Lymphatic System

when I first learned about the immune system  I remember being really confused I couldn't   visualize where it was and what it did and how  it related to other parts of the body so what   I'm going to do in this video is we're going to  take a look at a series of diagrams and reveal it   piece by piece so that you understand by the end  of this exactly what the lymphatic system does   how it's organized and where it is in the body so  let's uh jump to the Whiteboard and get started so   let's start with the three main functions of  the lymphatic system the first thing is it's   going to prevent swelling or edema by returning  fluid to the bloodstream so there's going to be   a buildup of fluid and tissues throughout our  body the lymphatic system is going to take that   fluid and return it to our blood circulation so  they don't have swelling throughout our body the   second thing is it's going to scan for pathogens  and initiate an immune response if it finds them   so it's going to take some of this fluid from the  tissue in our body it's going to run it through   lymph nodes the lymph nodes will be full of B  cells and t- cells all these immune system cells   that are going to detect if there's a pathogen  if there is it's going to fight that pathogen off   and start this immune response so that we can get  our body back to being healthy and that's why the   lymphatic and the immune systems are often lumped  together kind of as one system finally the third   thing it's going to do is it's going to absorb  fat from our digestive tract from the intestines   and bring that fat into blood circulation so it  turns out that fats that we eat can't go from   our intestines directly into our bloodstream it's  got to take a detour through the lymphatic system   in order to get to the bloodstream we'll talk  about why that is later on so those are the three   primary lymphatic system functions and throughout  the video we're going to be looking at those and   seeing how the fatic system is set up in order  to accomplish those three functions first we're   going to take a look at the fluid management  part of this the part where I talked about it   reducing swelling or edema in the body so we're  going to zoom in on some tissue in the body here   here we've got an arterial which is going to be  bringing blood into this tissue area and we've got   a venule which is going to be bringing blood out  of that tissue area and this arterial is bringing   blood from the heart that's oxygen rich the venu  is returning blood back to the heart that's oxygen   poor in other words it's given off its oxygen it's  returning back to the heart now let's draw some   tissue cells in here and so I've got a bunch of  cells here it kind of looks like a skull that was   unintentional there's a lot of epithelial cells  and there's going to be spaces in between some of   those epithelial cells the spaces between cells  are going to be filled with fluid now to deliver   the fluid and the oxygen and all the stuff that  these cells need we're going to need capillaries   so we have a capillary that's connecting in the  arterial over to the venil in the diagram you see   a color change from red to blue meaning that it's  going to be giving off oxygen I feel like I say   this in every video I make but the blood never  actually turns to Blue it's always red just a   slightly different shade of red but in diagrams we  use red and blue for oxygen poor and oxygen rich   blood now it's not just one capillary we've got  a whole bed of capillaries so we see this bed of   capillaries with all these branches and that's  so that it can give off the oxygen and fluid   and everything to all the different cells here  all right let's remove a few cells so we have   room to write some stuff here and like I said it's  going to be giving off oxygen to these cells it's   also going to be Distributing water or fluid these  capillaries are leaky so the water the oxygen is   going to be coming out of there it's also going  to have other things coming out such as protein   hormones nutrients all these different things that  the cells need to survive all of that is leaking   out of the capillary into the space between the  cells the main two we're concerned about here   are water and oxygen though and of course there's  other stuff that needs to go back into bloodstream   circulation waste products that we don't need such  as carbon dioxide that the cells produce during   cellular respiration as well as a lot of that  fluid that leaks out is going to be pulled back   into to the capillaries so we have water coming  out and we have water coming back in to return   to circulation now there's various forces that  are causing the fluid to move in and out we've   got hydrostatic pressure which is kind of just the  the fluid pressure of something moving through a   tube and that's going to be forcing a lot of this  water out we also have osmotic pressure which is   going to be pulling a lot of the water back in  but also like I said there's proteins and other   stuff that are leaking out so we've got proteins  floating around in this interstitial space between   the cells and that's going to be pulling on the  water and keeping some of that water outside of   the blood vessels because of osmotic pressure  hydrostatic and osmotic pressure are a little   bit confusing that's probably a