all right engineer so what we're going to do in this video is we're going to talk about antibody structure and function all right so antibodies there's actually these ones that we have right here one two three four five antibodies that we have listed right how what is an easy way there was an acronym that i found from someone who actually helped me when i first took this anatomy and physiology was this little this little mnemonic here called gamed and game gives you the all the antibodies that you have to know igg iga igm ige igd so it's a quick little way of being able to remember all the five antibodies all right so now what we're going to do is we're going to go into detail into each different type of antibody so let's go ahead and dive right in away right away to the igg antibody so igg antibodies one thing you're definitely want to know about this guy he is the most abundant antibody so out of all of these antibodies he is the most abundant antibody okay so a good portion of him literally about um 65 percent of him 65 to 70 percent of him is actually found within our blood plasma so 65 to about 70 percent 70 is found within the blood plasma and again who secretes these antibodies we already know this the plasma cells right so our plasma cells if you remember them the one with that really really big nucleus and again a large amount of rough endoplasmic reticulum these are the guys that are responsible for producing this one in this case what is this one here called this is igg antibodies now igg antibodies we're going to get into its structure in a little bit here but this guy is actually designed to be what's called a monomer what is a monomer that means he just has one of these antibodies here so there's only one of them so what is this guy here again he is actually a monomer all right so ig g antibodies are monomers so there's only one of these puppies all right now we know plasma cells make these guys right we know that it's the most abundant antibody we know that 65 to 70 percent of it's found within the blood plasma this antibody is actually produced within the second it's produced within both the primary and the secondary but it's the most abundant one in the secondary immune response so it's more abundant or the primary one in the secondary immune response but it is produced in small amounts during the primary immune response so in a primary meaning that you first get infected secondary is that you're getting exposed to that antigen or foreign pathogen again and we'll talk about that when we talk about the graph and we'll talk about somatic hypermutations all right so again he's producing the primary and the secondary immune response okay next thing what does this guy do so if you remember from before you'll remember that we had a bacteria here right and if you remember that bacteria what can be on the cell membrane of that bacteria or the cell wall right depending upon what type of bacteria it is gram-negative or gram-positive you know that it can have those antigens right so here's that antigen let's actually draw this antigen in blue here so here's this antigen right and then what can be bound to that antigen we can have the igg antibodies bind to that and if the igg antibodies bind to that what can that do that can activate if we remember already it can activate the complement system and what can the complement system do that can initiate the formation of a membrane attack complex or they can enhance opsonization right so that's that's one thing where they can form the membrane attack complex or they can enhance the opsinization right and they can cause c3 and c5a which enhance inflammation that's one mechanism another thing they can do let's say that there's a virus particle here's a virus so here's a viral molecule here so it's got like this nucleocapsid and then it's got some so let's say it's rna or dna that's actually present with inside of it and then let's say it has like these specific types of uh viral antigens out here on the surface what can happen is those igg antibodies can literally bind to every one of these every one of these antigens and whenever it binds to these guys this virus can no longer come and bind to an actual host cell so it can't infect it so what is that called that's called neutralization neutralization let's say these there's a free antigen right so there's some type of free antigen circulating in this vicinity of the plasma or within the extracellular fluid right and what happens these antibodies they bind to this free antigen and precipitates this antigen which can enhance uh phagocytosis so this can do two things it can actually initiate optimization and can initiate phagocytosis by trying to enhance the phagocytosis but what is this process right here called this is called precipitation right so it can do precipitation what else can it do it also because we can do precipitation it can do neutralization it could activate our our complement proteins and there's a lot of other things that it can do also right one other thing i want to mention is you know that whenever a baby is within the just it's just in the gestational phase right so it's actually uh in the fetus stage and there's the placenta that's developed around the 12th week right well the placenta let's just say here's our placenta right here the placenta can actually provide so here let's say some blood vessels coming from the placenta right they're like the umbilical veins they can allow for these antibodies to circulate through so let's say here i have ig g antibodies these igg antibodies can actually pass over from the placenta where to the baby right and so let's say here's your baby right so here's your baby all right what can it do it can pass these igg antibodies onto the baby so that that baby has what's called passive immunity so whenever it's born it's already going to have a small amount of immunity right to specific pathogens that the mother's been