this is part one for chapter 16 innate immunity your immune system is divided into two basic parts your innate immunity or innate immune response which is also sometimes referred to as nonspecific and your adaptive immune response which is sometimes referred to as your specific immune response your immune system is further divided into lines of defense first line of defense second line of defense are part of your innate immune response while the third line of defense is basically your adaptive or specific immune response and a little bit of detail on these lines of defense first line of defense involves keeping the microbes out of your body second line of defense are your initial defenses that occur inside your body when the microbes have actually entered into your tissue and then third line of defense is where specialized cells are responding to that particular microbe that has colonized your body so this is your overall immune response innate immunity is nonspecific and it is against all microbes in general whether they are viruses or bacteria and is composed of the first line of defense which is meant to keep the microbes out so prevent infection and if the microbes get past the first line of defense then it's up to your second line of defense to have nonspecific reactions to get rid of the infectious disease your adaptive immune response again is also referred to as your specific immune response and this is basically your third line of defense and is where specialized cells t-cells and b-cells and the antibodies are responding to that specific micro Fick sorry microbe that is causing an infection so this video is going to focus on your first line of defense so first line of defense remember this is non specific and it is meant to prevent infection so its whole purpose is to keep the microbes out of your tissues to prevent infection and for your first line of defense it is composed of several things first different tissues that make up barriers to prevent infection so that will be the skin and the mucous membranes also I'll talk about different secretions chemical factors chemicals that your body secretes to prevent infection and your normal microbiota and there's one more thing I'm going to add to this and that's something I call washing processes so it's how your body is structured to wash out potential pathogens so the first thing I want to talk about about your first line of defense are the barriers the different tissue types that are found on the surface of our body to prevent infection these barriers are part of the physical factors of your first line of defense so physical factors how the body is physically structured to prevent infection and the first barrier or type of barrier is the skin so the skin covers most of the outer surface of our body and if you've had anatomy you know the basic structure of the skin but the skin is a relatively thick tissue and it is very strong mechanically strong it does not easily tear and it is waterproof so the keratin keratin eyes level of the skin creates a waterproof barrier so the skin is very thick it is waterproof and strong and prevents infection over most of our body the second type of barrier that covers part of our outer surface are the mucous membranes mucous membranes you should know where they are located on our body so respiratory system digestive system urogenital system and the conjunctiva remember the conjunctiva is round the eyes and mucous membranes compared to the skin are relatively thin not a very thick material and relatively fragile it's easier to tear mucous membranes than it is to tear skin and also they are not waterproof you get diffusion of different molecules substances across the mucous membranes into the tissues but the mucous membranes are very good at protecting us from infection because they have these goblet cells which produce the mucus so the mucus is produced aligns the outer surface of the mucous membranes and it is able to trap microbes that are entering our body the next thing I want to go through there are several washing processes that's what I call them washing processes how your body is structured to flush out potential pathogens there are different areas of your body that have certain washing processes and the first one is the lacrimal apparatus the lacrimal apparatus is found around your eyes and it is composed of the lacrimal glands which are found around the outside of your eyes and they secrete tears that will wash over the eyeball and drain down the lacrimal canal and those lacrimal glands are functioning all the time not just when you're sad not just when you are cutting onions the lacrimal glands are constantly secreting tears that are constantly washing across your eye in the conjunctiva and washing any microbes down the lacrimal canal and where do those tears end up they end up going down the back of your throat where you swallow them and they go all the way to the stomach where the stomach acid will kill the microbes the second washing process that I want to talk about is the ciliary escalator and the ciliary escalator is found in your upper respiratory system specifically in the trachea and you should know that your upper respiratory system is composed of mucous membrane and the mucous membrane of course the mucus is there to trap the microbes that you are inhaling every time you inhale so the mucus traps the microbes and then the cilia which is in the trachea will move those microbes up and away from the lungs so of course you don't want infection in your lungs and this is protecting your lungs so you inhale the microbes they go down to the trachea the cilia moves the mucus away from the lungs and where does that mucus go it goes up to the back of your throat and then you swallow it and it goes down to the stomach where the stomach acid then kills the microbes so this is a self-cleaning process because of course the air you are inhaling is not sterile so all those microbes will be trapped to the mucus the mucus is moved up and away from your lungs and then it's swallowed where those microbes are killed in the ass and they estimate that every day a normal healthy human produces about a half cup of mucus so every day you have about a half cup of mucus being produced in your trachea and your upper respiratory system and ending up in the stomach the next washing process I want to talk about is saliva production and saliva is produced by your salivary glands so you have several salivary glands that are producing saliva and those salivary glands are producing saliva all the time and in terms of your first line of defense against