibodies and this kind of shows the whole process of what's going on we've got this macrophage which remember is part of the innate immune system okay and it chops up it will eat the bacteria and chop it up and it'll present it to a T cell see here it's like look look at this antigen remember antigen is a piece of a passion and it presents it to the T cell and then the T cell goes and talks to the B cell and activates it. And then the B cell starts to produce antibodies that will then fight that pathogen off. So the whole purpose is this macrophage is introducing the pathogen to the T cell, which talks to the B cell, which makes antibodies, which then go and attack that pathogen. So it's this big, long process of what's occurring, and that's why it takes so long. All right, we'll stop here, and we'll pick up on Wednesday, but you need to start. start studying now. I'm going to go back and see you tomorrow, some of you.

I haven't made the test yet, but I'll work on that soon and I'll let you test it. Any questions? How are we feeling about it?

How are we feeling about it? That's a great question. Like, is it going to be, like, pretty easy? This is not, this one is not as...

bad as test for usually is usually people do a little bit better on this one yeah okay so let's go ahead and get started we left off talking about these different components of the innate immune system remember we're talking about immunity and innate immunity is what kind of immunity Natural, okay. Is it specific? No.

No, okay. That means that you're going to have the same response no matter what type of pathogen it is, okay. And we've been going through, we've been talking about these different components, we've talked about the barrier.

which is the skin, the chemical components. We've talked about some of the cells. You remember we talked about neutrophils and basophils and their presence within the blood. And we're going to talk about some of the cells that are present in the blood.

So, we're going to talk about some of the more cells and some chemical mediators as well and so these two right here these make up the second line of defense so remember the first line of defense is those barriers those primary barriers and those secondary barriers gonna be things like the skin the chemicals that are secreted the mucous membrane stuff like this and the second line of defense is made up of a bunch of cells and proteins that we're going to discuss in just a second but But the main thing of what the second line of defense does is this list right here. This is what all it's composed of, okay? And one of the first things that it does is it acts as a recognition type of defense for the immune system. So the first type of, they're not really cells, okay, but the first thing that are present on cells that help with recognition for the immune system is something called a toll-like receptor, okay? So have any of you ever gone somewhere where you had to go through a toll booth?

Okay. This little toll-like receptor basically just goes through and it's what recognizes the pathogen. Okay. So we've got our macrophage, which is one of those types of cells we talked about. And on the surface is a receptor.

And what that receptor does is it goes through the body and it just kind of feels for stuff. And when it finds a foreign molecule, it binds that. And so these... Toll-like receptors act in recognition, okay?

And when they recognize a foreign molecule, that will start an inflammatory response, and then it can also promote those lymphocytes to become activated, those B and T cells to become activated. The second line of defense is also important in inflammation, okay? So we've already talked about the inflammatory response briefly when we talked about signs and symptoms, but the classic signs and symptoms... characterized by this inflammatory response is the redness, the warmth, swelling, pain, and even possible loss of function. So we gave the example of if you step on a nail or you stick yourself with a splinter, what starts to happen after that.

That inflammatory process is part of your immune system. It's part of your immune system and that helps to contain that pathogen within that area so that it doesn't doesn't follow through anywhere. else.

So the redness, the swelling, that's due to the fact that all of these immune cells are rushing to that area. And then the warmth is because of the increased blood flow and it starts to swell because not only are all of those immune cells rushing to the area to help protect, but it's also trying to keep that pathogen right there in that specific area. Okay, so this is an example of kind of what's going on.

This is actually, I showed this to my seniors for the immune system, but I like the picture because the book is like almost like an immunology for dummies book, but they use it at the med school too, so I really like it. But this is what's going on. We've got our skin layer. We've got our bloodstream right here, okay? And we see we've got red blood cells.

We've got these other types of immune cells floating through the bloodstream. And some of these immune cells are within our tissues, like within our skin. And so you may cut yourself. may accidentally stab yourself with, you know, a splinter or something like that, and you get dirt, grit, stuff inside of the skin, and you've got these little red bacteria. And so what happens is this neutrophil or this macrophage or whatever this yellow immune cell is, it recognizes the bacteria with those toll-like receptors.

