Chapter 21 Part 1 — Lymphatic System

welcome back to lecture this is chapter 21 part 1 we're gonna do this in two parts we're gonna do the lymphatic system first and then part two of chapter 21 will be the immune system so chapter 21 part 1 lymphatic system this is a series of tubes kind of like the vessels in the previous chapter except they're going to be picking up the leaked out three liters from the capillaries and the venules and returning it back to the venous system but in addition to that job the lymphatic system also takes that fluid that it's picking back up and cleans it it sends it through some lymph nodes and depending on where you're at you will also have the same kinds of white blood cells that are found in lymph nodes in other locations that need a higher amount of protection so the back of your pharynx where you swallow and you have the back of your nose you will have four groups of tonsils the paletine lingual and pharyngeal tonsils and the tubal tonsils the adenoids is the other name of the Ferengi Ilan CIL's and you can't see those by the way they're in the nasal pharynx up out of you some of you might be able to see the lingual tonsils and everybody can pretty much see the Palatine tonsils if you still have them the thymus is going to be an interesting organ that's only there temporarily while you're very young helping to Train T lymphocytes the spleen is going to act kind of like a lymph node but for blood so the lymph nodes will purify the lymph fluid that it picks up from the interstitial spaces but the spleen will have a splenic artery that takes blood into it and it'll help get rid of old dead dying and red blood cells and recycle them kind of like the spleen in the bone marrow and send it back again and then there's going to be places in our digestive system towards the end of it what I call peyer's patches that will help to make sure that anything that got that far down in the digestive system doesn't breach the wall so it's a combination of many different things the lymphatic system so here we can see that all the tonsils are oriented around the the nasal and the oral pharynx here's the location of the organ the thymus once again its its most active during your youth I'm talk about the spleen all of these are technically peyer's patches but the appendix is just kind of a special place that typically is more problematic when it comes to getting plugged up and getting inflamed which is why you have to have an appendectomy so this is kind of the basic overview so let's start with the lymphatic vessels that are going to be picking up that 3 liters of leaked out fluid in the interstitial spaces every day as blood circulates and it's bringing nutrients to the various cells and picking up waste products that are going to be heading towards the kidneys and the lungs and so on in exchanging gases of course some of that liquidy component of the blood is going to leak out at the capillary level and at the venule level and as that happens and once again the reason it's leaking is because you have a blood pressure and blood pressure is a hydrostatic force what's keeping you from leaking more than 3 liters is the colloids the proteins that are in your bloodstream kind of pulling some of that fluid to stay inside of the capillary bed but you are going to leak some stuff out it's that fluid that needs to be returned back to the venous system every day here's the basic layout so the heart's pumping blood you get the leakage the capillaries will of the lymphatic capillaries will pick that up it will shuttle it through a bunch of lymph nodes and merge together to dump back into the venous system oh and I'll show you exactly where that happens in a bit these capillaries that are picking up the leaked out fluid they're actually blind ended tubes and they're more meandering more branching more anastomosis than your capillary beds and they're more generous as to what can get inside of them so let's take a look here so the 3 liters very important to know that number is going to form air head to toe into the interstitial space and the lymphatic capillaries will pick that up they're gonna pick it up by basically bulk flow so there will be more entering that and that will cause these vessels to kind of bend their cells a little bit and that'll allow some fluid to kind of work its way in by the way the word limp means clear water and if you were to look at this stuff like you got a sample of it it's gonna look you know like water it doesn't look really like much of anything at all that means that there's no red blood cells in there there can however be any number of other things it could be white blood cells there can be obviously ions and nutrients and waste products cancer cells can get into these things from time to time the top cancers actually spread from location to location is through the lymphatic system and these are going to encourage one-way flow back towards the venous system right before the heart and then of course you can see here they're blind into little capillaries you do not need them where you have sinusoidal capillaries so all of these locations have sinusoidal capillaries so you don't need those they're absalom marrow bones of any kind really in teeth ever included are not going to have that the brain and the spinal cord remember these have continuous capillaries and those are at without intracellular class so when you look at how cerebral spinal fluid is formed it does start from a vessel circulate around a CSF and go back to a vessel but it don't contain flow system so you don't need lymphatics there as well so these are the two big categories we don't find them here's just kind of a close-up so there would be this little some collagen fibers here that'll anchor down one part of the cell the other part of the cell won't have it so this part can kind of bend inward a little bit like this and that can allow the lymphatic fluid to go for the interstitial space to inside of the vessel itself so lots of things can get in them you can like I said you can get any number of nutrients typically proteins in the interstitial space especially the bigger ones are unable to enter but cancer cells can move around white blood cells can move around