topic for another  video but the main thing to know here is that   water is coming out and water's coming back in but  there's more water leaving the capillaries than   there is water coming back into the capillaries  and so that's going to lead to a buildup of fluid   in this tissue over time leading to swelling so  we need something else in this tissue that's going   to remove that excess water and so that's where  the lymphatic capillaries come in the lymphatic   capillaries are these series of tubes that extend  up into the capillary bed we always use green and   diagrams to represent the lymphatic system and  they branch in and out here but they're not a   continuous stream like the blood vessels are the  cardiovascular system is a closed system meaning   that the fluid could stay in the cardiovascular  system and completing the circuit from the heart   to the lungs back to the heart to the tissues of  the rest of the body and then back to the heart   and so on the lymphatic system is an open system  it's not a continuous system that's going to go   throughout the whole body and return back to its  original location so it's going to be absorbing   some of this interstitial fluid and it's going  to travel through here and that's eventually   going to work its way back to the veins returning  all that excess fluid that it picks up back back   into Venus circulation but again the thing we're  focused on right here is preventing swelling so   like I said there's water leaving there's some  water coming back in but not enough water coming   back in so a lot of that buildup of fluid is  going to enter into the lymphatic capillaries   and travel down here so it can be returned back  to circulation now let's zoom in on the end of   one of these little lymphatic capillaries  so we've got our main capillary right here   the end of the lymphatic capillary and we got  all the tissue cells that are there now if you   notice and look closely there's these spaces  that are between the cells and the capillary   that's where the fluid is going to be leaving as  well as proteins and other things how they leave   the capillary through those little spaces right  there the lymphatic capillaries have spaces as   well can't really tell in the diagram but those  spaces in the lymphatic capillaries are a little   bit bigger and that's going to be important  later on and of course we have red blood cells   that are traveling through the capillary those  are carrying oxygen in carbon dioxide out now   we've got a lot of fluid in this diagram there's  fluid here in the blood capillary there's fluid in   the lymphatic capillary there's fluid between the  cells and they all have different names so blood   plasmas is what we call the fluid in the blood  capillary we have lymphatic fluid or lymph which   is the fluid that's in the lymphatic capillary and  then we have interstitial fluid which is the fluid   between the cells and the tissue interstitial  just means between things now most of this is   all the same stuff it's mostly water there's other  stuff dissolved in it and it's flowing in and out   between all these areas we just give it different  names depending on where it's located now let's   break down all the movement happening in this  diagram first of all we've got the blood that's   coming in so that's going to be blood plasma or  fluid and the red blood cell also white blood   cells coming through there that's coming from the  heart and then we have fluid flowing out of this   area traveling back to the heart of course those  capillaries are leaky so we have fluid that's   traveling out of the capillary which we see right  here and a lot of that fluid that leaves is going   to go back into the capillary which we see right  here of course not as much fluid is traveling back   into the capillary so we have a buildup of fluid  in the tissue space or a buildup of interstitial   fluid so a lot of that fluid is going to travel  into the lymphatic capillaries becoming lymph   where it's then going to travel through the  rest of the lymphatic system and then back to   a vein the subclavian vein where it's back into  circulation and again the fluid in here we call   blood plasma once it leaves the capillary we call  interstitial fluid and then once it moves from the   interstitial fluid to the lymphatic capillary we  call it lymph so this diagram is showing what's   happening in the lymphatic system at the tissue  level how these lymphatic capillaries are going   to be pulling fluid this excess fluid from the  interstitial space and bringing it out of that   tissue so that we don't have swelling or edema  throughout the tissues in our body next we're   going to zoom out and look kind of at the whole  body level so I've got a diagram of a person here   we're going to start here with the hands just  because it's a distal end of the arm here and   you can see all these little lymphatic capillaries  that are extended out into all parts of the hand   basically almost anywhere in your body where  there's blood or blood capillaries there's going   to be lymphatic capillaries that are there to  remove that fluid so those lymphatic capillaries   are going to be picking up fluid which came from  the bloodstream which then became interstitial   fluid and now is in the lymph vessels so it's  going to be bringing that lymph fluid up the   arm closer to the middle part of