And it secretes these molecules called cytokines, which we'll talk about. And what these cytokines do is they're kind of alert signals. And so when they are secreted, that causes all these other immune cells that are in the bloodstream to come to the area of infection. and it starts to fight off the bacteria that are there.

And so once those immune cells start to migrate, you'll notice that the blood vessel, you see how it dilates from here to there, that allows for things to leak out into that skin area. Okay, so that allows for destruction of the bacterial cells. It becomes red, it becomes inflamed, it becomes swollen, and so on and so forth.

So that's kind of the process of what happens with inflammation. And this is just another picture. This one actually comes from your book, but you have a needle or something like that.

There's bacteria on that. And so when that penetrates the skin, you get the inflammation process. Bacteria enter into the wound that cause. this pus formation and eventually you have all these immune cells these purple cells here that move to the area and then help to destroy those bacterial cells that were introduced into the skin okay now when these bacteria not these bacterial cells excuse me these immune cells can move from the vessels to outside of the tissue where you were maybe hurt we call this process diapodesis okay Diapodesis, POD, typically means foot, like podiatry, or pedal, if we talk about a bipedal organism, that's somebody that walks on two legs, quadriplegic, you know, anytime you see that word PED or POD, it typically means foot.

So, diapodesis is where these immune cells move out of the bloodstream into that tissue, okay? And it's done by the process of chemotaxis, and we've already talked about chemotaxis. about that briefly when we talked about bacteria will move depending on certain chemicals.

And so chemotaxis, a lot of these immune cells will move also in attraction to those chemical cells, those chemokines or those cytokines that were secreted at the site of infection. And so I have these videos down here. I want to show you the process of diuresis, what it looks like.

At sites of injury, infection, or inflammation, subclinics are released and stimulate endothelial cells that line adjacent blood vessels. The endothelial cells then express surface proteins called selectins. So what happens is the blood vessels bind these adhesions causing them to stick to the walls of the blood vessels.

This binding interaction is of sufficiently low affinity that the leukocytes can literally roll along the vessel walls in search for points to enter the vessel. And then they're able to squeeze through. So they're tracked in through the metaxas.

squeeze between individual cells without disrupting the vessel walls. Then crawl out of them. So they show a picture, they show like a real-life process at the end. I'm going to move to that.

But what happens is you've got these immune cells in the bloodstream and your blood's moving pretty fast and so what happens is these little yellow rectangles are expressed by the blood vessel cells and they will literally kind of like allow for an attachment for these immune cells so that they can bind and kind of roll and move through the area of infection because if not they're just moving through quickly. So you've got this immune cell right here. You can see all the blood cells rushing through.

You can see them rolling. So all these little cells that are attached to the bottom that are rolling slowly, those are the immune cells and they're trying to go to the area of infection. So you see it's about to move through the area from the bloodstream into the tissue.

Whereas others have already left the vessel and are seen in the surrounding connective tissue. So it'll move through that area. When the blood cell is stopped temporarily by gently clapping the vessels. You see all the red blood cells.

How densely both vessels are filled with red blood cells. They're moving through the bowel. So a lot of that you don't have to know the details, but I do want you to just see how that process works, okay? And then let's see, chemotaxis.

This is a picture of a video of a macrophage, this big cell right here. Because remember, macrophage means big eater. This is a type of immune cell that destroys pathogens through phagocytosis. And this little black blob right here, that is a bacterial cell. So you see that the neutrophil...

this, well excuse me, it's a neutrophil, not a macrophage, but a neutrophil is another type of immune cell and it still eats things by phagocytosis and so it's attracted to this bacteria through chemotaxis. In this spread, a neutrophil is seen in the midst of red blood cells. So neutrophil, staph, red blood cells. Release chemoattractant that is sensed by the neutrophil.

So neutrophil basically... Chases it. And starts chasing the bacteria.

And that's due to chemotaxis. The bacteria, bounced around by thermal energy, move in a random path, seeming to avoid their predator. Eventually, the neutrophil catches up with the bacteria and engulfs them by phagocytosis.