so they can crawl in on their own tiny little things like bacteria and viruses surely can get in and little chunks of dead cells they can get in as well the more inflamed an area is the more accommodating and the bigger the openings of these lymphatic vessels and capillaries are so they'll take up even more stuff the pathogens can obviously use these to spread so if bacteria got into the lymphatic vessels they can spread the infection assuming the white blood cells can't handle it this is also once again how cancers can spread from say like a skin cancer location to a system-wide and spread it to your brain or your liver throughout your body there are some special areas in the body when it comes to the lymphatic system and one of them is in the GI tract here the lymphatic fluid is not clear it's actually milky white and we call it Kylie instead of just blimp fluid and it's in a special area called lacteal so lacteal like lactate obviously referring to the milk that is released from lactation the stuff here is obviously milky white why is it milky white is because it's how your digestive system gets fats absorbed that's obviously like oils and fats they don't mix well with water so they don't go into capillaries very easily so you'll see this in the digestive system coming up but the fats will be surrounded by a bunch of little molecules that are kind of like the molecules you see on the cell membrane and that big giant molecule will then work its way into a lacteal because it's just too dang big to go into a regular fenestrated capillaries and the GI system are finist rated they're that middle sized holed capillary so this these have to go into something that's a little bit more accommodating which is why they have that milky white appearance lymphatics capillaries will merge together so there'll be you know tens of millions of these things they'll merge into these larger collecting vessels that's where you'll see a lot of the lymph nodes and then they'll merge into exactly nine trunks and two dumps the two ducts are right here so we got the right lymphatic duct and the thoracic duct they don't call it the left lymphatic duct they call it the thoracic duct because it's so big and it runs right through your chest so these nine will be divided up into these two exits these two dump into the venous system and I'll show you where that is in a second so if you look at the collecting vessels they pretty much look like just crazy veins they have the same three tunics Tunica intima media and externa they have just really really thin walls they have many many more vowels or there's more merging that's going on and in general if you look at the lymphatics in your arms and legs they're really close to the skin but that's flipped when you actually look for them in the the torso if you're looking your chest abdomen and pelvis they run really deep next to the bones and the artery so you can't see them and the that distribution is extremely variable by the way these because the numbers are so few these have names I mean after all I mean I got two of the names right here these don't have names are two highly variable there's just too many of them so what are the nine lymphatic trunks well we have two for the lumbar region these will go down to your legs so that's kind of easy to remember we got two that are going to drain your chest that's why we call it Bronco mediastinal so basically your left lung and your right lung they're gonna be training there's two that are going to be draining each of your arms or your upper extremities so those are subclavian's remember your clavicles are kind of right this is part of your shoulder so that helps you to remember they're going to be joining your arms we also have jugulars which are going to be doing each side of your head and neck so if you have an infected left ear it's going to drain down into the left jugular trunk if you have an infected left arm it's gonna drain the the infection down into the left subclavian trunk same thing with any of these others the only one we have a single one of is the intestinal trunk and it's picking up your dietary fats and anything else that got kind of into the interstitial space and not into a capillary so how do we take nine and divide it into two locations so obviously somebody's going to get more it's not 5 4 it's actually 6 3 so you'll see that the right lymphatic duct is going to do just three things it's gonna do the right arm to the right entire upper extremity the right side of the chest and the right head and neck that's it the thoracic duct does everything else so if you memorize this one then it's really easy to kind of figure out what the thoracic duct actually does the also that intestinal trunk has a big dilated area where a lot of the little capillaries are kind of dumping into it that one is called the cisterna chyli it is picking up not only lymphatic fluid from the digestive system but from the the legs as well so you get the lumbar is dumping into it and the intestinal trunk look at the name cisterna that just means container like a cistern Kiley tells you what's in it that milky white stuff from the fat of your diet so so it's the container with the milky white stuff so it's basically like a jug of milk down in the lower part of your abdomen let's take a look at where we're altom utley dumping back into the venous system we're going to take the lymphatics and we're gonna dump into the junction of the internal jugular so here's the internal jugular coming down and the subclavian coming over like this so here's the subclavian coming this way and then here's the was called the brachiocephalic truck and so the blood is flowing in this direction and right there and so here's the heart so here's the right atrium down in there so we've got superior vena cava so the SVC here's the other brachiocephalic trunk here's the other internal jugular here's the other subclavian and then here is the thoracic duct so I got thoracic duct here you got the right lymphatic duct over there and they're dumping into this very large set of vessels at their bifurcation point so it's kind of like a four-way intersection except that you know we got three ways into this brachiocephalic trunk now any