infection the purpose of saliva is to wash over your teeth and to wash away any microbes that have come in on your food so the transient flora that has come in on your food it remains in your mouth on your teeth the saliva is going to wash those microbes off of the surface of your teeth and where does that's live ago you swallow it and it goes down to your stomach where the stomach acid kills the transient flora the last washing process I want to talk about is urination and urination is a way to protect from UTIs urinary tract infections and as I mentioned before females are predisposed to urinary tract infections because of the distance from the anus to the aretha urethra is really really short compared compared to the male's where the distance from the anus to the distal end of the urethra is fairly long but regardless microbes ecoli just tends to migrate from the anus to the urethra it's just a natural progression it's just what happens but every time when a person urinates the urine comes out at a fairly high pressure and it's going to flush out any microbes that are starting to migrate the urethra so this is another washing process that protects from infection so I have talked about physical factors that protect from infection so the different types of barriers skin and mucous membranes and then various washing processes and all of those are how your body is structured to protect you from infection second part of your first line of defense are chemical factors these are substances that your body secretes to protect you from infection and this is a table of different chemical factors that your body secretes first is sebum sebum is basically the oil that is produced on your skin and it protects you in several ways one way it protects you is it is a little bit acidic so it prevents or inhibits the growth of many microbes the other thing that sebum does is it helps to maintain the integrity of your skin because if your sebaceous glands are not very active the sebaceous glands produce sebum then your skin becomes very very dry and dry skin can crack and if the skin cracks then it is no longer functioning as a barrier to prevent infection so sebum protects you by creating an acidic environment which will inhibit the growth of the microbes and it also maintains the integrity of the skin another chemical factor is lysozyme lysozyme is produced in lots of different types of secretions and its purpose is to break down peptidoglycan so peptidoglycan is found in the cell wall of bacterial cell walls and the purpose of the bacterial cell wall is to project from osmotic lysis so if the peptidoglycan is broken down then when the bacterium enters the human body bacteria tend to be hypertonic compared to the human body then most of the time those bacteria will lice by osmotic lysis saliva is technically a chemical factor and so it's technically a chemical factor because it contains the lysosome lysozyme so lysozyme and other secretions gastric juice is a really important one gastric juice is important because it has a very low pH so it has a very very low pH which will end up killing the bacteria when they get to the stomach urine also contains lysozyme lysozyme is found in urine and the vaginal secretions Bosch vaginal secretions tend to be acidic so remember acid is one of the ways to control microbial growth so several of your chemical factors sebum saliva gastric juice and vaginal secretions tend to be slightly acidic which discourages microbial growth as a review of the physical factors and chemical factors that help protect you from infection you have sebaceous glands sebaceous glands producing sebum to lower the pH of the skin and to maintain the integrity of the skin tears contain lysozyme which breaks down peptidoglycan but they are also involved in the washing process of the conjunctiva mucus is used to trap the microbes and in several different instances they are also involved mucus is involved in washing processes like in the ciliary escalator saliva again contains lysozyme so lysozyme again breaks down peptidoglycan but the saliva also is washing the microbes off of the teeth and into the stomach wacks earwax that is a type of sebum which is protecting you from infection in the ear again sebum has a low pH so creates a low pH on the skin cilia in the ciliary escalator is a washing process intact skin is important barrier sweat has lysozyme in it mucus again with a ciliary escalator stomach acid is really really important because you have several washing processes that end up flushing the microbes into the stomach where the stomach acid is very good at killing the microbes of course mucus in your digestive system and the enzymes in the mucus and you have urination which I talked about to flush the microbes out of the urethra to prevent UTI and defecation also can be considered part of that especially when you have food poisoning it facilitates diarrhea which increases the flushing out of the microbes the last part of your first line of defense is your normal flora so normal flora I've already talked about this several times how it protects you from infection by microbial antagonism so your normal flora is your permanent flora and it will out-compete transient flora so remember transient flora are the microbes that you pick up during the course of the day that you inhale that you ingest and your permanent flora is going to prevent that transient flora from causing disease so I've talked about your first line of defense first line of defense again is preventing infection so some of the types of tissues that cover the outer surface of your body skin and mucous membranes also chemical factors that your body secretes to prevent infect your normal microbiota performing microbial antagonism to prevent transient flora from causing infection and then again I added those washing processes if the microbes get past your first line of defense then it is up to your second line of defense to combat the infection your second line of defense involve things that occur inside your tissues so this will involve different types of white blood cells and different responses that occur inside the body in order to understand how your second line of defense functions you need to have a good understanding of the different parts of the immune system and how they interact so before I go into your second line of defense I'm going to give you an introduction to all the different parts and components of your immune system and how they function and those parts include lymphatic vessels and organs lymph nodes and the blood the lymphatic organs are not quite as important