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免疫反应的种类: 先天和获得性、体液免疫与细胞介导

先天免疫与获得性免疫。体液的获得性免疫与细胞介导的获得性免疫。 Sal Khan 创建




in the last video we talked a little bit about the immune system and in that video we focused on the nonspecific or the innate immune system so let me write that non specific nonspecific immune system and even in the nonspecific immune system we subdivided that into kind of the first line kind of barriers and those are things like the skin or the stomach acid or the the acidity of the oils on the outside of your skin these are just natural barriers to not allowing things inside of your body but then once they get in so you could almost imagine these were the first line first line of defense and then you had your second line of defense but these are still nonspecific and then we say nonspecific it means that they don't necessarily know what type of virus what type of protein what type of bacteria they just know that this thing looks Shady let me eat it up let me kill it let me have an inflammatory response so in there we said well there's an inflammatory response which I'm actually going to do I'm gonna talk about after we do video videos on the specific immune system you have your inflammatory response which really just gets things to where the action is at and then you also have your phagocytes phagocytes which are these things these cells that are engulfing things phagocytes and just so you know all the phagocytes that we talked about in the last video these are all instances of white blood cells or leukocytes so these are all infini I'll write that in white these phagocytes right here these are all you know when I talk about dendritic cells and and and macrophages and neutrophils these were all white blood cells these weren't all the kinds of white blood cells we're about to talk about more and sometimes the other word for white blood cell is also leukocyte leukocyte so that is nonspecific it just said well one it just doesn't let you win but then when you're in it says hey you're just shady I'm gonna eat you up I have receptors you have some double stranded DNA floating around only viruses have double strand DNA I'm gonna eat you up I don't know what type of virus you are I don't know if I've seen you before or not that's why it's nonspecific now the really interesting thing about our immune system and and and this is nonspecific this is this is kind of a this exists across many many many species and and and and and types of organisms but the specific the specific is kind of a we it's it's thought to be a newer adaptation what I'm going to talk about is the specific immune system that's particular to humans so you have the specific you have your specific immune system that's our other classification let me do it like let me do it like that so then you have your specific specific or you can imagine it's an adaptive immune system so and yeah I think you've you've probably heard of things like that oh I have I have a resistance to that that bacteria or that virus so this is adaptive and it's really all based on having exposure to things and I'm gonna and you know within within the specific immune system we talked a little some of when we talked about the antigen presenting molecules that the phagocytes do that plays a role in this we're gonna go into more detail but I don't want to confuse you but the main actors here called the lymphocytes not to be confused with leukocytes because they still are leukocytes so let me write this down lymphocytes so these are the main actors lymphocytes lymphocytes and I want I want you know these are specific phagocytes for the most part are nonspecific but both of these are white blood cells lymphocytes are another type of white blood cell or leukocyte I don't want to confuse you with you know this convoluted diagram but I just want to make the terminology clear when someone talks about a white blood cell they're really just talking about a set of cells that when people first tried to separate the components of blood you'd have your red blood cells that would kind of settle in the bottom then you'd have this layer of white frothy stuff in the middle that was really made of white blood cells and then on the top you had the fluid the plasma from your blood that kind of the watery part so that's where the name came from but they have different roles but they interact with each other now lymphocytes can be divided into B lymphocytes B lymphocytes usually referred to as b-cells and t-lymphocytes amazing you know where those words B&T t-lymphocytes and the B and T just come from where the develop B lymphocytes were first recognized in the in in the bursa of Fabricius that's what's called B that's actually a part of birds that participate in the immune system and so the bee came from Bursa but B also applies to the human immune system because it's produced in bone marrow so that might be an easier way to remember it's produced in bone marrow it's developed in bone marrow bone marrow but historically the B came from the bursa of Fabricius just in case you want to know but it's easy to remember that B could also stand for bone marrow because that's where it produced T lymphocytes actually do start off in the bone marrow but they mature and become what they what they are in the thymus so that's where the T comes from T for thymus now in this video I'm gonna focus just on the B lymphocytes because frankly if I focused on everything it would be an hour-long video but the B lymphocytes frankly on some level well I don't want to I don't want to pick and choose favorites but first something in my brain I just really like the B lymphocytes so the B lymphocytes participate in what's called the humoral response humoral and I'll tell you what humoral means in a second humoral doesn't mean it's funny humoral response humoral response and you'll see the T lymphocytes participate in what's called the cell mediated response so we're gonna do that in a future video cell mediated responses they actually do certain classes of T lymphocytes we'll see that their helper there our helper T cells and there they're cytotoxic T cells and it's all very confusing the first time you see it that's why I just want to focus on just this part right here we're gonna see in the future that the helper T cells play a role in amplifying and really activating this humoral response but a simple way to think about the difference between the humoral response and the cell mediated response is when I get infected let's say I get infected by a virus right let's say you know these are let's say that's my body cell and that's my body cell at first when a virus comes into my system it's just floating around and the fluids in my system and that when we're the fluids of our system that's really what humoral response to into the into the humoral fluids of your body so you have your viruses let me do it a different card color you know these are little viruses floating around so while they are floating around and they're not sitting inside of cells when they're not sitting inside of cells that's where the humoral response can come into play same thing if we have little bacteria floating around and they haven't infiltrated cells yet they're just floating around in the fluid then the humoral response will be it can be useful for that now if all of a sudden these guys have infiltrated cells if they've infiltrated cells so if the cells are now infected with the virus and they're producing the viruses using the mechanisms of the cell to produce more then all of a sudden we have to be a little bit more sophisticated and how we deal with these cells and how we deal with the viruses because they're not just gonna be floating around anymore we probably want to just kill the cell even though it was one of our own but now it's helping to make viruses or maybe it's been colonized by bacteria so in either case you want to kill this and that we'll talk more about that in the cell mediated