kind of activities going to increase return into these locations and is very important that especially substances like the Kylee from your digestive system of the fats is dumping into a location like this because we have a large bulk of volume of blood going through here so it'll circulate well this is actually the same clinical location that central lines go so if you put a central line and the subclavian it goes down to the superior vena cava or you put it in an internal jugular line in it goes down to the same place and those you can draw blood out of you can put in really thick you know IV fluids things that are basically digested food as because you're doing that's the same basic place you also do it under normal circumstances so if you see a subclavian or an IJ line in keep in mind your body has a natural connection there for the right lymphatic duct and the thoracic duct as well so here's so this is we're gonna do a close-up there here's that cisterna chyli that you can see and then of course you got your lumbar trunks coming in you got your Bronco mediastinal x' coming in your subclavian's coming in your two jugulars coming in so you got one two three four five six seven eight and then basically nine the intestinal trunk is kind of right in there so this is just kind of a nice close-up so it just once again there's your internal jugular there's just a play vien and then there is your right lymphatic duct so and then there's your two brachiocephalic veins and then your superior vena cava right there so you can see nice to dump this thick fluid into a place with a large volume of blood to mix it with the lymphatic system lacks an organ to pump it it doesn't have its own heart the lymphatic fluid can very easily go backwards and so there's a lot of helps to get it to go to the correct direction there's obviously the when you move the skeletal muscle of your arms and your legs it kind of squeezes it back towards your heart as you breathe those Branka mediastinal vessels will kind of squeeze also towards their exit as well the obviously the big thing just like veins is the valves are very important if you're one of the lymphatics that are deep inside the torso the abdomen or the pelvis you can even the pulsation of nearby arteries to help out and then once again their vessels so they have smooth muscle in their walls it just you know once again it's not going to be as awesome as you think it is the lymphatic transport is very sporadic and very slow I mean it is very very sluggish but you got 24 hours to get three liters back and so every day you accomplish that little goal and then you have to start all over again every single day any kind of physical activity will increase blood flow so if you have a cut and this really honestly only works for cuts on like arms and legs close to the hand or the foot you might want to make sure that until you get to the doctor and you can get on antibiotics you don't move that limb around very much because the more you move it around the more the skeletal muscles squeeze on those lymphatic vessels and encourage the flow of blood sorry the flow of the lymphatic fluid back to the blood stream the last thing you want is to bacteria to have bacteria if I'm a cut on your hand to get into the lymphatic fluid and then be dumped by save the thoracic duct or the right lymphatic duct right into the blood stream right before your heart so that's how you can go from an infection in your hand to full-blown sepsis and sepsis is a blood infection so you look for problems like lymphangitis lymphangitis really honestly you can only notice it on the arms and the legs so let's take a look at the upper and the lower extremities and the reason for this is is the lymphatics wrap around and run with the veins and venules that are in your upper and lower extremities so they're really really visible so if the vein is irritated the lymphatics are definitely picking something up and so that's what you see here so here's an armpit the hand would be way over here so this person had like a bad IV and you can see the infection is spreading in fact a lot of times in the hospital you'll see the like say the nursing or one of the doctors will have outlined the infected area with and then they'll put their initials and the date on it like that and then they'll come back later they'll put the time too so a little bit like noon and then they can come back later and say oh you know that you know now it's like up into here or now it's up into here this is obviously ominous and you need to make sure the antibiotics are the right ones in definitely working because as soon as this infection gets into the circulation right in front of the heart this person can get sick really really quick and sepsis can lead to many problems including death so lymphedema if you can't get the fluid back it just stays there it just stays in the interstitial space so any kind of swollen arm or leg is really easy to kind of notice lymphedema and it's a lot of times that's due to one of these two things it's usually due to you have some sort of surgery or injury where the lymphatics were destroyed or removed or you got something that's squeezing or pressing on the vessels themselves a tuber could do it but it could just be tight clothing I mean it there's a number of styles that would be too tight to prevent not only the venous blood from returning but lymphatic fluid as well over time the fluid just backs up in the you know you get edema so whenever you hear the word edema and for those of you who are from Europe yes he does have an O in front of it if you really wish to but you'll see me just write it this way but I was trained by some Brits and so I got I'll still have the habit of writing edema with an O but here you can see somebody who had bilateral mastectomies and the breasts are gone which means they had to take out the lymphatics for the subclavian trunks over there and so this person has mass of edema so how do they get this out of their arms they put on one of these things like this that are made for like the arms they're called sequential compression devices and so what they'll do is they'll squeeze here first hold the pressure squeeze at the ankle hold the pressure squeeze