 Hello everyone, welcome back to another session on dentistry and more. So today we have a new topic in microbiology that is types of immunity. So we know immunity, it is our body's defensive mechanism or it is the ability of the body to protect against all types of foreign bodies like bacteria, virus, toxic substances or whatever which enters the body as antigen. So let's learn the types of immunity and further classification. So as I mentioned, immunity is the ability of the body to protect against all types of foreign bodies like bacteria, virus and other toxic substances. Since it protects us from the disease, it is also called as disease resistance. Okay, disease, resistance. So lack of immunity is known as susceptibility, this is common terminology which we come across in microbiology and pathogenesis that is susceptibility and disease resistance. So lack of immunity is known as susceptibility and immunity is also known as disease resistance. So immunity is commonly done by our immune system which is a complex network of lymphoid organs. So what are the lymphoid organs? They are bone marrow, what else bone marrow, thymus, you know thymus gland and spleen. So all this includes in our immunity system or immune system which is a complex network of all these lymphoid organs such as bone marrow, thymus and spleen. Now let's move on to the classification of immunity. Basically, we have two types of immunity. One is innate immunity and other one is adaptive or acquired immunity. Okay, innate immunity is by default, we're getting some immunity before any type of infection. We already have this immunity to many diseases but acquired immunity is after the infection or after the entry of a pathogen or after a particular microorganisms enters which causes specific disease. Then our body creates or body develops a particular immunity which is known as adaptive or acquired which is acquired after the infection. This is by default innate immunity. Okay, so this acquired immunity is further classified as natural and artificial, naturally acquired and artificially acquired. This artificially acquired we commonly seen like vaccines and antibodies transfer whereas a natural one we have the maternal transfer of immunity to the child that is passive immunity and infection like smallpox through smallpox we get infection and later we develop immunity against such diseases because people with infection of cowpox is already having immunity against smallpox that's how this development of smallpox vaccine came into existence. Anyway, that is another story. So this is the basic classification innate immunity and adaptive immunity which is also known as acquired immunity. The acquired immunity has natural and artificial one is naturally acquiring one is through the vaccines and antibodies so this is passive and active the further classification. Okay, now let's come back to our innate immunity which is also known as natural or native immunity. Natural or native immunity this is by default we are getting this immunity which basically consists of mechanisms that exist before the infection that is a crucial point it the immunity we get before the infection okay so before the infection there is no infection here before the infection we get this immunity and are capable of rapid response to microbes so it comprises of basically four types of defense barriers that is anatomical barriers phagocytic barriers, blood proteins and cytokines so let's see one by one so what could be the anatomical barriers the most common one is our skin right skin is a big anatomic barrier which gives a mechanical barrier and retards the entry of microbes and mucus membrane is another one mucus membrane mucus membrane which is having which entraps the foreign microorganisms and there will be acidic environment like pH around 3 to 5 which also retards the growth of microbes whereas we have phagocytic barrier which includes neutrophils macrophages and natural killing cells which is like which destroys microbes by endocytosis and phagocytosis which is engulfment of this antigens or the foreign particles and also our body has temperature pH temperature like body temperature when we get fever is a response to infection right so we get an infection body rises its temperature in a response to kill those pathogens and we have acidic pH in our stomach around 2 to 3 which kills most of the interested microorganisms and these all are our anatomic barrier which is an innate immunity the phagocytic barriers are like phagocytosis and endocytosis by neutrophils macrophages and other cells and we have various blood proteins and cytokines are also providing innate immunity okay so we have a few types of innate immunity one is species immunity and racial immunity and individual immunity so species immunity is like it is a species is having immunity against particular pathogen like birds is having immunity against tetanus racial immunity a few races have protection against certain diseases and also some individuals some individual immunity some very specific for each because not we know about the food allergy so some people are allergic to seafood but many are not allergic to seafood because they have already some kind of innate immunity against those pathogens which is actually creating those food poison or allergy in that people so some are having individual immunity against those allergen so these are the types of innate immunity now let's move on to our acquired or adaptive immunity which is the type of immunity which is developed by the host in its body after the exposure of suitable antigen okay or after transfer of antibodies or lymphocytes from an immune donor so we are acquiring it either it could be due to the presence of infection from from the infection the body develops body develops its immune system that is active immunity smallpox and it is providing some vaccine which creates immunity like polio and cholera vaccine that is the immunity and also it could be like passive like we are transferring antibodies which is created in another donor like host and we extract the antibodies and antibodies will be transferred to our body and the passive natural is the mother in transferring immunity through the placenta to the child that is mainly IgG antibodies so antibodies are passive