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Current time:0:00Total duration:14:35

Video transcript

we've all had cuts on our finger or wherever else on our body and immediately that part of the body that gets a little bit of redness a little bit of swelling a little bit of swelling some heat maybe some heat and of course there will be some pain associated with what's going on there and in general this the set of symptoms that we experience these are known as the inflammatory response or you might say that there's some inflammation going on there and people have known about this I guess ever since really people have been having cuts they've probably I think you're probably with modern medicine have people been a little bit more particular about actually classifying the symptoms but this isn't anything new for someone to say that there's some type of inflammation going on or some type of inflammatory response but what I want to do in this video is understand what's causing these I guess we call the macro symptoms what what's happening at a cellular level because really inflammatory response is essentially the initial field of battle of our immune system you know our first line of defense is our skin or our the fluids on the outside of our skin or the mucous membranes but the inflammatory response is what happens when something gets beyond that we get punctured with a nail or there's some type of virus or bacteria gets beyond our skin or our or the mucus that surrounds our membranes so let me the battle this is the field of battle field of battle especially the initial field of battle so let's set up let's set up a an immune battle so we can see exactly what's going on with the inflammatory response and I want to be very clear immunology people it's still a very under understood field it's an area of active research people are still discovering the mechanisms and it's hugely complex I'm sure we'll probably be studying this for a long time to come so what I'm going to talk about it's just the overview just so you know the general actors and you know in general what's causing the redness the swelling the heat and the pain so let me draw some skin cells so let's say that these are skin cells this is a gross oversimplification of everything but it's really just to give an idea of what is going on so I'm going to do a cross-section so those are some skills skin cells in there and then I'm going to so this is the outside world right here outside outside world and amongst those skin cells I'll do some other cells and we'll talk about what they do I won't go to huge detail about them let's call this cell right here let's call this a mast cell I'll draw a few more mast cells maybe another one right there that's a mast cell and if you remember from the videos on phagocytic action or phagocytes you remember there was one type called dendritic cells and they tend to hang out near our skin they kind of hang out near areas that might interface with the outside world so I'll draw a couple of dendritic cells and these were also the ones that were really good at activating so this is dendritic at activating helper T cells dendritic maybe I'll do one more dendritic cell right here right there that's a dendritic cell and they're called dendritic cells they have no relation to the nervous system they just look like they have dendrites on them and that's why they call them dendritic but they're really phagocytes and they tend to be near external interfaces and they they phagocytose particles and they're good at presenting them to helper t-cells so that they can get activated and ring the alarm bell so to speak so this is just a normal functioning happy skin so that's the outside over here this is the interstitial fluid interstitial fluid that's just a fancy word for the fluid that cells are kind of being surrounded by or that bathes cells you know the cells aren't all directly connected to the circulatory system the oxygen goes from the circulatory system to the interstitial fluid and eventually finds its way into cells so it's not you know everything is directly connected to capillaries but capillaries play a big role our circulatory system so let me draw that instead of just drawing them as tubes I'm actually going to draw the cells of our circulatory system so let's say that this down here these are the endothelial cells of our capillaries so these are literally the cells that make up the walls of our capillaries right there let's say that's one side and let me draw the side right here these are the actual cells and of course this is a cross-section if I were to you know I would draw it as a tube somehow this isn't it's not like it's a sandwich it's actually a tube obviously everything is in cross-section so these are endothelial and though the endo spelling is the hardest part endothelial capillary organize the capillary capillary endothelial cells and of course right in here this is what we have our we have our blood flowing and we'll have red blood cells in here maybe we'll draw a couple of red blood cells in here these are red blood cells maybe they're flowing in that direction on this side they're oxygenated this would be arteries and then they've become veins as the red bloods red blood cells lose their oxygen and of course you might have circulating white blood cells inside of your obviously a much lower quantity than your red blood cells but just to show that they're circulating and they're moving with your circulatory system being pumped by the heart now under normal circumstances there is an exchange of obviously of gases between what's going on in our circulatory system and the Institutional fluid and there's also a mild exchange of some cells and proteins but we're going to see now is what happens when we have an intruder so let's say someone takes and nail dips it in some cow manure and then pokes you with that nail so let me let's let's see what happens so this someone pokes pokes with them you know it's a big nail you know this is the cells are so let's say someone pokes you with this nail dipped in cow manure so it's got all sorts of nasty all sorts of nasty stuff on it pathogens on it probably has a bunch of bacteria sitting in the cow manure I didn't pick cow manure at random it's probably a good source of bacteria so as soon as it pierces the first line of defense as soon as it pierces your skin a couple of things are going to happen a lot of these bacteria are immediately going to start floating around in your interstitial fluid these the cells that it came in contact with it pierced them it probably killed some cells it's also going to damage some of these skin cells and those skin cells are immediately going to start releasing chuckles the ones that are still in a position to do so they're going to start releasing chemicals that are essentially chemical messengers that move through the well at first the locally in the institutional fluent says something is going on something has you know happened to me and these are called chemokines chemokines and chemokines are just a very general word really for small molecules or small proteins that cells release as a kind of signaling mechanism chemo for chemical kind for kinetic for moving these are these are messengers they move so these chemokines get released this is all tremendously complicated so I'm doing a you know very high-level there are many many types of chemokines and also you have these mast cells here these mast