here at the like the mid-calf and then the knee and then and then the thigh and then the whole thing will deflate and then it'll start all over again and so it'll basically squeeze the the interstitial fluid back up the lymphatics are the main way to get fluid back but the interstitial spaces are all basically connected throughout your entire body so all you got to do is hand or machine massage this liquid out but you have to do it every day multiple times a day just to kind of keep up with it the problem is is when this fluid accumulates this massive amount of edema is the blood flow to other parts of that extremity starts a lesson so notice there is no hair on these legs it's not because they shaved it it's probably because especially this one because of the poor circulation same thing with this arm over here for sure and this can lead to what we call venous stasis ulcers where the blood flow is so slow any kind of NIC or cut just get too out of control and you get these nasty nasty wounds now as you go into those vessels there's going to be cells in them that are part of the immune system that are going to inspect it and make sure it's sterile if it's not sterile or there's a cancer cell or bacteria virus fungus whatever they will start the inflammatory response one type of cell is the phagocyte Faygo means eat site just means cell so and these are big eaters and these neutrophils and macrophages remember macrophages or monocytes that have left circulation and gone into the tissues and so they've become those these tend to live a long time these tend to die pretty quickly and so but they're all graded eating and initiating the inflammatory response and we'll go over more details of how that works in a bit the lymphocytes also part of the immune system they're going to contribute to things like making antibodies so but anyway they're all there and they're all important the lymphocytes are going to be these really critical main warriors in the immune system they're basically helping to recognize self versus not self and so once they've recognized something is not self the B cells or B lymphocytes especially their offshoot called plasma cells they're gonna make antibodies that's the thing we're going to talk about in a minute that looks like the letter Y that has unique three-dimensional ends on the end of it those unique three-dimensional ends will perceive anything that's foreign like bacteria or viruses or the roam blood or cancer cells or any foreign material and stick these little antibodies to them and then other cells like macrophages and neutrophils will come along recognize the tagged item and eat it and so and then they'll present little chunks of it to other cells in the immune system it's basically the big overview of how the immune system cells work they are they are all created in the factories the bone marrow the liver of the spleen but they have to get their training either in the bone marrow or the thymus so the b-cells get their training in the bone marrow the t-cells obviously in the thymus don't confuse thymus with thyroid thyroids in your neck thymus is like a little hat sitting on top of your heart so the t-cells they're going to once again also participate in this recognition of self versus not self some of them can directly attack and destroy any kind of target but a lot of them are also important in making other chemicals that attract cells like B cells macrophages and neutrophils to the area like I just showed you on the previous slide these are gonna make plasma cells which make antibodies antibodies are like little red flags except they're shaped like the letter Y and they're good at sticking to things that are abnormal no matter what it is and marking it for phagocytic destruction or just taking it out of solution there's a lot of ways that antibodies work so macrophages I've already kind of spoiled that for you those were the monocytes in circulation so they've just left a blood stream you'll find them in the interstitial space and lymphatic tissues and they're just gobble gobble gobble all the time like a pacman when they eat something they break off little pieces of it and then they show other cells like your T lymphocytes a I hate this thing it's cool and then the t-cell says okay I'll trigger other cells to come here because you probably need help and there might be more of them around dendritic cells are cells that have spiny extensions so if you look at the the Langerhans cell that's in the stratum spinosum of the skin it has these big crazy extensions because you don't know where the bacteria is going to show up it might come over here over here so they stretch out and basically can cover a wide range of territory and then of course you need a way for these cells to move around it does you no good to have a car if you don't have a road and so these cells use reticular fibers to crawl around and so the reticular cells will produce a lot of these fibers and they'll basically kind of act like the little branches in a sticker bush for these cells to crawl around like a bunch of spiders and that's what you see here so here you can see the blue sticker bush and then you can see various lymphocytes crawling around and here's a macrophage eating some sort of target so that's pretty much it that's what a lymph node or a spleen looks like on the inside of it it's a lot of these reticular fibers and white blood cells and their targets that they're consuming the lymphoid tissue is going to not only provide a place for these lymphocytes B cells and T cells to be but you'll also see a lot of these cells reproducing especially after they've recognized something that is not so so you'll notice that the lymphoid tissues are always in places where we have routine problems with sterility so there are places where bacteria viruses fungi you know parasites cancer cells damaged cells show up on a regular basis so you know that's why this whole chapter kind of has a similar theme and then of course the reticular fibers help these cells to crawl around the only place you don't find reticular fibers is the thymus the family says a lot of exceptions they don't follow the basic patterns that we see everywhere else basically just think of the