the body and  if you notice right here we've got some spots   in the those lymph vessels and those are going  to be lymph nodes and this is where we're getting   into that second function of the lymphatic system  where we're scanning for pathogens and initiating   an immune response the lymph nodes are where a lot  of that is taking place so let's zoom in on one of   those lymph nodes and take a look at the structure  of the lymph node and how it does this all right   so there's our cute little lymph node and we're  going to have first some vessels that are bringing   the lymph into the lymph node we call these afren  vessels affrant just means toward and I have the   a capitalized there because in a second we're  going to see an ephant vessel so these vessels   like this one right here that's going to be an  affrant vessel that's bringing lymph into the   lymph node now notice on these vessels there are  these little valves which are going to make sure   that the lymph is only flowing in One Direction  and if lymph tries to flow backward those are   going to snap shut and prevent the lymph from back  flowing since we don't have a lymphatic equivalent   of a heart to push or pump the lymph fluid through  the lymph vessels we've got these one-way valves   so that that lymph fluid is only traveling in the  correct direction so lymph is coming in through   multiple afferent vessels here and then the lymph  is going to travel out of the lymph node through   an errant vessel and there's only ever going to  be one errant vessel leaving a lymph node all   right now let's take a look at a couple regions  of the lymph node here first we've got the medulla   which is going to be kind of in the center of the  lymph node right there where the lymph is passing   through to get to the errant vessel and then we've  got the cortex which is going to be the outer   part of the lymph node so all these sections  right in here are part of the cortex now for   this to scan for pathogens we have to have white  blood cells present or lymphocytes present those   lymphocytes are going to be B cells and t- cells  and macrofagos and a few others but they've got   to get there somehow now they're white blood cells  they need to come through the bloodstream so we're   going to have some blood vessels coming into each  of the lymph nodes those blood vessels are going   to enter in right by the errant vessel right in  here it's going to be bringing blood in including   white blood cells and then of course you've got to  have a vein which is going to be traveling out of   that area and so we've got a little capillary bed  and that's how the white blood cells are going to   make it to the lymph node so we're going to have  B cells all throughout this outer part of the   cortex we're going to have t- cells kind of mainly  clustered in the inner part of the cortex so any   pathogens that get into your bloodstream some of  those are going to end up in the lymph fluid where   they're going to pass through here and they're  going to have to pass by these B cells and these   t- cells which are going to be on the lookout for  antigens on those pathogens that they recognize   so they can start attacking them and initiate this  immune response by the body so the lymph fluid is   going to pass by there it's going to fill in this  medulla and then come out through the eant vessel   where it's going to continue on its path and we're  going to see where that path goes to next so again   how does lymphatics system scan for pathogens and  initiate the immune response well lymph is going   to be traveling through these affrant vessels  through the cortex where it passes by B cells and   t- cells those are going to be trying to detect  and see if there's a pathogen present and they'll   start that immune Cascade if there is and if not  that lymph fluid is just going to pass by out the   eant vessel where it can continue on its path all  right let's see where all of this goes next but   first I want to point out if you notice that the  lymph nodes aren't just throughout every part of   these lymph vessels they're kind of clustered in  certain regions throughout this next part of our   diagram here I'm going to be pointing out lymph  node regions in green and this first section here   that you'll see is the epitrochlear section of  lymph nodes there's going to be located kind of   on the medial side of the elbow right in there  now all of this lymph fluid that's traveled up   from the hand it's going to be traveling up here  through this axillary or armpit region and we're   actually going to have a lot of lymph nodes in  that axillary region so you got a lot of lymph   nodes in your armpit kind of extending up here  toward the neck region notice that almost all   of those vessels are starting to converge into  one bigger vessel right there this is where the   lymph fluid is about to drain back into the veins  so it can return to our blood circulation so here   in our diagram we have the right subclavian vein  and the left subclavian vein the subclavian veins   connect together to form the superior vnea and  the superior vena is going to bring the blood   back into the heart to the right atrium right  ventricle it can pump it to the lungs but all of   the lymph fluid that we gather is going to drain  back into either the right subclavian vein or the   left subclavian vein through two