That's what happens. So they consume it and then it's got digestive enzymes in there, it starts to break it down. So that's the process of phagocytosis.

And so they phagocytose and they're attracted to that bacteria because the bacteria will secrete these specific chemicals. And that immune cell is attracted to that. okay any questions about that all right so the third action of the second line of defense is to act as phagocytosis which we just saw this video of how that occurs okay but phagocytosis phago means to eat cyto means cell and so this is where you literally have an internalization of some type of pathogen whether that's bacteria whether it's virus of this immune cell and those immune cells are called phagocytes so that's a phagocyte is an immune cell that participates in phagocytosis. And so what happens is you've got this bacteria and the phagocyte will eat that bacteria and consume it and inside of that it's got all of these hydrogen peroxide and all these granules that will then degrade those bacterial cells and then it'll present it to the B cells and T cells for a more specific response. And so the innate immune system and the adaptive immune system system, even though they are separate immune systems, they do act together to have this common goal to protect the body and to create this immune response to get rid of the pathogen.

So the phagocytes, what they do is they go throughout the body and they survey. They survey the tissue. They look for pathogens, okay, dead, injured cells, something like that. They will ingest and eliminate those materials, and then they will take immunogenic material, which means some type of material that the other parts of the immune system will recognize and present it to them. And as we discussed when we talked about the phagocytes on Friday or the different cells, cell types, neutrophils and macrophages, both of these are phagocytes.

These are both examples of phagocytic cells. Okay. And remember, neutrophils just kind of have a general purpose.

They're usually really early. They have a large amount. Remember, never let monkeys eat bananas. That never stands for neutrophils and they're present in the greatest amount in the body. And macrophages are big eaters and they come from monocytes.

And so they also participate. in phagocytosis. So here's just a couple of pictures of how that works. You've got these phagocytes that are in the bloodstream. Some of them are in the tissue.

But what happens is when you have a damaged tissue, you've got all these signals being released, some from the skin, some from the phagocytes. And that causes all these other phagocytes to move to the area of infection to help fight off that infection. And so those phagocytes will consume the bacteria and...

and basically chop them up inside. And so this is kind of a picture of an electron micrograph that they've colorized to help it be visually more pleasing, but this is kind of the process. The big pink blob, magenta blob, is a phagocyte, and the yellow cells are bacterial cells.

And again, this is just another picture. You've got this large cell right here, and it consumes these bacteria, phagocytes. And so upon phagocytosis, it starts to destroy those bacterial cells, and then it just releases the debris into the body.

Okay? The next purpose of the second line of defense. This is an interferon response, okay?

So interferons are not cells. They are small proteins that are released, okay? So the second line of defense is made up of specific types of cells and specific type of chemicals that are released.

An interferon is a protein chemical that is released by certain types of immune cells in response to viruses, okay? Interferon, when you see that word, when you hear that word, you typically associate it with the virus. And so here's a picture of what's happening. When a virus infects a cell, okay, and it goes to the nucleus to start to replicate, the cell recognizes that virus, okay, because it realizes it has been hijacked.

And so what it does is it starts to secrete interferon. And it lets the body know, look, I've been infected by a virus. I need some help and so when it secretes that interferon that allows for the immune system to come and attack this virally infected cell Okay, so it binds to the cell surfaces So you see interferon is secreted and it'll bond to the surface of a neighboring cell And so what that neighboring cell does is it starts to secrete these other types of proteins That then can chop up the virus before it allows to infect that next cell Okay And the last purpose of the second line of defense is in complement protein.

Okay, so the second line of defense, it plays a role in recognition with those toll-like receptors, plays a role in inflammation, and that allows for that pathogen to be contained in a specific area. The second line of defense also plays a role in phagocytosis, which is where it consumes the bacteria. It secretes interferon, which is a specific type of protein. that helps with virally infected cells and it also helps with the complement system and the complement system is part of the innate immune system so the complement system is made of 26 different proteins that are inactive in the blood rather inactive in the blood but these 26 proteins work together to destroy whatever pathogen is infecting those and so it forms this cascade and that eventually leads to lysis of that pathogen, okay, or phagocytosis.