exposed to so that's kind of cool so again what do we have for the igg antibody most abundant antibody 65 to 70 percent of it's found within the blood plasma are extracellular fluids it's secreted by plasma cells in the monomeric form it's secreted within the primary and the secondary immune response but it's more abundant within the secondary immune response and what is its effects it can enhance the complement proteins by doing the membrane attack complex and optimization it can bind and cause neutralization of certain types of viruses or other microbes it can cause precipitation reactions which can enhance oxidization and phagocytosis and it can also pass the placenta and confer passive immunity between the mother and the baby right that's that apart for igg antibodies now let's go to iga antibodies so iga antibodies all right so ig antibodies you would find these where would you find this because we talked about these guys where would you find these guys and again well first off who secretes them again it's going to be the same cell constantly over and over and over again but we're going to keep mentioning that so you don't forget it this is actually going to be the plasma cells so the plasma cells secrete this antibody but iga antibodies interesting look at this see you notice something right here look at that they're linked together but it's not a monomer there's two of them so if there's two of them what do we call this this is called a dimer this is called a dimer so again plasma cells secrete these iga antibodies but they're in the dimeric form so it's two monomers linked together so this is a dimer all right so now where would you find these iga antibodies well these plasma cells they're secreting these antibodies that's present within a lot of the actual fluids within our body for example you can find this within the saliva you can find this within the skin so it can be on the skin secretions like your sweat secretions so we'll put sweat you can find it within the mucosal lining of our gi tract so the mucosal lining of the gi tract oh and one really really good one too this is an important one i'm going to mention this one within the milk the milk of the mother right so whenever the milk so we'll call this the milk the milk produced by the actual mother within her alveolar glands right so the milk from lactation so whenever the baby is actually suckling and it's actually gaining that milk from the mother these ige antibodies can actually get pushed into that actual milk and those iga antibodies can get passed from mother to the baby and that can help with some of the actual immunity that's why you want to be able to breastfeed right all right so again that's pretty much these ones that you would find them in again so it's a lot of our actual body fluids like saliva and the sweat and the mucosal lining of our gi tract and within the milk and even with some within the urogenital tract and stuff right so you can even say urogenital tract but now what are these designed to do so what they love to do is they love to be able to destroy certain types of bacteria that might actually show up within this area that's pretty much it how can they do that they can do a lot of the similar mechanisms that we already talked about right so again these ig iga antibodies they're really really good at being able to let's say here we have a bacteria here that somehow gets inside of the actual gi tract or within the saliva or it's actually on the skin or it's within the mucosa lining or whatever then you would have let's say here's the antigen here you would have this iga antibody here that is actually going to be a dimer and he can actually bind this point right here but if he's actually a dimer maybe there might be another bacteria within the vicinity or some type of microbe right here and what can it do it can also bind to that antigen so again that's why he's a very good one right there he is a dimer all right that's pretty much about h i g a antibodies again you'd find it within a saliva the skin the mucosal lining certain types of milk within the mother and you can even find it within the urogenital tract and just know that it is a dimer okay next one igm antibodies so igm antibodies are actually going to be another very very important one and again we should continue to keep doing this who secretes this guy plasma cells right so the plasma cells are the primary cells that are going to be the only cells really there is other cells that can make antibodies but these are going to be the primary ones and these guys are going to be our plasma cells and they are secreting ig and antibodies you guys are going to crap your huggies right here because this guy he is a pentimer he can look at this guy he can exist in two forms he can exist in a pantomeric form and he can exist in a monomeric form right so we have two of these guys right here we can exist in this form which is what one two three four five this is a pentamer and it's all linked together through what's called a j protein but again this is a pentamer so it can secrete these antibodies in the penthomeric form or can they can be secreted in the monomeric form right so there is two different forms of this antibody the monomer and the pentimer igm antibodies are very very important right so they're secreted by plasma cells and they're pretty abundant too now what do these guys do so these guys are the ones that are secreted within your primary immune response so this is the one that's made during your primary immune response alright so this is important why is this important because this could be a good diagnostic tool if you actually run somebody's actual blood or their antibody titers and you find out that they have elevated levels of igm they could actually let you know that they're undergoing some type of active infection some type of primary exposure first time they're being exposed to some type of foreign antigen and they're