- [Instructor] In this video, we're going to be talking about the lymphatic system. Now, the lymphatic system is a little bit different than other systems because it's very spread out throughout the body. It's very extensive and it goes hand in hand with the immune system, but we're just going to cover the very basics of the system today because other details are beyond the scope of this course. So let's talk a little bit about what the system is. All right, so it consists of vessels, cells and organs. The function of it is that it carries excess fluids to the bloodstream. So it takes those fluids from throughout the body, bringing it into the bloodstream. And in doing so, it also filters pathogens from the blood. So it is a very important, extensive system. Now I just wanna provide a couple of examples of the actions of this lymphatic system. So an example is you have lymph nodes, and they swell during an infection. Another example is that you have lymphatic vessels that transport... lymph cells called lymphocytes. Now, when we're referring to the lymphatic system, oftentimes we're going to be talking about a substance called lymph. So let's learn about that. And let's just mix it up with another color because black is gonna get boring. All right, lymph. So lymph is a colorless fluid. It contains white blood cells. It bathes tissues, and it drains through the lymphatic system into the bloodstream. Now in terms of the lymphatic system, it's kind of similar to the circulatory system in that the way in which it flows and the areas in which it flows make it as important as it is. So I wanna talk to you a little bit about how that flow of lymph works now that we've talked about what lymph is. So lymph will go from capillaries into lymphatic vessels, which is kind of analogous to the blood vessels that we talked about in terms of arteries and veins. But these are just lymphatic. Next, they're going to go into what we call ducts and we're gonna talk about a few of those ducts. And then they're gonna make their way into the bloodstream. Now along the way, lymph is also gonna travel through the lymph nodes. So let's, I'm going to write a little note, will travel... through lymph nodes as well. All right, so we have a couple of different nodes, like little clusters of cells. And you may have had someone like feel your lymph nodes, for example, on your neck, if you've gone to the doctor and you've been sick. So let's talk a little bit about lymph nodes really quickly. So lymph nodes, you actually have a bunch. I think it's around 600 in the whole body is what the approximate number is, but you have clusters of these lymph nodes. And the clusters are centered around the groin, armpits, neck,... chest and abdomen. All right, now that we've reviewed the flow of this lymph, the fluid that goes from capillaries into lymphatic vessels, then into ducts and into the bloodstream, I want to talk about a few specific ducts and we'll draw them out together. So I'm going to move this up to give us a little bit more room, and I'm actually going to draw a person out. So we're gonna be looking at an anterior view of this person. And I'll explain in a moment why I'm drawing him so funky. As always, my drawing skills are quite questionable 'cause this man looks kind of funky. But anyway, my point in doing this is I'm using two different colors to separate the body into different sections. So this is right, and this is left. This is an anterior view of my weird looking dude here. Here I'm going to explain ducts. All right, so this purple part is the area of the body that drains into one duct. And this brown part of the body is the area that drowns into a different duct. Now we have the purple part. We're calling that the right lymphatic duct. And what happens is is that duct is going to drain into the subclavian vein. So I'll just show it for you. We're gonna draw it out as like a little zoomed in thing. It's going to be... here, and then we'll have a little right subclavian vein right there. So this is a zoomed in version of what that looks like. Our right lymphatic duct drains into... our right subclavian vein. Okay, so this is just like a little zoomed in image of that right there, because, you know, that's super tiny. Now on the other side, so essentially that right lymphatic duct is taking fluid from this right upper part of the body and head. And that it'll take that lymph fluid and it'll drain into the right lymphatic duct which will go into the right subclavian vein, which is essentially what we talked about right here, right? We talked about capillaries to lymph vessels going to ducts like the right lymphatic duct, and then going back in through the bloodstream. So for fluid from this part of the body, it's gonna go through the right lymphatic duct into the right subclavian vein. And that's how that fluid will return to the bloodstream. Now let's talk about the brown part of the body which is the rest of it, the majority of the body. Now that is the thoracic duct. And we're gonna do the same thing here. And we're gonna zoom in. Our thoracic duct is going to drain into... our left subclavian vein. Drains into... left subclavian vein. Now we have another reason to note that our veins and the names of them are very important because they're gonna intertwine with other systems like this lymphatic system. Now there are also other important structures that are part of