So these complement proteins, like I said, it's a cascade. There are about 26 of them, and so you can see here some right here, C5B, C6, C7, C8, that C stands for complement, and they either help to poke holes in the membrane, so like this, all those little dots within the cell, that is due to something called the MAC complex, the membrane attack complex, and this is due to all of these complement proteins. that basically form a pore within the membrane, and that allows for all the contents of the cell to leak out.

So it's kind of like those actions of like polymyxins and those cell membrane antibiotics that we talked about, except this is part of the immune system that does that. And complement also helps with a process called opsonization. And opsonization is basically where I call it candy coating.

It's where the complement system, these proteins will tag. a bacteria for destruction. And so we see here you've got the bacterial cells seen in green okay and so this C3b anytime you see the C that stands for complement it will tag the bacteria and that allows for a phagocyte to come and consume that bacteria.

So candy coating just means that it tags it for phagocytosis. Okay all right and so this picture right here is important. because it just kind of shows you the breakdown of the host defenses. So remember we've got the innate immune system, the acquired immune system.

Innate is nonspecific but the acquired or the adaptive, they're interchangeable, are both specific. And there are three lines of defense. The first two, first and second, are part of the innate immune system and the third line of defense is the acquired immune system.

And the first line of defense is typically your barriers, whether that's your physical or your chemical barriers, and then the second line... line of defense are all those things that we just discussed. Inflammation, interferons, phagocytosis, complement.

Okay and all of this works together to achieve a common goal which is to protect the body. Okay any questions about that PowerPoint? I know spring break is on the mind but... It can be this this can it has the potential to be a hard test if you do not study okay but it is straight up memorization.

So I'm gonna call roll real quick, okay? Now that everybody I think has gotten here. Pearl, Liz, Jamaria, Lorelai, Miriam, Emma, Pierce, Kinsley, Aiden, Brecken, Olivia, Ashley.

Cole, Vanessa, Liv, Bailey, Desiree, Savannah, Kitler, Brynn, Marlee, Savannah Martin, Maggie, Matthew, Mira, Anderson. Okay, Campbell. She's not here.

Okay. Hannah, Pierce, Will, Elizabeth, Anna Claire, Jaden, Carly, Don, Anna, Reagan, and Ava. All right, everybody get up real quick and stretch. Do a minute or so to just stretch, okay? Wake up.

Alright, while we're stretching, while we're getting our brain working, what's the first line of defense of the immune system? Barriers. Barriers. What kind of barriers? Skin.

Skin, okay. Why is skin important? It's a barrier. Guess what?

Germs. Yeah, bacteria, viruses, anything like that, okay? What is another type of barrier? Chemical barriers, where our chemicals are important. Y'all can sit down if you want.

Let's get your brain going. Head just stretching. Wake up.

So, what is the purpose of these chemical barriers? So, yep, they're secreted by our body and it helps to inhibit the growth or destroy some type of bacterial or viral cell, okay? What is the second line of defense? First of all, is it part of the innate immune system or adaptive?

Innate. innate immune system okay so give me some things that the second line of defense does do it yes different types of cells and what are those cells involved in? Vagocytosis.

Vagocytosis, which is the process of? Eating. Eating, yep, big eater.

Okay, eating the cells. And what does it do when the bacteria is vagocytosed? What does that immune cell do?

Inside of the cell. Destroys it. Yep, okay, destroys it.

Alright, what's another process besides vagocytosis? Inflammatory response. Inflammatory responses.

What's the purpose of that? To alert the body that something's there. Yep, to alert the body that something's there.

keep that pathogen contained, and you start to see all the signs and symptoms. Okay? Three more. What else?

Identification. Yep, identification. And so those are called toll-like receptors, and they sit on the surface like an antenna, and it recognizes all those foreign materials.

And what does that toll-like receptor do? What? It attaches onto it.

It attaches onto it, and it takes it to what? It doesn't consume it. It takes it to another cell and usually it turns on the adaptive immune system. Okay.

Alright, so that's three. Got two more. Last two we talked about. They're not cells per se, but they're proteins.

Interferon. What's the interferon do? It's a protein that does what?