producing antibodies against that right so that's important for understanding that these igm antibodies are made during their first prime or primary immune response right what can these antibodies do all right well these antibodies and they can also be found within a lot of our extracellular fluids also this guy he actually is going to love to be able to activate the complement protein so if you remember here we had that bacteria let's say here we have that bacteria and if we have that bacteria there and again what did that bacteria have on its cell membrane it had specific types of antigens and what can happen is this monomeric form of the antibody can bind on to that guy right there and then what can happen we already know what's going to happen you could activate the complement proteins right and the complement proteins could lead to membrane attack complex or optimization right so that's that what else can he do he's really good at being able to pick up so you know whenever you get a mismatched blood transfusion if you get a mismatched blood transfusion so let's say that you have a mismatch blood transfusion so here's your red blood cells here let's see i have a couple red blood cells here and these red blood cells here they all have foreign antigens maybe it's an a antigen and you weren't supposed to give an a antigen to this individual but here's this a antigen and you have let's say anti-a antibodies well guess what this igm can actually bind right here look at this this is a beautiful thing and then all of these guys can bind here so again what is that molecule called it's called a j protein that links them all together this right here this molecule right here is our i g and the antibody and what is he doing remember when we talked about this when we talked about this in the blood typing videos that whenever we have any type of mismatched blood transfusions and there's a antibody antigen interaction well an antibody antigen interaction can lead to what's called agglutination and agglutination is clumping right and that can cause a lot of problems here so again there can be agglutination this is a type 2 hypersensitivity all right so this is actually what's called a type 2 hypersensitivity whenever there is a mismatch blood transfusion and we'll talk about that more pathology so again what can this guy do okay he can be made by plasma cells in the epinephrine form or the monomeric form he can be made during the primary immune response and he can even be made a little bit during the secondary immune response but very very little what does he do he can bind on in the monomeric form to foreign antigens and initiate the complement system and activate the membrane attack complex and oxidization mechanisms or he can bind on to multiple different antigen binding sites so he has multiple antigen binding sites if you think about it when we draw the structure of the antibodies and discuss them he has 10 different antigen binding sites or epitopes so he has 10 antigen binding sites and for right now you're just gonna have to trust me what i'm saying that it has 10 because you might be like oh it only seems like it has five well you'll see here in a second whenever we talk about it okay so again that pretty much covers igm antibodies let's go to the next one which is ig e antibodies all right so now ige antibodies what do ig antibodies where okay where are they secreted from again let's just keep doing this just so we can be consistent here they're made by plasma cells but we can kind of expand on this a little bit so they're made by plasma cells all right and when they're made by these plasma cells so they can be secreted by plasma cells because these are the only ones that are really releasing the antibodies the plasma cells plasma cells are the only cells that are making these antibodies now ige antibodies are monomers also so these are also monomers so these are monomeric proteins or glycoproteins so this is a monomer and where would you actually find this guy well you can find it within the actual respiratory tract so the respiratory tract mucosa you can also so it's fine within the respiratory tract mucosa and you can even find it within some of the urogenital structures too right so you can also find it within the urogenital structures and you can also we're going to discuss another thing you can also find it within the lamina propria too or certain types of lymphatic tissue so we'll put lamina propria or in lymphatic tissues okay so now these antibodies are pretty cool what do they do all right so let's say we talk about the respiratory tract mucosa first because this is it has a very important role within what's called type 1 hypersensitivities or anaphylactic shock you might have heard of that right so let's say here i have a mast cell you guys remember mast cells right so mast cells right here we talked about this in other videos but we didn't go into super super depth on it you know you have these receptors right these receptors are called on the mast cell f c epsilon r one receptors so again what is this called fc fracture stands for the fc portion of the antibody epsilon r one okay so this is the fc epsilon r1 receptor why do i mention that well guess what you see this monomeric antibody whenever there's some type of inflammatory response that monomer will literally bind in right here so that monomer will literally bind in right here so now you have the f sleet fc epsilon r1 receptor bound with the monomeric ige antibody why is this important because whenever someone is exposed to some type of allergen something that they're allergic to for example let's just say it's a ragweed pollen that i draw here in blue whenever these ragweed pollen molecules activate this actual ig ige antibody sorry ige antibodies it can signal the actual mast cell to start producing tons of different types of inflammatory chemicals so again you already know these molecules what are