the lymphatic system, and we've already gone over or will go over all of the structures. So I'm just going to list them out to you. Other lymphatic... system structures. The structures are the thymus, which we already discussed in the endocrine system, the spleen, which we'll touch on briefly in the digestive or gastrointestinal system, also the appendix, which we'll address later as well. I just want you to know that these structures exist, and they interact with the lymphatic system, but we're just not gonna go into detail in terms of specific functions. Now, one other thing that I do want to address that is part of the lymphatic system are tonsils. All right, so let's do the same thing as always. We're gonna draw a little figure. All right, so that's a lateral view of this person's head. And I'm going to draw a few tonsils, but first I just wanna address why they're important. So these are lymphoid nodules. And essentially they serve a couple of different functions, but it seems to be most important for children. And we're not sure about all the other specific functions but it's very important. And its function to help... children's bodies... recognize... destroy... and develop immunity... to pathogens. And essentially, so this is both part of the lymphatic and the immune system which really go hand in hand together and can kind of be considered one main entity. Now let's draw these out. And essentially remember last time we talked about the pharynx in our respiratory system lecture? Now these tonsils are located along the inner surface of the pharynx, just so you have a reference for where we're drawing these on this little dude's head. So we're going to have three different tonsils. Let's draw out the first one. So the first one is going to be the pharyngeal tonsils which are going to be a little bit higher up near where the nasal pharynx is. Oops, let's see. So these are also called adenoids. And you may have heard of like especially children having their adenoids removed. So with that, we're referring to the pharyngeal tonsils. Then we're also going to have the palatine tonsils and those palatine tonsils are going to be up a little bit more superior than the next tonsils we're gonna draw but inferior to the pharyngeal ones. So it's gonna kind of be like in line with the mouth. Oftentimes like we mentioned with adenoids, children can have them removed. And with these palatine tonsils, these are the ones where if you open your mouth and like when a doctor asks you to say, "Ah," not only are they looking at that uvula which is the structure we talked about last time during the respiratory lecture as well, where it's that piece of tissue that hangs off of the soft palate in the back of your throat, the palatine tonsils, which is this purple thing that I just drew in this midsagittal cut, or just off midsagittal cut, of this lateral view of this person's head, that's the look at our palatine tonsils. And if they're swollen due to an infection, when you open your mouth and you stick out your tongue, you say "Ah" when a doctor asks you to do that, you can see them peeking in towards the sides. So those are your palatine... tonsils. And it makes sense because they're right around where your soft palate is. So that's how we can remember the name. And then lastly, we're also going to have lingual tonsils, which are going to be a little bit lower right around area of the tongue. So it's like right where the root of the tongue is. Now oftentimes if someone mentioned getting a tonsillectomy, it will be these palatine tonsils that are being removed. Oftentimes that will be done in children, just like we talked about the adenoidectomy being done in children. I believe the palatine tonsils or the tonsillectomy of those palatine tonsils are a little bit more common, but both of them can be common if people suffer from recurrent infections or recurrent tonsillitis. They'll often do it in children, but they'll sometimes do it in adults. I don't know if any of you have ever had your tonsils removed as adults, but it is an extremely painful process. So children tend to have a lot easier, better recovery from a tonsillectomy. But that wraps up what I wanted to cover with this lymphatic system. This lecture was a little bit less... focused on drawings, just because the lymphatic system is so broad. And when we're looking at this picture, for instance, you have lymphatic vessels going all the way throughout your body. We don't have really any main lymphatic vessels to draw other than when we're talking about these ducts. So if we were to draw the lymphatic system, it would just be a bunch of like, oftentimes in textbooks, they use green to note lymphatic tissue. And so we would have just a green vessels all throughout this entire body. So for this, it is a little bit different than our other lectures in that there's not as much to know in terms of true structure that you can draw out in your notes. But do know these and do just know the structures involved. Remember we talked about all of the other lymphatic system structures here. We talked about the tonsils. We talked about the general flow of the lymphatic system and those ducts that things drain into, where the lymph nodes are located, and we just talked about the lymphatic system in general, and lymph, that fluid that flows throughout the lymphatic system. And that wraps up our lymphatic system lecture.