as the lymphatic vessels and the lymph nodes in the blood but I want to go through some of those lymphatic organs the first one that is really important is the red bone marrow so the red bone marrow this is found in mainly in the long bones and this is where the white blood cells are generated in the red bone marrow then another organ is the spleen so the spleen this is where you can find a lot of white blood cells the thymus is another one famous it's really important to know that the thymus is located over the heart so not the thyroid some people confuse the thymus and the thyroid thyroid is found in the neck the thymus is found laying over the heart and other lymphatic organs technically I guess they're called organs but we'll talk about them separately are the lymph nodes and the lymph nodes are all these little green dots that you see along the lymphatic vessels and so depending where they are they have different names like peyer's patches those are groups of lymph nodes tonsils technically our lymph nodes also the next thing I'm going to talk about are lymphatic vessels and I'm going to spend a lot more time on the lymphatic vessels and just with the overall diagram like lymphatic vessels are similar to blood vessels except when they draw them they always draw them in green but the lymphatic vessels are found everywhere you have blood vessels so they are throughout the body lymphatic vessels in terms of their structure they're very different from blood vessels the most important difference is that lymphatic vessels have an end so blood vessels do not have an end to they are interconnected the lymphatic vessels all have an end and they also have valves by which the liquid will enter into the lymphatic vessel in terms of the circulatory system lymphatic vessels are very important because what the lymphatic vessels do is at the capillary bed so this is a capillary bed this is where the blood flows from the arteriole it flows from the arteriole to the venule but in doing so at the capillary bed liquid is going to be forced into the tissues and that's where you get gas exchange nutrient exchange exchange with the tissues when that liquid returns to the circulation only about 90 percent of the liquid that was forced into the capillary bed is going to return that remaining 10 percent of fluid that does not naturally return is going to drain from the shoes into the lymphatic vessels and then eventually that will get returned to the circulatory system so that remaining 10% of fluid is going to drain from the tissues into the lymphatic vessels and eventually get returned to the circulatory system so eventually you get all a hundred percent of the fluid back into the circulatory system which is really important to maintain blood pressure you don't want to lose blood volume because that will reduce blood pressure and also it prevents a demon the tissues prevents the tissues from swelling this process of draining fluid from the tissues is going to be very important in protecting you from infection because as these lymphatic vessels are draining fluid from the tissues that fluid is going to be passed through a lymph node so in in the lymph node this is where you find many types of white blood cells so the lymph nodes are areas where white blood cells gather and remain so if you have microbes entering into the tissues they enter through a cut they get past your mucous membranes as the fluid is washed from the tissues into the lymphatic vessels get that to work into the lymphatic vessels those microbes will be carried to a lymph node where those microbes will be brought into the presence of white blood cells and the white blood cells will destroy the microbes so the lymphatic vessels by draining the fluid from your tissues they are able to drain some of the microbes that may have entered into your tissues and bring those microbes in contact with white blood cells which will destroy the microbes the last important component of your immune system is blood and blood has two parts blood has a liquid component called plasma and it has a solid component called the formed elements armed elements and both parts of blood are important for your immune system in the liquid part of the blood this is where you find nutrients dissolved nutrients dissolved gases dissolve waste products but you also find proteins and there are two proteins that you find in the plasma that are important for your immune system the first one you have heard about and those are antibodies and these are part of your third line of defense so we're not going to talk about them just yet but the other type of protein that you find in the plasma is called complement complement and complement this is part of your second line of defense so I will be talking about that in part two but you should remember that in your blood the plasma the liquid part of the blood has immune components proteins that are associated with your immune system the formed elements this comprises all the cells and the important part in terms of your immune system is this buffy coat here because that comprises all the white blood cells now I want to focus on the white blood cells and you should know that the white blood cells arise from the hematopoietic stem cells found in the bone marrow so those ourselves that are dividing constantly to produce all the formed elements of the blood so all the formed elements of the blood include the red blood cells that's the party of the formed elements the platelets which you should know are involved in blood clotting and then all of the white blood cells so now what I want to do is go through the different white types of white blood cells the technical name for white blood cells are leukocytes leuco means white site means cells so this is the technical term for white blood cells and white blood cells in general can be divided into two groups so you have the granule sites granule sites are called granule sites because they have granules in the cell membrane that you can see and there are three types neutrophils Isana fills and basophils and the second type are the a granule sites a means without because you don't see those granules in their cell cytoplasm and those are the monocytes and the lymphocytes first I'm going to go through the different types of granule sites so remember granule sites granule sites have granules in the cell membrane first the names neutrophils Isana fills and basophils this refers to the pH of the stain that stains the cells so neutrophils it's a neutral stain Isana fills this actually refers to acid so it's an acid stain and basophils a basic