When you guys study together, this is how you should be studying. No. It is released by white blood cells. When viruses. Viruses, yes.

Virally infected cells. And last one is the complement system. The complement system is composed of what?

26-ish proteins. And they work together to do what? Destroy the bacterial cells.

Destroy the bacterial cells how? There's two ways that they can do that. Cascade, okay, and then the two... Two end products of that is what? MAC and candy coating, the opposite of that.

Membrane attack, so it can poke holes in the membrane, or it tags the bacteria, okay, and lasts for destruction. This is how you should be firing off questions. What a neutrophil.

okay what does this look like what is the monocyte what comes from the monocyte what a basophils do what a eosinophils do which one of these cell types this is how you should be quizzing each other okay this is what helps all right so it on to the adaptive immune system so I thought this was funny in the marrow where I reside this is a hematopoietic stem cell in the marrow where I reside with my progenitors at my side for immunity for blood I will divide divide divide but he's a hematopoietic stem cell because remember these stem cells can either become red blood cells or white blood cells okay when you start getting these that's when you know you've reached nerd status okay when you start laughing at them and y'all will start laughing at them before the end of the class i promise all right so we're talking about adaptive immunity which is a specific type of immunity okay and when we talk about adaptive immunity we get to move into immunization so we're going to talk about vaccines as well and how vaccines actually work okay so this picture right here is just another chart to kind of show you these host defenses remember the innate immune system is non-specific which means you're going to have the same exact response no matter if you come into contact with pollen or the measles same exact response okay it is composed of these physical barriers these chemical mediators and these cells and tissues that all work together in a non-specific fashion to be able to get rid of some type of pathogen now the adaptive immune system or acquired they're used interchangeable so you may see in this book it is a specific specific type of response. And so what that means is it remembers when you come into contact with a pathogen because it creates these memory cells. And that's why we call it specific type of response. Because once you're exposed to something, your body makes cells that will then remember the next time it comes into contact with it.

So the adaptive immune system. This is specific immunity, okay? Because it does distinguish between pathogens.

So it will recognize if you come into contact with a pathogen that you have come into contact with before. The immune system that is adaptive is less rapid, but it is more targeted. So it is specific, and so it is more targeted.

But because it is more targeted, it takes a little bit longer for it to form. So one of my big pet peeves, and I think I've told you guys this before, I can't remember. I tell it to every class probably.

three or four times because I can't remember who I tell it to. My biggest pet peeve is when people say, I'm not getting the flu vaccine because I got the flu when I got the flu vaccine, and that is not the case. Most people get the flu vaccine because so-and-so had the flu, and you're trying to protect yourself, but you've already been exposed, and it takes your body about two weeks to make an adaptive immune response against a pathogen, and so what happens is you think you're going to be protected by the flu vaccine but you've already been exposed to the flu and so the flu divides and you get sick from the flu but you blame it on the flu vaccine even though you've already been exposed because it takes your body like I said about two weeks for you to create an adaptive immune response for that vaccine to work against the flu or any type of other pathogen okay so the adaptive immune system is regulated by immune cells the t-cells and the bees cells.

Now the innate immune system has a ton of cells. Neutrophils, basophils, eosinophils, macrophages, monocytes, natural killer cells, all of those are innate immune cells. The only two immune cells of the adaptive immune system are T cells and B cells.

And so we say that adaptive immunity is divided into a humoral arm and a cellular arm. The humoral immunity is B cell mediated and the cellular immunity is T cell. mediated.

So we talk about immoral, we talk about what's in like the bloodstream. And then cellular, what type of cells are typically utilized in this adaptive immune response. So right here, this just shows you've got this phagocyte that consumes an organism. And that phagocyte processes that organism, that pathogen, that virus, that bacteria, and then it's just a bunch of bacteria. and it presents it to the adaptive immune system, the T cells and the B cells.

And those T cells and B cells then have a humoral arm of immunity and a cellular arm of immunity. So the B cells, what they do is they create memory B cells, and they also create these plasma cells that then secrete antibodies. So antibodies come from B cells, and they are part of the humoral arm of immunity.