thymus at school for t-cells and that's it and you'll be good so let's take a look at the lymph nodes along the way as you go through the lymphatic system you're gonna run into a lymph node there's hundreds of them but they tend to cluster in regions regions like your groin that's the inguinal region your armpits the axillary region or the front and back of your neck the cervical region but there's other ones so there's no little ones although you can find a couple in your elbow and in your knee you don't find them in your wrist or your ankles or your feet or your hands they tend to be more proximally located what they do is they take in dirty lymphatic fluid check it inspect it send it out the other end so they're acting as a filter and if there's anything bad in there anything that's not self they'll present those chunks whatever it happens to be to the immune system and there's lots of cells there to accommodate that the cells us are the little lymph nodes themselves are being shaped so they're you know they're kind of like this they have a lot of ways in but they have a couple ways out here so this is going to really dramatically slow the flow of the fluid down as the lymphatic fluid comes in it has to go around these big piles of typically as B lymphocytes and so as they go around the piles they're going to go into this little space where they can actually floo and this is you know going to eventually lead to the middle of the lymph node or there's even more piles for the fluid to kind of negotiate so it's going to be kind of like a maze of B cells that the fluid has to flow around but once again a maze is going to slow things down and allow time for inspection the lymph nodes are going to be loaded with reticular loose connective tissues that the cells are just kind of hanging out on as this lymphatic fluid flows past them so if you look at the outside of a lymph node and once again I'm just going to kind of talk about all of this and all of this on slide 33 and 32 on this picture so you got many ways in alright as you go in you have to go around so here is one of those germinal lymphoid follicles with the germinal Center so this is a big pile of B lymphocytes you know there could be other cells in there but it's primarily B lymphocytes that are multiplying and dividing so a lot of times you'll hear the phrase lymphoid follicle with a germinal Center when we get to the tonsil you'll see the same thing it'll be a lymphoid follicle with the germinal Center any of the peyer's patches in the digestive system will look at lymphoid follicle with the germinal Center if we see other like say mucosa associated lymphoid tissues that are lining the trachea you know or the other parts of the digestive system those are also lymphoid follicles with a germinal Center the only place you don't see this kind of stuff is in the thymus so these are pretty common even tonsils will have these big piles of B lymphocytes where you got to go around it and so that's what the lymphatic fluid does it goes around it following the sub capsule or sinus so that's what this little space is right here to go around the sub capsule or sinus and then you get into the middle so this this is the medullary region this outer region is to cortex and in the medullary region you have walls of same stuff b-lymphocytes it's just it's arranged instead of in these piles like a germinal center it's like little maze walls so let's kind of exaggerate this a little bit and so as the fluid comes in I'm gonna have to switch colors new green the fluid has to go around this stuff and then eventually find its way to the exit so the fluid is flowing once again in a space the medullary sinuses a space the sub capsular sinuses a space the afferent and efferent vessels are also tubes which obviously have lumens or spaces inside of them those are the locations the lymphatic fluid is going the medullary cords and the lymphoid follicles with the germinal centers those are physical clumps of cells the fluid has to flow around and of course the whole point is right here because there's fewer ways in sorry if you're always out then in and all of these little mazes to kind of negotiate everything slows down and allows for good proper inspection so what happens when a lymph node gets like a whopping load of infectious material well it can swell up if it swells up very very quickly it'll be tender there's a capsule around your lymph node that has a lot of nerve endings in it and if it swells fast it hurts anything in your body honestly the swells fast will always hurt if you ever had really bad gas pains and it is actually technically worse than like say getting step so I guess the only way I can kind of think of this is if you had like a really really bad bout of gas cramps and compared that to like say a bellybutton piercing the bellybutton piercing only hurt for that really brief moment the the piercing was occurring and then after that the pain went away it's like having a chance to burp or you know fart and you can get rid of the gas and then the pain goes down immensely any kind of stretching is always very very tender on the body these are infected lymph nodes they have a name they're called buboes this is tied in historically to the name disease where they were commonly noticed when they were infected called the bubonic plague the reason the bubonic plague also has the nickname the Black Death is when you swallow up a lymph node really really quickly boom it can pop and if it pops of course it bleeds and clotted blood looks black so these all kind of go together if you swell the lymph node very slowly maybe there is a chronic infected area or maybe the person has a slowly developing cancer that's trying to spread then you might have a non tender lymph node and that's it is a potential sign of cancer but don't think that every non tender lymph node means you got cancer you could just have had like say so many ear infections as a kid you scarred up the lymph node on one side of your neck and it's just kind of stuck in a large non tender state so you know slow repeated infections can also lead to non tender swollen lymph nodes as well so this guy says that you know these things don't hurt but they're really lumpy