these molecules called they're called histamines and i'm not going to go over all them but they could be leukotrienes right so they could be leukotrienes they could be prostaglandins right so and what are these molecules designed to do well if you remember they cause widespread vasodilation right and another thing that they're going to do is there's also going to be other molecules that are produced too whenever they cause that widespread vasodilation it's going to cause the blood vessels to start getting leaky and if this is happening within the respiratory mucosa if you imagine here if i were to draw someone's bronchi here let's say i draw a bronchi and i have a blood vessel right here serving that bronchi and i have a lot of capillary permeability coming out of that i have an increased capillary permeability what's going to happen to that actual space right there it's going to start getting bigger and bigger and bigger and it's going to cause a lot of edema and that's going to create swelling which can actually start restricting the airways all right so that's where people can actually have a problem breathing so there'll be a lack of oxygen coming into this area here and a lack of co2 getting out and that's because of that a lot of that edema here that accumulation of fluid there another thing that happens is these actual molecules they bind onto different receptors now we know that they cause vasodilation right they also bind onto smooth muscle cells here within the bronchi and when they bind onto these smooth muscle cells within the bronchi they actually cause these smooth muscle cells to actually contract and when the smooth muscle cells contract here so it's going to cause contraction of the smooth muscle cells within the bronchi it actually decreases the size of the airway and if you decrease the size of the airway can as much oxygen get in and as much co2 get out no and that can affect breathing right that's what people know to be called as ana anaphylaxis right so anaphylaxis this is actually a type one hypersensitivity okay that's one of the big big important things with these respiratory tract mucosa is that they play a very very huge role within these allergic reactions specifically type 1 hypersensitivities or anaphylactic shock right all right what's the other thing urogenital is also important of right and it's also part important within this laminar propria and lymphatic tissue it's also important within the gi tract mucosa why is it important within the gi tract mucosa let's say that i decide to eat some type of uncooked bear meat and i'm an idiot i don't know why i would ever do that but i did so here's my gi tract right i eat this undesirably uncooked meat or whatever whatever it might be and i end up getting somehow i get parasites so i get a parasitic worm in here look at this puppy right here i got a parasitic worm floating around in me that's nasty right but what happens these actual parasitic worms we actually can produce antibodies against them and guess what antibody we produce against them ig e antibodies and then we can tag these ige antibodies for what type of white blood cells you should know this this is actually going to be our eosinophils so if you remember from before what was this actual cell called this was called a eosinophil because he loves to release the major basic protein and the cationic peptide which cause destruction of the actual parasite so come over here and i'll actually destroy that parasite all right so that's that for the ige antibody and there is small traces of it you can find tiny amount of traces of it within the blood plasma so very small traces in the blood plasma okay so that's a cool antibody there all right now let's come over to the last and the final one the easiest one igd antibodies igd antibodies are again they're made by plasma cells what you're going to love what they do because they're not not that hard to remember they're actually made by the plasma cells and they are also monomeric so these are also monomeric all right so they're only going to be one of these molecules here so again this is a monomer but what do you think this guy does it's actually not bad guess what he decides to come back or actually he wouldn't be secreted because you know proteins whenever they come from the golgi apparatus they can actually become a part of the cell membrane or they can be secreted i just wanted to show it so you guys could see this guy here and a larger view here he actually is going to whenever the golgi apparatus has those vesicles it's actually going to fuse with the cell membrane and when it fuses with the cell membrane it's actually going to express that actual monomer on the b cell surface so this is our b cell receptor this is going to act as a b cell receptor what we talked about in the actual humeral immunity or the adaptive immunity video right so he's a very good b-cell receptor all right so that pretty much covers everything for him for the igd antibodies right so he's a very good b cell receptor just like the actual monomeric form of the igm antibody all right so again come back over here to the igm antibody really quickly another thing that can actually happen with this monomer that i didn't mention is that this monomer can also exist as a b cell receptor so you can also exist as a b cell receptor just as the igd antibody can all right now that we've done that i want to talk about what's called somatic hypermutation what is meant by somatic hypermutation all right so if you remember we talked a little bit about this already when we talked about the igm and the igg antibodies how they're a part of the primary and the secondary immune response so here on the y-axis i have the abundance of antibodies within our serum and here on the x-axis i have the time is actually going to occur over time in days so let's say all right first thing i get exposed to an antigen let's say i get exposed to antigen x so