T cells, on the other hand... T cells also create memory cells, but they create an effector T cell, some type of T cell that does the effect, that does the killing, or something like that. So the host adaptive immune system is the third line of defense.

Those T cells, those B cells, those lymphocytes, those are the third line of defense. So when the body comes into contact with a foreign molecule, we call this an antigen. Now an antigen is just a piece of that bacteria or that virus. So a carbohydrate, a protein that's on the surface.

You remember how we talked about the bacterial cell can have stuff on the outside? Like the polysaccharide. It has peptidoglycan. It has the capsule.

Remember how we talked about all those different things on the surface of the bacteria or the virus? virus, those spike proteins, that is called an antigen. Okay, anything on the surface, a piece of bacteria or virus, a piece of a pathogen on the surface that the immune system recognizes is called an antigen. And when the body comes into contact with an antigen, that is when those B cells and T cells become activated and the B cells start to make antibodies that are specific towards that pathogen.

okay now adaptive immunity is specific and it also produces memory these are two hallmarks of adaptive immune immunity okay adaptive immunity is specific it creates antibodies or t cells that are specific against a specific type of pathogen okay so if you had the fluke last year and you had the flu this year i just use fluke because you know we We've had this little endemic going around here at MC. But if you had the flu last year and you had the flu this year, it's two different strains. And your body has created an immune response against each one.

So you have cells directed at each one. And that's why the flu changes so much is because it knows that if not, then it doesn't survive because the immune system would attack it. So antibodies are produced that function only against the antigen that were produced in response to.

The adaptive immune system is specific. The adaptive immune system also develops memory cells. So the adaptive immune response is specific, and it also produces memory.

These lymphocytes, they can remember whatever they come into contact with and then remember it every single time after they come into contact with that. Now, there's different types of adaptive immunities. There's active... immunity there's passive immunity there's natural immunity and there's artificial immunity and all of these are different types of adaptive immunities okay now active immunity what does it mean to be active alert moving yep okay so this is when a person is challenged with an antigen what's an antigen a piece on the bacteria that creates a response exactly okay so when a person is challenged with an antigen and it produces antibodies, okay? It creates memory, it takes time, and is lasting.

That is when you are actively producing antibodies on your own because you come into contact with a bacteria or a virus or something else. Now, passive immunity, on the other hand, what is passive? How does passive differ from active?

Less harmful. No, not necessarily less harmful, but passive. What does passive mean in general? Not as alert.

Yeah, not as alert, okay. So passive, just kind of brushing by, right? Passive immunity is when antibodies are donated to an individual, okay?

It doesn't create memory, it acts immediately, and it's short-term. So do you remember during COVID-19, when people would get sick and they would go get monoclonal antibodies that is a passive form of immunity because what's the body creating its own immune cells it was but it takes a while for that to happen remember it's a slow response so People were going to get these preformed immune cells, these preformed antibodies, and that helped to attack the virus quicker, okay? So passive immunity. This means that antibodies are donated to an individual.

Yes, ma'am? This is also what happens with breastfeeding? Yes.

Yes, it is. Okay. Passive.

And I've got a picture that shows that in a second. Now, there's natural and artificial immunity as well. So natural immunity is natural.

This is part of life experiences. When you are a small child and you get sent to daycare or kindergarten or whatever else for the first time, you get sick. You always have a snotty nose. That's just what happens in daycare because you're protected in a bubble at home and then you go into the germ factory, which is daycare or preschool.

And you come into contact with all kinds of pathogens because kids are nasty. Kids don't wash their hands, they share stuff, which is nice, but they also share germs, which is not so nice. That is natural immunity. You come into contact just in the wild.

Artificial immunity is acquired immunity through a medical procedure such as a vaccine. When we get vaccines, that is kind of considered artificial immunity because it's not a natural process. It's not you coming into contact with a virus and your body producing a response to that.

So I've got this picture here that kind of shows all these differences. And you are going to have to know a couple. of these okay now acquired immunity can either be natural or artificial what is natural adaptive or acquired immunity what does natural mean happens on its own yep okay part of natural processes and artificial is done through some type of medical procedures not natural right okay now for natural immunity you can have active natural immunity or passive natural immunity okay now active natural immunity this would be you coming into contact with a microbe okay so you go to kindergarten in my case Everybody had the chicken pox in kindergarten. You guys didn't, because you guys had the vaccine. I had the chicken pox.

