Immune cells | Introduction

[Music] welcome to this short lecture on immune cells this particular lecture will build upon the first lecture that we did with the overview of the immune system so if you haven't watched that one I encourage you to have a quick look so when we look at the immune system the immune cells of the immune system basically they will be broken into two functional groups those that partake in the innate response and those that partake in the adaptive response when we think about the innate response or the innate part of the immune system this is what we think or consider as the first line of defense to protect us against invasion and pathogens and antigens so this is an older evolved process so it's always there and it its response is going to be the same regardless of the invader whereas when we look at the adaptive immune system and particularly the adaptive immune cells this is a more recent evolved process and it's very specific to the type of pathogen or invader that is coming in to us now when we look at either one of these immune categories basically the function of the cells are to do a number of things one being in phagocytosis this is to eat things up two to swallow things that seem to be foreign or dangerous to produce inflammation or to modulate immune system to present antigens to kill or to or to kill cells that are either infected or team alike and finally to produce antibodies now let's go to the image here so this is a schematic image so it's quite busy at this point but I'll walk you through it so firstly in black on the outside is a bone so this is a schematic drawing of a bone and this is important for this is where our immune systems start around the bone in these red pipes so this is to indicate blood and blood vessels and then Phi the blue box is all the other extracellular tissue of your body down here we just have a small black box which refers to lymphoid tissue in your body specifically secondary lymphoid tissue which looks at certain things that are either encapsulated lymphoid tissue like your spleen or lymph nodes or non encapsulated lymph tissue like mucosal like lymph tissue so that's your diagram that's what we're going to work off so when we look at the your immune system or the immune cells of your immune system if we were in the embryo a lot of these cells originated either from the yolk sac or the liver but when we move to postnatally so as we become infants into children and adults all this and all your immune cells are made within bone marrow so this is why we've drawn a bone now predominantly this will happen in the red bone marrow so these are bones like your vertebrae your sternum your clavicle your ribs sometimes even to a degree in the long bones like your femur and tibia so the cell that makes all your immune cells is this one here that I've drawn which is what we call a hemopoietic stem cell now that particular stem cell there's thousands and millions within all your red marrow but this particular type will create all the immune cells specifically the ones we're going to do now now the division so the differentiation that they will divide into our two main types we have these green group here which is going down a myeloid like stem cell or a myeloid line whereas this one over here in blue is the lymphoid line now in many cases the blue so the lymphoid line will partake more in the adaptive immune system however the one exception being this one being the natural killer cell whereas the green the green cells will manifest and be partake in the innate response so there they're going to be more the innate first defense immune cells so let's start off with the green so this is the myeloid line and this is in no particular order firstly we have a response which we call phagocytosis so there are number of cells that partake in phagocytosis there are neutrophils as asano fuels and then it's as macrophages and monocytes so let's have a look at see how they form firstly in the myeloid line one group of macro fur or one group of phagocytes are going to go down what we call a mononuclear lineage so they've only got one kind of load nicholas and the first derivative is what we call a monocyte so the monocyte are actually a early precursor type phagocyte or macrophage like cell that really stays within blood and they partake in phagocytosis so eating certain extracellular pathogens for example within the blood now if the monocytes were to migrate out into the tissue of your body now sometimes this could just be in connective tissue or certain other types of extracellular tissue but sometimes they are specific to certain locations like in your lungs where you can have a viola macrophages sometimes in your kidneys which are mesangial cells or sometimes in your liver which we call kufta cells but they essentially are still macrophages and they play an important role in digesting and eating things that aren't supposed to be in that tissue such as bacteria or disease cells now some macrophages will actually move into lymphoid tissue such as the spleen or lymph nodes and they also partake in certain roles within they're not only phagocyte phagocytosis but they also become antigen presenting cells now just as a point here that I need to just make I will go into depth on separate videos on each one of these cell types so I'm not go into too much depth with these today this is more of a broad overview so these macrophages can also be in lymphoid tissue to be antigen presenting cells so that's one lineage from the myeloid line another lineage is what we call the Marcel so the Marcel