i get exposed to antigen x what happens is after we're exposed to antigen x there's a lag period so there's this period there's this lag period where nothing's happening right so here's this lag period but then let's say after maybe a day or something like that we start producing antibodies and this starts rising look at this it starts rising all right and then after that it'll actually come back down but then there's another antibody that'll also be produced but he's actually going to be produced a little bit later even that longer than that look at this guy here and then he comes back down so whenever we have a primary our first exposure to an antigen we produced an antibody a little bit for like there's a lag period what is this thing right here called this is a lag period and this lag period is actually going to take some time and for our plasma cells to start producing antibodies let's just say for this case it's two days whatever let's just say it obviously could even be a little bit longer maybe five days let's say two to five days so two two five days and then what happens during this lag period we start producing a specific type of antibody what is that antibody this is called i g m antibody that's the first antibody that we're going to produce during the primary immune response but then later on in that primary immune response we make another antibody and this antibody is actually going to be called and as this antibody is going down this antibody is actually going up that's interesting right because now that means what does that mean that means our plasma cells were designing themselves to secrete what at this point in time ig and antibodies but then over a certain amount of time they switched and then they started producing igg antibodies well how does that happen that's weird right the genes get activated by certain types of interleukins and cytokines so there might be for example for this igm antibody there might be certain types of cytokines here so there might be certain types of cytokines or stimuli like the microbe itself that's activating this guy to produce igm antibodies whereas there might be other types of cytokines or there might be other types of microbes that is actually going to tell this plasma cell to start changing its gene sequence changing the actual genetic transcripts and producing igg antibodies so whenever there's this change or this shift with from ig m to ig g antibodies that change in the production this right here is called somatic hyper mutation okay now we're not done yet so now as this starts dropping and then eventually this starts dropping so again what is this antibody here this is ig g here's where somatic hyper hypermutation takes a definite huge change so again let's say we're coming over here it's that we're not actually getting exposed to anything and then right away i give a second exposure so now i'm exposing them to a different type of integer maybe i'm just having a second exposure to x if there's a second exposure to x now watch this the igm antibody actually has a little lag period but then it produces it again but it's not as much now watch what's going to happen to this black line here it's going to go ham and it's going to go all the way up here right so there's that change right so look how much of a difference there is here this is the big difference this is really the definition of this is really the better example of somatic hypermutation because primarily we were making igm antibodies right that was the first one that we were making and we still do make a tiny little bit about uh amount of them in the secondary immune response but look which one we're making primarily igg antibodies so this is how we actually should describe somatic hypermutation is that how we were making igm antibodies primarily and igg at almost equal amounts pretty much close to equal amounts there was a greater lag period for the igg though and then afterwards when we were exposed to the antigen a second time we didn't even make that many igm antibodies at all we primarily produced igg antibodies that is somatic hypermutation okay now we're getting close to done let's talk about a couple more things and we're we're done with this lecture here right immunity there's two types one type is actually going to be called passive and the other type is actually called active now what is the difference between passive immunity and active immunity passive immunities means you didn't have to do anything to be able to get that form of immunity it was given to you without you having to do any work right or produce any antibodies in response to it so you weren't you were given these it's like it's like someone actually me working to be able to get money or me just getting money from somebody if i'm just getting money because i'm an heir it's a passive form right if i'm actually working to gain that money that's active that's how this is actually going to work so let's explain what i mean by this so passive there's two types of passive immunity as there is two types of active immunity passive there's what's called naturally acquired so there's the ways that you can naturally acquire immunity and then there's a way that you can artificially acquire immunity right so artificially acquire what are these ways that you do that so naturally acquired we already talked about one example it's a perfect example that would be the igg antibodies and the iga antibodies so again what is these ig g antibodies and the ig a antibodies that we got from are mother right so igg antibodies that would be the ones that cross the placenta and then the iga antibodies are going to be the ones that we got from the mothers milk these are naturally acquired we didn't have to do anything to get these we were given these naturally right so we were given these molecules if we were given these iga and igg molecules naturally we didn't have to work for them they were given to us right