cells can be activated by direct contact maybe with the rusty nail it could be from the chemokines released by some of these cells up here it could be from some of the molecules released by the actual bacteria these bacteria are also releasing you know different byproducts as they enter the body and any of the above can it can activate the mast cells and mast cells release histamine histamine so the mast cells release histamine so I'll do that in that color histamine so you can already appreciate I'm doing a high level over unit already is kind of complicated but I think you get the sense of what's going on and if the word histamine sounds vaguely familiar it's probably because you've taken an antihistamine sometime probably in the last several months if you know especially during cold season histamine is what is kind of one of the main actors in the inflammatory response and when you have a cold and a runny nose and stuffy nose and all of those type of things those are all byproducts of the of the inflammatory response and antihistamines essentially try to shut down that and inflammatory response so some of those symptoms disappear but you know it begs the question of is that necessarily always a good thing because as I'm going to talk about in this video this is the first line of defense this is the first part of the battle of our immune system but anyway so the histamine one of the things that the histamine does is it goes to the endothelial cells that line your capillaries and it causes them to separate away from each other and and make the actual capillaries larger this is called vasodilation so let me let me erase it some of these and make them make them get larger and make the area let me make it the area larger so let me erase these let's say that histamine they've all been activated with a little bit of histamine and so let me go back okay so then the histamine has come in so now these guys get further apart they get further apart and the actual capillary becomes larger so there you go and then on this side it's also going to happen so this is where you get a lot of your swelling because all sudden the capillary is larger more fluid and actually it gets smaller further down so it really it encourages the fluid to collect right around here so this is called vasodilation just another fancy word for saying your capillaries are getting dilated they're getting larger fluid is filling them up and not only is thing are things starting to collect here more and more red blood cells are collecting here you know obviously there's a lot of fluid here that the white blood cells but also the capillary walls are becoming more porous all of a sudden things that couldn't get through them are going to have a much easier time getting through them and one of those things that are going to they're going to have an easier time getting through them and once again remember all this other stuff is going on you have these histamines that are you know being that are being dumped on these endothelial cells and maybe some of it's getting into the serum you have these chemokines you have these chemokines being released locally from this area of damage you have the the actual things being over the green was the color of the of the molecules being released by the viruses you have the chemokines which are in blue they're all being released here and your first law and so the first responders which we talked to the phagocytes and in particular the neutrophils which are the most abundant of the phagocytes a subclass of white blood cells they're attracted to these chemicals they're attracted they want to move in the direction that there's more of these chemicals and now that now that the the space between these ends these capillary cells have gotten further apart they can get through so what they actually do is let's say that this right here is a neutrophil this right here is a neutrophil they start kind of rolling along the wall right here that's called margin ization they roll along this wall and eventually you know so they kind of stick to the wall they adhered to the wall and then eventually they they squeeze through they squeeze through these gaps in the capillary wall this is called dyad esis or extravasation sometimes it's called emigration there's all fancy words but essentially it's just squeezing through the wall so that's the neutrophil right there and then of course because of the vasodilation this is where the neutrophils will be getting dumped in and this is exactly where they're needed so these neutrophils are going to be here and then they're going to do what they do they're going to phagocytose some of these bacteria and start eating up and maybe even some damaged cells up here and so that's what you want to happen that's why I said this is the field of battle at the same time your dendritic cells other phagocytes they will they will eat up the viruses and then they'll present them on their surfaces and it's not just neutrophils that are coming in because this is kind of an area of congestion and you're in your you know all of the fluid is coming here all you'll also have b-cells and t-cells they'll also make their way they'll also they'll also experience margin ization where they roll up against the sides of the capillary and then diet diet diet diet the dices or extravasation where they go through and then they'll be activated and they can actually do the specific immune system so so the whole point here is I wanted to show you and this is why I delayed the whole video on the inflammatory response because it isn't just some you know one type of simple thing it's actually the field of battle where all of the actors come and play even the first line of defense of your skin and then all of the actors the nonspecific reactions of you know inflammatory responses normally categorized is nonspecific because it's going to happen no matter what comes but that you have the nonspecific actors like the neutrophils you have your specific actors like your b-cells and t-cells and you also have the nonspecific complement system and I'm not going to go into detail here but you actually have proteins that are flowing in your blood plasma that are normally in an inactive state but when the inflammatory response occurs these proteins they get essentially activated and sometimes and this is all not 100% well understood they become activated they get cleaved up and then the cleaved up versions of those proteins are really good at in a very nonspecific way helping to helping to kill off at least some of what's getting you know maybe the bacteria in this case so this right here this is the complement system which is really just a set of proteins that always just floats around and they are good a kind of first line of nonspecific fight against some type of invading pathogen so hopefully this gives you a good sense of what is going on in the in the inflammatory response and as you can imagine you have all of this fluid coming here all of this blood is collecting here you have all of this fluid coming in too so yeah so not just cells that are going from our capillaries into our institutional fluid you'll actually have fluid going in and that fluid that's going in is called exudate exudate so this whole thing becomes swelling in red and engorged and that's why you see on kind of a very macro level these type of symptoms anyway hopefully you found that useful
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