I had polka dots. I had stealth scars all over my body from the chicken pox, okay? So, went to kindergarten, everybody had the chicken pox.

I got the chicken pox. That's natural because it was part of the why, okay? And it's active because my body started to form antibodies against the chicken pox, okay? So it's natural because it's happening on its own, and it's active because my body's doing the producing of the antibodies. Now, passive natural immunity is where one person receives preformed immunity by another person.

And an example of that is breastfeeding. So when a baby breastfeeds, the mother produces antibodies that pass through the breast milk. Is that a natural thing? Are those natural antibodies?

Yes, from the mother. But is it active? Is that baby actively making its own antibodies? Or is it receiving some that are preformed? receiving something so that's considered passive it's being passed along okay it's not a natural process artificial immunity okay you can have active immunity or passive now what is artificial immunity Yes, done by medical procedure.

Your body's not doing it on its own, okay? It's not just because you come into contact with a pathogen. Now, active artificial immunity, okay? is vaccination.

This is where you guys went before you went to kindergarten and you got your chicken pox shot. Okay, so you didn't get the chicken pox. You weren't covered in polka dots like I was. Okay, so you go you get the chicken pox shot and what happens is that That prevents you from coming into contact with the chickenpox in the wild. So a person develops his own immune response.

It's active because that vaccine exposes you to the pathogen, but it's artificial because it's not natural. But you're still making your own antibodies against that pathogen. So it's artificial, but it is active because you're the one that's doing the antibody production.

Now, passive artificial immunity... That's like when you go to the doctor and you get antibody therapy. It's artificial because you're getting therapy.

It's a medical type of procedure. And it's passive because it's not your own. So active immunity is when you create it your own.

Passive is when you get it from another person. So I will give you an example of something, and I'm going to say what type of immunity is this. It's going to be natural or artificial.

but notice that active and passive can fall under natural Or active and passive can't fall under artificial, okay? So I would give you an example. A kid goes to kindergarten and gets sick with the flu. What type of immunity would that be?

That would be natural and it would be active, okay? So I would say something like you have COVID and you are sick so you go to the doctor and you get monoclonal antibody therapy. What kind of immunity would that be? Artificial.

it would be passive okay so I will give you examples you will have to tell me that okay all right so antigens this is the piece on that back to this is perceived as foreign it is not a normal part of the body okay and that's why the immune system recognizes it so microbial cells viruses it could be foreign you think about blood typing okay ADO blood typing you have to have a specific type of blood that's passed on to you before you get a transfusion, things like pollen. All of those are considered foreign to the body and they will amount, they will mount an immune response. Now an epitope, okay, an epitope is a part of an antigen. So an antigen is a piece on a pathogen and an epitope is a specific part of an antigen, okay, and it is recognized by the lymphocytes.

So these little pieces right here, this is considered the epitope. of the antigen. It's just a specific piece of an antigen and remember an antigen is a specific piece of a pathogen. Now there are different types of antigens that exist. Antigen is a piece on a bacterial cell or a viral cell that is going to create an immune response.

There's something called alloantigens and this is a marker of one individual that are antigens to another of that same species. Allo means same. So an alloantigen would be like if you have type B blood and I have type O blood and they try to give me your blood, my body's gonna mount an immune response against that type B blood because it does not recognize it. So that alloantigen is that type B blood. A superantigen, okay super, think about great.

This is something that creates an overwhelming immune response almost. the point to where it can possibly kill you. An allergen is an antigen. Okay, we know what an allergen is.

A pet dander, dirt, dust, okay, anything like that. Any type of antigen, remember it's a piece on a bacterial cell or virus cell that provokes an allergy. And then we have an autoantigen. Auto means self, so this is any molecule on self tissues.

And autoantigens are typically responsible for autoimmune disorders because the body recognizes itself as foreign and will attack it. Okay so these are just different types of antigens that exist. Okay now let's talk about these lymphocytes for a second. So we talked about these briefly.