type of immunity in acquired and in active type it is either vaccines and the smallpox infection so the active immunity so active immunity is induced by the natural exposure to a pathogen or by vaccination so when we are exposed to a peculiar cowpox infection we get immunity against smallpox or we get a vaccination against certain diseases like polio and cholera we get immunity that is active immunity whereas a passive immunity passive immunity is like achieving by the transfer of immune products such as antibodies or sensitized t-cells from an immune individual to nonimmune one so people with immunity will produce antibodies in their body so these antibodies will extract from that peculiar person or peculiar organism or a animal and transfer it to a non immune individual that is passive immunity that immune immunity is produced outside the person okay as antibodies and that is that will be transferred to it okay but active is the body itself is creating but the antigen is coming from outside here the antibody itself is coming from outside that is in passive here the body itself producing antibodies but the antigen or the infection we are getting from outside that is smallpox or the vaccines so that is the basic difference between this active and passive coming under adaptive or acquired immunity okay so another type of classification in acquired immunity is humoral and cellular immunity so this is a different classification and we have one more classification that is humoral and cell mediated okay so this is basically by beta cells and this is why t-cells okay so the humoral immunity which is also known as antibody mediated immunity antibody mediated immunity so with the assistance from helper t-cells with the assistance from helper t-cells the beta cells will differentiate into plasma beta cells that can produce antibodies against a specific antigen so this humoral immune system deals with antigens from pathogens that are freely circulating or outside the infected cells so antibodies produced by the beta cells will bind to these antigens neutralizing them or causing lysis by dissolution or destruction of the cells or even by phagocytosis so this is mainly by antibodies okay whereas a cellular immunity or cell mediated immunity which occurs inside infected cells and is mediated by t lymphocytes this is beta cells and this is t lymphocyte so the pathogens antigens are expressed on the cell surface or on an antigen presenting cell so these helper t-cells release cytokines that help activated t-cells bind to the infected cells and differentiate this t-cells into a cytotoxic t-cell and the infected cell then undergo lysis so the basic difference between this humoral and cell mediated as I mentioned the humoral immunity produces antibodies against the antigen which are present outside the infected cells or free circulating in the blade okay whereas cell mediated immunity works inside the infected cell where it destroys the pathogen or microorganism by the process of lysis by release of cytokines okay this is present outside and this is present inside the pathogen so our humoral system which shows very quick response against pathogens while the cell mediated is slow in action but both the types are part of our adaptive or accurate immunity okay so that is the difference between this humoral and cell mediated immunity so we can summarize this humoral and cell mediated as the humoral immunity is associated with beta lymphocytes so beta lymphocytes okay and is responsible for destroying the pathogen by producing antibodies against it whereas the cell mediated is associated with t lymphocytes and is responsible for destroying the pathogen or microorganisms so this humoral is mediated by beta lymphocytes and this is mainly by t lymphocytes natural killer cells and macrophages so this is mainly by antibodies okay here there is no production of antibody that is a basic difference cell mediator is not working under the principle of antibody here the production of antibodies is there so this humoral immunity it plays a major role in recognizing antigen or any foreign particle and in producing antibodies against it whereas the cell mediated immunity is related to t lymphocytes which work by identifying the viruses or microorganism and destroying them by the cell lysis or phagocytosis okay there is no production of antibodies so humoral immunity is known for working against extracellular pathogen and this is known for working against intracellular pathogen this is extracellular or which is circulating to the blood this is intracellular and this basically secretes antibodies okay this is secreting antibodies this is secreting by cytokines okay humoral is done by antibodies cell mediated is done by cytokines and humoral immunity is rapid or quick in the response this is delayed though the permanent action against any pathogen and this is most commonly regarding the hypersensitivity type one two and three this will be definitely type four because it is a delayed reaction and that is about the difference between humoral and cell mediated immunity it is another type of classification adaptive or acquired so we have the first classification which was natural and artificial natural passive natural active artificial passive and artificial active this is a mother to child this is infection by smallpox this is antibody transferred from a different animal or different person who is immunized we are taking we are extracting the antibodies from the immunized person to a non immunized one this is by worried itself creating immunity against certain diseases like polio cholera by introducing vaccines okay so that's all about our immunity we have basically two types one is innate or native default immunity and another one is acquired immunity this is before infection this is after infection this again has all this classification natural artificial passive active passive active there is another classification of acquired one which is humoral immunity and cell mediated immunity it's a very common question and microbiology could expect humoral immunity or cell mediated immunity or you could expect innate immunity or adaptive or any individual type of immunity so that's all about immunity i'll come up with a new session and industry and more thank you