different ducts  du s the first of those is the right lymphatic   duct and then the second is going to be the  thoracic duct the thoracic duct is going to   extend down into your chest and down toward the  abdomen and the thoracic duct is going to get   most of the lymph drainage and the right lymphatic  duct is going to get just a smaller fraction of it   we'll see more of this in a second but the right  lymphatic duct is going to get lymph from the   right arm the right side of the face and a little  bit in this region right here whereas the thoracic   duct is going to drain all of the lymph from the  left arm the left side of the face as well as   like the whole lower half of the body so right  lymphatic duct is getting just lymph from this   region right here thoracic duct is getting lymph  from this region down here and the whole lower   half of the body the chest is also going to have a  lot of lymphatics and so we see a lot of lymphatic   vessels right here that are going to be collecting  fluid and bringing up into that axillary region up   next is the region where we actually have the most  lymph nodes and that's going to be in the cervical   region so there's going to be a lot of lymph nodes  in our neck there's going to be a lot kind of in   the side of our face right in here and often  times that's broken up not just into cervical   but other names of regions as well but in this  video video I'm just giving kind of an overview   of the location of the lymph nodes so we've got  all those lymph nodes in the cervical region in   the left side of the face they're draining into  the thoracic duct and then in the right side of   the face all of those are going to be draining  into the right lymphatic duct so if you were to   trace the path here from the hand the lymph is  traveling up this way into the right lymphatic   duct from the face is traveling down to the right  lymphatic duct or from here it's traveling up the   arm to the thoracic duct or from the face down  to the thoracic duct now let's move on to the   lower half of the body we're going to start down  at the very bottom or inferior part we're going   to have some lymph nose in the knees and those  are going to be the poal lymph nodes pole is just   referring to the knee that lymph fluid is going  to be draining upward it's going to head toward   the inguinal lymph nodes the inguinal lymph nodes  are found right in here and then from there lyph   fluid is going to travel up into the abdominal  lymph nodes right in through here so if you'll   notice you don't have a lot of lymph nodes in the  leg you don't really have any below the knee youve   got a few in the knee you've got a lot in the  inguinal area right here you've got a lot in the   abdominal area right here now almost all of the  lymph fluid that's coming from the lower half of   the body is going to be right in here where it's  going to enter into something called the CNA kyai   the CNA kyli is just this big collecting duct for  lymphatic fluid it's going to connect all these   lower lymphatic vessels up to the thoracic duct  and all that lymphatic fluid is going to drain   into the left subclavian vein via the thoracic  duct a couple more branches here that I need to   draw in the next one is going to be the thoracic  lymph node so there kind of a more lateral Branch   that's going to come up here that's going to have  some thoracic lymph nodes we're going to have   those on the other side as well from what I can  tell on most diagrams that I've seen there is a   lymph connection from the CNA kyai right here up  to the right lymphatic duct so I'd imagine there   is a little bit of drainage from this lower part  of the body up into the right lymphatic duct but   the vast majority of lymphatic fluid from the  lower half of the body is going to travel up   through the thoracic duct into the left subclavian  vein so all of these lymphatic vessels that are in   almost all parts of the body they're pulling fluid  in to scan for pathogens and initiate an immune   response so if there is an Invader in the body the  lymph nodes are going to find it but don't forget   about about our first function of the lymphatic  system which is preventing swelling and so they're   pulling this fluid from all these different body  regions where that fluid may be building up more   than it should so they're pulling that fluid out  all that fluid is going to travel toward those   subclavian veins either via the right lymphatic  duct or the thoracic duct to get all that excess   fluid back into the bloodstream where it belongs  so we don't have swelling throughout the body all   right next let's talk about that third function  the absorbing fat from intestines and delivering   it to the bloodstream so let's draw in a little  branch of the small intestine right here and   we've got a lymphatic vessel that's going to be  pulling fluid from that intestine and connecting   it to the cic kyi right in here we can drain it  back into the thoracic duct I just have a small   section of intestin drawn but that's so that my  diagram doesn't get a little bit out of hand but   really these lymphatic vessels are going to be  connecting all throughout the small intestine to   pull that fluid out so really this whole area  right here would be full of these lymphatic   vessels pulling fluid out of the intestines and  into the cic kyli now when I first