We talked about the hematopoietic stem cell and we said that it can create either red blood cells or white blood cells. And so we talked about the basophils, the neutrophils, the eosinophils, the monocytes, and then we said the lymphocytes which are created from this hematopoietic stem cell. They are considered cells of the immune system, but they are part of the adaptive immune system.

So B cells and T cells are the cells of the adaptive immune response. Now B cells are made in the bone marrow and they stay in the bone marrow. That's where they go through maturity process.

T cells on the other hand, T cells migrate to the thymus and the way that you can think about is B and TT. The thymus, not the thyroid, the thymus. The thymus is one of those organs that is a, it's a lymphoid organ, okay? And then afterwards, those T cells and B cells can move to secondary lymphoid tissues, which we talked about on Friday.

So everything is made in the bone marrow, okay? The B cells stay in the bone marrow, and the T cells move to the thymus. And when they move to those areas, they go through an education.

process, okay? And when they become mature, then they can move to other parts of the body. All right, so this is kind of the process of how that happens. You've got the bone marrow, you've got T cells and B cells that are made. B cells stay in the bone marrow, they become grown up, mature cells, and then they move to secondary lymphoid tissues like the lymph organs, lymph node, the spleen, different things like that.

T cells are made in the bone marrow, they move to the thymus, where they become mature. and then they can move to those secondary lymphoid tissues. All right, now T-cells.

Let's talk about the specific type of T-cells, okay? T-cells are broken down into two categories. They are called CD4 positive T-cells.

and CD8 positive T cells. Now, CD is just a marker that's present on the cell, specific type of marker. CD4 positive T cells, they're called helper T cells. That's what they do. They help.

okay they activate B cells to produce antibodies those T cells come along they handshake the B cell and that activates the B cell they help the B cells they're called T helper cells and they're the most common type of T cell that exists the cda-positive T cells they're called the cytotoxic T cells and so they destroy host cells that are affected they are important in destroying abnormal cells like cancer cells and viral infected cells. CD4 positive, CD8 positive. These are the two types of T cells that exist and they have different functions. They have different functions. So we see here this is how the CD8 positive T cell works.

This is a T cell. We see these little viruses and what it does is it starts to secrete these molecules that will then... kill that cell. Now it's a very complicated process.

You don't have to know this. This does come from your book. This is actually what's going on. Okay. There's a lot that we are not teaching you that's under the surface.

Okay. But you've got the CD4 positive T cell and the CD8 and they have a lot of different functions depending on what's being produced. But what you need to know is that the CD4 positive T cells are helper T cells and they activate B cells.

CD8 positive T cells. cells they destroyed abnormal cells whether that's a cancer cell or a virally infected cell and that cell dies by a process called apoptosis. Now B cells on the other hand, B cells produce antibodies.

That is their job. T cells activate B cells and B cells produce antibodies. Okay that is how that works.

So B cells also produce something called a memory cell. This looks like a cigarette. I really that just looking at it briefly but it's actually where they're doing like a handshake okay so you've got a T cell that helper T cell that is activating the B cell and then the B cell once is activated can produce antibodies against a specific pathogen okay now it's a big long complicated process you do not have to know this picture but I just want you to know that we are just teaching you surface level okay what is going on two types of T cells exist cd4 positive or helper T cells they activate these cells these cells make antibodies and this kind of shows the whole process of what's going on we've got this macrophage which remember is part of the innate immune system okay and it chops up it will eat the bacteria and chop it up and it'll present it to a T cell see here it's like look look at this antigen remember antigen is a piece of a passion and it presents it to the T cell and then the T cell goes and talks to the B cell and activates it. And then the B cell starts to produce antibodies that will then fight that pathogen off. So the whole purpose is this macrophage is introducing the pathogen to the T cell, which talks to the B cell, which makes antibodies, which then go and attack that pathogen.

So it's this big, long process of what's occurring, and that's why it takes so long. All right, we'll stop here, and we'll pick up on Wednesday, but you need to start. start studying now.

I'm going to go back and see you tomorrow, some of you.

Transcript for:Overview of Immunity and Its Components

Transcript for:
Overview of Immunity and Its Components