and in my armpits but this is almost guarantee you that's cancer this kid maybe they had a really bad ear infection of the ears here the drainage would work its way down through the cervical chain of lymph nodes and then one of them that's close to the surface of the skin might be easily noticed this obviously the lymph node ruptured due to an infection with your seniya pestis the bacteria that causes plague the spleen kind of like a lymph node it takes in a dirty product turned and releases a clean product it has one way in so this is how you get in this is how you get out as you take in the dirty oxygenated blood some of the cells in that blood will be broken down they might be all of they might be you know you know run out of their lifespan and then they'll be destroyed and recycled and then the venous blood will be of course deoxygenated and much cleaner so this is cleaned up as dirty obviously this is oxygenated and this is deoxygenated it's here so where do you find the spleen is in the left upper quadrant right up underneath the diaphragm and behind the stomach so under the diaphragm but behind the stomach it is small enough to usually be completely protected by all your ribs but if you have splenomegaly which is an enlarged spleen it can actually poke out underneath your ribcage on the left side this place where all the vessels come and go is called the splenic hilum so the spleen takes in the dirty blood and it sends the blood down these tiny little central arterioles and as it goes down the central arterioles it goes into capillaries but these little branches of arterioles are completely surrounded by white blood cells and then once again they're doing what you saw just in the lymph node they're doing immune surveillance and response this is why the spleen is called the graveyard of old red blood cells because one of its main jobs is removing defective and old red blood cells and platelets as well as doing what even a lymph node does removing debris in any format or remember lymph nodes almost always never have any red blood cells going through them so the spleen is obviously playing a big important role here if you lose your spleen never fear you have a liver and bone marrow that can do the exact same jobs that you see listed here interestingly the spleen during your fetal time is actually producing lots of red blood cells but then again the spleen like the liver and the bone marrow is also capable of producing red blood cells white blood cells and platelets and one of the things that can also do is store extra platelets the structure kind of like a left out it has a capsule which means yes if you swallow it really quickly and have splenomegaly like say after a bad case of mononucleosis and yeah it's going to hurt a little bit but as the our arteries are flowing through the spleen and breaking but those tiny little arterioles they're gonna be surrounded by white blood cells and these white blood cells they're going to when you slice the kidney and look at it they're going to have a white appearance now this white appearance is on a raw spleen it's not on a prepared slide or anything like that although you can choose stains that will mimic the raw appearance but the raw appearance of the white pulp and the red pulp is due once again to looking at a raw spleen so and they're a TBD these white pulps are pretty small but they're scattered all over the place like a bunch of white polka dots the spleen once again if you slice this right here you know and you look at the slide coming up you'll see what I'm talking about but you can see the central artery coming down and then it's just surrounded by a bunch of white blood cells here so here is wasn't the very next slide it's that's like alright so here you can see the diaphragm here you can see a spleen this will be the splenic hilum where the here's the the artery coming in and the veins underneath it coming out the stomach was removed so you can actually see it so this this is what it looks like this is not very magnified I don't have the mag on here that's at a hundred this is at 400 x over here but you can see this whole thing that's what white pulp is and if you look in the middle of it you'll see a couple of these little central arteries and that's the artery right there and you can see this is the dirty oxygenated blood coming in some of this will leave eventually when it gets to little capillaries the white blood cells excuse me and the the white pulp will inspect it cleared out and then it'll move out here so eventually everything ends up in the red pulp and then the red pulp is where the veins start remember the sorry the capillaries and the veins are down in here the it'll pick it back up and then I return it by the splenic vein to the rest of the body now the spleen is interesting in that it can be removed and you can live just fine without it it give me you can be born without one that would be a congenital absence of it and of course if it's removed or you're born without at the liver and the bone marrow like I've been saying many times can assume it's functions historically this is primarily started to change around the Korean War and Vietnam as more and more ruptured spleen were coming into the or during those Wars surgeons a lot of times it would just kind of have to give it a chance to heal on its own so the old removal rate was upwards of 70% but over time especially by the time we got to the mid to late 70s the removal rate had dropped quite a bit and that's just because of through trial and error surgeons realized the spleen kind of like the liver has the ability to regenerate and repair itself especially if you're quite young here's a spleen that had to be removed you'll see that you know obviously very jagged opening and of course it's a very bloody organ moving on to the thymus the thymus is an organ that sits on the top of your heart kind of like a little hat it's got two little lobes to it so it's got a right and a left lobe and it's going to be one of these temporary organs that primarily is doing its work while you're a child in fact wha you're a very little child and we're talking around the age of like say you know a year younger it can be quite big in fact it can be even