all right artificially acquired this one would be let's say that i got um bitten by a snake i got bit by a snake and the snake has a specific type of venom right and that venom is actually causing damage to my tissue and i have to get the antidote so then what they do is they give me an artificial form of the antidote which is an immunoglobulin so let's say that they give me an anti-venom or maybe i got bit by a uh like a black widow which has a lateral toxin i have produced they give me specifically antibodies immunoglobulins that will actually ward off that venom so it's an anti-venom so you can think about that i didn't do anything against it i didn't produce the antibodies they gave me the antibodies so think about that as like a anti-venom the anti-venom is actually immunoglobulins and what do i mean by immunoglobulins i'm just now mentioning this and i'm sorry this is another word for antibodies so antibodies they literally gave me antibodies against the actual so these antibodies are against the venom from a snake and this could be other examples this is just the first example that popped in my head right so that's artificially acquired now let's come over to active active is the one that we actually have to produce antibodies against and again there's two types there's naturally acquired right naturally acquired and then there's also artificially all right so again naturally acquired what does this mean so naturally acquired is i was exposed to it so me actually being infected with e coli so me actually being infected by pathogen because if i'm infected by a pathogen like uh maybe streptococcus b hemolyticus uh landsfield type a strep throat right i have to produce antibodies against that pathogen that is an active form of immunity naturally all right what is the artificial form this would be an example of vaccines and booster shots right so vaccines and booster shots why is this active because you know when vaccines are in certain types of booster shots they literally give you a week so here's let's say here's the antigen this antigen is weak or we can even say dead so they're weak or attenuated or they're dead antigens and then what happens is my immune system produces antibodies against that actual weak or dead pathogen and then when i produce antibodies against that weak or dead dead pathogen that is an artificial way of having active immunity and that could help us to be able to have specific types of immunity against certain types of flus or viruses or certain types of bacteria right that's the purpose of artificial vaccination all right last thing and then we're done guys let's talk about the structure of an antibody let's take the structure of our antibodies so what we have here is we actually have these two different types of chains here look at this so right here i have what's called a this whole part right here all the way up all the way up all the way up right here i'm going to shade this in right now this whole thing right here is called our constant heavy chain and if we have one here we should have one right here too so all this right here is also constant heavy chain then we have another chunk of it over here let's draw that other chunk over to here so now we have two chunks over here also so we have a constant heavy chain then over here we got another piece right here this piece right here that i'm going to shade in and this piece right here that i'm going to shade in this is our constant light chain and this over here is our constant light chain this right here and i'm going to draw a little bit of a different structure here it can actually kind of look like this maybe this is our variable heavy chain and then just right here this can also have a different type of structure here this is our variable light chain and the same thing over here this would be variable light chain this would be variable heavy chain and then look what we have connecting these guys together right here we're going to have disulfide bonds linking that guy together disulfide bonds like in this part together and disulfide bonds linking that guy together this is the structure of the antibody why is this important all right let's finish up here this portion of the antibody is a good attachment point for complement proteins complement proteins love to be able to bind to these portions right here all right that's one thing second thing that's really really important you see how i drew these variable regions a little bit different these variable regions differ from antibody to antibody in other words let's say right here i have three different types of antigens this undergoes recombination in such a way that every variable region is different for every type of antigen so in other words if this one is going to be for this one right it's going to make a variable region that's specific to this antigen right here if we wanted it specific to this antigen what would it take on the variable shape would look like this and if we wanted to be able to fit this what would it look like it would look like this that is the purpose of these variable heavy chains in these variable light chains is that they can undergo recombination to make different structures to accommodate these different types of antigens which makes them good for being able to bind on to foreign invaders right plus if you think about it i have two binding sites here for one antibody so this technically has two antigen binding sites what does that mean remember when i told you i'd explain to you what was the purpose of that anti antibody for igm let's come over here real quick remember i told you has 10 antigen binding sites it's because of that each one of these antibodies has two antigen binding sites and it's a pentamer that's a total of 10 antigen binding sites alright guys so in this video we covered a lot on antibody structure and function all right all right i hope you guys enjoyed i hope it helped see you ninja nerds