granulocytes so they had preformed granules in them and these actually as immature precursors migrated out of the bone into the blood and then finally they come into the tissue where they mature and ultimately differentiate in them they have preformed granules in most cases they're going to be histamines and heparin and they are very important for initiating and modulating the inflammatory response so these guys can be located in connective tissues such as just under your skin around your blood vessels in your mucosa such as in your gut or in your bronchioles and these are some common areas where if these marcelles do granulate they're going to cause inflammation in that area such as hay fever such as vasculitis or dermatitis another line of the my Lloyd's go down a path that we call a megakaryocyte and then they this big large cell as it moves into the blood breaks into finer cells which we call platelets and the platelets also help with modulating the inflammatory response but they also have a role in clotting so they also have that effect in the immune system now finally this group of cells which kind of differentiate from the myeloid line comes under the banner of p.m. n which is poly Morpho Nicola granulocytes which means they appear to have multiple kind of nuclei just through the lobes which is just different to these mononuclear ones in the monocytes and macrophages so they look like to have multiple nuclei in their cytoplasm but they also have preformed granules within them so there are also granulocytes like we saw in the marcelles however there's some differences here well one of them is the neutrophil and the sauna fuel also phagocytes so they do play a role in eating things up like we saw with a macrophage the neutrophil which comes off this line they are the most abundant white cell and they are very important in the early phases of inflammation and injury so they're the most abundant white cell and as I said they have a strong role within phagocytosis another one is asana fuels so asana fuels the next abundant cells are about 2 to 5 percent of white blood cells from this lineage asana fuels so they do also have a phagocytic function and they seem to also have a an effect with parasites so that's one role they do have finally the least abundant white blood cell is your baser fill and this one doesn't do any phagocytosis but it does have preformed granules in it which seem to have a role within allergic responses but it's important to note that these three cells only remain within the blood so that is the all the lineages that are coming from the myeloid line coming across to the blue we've got the lymphoid line as I said earlier one early division that comes out is the natural killer cell so these particular cells generally will stay within the blood but one of their role too to partake in is to kill off damaged or infected cells so if you have intracellular infected cells like virus cells these will do the killing also important for the destruction of cancer cells so any kind of cell that seems to be dysfunctional the natural killer cells have a strong role in it's important to note that this branch is actually part of the innate immune response which is similar to what we saw over here finally we move to the last type of cell that comes down at the lympho with lymphoblastic line and this is the B and T's cell lymphocytes now the reason why they named that is because where they maturer in the primary lymphoid tissue the b-cells will primarily mature or mature in the primary lymphoid tissue of the bone and that's why they could be whereas these group they actually mature in the primary lymphoid tissue of the thymus and that's why they called T specifically these cells are important for the production of antibodies and T cells a cell mediated response so they're a very specific type of response to the antigen that is being responded against to two main divisions being the helper cells and then cytotoxic T cells but a lot of those will go into the blood and then that both of them B's and T's will migrate to the secondary lymphoid tissue as we can see here with the L and they seem to have their specific differentiation in that tissue so when they are respond once they have responded to their specific antigen that's where their final level of differentiation occurs another final cells just to be mindful of is what we call dendritic cells and these cells come from actually both lineages and their job primarily within the lymphoid tissue is to phagocytose foreign material and then antigen and present it to in most cases the T cells and so these two group of cells we've already spoken about macrophages but also the dendritic cells are the antigen presenting cells and so that is essentially all the different cell types within your immune system we've seen that there's two main divisions being the myeloid line and lymphoid line mostly on this side they're taking the part taking the role of the innate system whereas most of this is in the adaptive system but it's important to note that they will work together to do things like phagocytosis inflammation antigen presenting presentation to kill infected cells or cancer cells and to produce antibodies which are important for memory as well so that's the immune cells we're going to move on to the subsequent videos which will focus on each subtype

Channel: Dr Matt & Dr Mike

Views: 13,997

Keywords: Immune system, Immune cells, White blood cells, Neutrophils, Macrophages, Monocytes, Lymphocytes, Myloblasts

Id: Q8YeuicRNxc

Length: 13min 28sec (808 seconds)

Published: Fri Mar 20 2020