wider than the thymic than the heart itself so I can cast what we call a thymic shadow on a child's chest x-ray so you'll see that on the slide coming up the thymus makes hormones time oppo Aten and time assim and once again this is school for T cells T cells are learning their job becoming immunocompetent at this location so it's got a little bit different organization its cortex and medulla has you know obviously a lot of the t-cells doing their schooling and the cortex the t-cells are rapidly dividing and in the medulla in the center of the thymus lobes you'll see these areas that look kind of weird they have kind of this pink swirly look and that's what's called a PHY McCrory hassles core puzzles now the early thought was that this is where t-cells that failed school went to die it didn't look like anything was going on there but now the thought is that this is where t-cells are having some sort of regulatory steps taken so that they don't cause autoimmune diseases so still an area of research and you can see that even after thousands of years we still don't know everything about the human body this is obviously just for t-cells it's an exclusive school just for them so no b-cells at all remember b-cells like to organize themselves into lymphoid follicles with germinal centers you're not going to see that kind of arrangement and because the thymus is just school and it's not doing any direct fighting of foreign things at all no matter what it is there is actually a blood thymus barrier to make sure no B cells or other white blood cells get access to the thymus so think of the thymus like is one of those exclusive high-end schools with a gate around it you know it's it's and it's only for you know K through five so it's really for little kids that it is actually present so here is the cortex you know you can see the cortex is that region here this is all the medulla here if you look at the medulla that's what a hassles corpuscle is so how can you tell this tissue from a spleen because some people can look at the angle isn't that like the white pulp and that's the red pulp look at the hassles corpuscle this is a swirl that is solid this is not a tube remem in the spleen this is a vessel it's got a lumen in it so look for the lumen it's a central artery not a swirly clump of cells so that'll be the big difference that can help because otherwise they look very very similar so it's solid and you can see different sized ones over here so once again these are just swirls of epithelial cells we don't quite know exactly what they do so here is the kids heart here you can actually see the aortic arch coming out and then over here is the thymic border it's huge and so as the kid ages and you can see this kid has like no neck so obviously they're quite little probably definitely a little toddler you will see that the thymus will shrink as the body grows and eventually as you age it'll turn into fat and connective tissue so you know when you look at a cadaver and they're 70 80 years old you're not gonna see a thymus but you'll see a weird chunk of fat right on the top anterior surface of the heart where the old thymus was all right moving on to tonsils tonsils unfortunately are gonna look very similar to your spleen and to your thymus so how do you tell them apart well first off let's jump into their names and these are all based on location so the palette teams there near the soft palate of the roof of your mouth these are the ones that you can easily see in the bathroom mirror lingual tonsils on the back 30 of your tongue that's where you do taste on the back third remember that was innervated by cranial nerve nine glosso pharyngeal the pharyngeal consoles are technically in the nasal pharynx so they're kind of up in the back out of view these also are called the adenoids and sometimes they have to get removed if you have a hard time breathing through your nose the palate teens are the other ones that are commonly removed so the two that start with P or the the more common ones surgically excised lingual is a very thin counsel on the back third of your tongue two bowls are really small and they're right at the opening of the eustachian tubes to make sure that nothing bad crawls up there and affects your middle ear cavity the tonsils how you tell them from the previous organs like the thymus or the spleen is the tonsillar crypt they have big giant pits on their surface that go down and then they kind of just come to a stop these tonsillar crypts are great at track trapping not only food and giving you really bad halitosis or bad breath but they can trap bacteria or any other kind of particulate matter occasionally the the stuff in there it gets hardened and can even become stone like so you could have what we call a tots a little lift lift the mean stone or they can get infected so itis means infection what do you find helping to eat or destroy or present to other white blood cells bits and pieces at the bacteria you find B lymphocytes so let's take a look here so this is gigantic this whole thing look at the magnification it's hardly anything at all only 20x so here we got a lymphoid follicle with a germinal Center there's another one there's another one you're looking at tens of thousands of white blood cells notice how the capsule is nice and thick and then as it comes down it breaks up if you're actually getting little chunks of it all over the place so the capsule unlike the spleen unlike the lymph node is discontinuous it actually breaks up now this is important because as the capsule breaks up deep in this tonsillar crypt that allows things that are like you know a little food particles in here to kind of get access to the white blood cells that are in these areas and of course this place is loaded with capillaries if you've taken a microbiology before and you've done the lab where you sampled your throat this is why we put this sample with the swab so you got like a big old swab coming in here and you're swabbing your throat trying to pick up some of these little green bacteria and then you put this onto a blood auger plate and then you put the blood agar plate into what's called a candle jar the candle jar is really just a jar with a tight airtight seal on