learned about   all this stuff I learned that the fats and sugars  and proteins and all the nutrients that we eat are   going to go from the digestive system straight  to the bloodstream all those things get absorbed   from the small intestine into the bloodstream  but it turns out that's not quite the whole   truth take a look at this diagram there's a lot  going on here but let's break it down we've got   a section of the small intestine inside that  small intestine if we cut it open we'll see   there's these Villi or these tiny little kind of  squiggly looking surface membranes that are on the   surface of the small intestine all the food that  we eat after it's been broken down is traveling   through this tube of the small intestine now we  got to get get those nutrients from the Lumin of   the small intestine into the bloodstream so let's  zoom in on one of these Villi or on a villis here   are the absorptive cells or ocytes the nutrients  that we've digested are going to pass through   there and most of those are going to pass into  the capillaries right here and they're going to   be traveling through the capillary through the  venule and then back into circulation it goes   directly into the bloodstream that's going to  be true for proteins and sugars because they're   soluble in water and they're pretty small they  can pass through the membranes fats or lipids are   a different story lipids are not water soluble  so they can't just go directly into the water   they've got to be packaged so in these absorptive  cells they're going to be packaged into something   called a kyom micron a kyom micron is a is a  long fancy name for basically a little water   soluble package that the lipids will get packaged  into so they can enter into the fluid so they get   packaged into a kyom micron but unfortunately  the kyom Micron it's a little bit bulky it's   not going to fit into the capillaries to make it  into the bloodstream there's just not enough space   between the cells and the capillaries however the  lymphatic capillaries actually have more space   between the cells and the kyom microns can fit  into there so with the lipids which are in the   kyom microns what they're going to do is they're  going to travel through the lymphatic vessel right   here and they're going to travel out then they're  going to travel through here up through the cic   kyi and the thoracic duct and then boom they're  back into blood circulation but they never had   to travel directly through a blood capillary  they entered the lymphatic capillaries instead   so that's the third function absorbing fats from  the intestines delivering those to the bloodstream   through the lymphatic system all right next let's  go back to that pathogen and immune response thing   again these other organs we're about to talk about  are included in the lymphatic system because they   help with this immune response the first one is  going to be the thymus the thymus is located sort   of anterior to your heart it's actually bigger  when you're a kid and then it shrinks over time   by the time you're an adult it's like a tenth of  its normal size usually but what the thymus does   is it's going to produce T lymphocytes those T  lymphocytes first grew in the bone marrow that's   where your white blood cells and red blood cells  are mainly produced they'll travel from there to   the thymus and the thymus is going to have them  develop and mature into te- cells why do we call   them te- cells well because they're made in the  thymus which starts with T from the diagram I   just realized it looks like the uh thoracic duct  is going to be connected to the thymus it's not   a thymus has blood vessels that are connected to  it and that's how it's getting these te- cells and   then sending these tea cells out and of course  A lot of these t- cells are going to end up in   the lymph nodes throughout the body so the thymus  is considered a lymphatic organ because of that   next we have bone marrow and so the bone marrow  is going to be in Bones throughout the body I   just drew kind of the head of the femur down here  to represent the bone marrow the bone marrow is   going to be where all these white blood cells are  created and specifically it's going to be where   the B lymphocytes or B cells are developing and  maturing why are they called B cells well because   they're made in the bone marrow which starts with  B of course a lot of those B lymphocytes are going   to travel through the bloodstream and they're  going to make it to the lymph nodes throughout the   body so they can hang out and look for pathogens  in their lymph fluid the thymus and the bone   mirror are considered primary lymphatic organs  because they're actually producing the cells   of the lymphatic system another organ to talk  about here is the spleen which is considered a   secondary lymphatic organ it does a couple things  one thing it does is it kind of acts like a lymph   node for your bloodstream there aren't lymphatic  vessels going to it but there are blood vessels   going to it and it's going to have a lot of  these B cells and t- cells that are going to   kind of hang out and fight pathogens if there's  any that come into the spleen through the blood   vessels right there but another big thing that  it does is it breaks down old red blood cells so   red blood cells cells have a very limited lifespan  and at the