stain so that's just where the names come from neutrophils are a very important part of your second line of defense and neutrophils are found in the blood so these are neutrophils and this is a blood smear so these are the red blood cells and the neutrophils make up about 90% of the white blood cells circulating in your blood and their purpose is to phagocytose any microbes they come in contact with the only problem with the neutrophils is that once they phagocytose one microbe then they died so individually neutrophils are not very effective but because there are so many circulating in your blood they're a very strong force against infection when I was looking for pictures of neutrophils I came across this picture charge of the neutrophil so you have a little neutrophil here charging into the site of infection because that's what they do when you get a cut in your skin and microbes entered into the or enter into your skin the blood is going to bring many many neutrophils to that site of infection and those neutrophils are going to flood the area and phagocytose the microbes and destroy the microbes and this is very effective so when you have a breach in the skin or the mucous membranes the neutrophils are very effective at inhibiting infection killing the microbes because you have so many neutrophils charging in and phagocytosis the microbes basophils so basophils these basophils are also found in the blood but there aren't very many of them they make up about 1% of the white blood cells in the blood but their purpose is to release histamine so they will release histamine which will trigger inflammation so they do not directly destroy microbes but they trigger an inflammatory response which I will talk about next time the last type of a granule site are the asana fills and the asana fills also are found in the blood and again they make up a very low percentage again about one or two percent of the white blood cells in the blood and the job of the asana fills is to be anti-parasitic so these asana fills are specifically activated against eukaryotic microbes so the protozoa and the helminths that is there job the second group of white blood cells leukocytes are the agranulocytes a means without and these are the two types of cells where you do not see the granules in the cytoplasm so they don't have all those granules like the neutrophils basophils and asana fills and the two types are the monocytes and lymphocytes okay first monocytes monocytes are found in the blood so they are found circulating in the blood but what a monocyte is is an immature macrophage so the monocyte by itself can't do anything but once it leaves the blood and goes into the tissue then it becomes a macrophage so a macrophage in a macrophage like the name suggests macrophage macro is big phages eater these are cells that can phagocytose many many microbes so at the same time or subsequently and nothing happens to the macrophage so they are basically eating machines they can continue to ingest all sorts of cells so they're different than the neutrophils neutrophils are set phagocytic also but they can only ingest one and then they die macrophage that's their job is to go around phagocytose in all sorts of microbes and there are two types of macrophages first type are called wandering macrophages wandering and wandering macrophages are wandering through your tissues so these are macrophages that are crawling through your tissues looking for any cells that should not be there so it could be foreign cells like microbes it could be dead cells dying cells it could be cells that have a problem like they're infected with a virus or they're cancerous or it could be transplanted cells anything that should not be in your body the second type of macrophage are called fixed and fixed macrophages go into a tissue and they become fixed in one spot so they become part of that tissue so the fixed macrophages that when they move into a tissue they find one location and stay fixed in that location and often those macrophages then become part of that tissue and if you have studied Anatomy you have studied fixed macrophages they just have different names so in the liver you probably studied Cooper cells Cooper cells these are macrophages so they are white blood cells that moved into the liver and took a permanent residence in one area neurons if you've studied neurons and nervous tissue you have microglial cells microglia cells these are derived from macrophages in the skin you probably studied Langerhans cells so Langerhans cells these are derived from macrophages they are fixed macrophages and in the osteon the osteoclast is a macrophage so the purpose of the fixed macrophages are to remove things to break things down so they would remove any infection they remove dead or dying cells also so as a review for the leukocytes that we have been talking about so far we have the neutrophils Isana fills the basophils which i've mentioned and then the monocytes the last one I will mention now are the lymphocytes and lymphocytes the important thing about them is that they're part of your third line of defense so I'm not going to go through them in much detail now but where do you think they are found if they're called lymphocytes these are the white blood cells that you mainly find in the lymph nodes and the two types of lymphocytes are the B cells and the T cells so these are sparked part of your third line of defense your specific immune response so we'll talk about those in a lot more detail in chapter 17 but for your second line of defense the neutrophils Isana fills basophils and monocytes which are the macrophages these are really important for your second line of defense so as a review of your immune system which is defending you against infectious disease it has two parts your innate immune response and your adaptive immune response innate is also known as nonspecific adaptive immune response is specific today I've gone over your first line of defense so your first line of defense is how your body is structured different chemical factors your normal microbiota and all of that is to keep the microbes out to prevent infection second line of defense this is what I'm going to talk about in part two and this will involve some of those white blood cells I have introduced you to and how those white blood cells help facilitate responses such as inflammation and fever and I will also talk about complement and that's the antimicrobial substance one of them I will talk about your third line of defense this is chapter 17 so that will come up in a lot of detail when we go through that chapter