it well the blood auger plate is replicating the access to blood that these bacteria potentially have like streptococcus pyogenes one of the most common bacteria that causes strep throat and so we got the blood auger but this tonsillar crypt it has a very low Oh to content as you go further down into it yeah it's in your mouth but this is basically a wet pit and so it's a lot of times it's touching and that's what the candle jar does it replicates the tonsil or crypt and so that's how you find out truly what the organism is that's causing your infectious tonsils let's take a look at some tonsillitis so you would swab this put it on a blogger plate put it in a candle jar look at it the next day and then do some more investigation to see what organism it actually is but this is these just the tip of the iceberg this is if the pit goes deep down into the tonsil and it might have branches and stuff so and some of these might get some hardening that actually occurs and they have to be removed by the way these are what we call three plus tonsils four plus would basically touch they would be what we call kissing tonsils a little less would be a two and a little less so that would be a two that would be like a 1 and a lot of times people have ones or zeros where you can barely see anything tonsils are also kind of like a plant that you just kind of ripped out of the ground if you leave the root of it behind it can kind of grow back a little bit just like a spleen can regenerate it so for a liver can regenerate itself tonsils can do the same thing usually however that's not going to happen to any great degree because when they scoop these out they use a metal kind of heated up scooper basically and just kind of carve out the back of it and it kind of scarves down later when we get to the digestive system we'll talk about this but see this fold of muscle right here this connects to the avila so this is a fold of muscle that is right in front of this tonsil there's actually another fold of muscle we do it in blue that's in the distance and going down so this is the Pilato glosso fold and this is the pelota friend you'll fold these folds could track to raise the back of your tongue up when you initiate a swallow reflex here you can see one of those hardened stone like nuggets called a tonsil Olaf sometimes you'll like coughed out so this could be a sneeze or a cough nugget doesn't really matter but you sneeze you you cough and sometimes the pressure knocks one of these loose and you'll a cough and all of a sudden goes something's in your mouth and you end up spitting it out and that's basically what you spit out a little tonsil a lift so and these stink so if you ever get one popped out and this is also a fun youtube search by the way just search YouTube for tonsilloliths and you go watch people trying to video themselves popping these things out what about other places of the body other tubes that need to be protected from things by having the immune system nearby well these are called malt tissues so malt tissue is a generic location if any place it has a mucosa so it's you know that's why we call it a mucosa associated lymphoid tissue where do you find mucosa you find them basically in your Airways so we have the bronchial Airways in fact we call that bronchial associated lymphoid tissue vault we have stuff in the digestive system we typically sometimes we'll call these peyer's patches or specific location like the appendix or examples like the tonsil all of these are example of gastrointestinal associated lymphoid tissue or goalt and then we even have some in the genital urinary organs basically the urethra so you know because obviously these are all wet tubes so they all need multi-issue what does bulk tissue look like well the example I'm going to show you is going to be basically the Pyrus patches at the appendix and this is where you have once again these are all let me just go back to this these are all wet tube locations so what you need to look for so that you know that you're looking at one of these instead of a tonsil or perhaps a spleen or you know thymus is you need to look for the large lumen so that they're all going to do the same thing any of these locations will make sure that bacteria is destroyed they'll activate the immune system and we'll talk about that memory cell formation here in a bit so here is a cut section of an appendix it could have been the ileum but these are gigantic tens of thousands of white blood cells organized into lymphoid follicles with germinal centers so you know this this would be in the case of the appendix where the digested food would be this is a lumen the space is called a lumen the contents depend on where the lumen is this you'll see peyer's patches like this also in the walls of the trachea and the main bronchi going into your lungs because that's a dirty air tube that needs to be sterilized on the way down to the alveolar air sacs last topic for this part is elephantiasis there are some itty-bitty parasitic worms that can be transported underneath your skin into the interstitial space by mosquito bite so this is a very small work because it's fitting inside of a mosquitos proboscis as it bites you this worm will work its way into the lymphatic system and just hang out that'll be its new home and of course if you've got a bunch of worms in the lymphatic system like say of your leg it's gonna block the lymphatic return because remember this lymphatic fluid is trying to get back but if it's blocked it just accumulates this is a particular worm called cheriya Bancroft II and it's causing a disease called elephantiasis obviously because you legs start looking like an elephant or the other name is called filariasis because a filariasis refers to the worm here and that's basically it these individuals unfortunately this is not really going to you can kill the worm off with Mubeen dissol but the damage is already done so they're still going to have permanent lymph edema the rest of their life but at least they can get rid of the worms all right that's the end of part 1

Channel: Aaron Ament

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Id: DYHkfgglhVo

Length: 58min 22sec (3502 seconds)

Published: Mon Jun 08 2020