end of their lifespan they're going to   get broken down by the spleen so that we can then  get rid of them one more thing I don't have that   diagram is our tonsils our tonsils kind of work  like the spleen does they contain lymphocytes to   fight off pathogens but they're up in the face in  some of the cavities up there all right that was   a lot of information now I'm going to give you a  chance to practice some of that information and   see if you can recall it here's a blank graphic  of the lymphatic system functions pause the video   see if you can name the three functions of the  lymphatic system and those functions are one   it prevents swelling or by returning interstitial  fluid to the bloodstream second it's going to scan   for pathogens and initiate an immune response if  it finds pathogens and third it's going to absorb   fats from intestines and deliver those to the  bloodstream up next we have this diagram of the   tissue capillaries and lymphatic capillaries  take a minute pause the video see if you can   describe everything that's in this diagram  as well as describe what's happening in all   the different parts of the diagram all right and  here's a completed version of that diagram as a   quick overview we've got blood coming in traveling  through here it's going to be dropping off water   and oxygen and proteins and other nutrients to the  tissue cells water and carbon dioxide is going to   be traveling back into the tissue capillaries  so that we can get rid of it however we've got   a lot of water leaving and only about 90% of that  water is coming back so we've got an extra 10%   that we've got to get back into blood circulation  that's where these lymphatic capillaries are going   to come in so a lot of fluid is going to travel  back into the lymphatic capillary and it's going   to take it out of this tissue and get it back into  blood circulation we've got a zoomed in version   of that which includes blood plasma interstitial  fluid and then lymph or lymphatic fluid fluid from   the blood plasma is going to travel out into the  interstitial space about 90% is going to travel   back into the blood capillary that other 10% we  need to get it back into blood circulation so   it's going to travel through the lymphatic vessel  and then back into that subclavian vein later on   another thing that we talked about is the lymph  node so here's a blank diagram of the lymph node   again pause the video see if you can identify  all the parts of the lymph node as well as the   direction that fluid travels and what all it does  all right here's that completed diagram now we've   got lymphatic fluid that's coming in into the  afren vessels we've got the lymphatic fluid   coming out through the ephren vessel that fluid  has to travel past B cells and t- cells which   are scanning that fluid looking for any pathogens  to fight off if it finds them it'll initiate the   immune response if not that fluid will travel out  through that errant vessel and we have the medulla   here and the cortex is the outer part where the  B cells and t- cells are found and then finally   here's our picture of the whole person pause the  video see if you can name all of the lymph node   regions as well as the other lymphatic organs and  what all those lymphatic organs do and there's all   those terms again the lymphatic fluid from the  hand and the arm is going to travel up through   this region past the epitrochlear lymph nodes  through the axillary lymph nodes and then into   the thoracic duct or on this side up through the  right lymphatic duct majority of our lymph nodes   are here in the cervical region those are going to  drain down into the thoracic and right lymphatic   duct fluid from the lower leg is going to travel  up through the poal lymph nodes up through the   inguino lymph nodes abdominal lymph nodes into  the cernic kyi which going to travel through the   thoracic duct all of that lymph fluid is going  to make it back into the left subclavian vein or   the right subclavian vein we have lymph vessels  that are taking fluid from the small intestine   that's where fats are going to get absorbed into  the lymphatic system so they can return to Venus   circulation and finally we have these other  lymphatic organs the thymus where tea cells   develop and IM mature the bone marrow where  B cells develop and mature and we have the   spleen which contains a lot of lymphocytes which  will fight off pathogens as well as being a site   where red blood cells are broken down all right  so that was a lot of information it turns out   the lymphatic system has a lot of parts there's  a lot of complexity to it I didn't get into how   the B cells and T cells actually do the immune  response if you're interested in that I've got a   video on that so check that video out it should be  linked right here special shout out to my patrons   on patreon who helped make this video possible if  you're looking for the diagrams from this video   both the blank and completed diagrams those are  available on my patreon so check that out there's   a link below and good luck learning Anatomy hope  to see you in the next video I'll see you then

Channel: Siebert Science

Views: 252,160

Keywords: science, anatomy, physiology, ap chemistry, physics, education, flipped classroom, high school

Id: X2hHK1BHV2E

Length: 23min 50sec (1430 seconds)

Published: Mon Jan 22 2024