welcome to unit 4 part 4. in this lecture we are going to talk about connective tissues this is the longest and most complex lecture of this unit because connective tissue is so varied and there are many subtypes so as you are going through this lecture try to understand the characteristics you may be fill in that chart and then come back when you're rewriting your notes and maybe make this into a concept map so that you can understand the different subtypes and the sub subtypes of tissues so just because we have been a couple lectures since we had our introduction remember that where tissues are made of similar cells working together for a common function so I only have one kind of tissue cell in one kind of cell in a tissue and that we have a matrix that has the non-living substances in it and because this is connective tissue this is the special characteristic of connective tissue is that all connective tissue have protein fibers in their Matrix we have three different kinds of fibers and the different mix of those kinds of fibers in a tissue structure will help the tissue with its function also and so when you see CT that's connective tissue also connective tissue is the only kind of tissue where we have a varying consistency in The Matrix so when we talked about other tissues The Matrix was always assumed remember that was the milk in the Cheerios always assumed to be kind of liquid so we certainly have some connective tissues that have a liquid Matrix but we're also going to have some that have a gel Matrix that's your cartilage and some that have a solid Matrix and that's going to be bone and if you when we learn about their functions we'll see that that change in the consistency of the Matrix assist the tissue with its function okay here we are in connective tissue okay so functions of connective tissue it in fact connects two different kinds of tissues or two different kinds of organs so we saw in that chicken example the epithelial lining skin cells and the muscle below it um but we'll also see different organs we're going to look at ligaments that connect bone to bone or tendons that connect muscle to Bone so connective tissue is the most varied type of tissue we have uh connective tissues will bind and support like we see in the skeleton they are going to transport substances like we'll see in Blood and lymph they're going to have a role in protection which again bones create a bony structural cage that protects our vital organs like our heart and lungs and our skull protecting our brain WBC is white blood cells so white blood cells um exist in connective tissues and they serve an immune function and we also have some insulation and protection through adipose which are your fat tissues let's see if we said this already it is the most widespread with the most number of subtypes it has a varying Matrix it can be solid or hard as in bone gel like in cartilage and liquid in blood it has varying vascularity so one of the other ones all muscle was vascular all epithelium was avascular we're going to see some connective tissues are vascular and some are avascular and it will vary even in the vascularity in general we're going to see a lot of Matrix and fewer cells and that the Matrix has different kinds of protein fiber so we've talked about these fibers before these three different kinds so I'm going to give you some visual analogies for these collagen fibers are like those big giant ropes that you had in gym class or at the gym if you do the battle ropes or whatever so these are big thick white and super strong elastic they're going to do that they're going to they're less strong and more stretchy so these are like rubber bands or hair ties and then reticular are going to create a mesh where we are like a supporting device for other cells to kind of hang on to um in um in some of our lymphatic tissues so when you think of reticular I want you to think of mesh or maybe like a window screen so all the fibers are making are like the screen and so it's kind of a filtering tissue excuse me particular connective tissue is a filtering tissue and the reticular fibers make the mesh that helps with the filtering okay so we're gonna break connective tissue into three different kinds well the kind of generic connective tissue the supportive connective tissue and the fluid connective tissue so when we are looking at these this is a breakdown of what we're going to cover so the connective tissue we're going to look at loose and dense that's the looseness and the denseness of the connective tissue proper is going to refer to the arrangements of the fiber so dense these are going to be a lot close together less Matrix loose is going to mean there's more Matrix less cells and less fibers the supportive connective tissues are going to be your three types of cartilage hyaline fibrocartilage and elastic cartilage and also bone and then we have two types of fluid connective tissues um blood and lymph so here is I kind of Drew you a map here but um you could you have this to kind of um check yourself copying this or taking a picture of it with your phone is not going to help you learn it like if at the end you rewrite your notes and try to create this yourself and then you can kind of check yourself against it but but the the magic comes for concept maps and actually creating them so not just having a picture of it you'd have to understand why things are branched in certain ways okay so first we're going to look at this connective tissue proper and we have the dense and the loose and the elastic is really kind of part of the dense but um we'll talk about it kind of separately so all subtypes of connective tissue contain cells called fibroblasts so um blast is a kind of cell that um makes something and this is going to make fibers most cell most tissues also have macrophages those are the kind of cells I think we talked about in the tissues they're like the Cookie Monsters they go around gobbling up all kinds of cell debris and breaking things down and kind of like vacuum cleaners or otherwise just gobbling up stuff mast cells are immune inflammatory cells lymphocytes are your white blood cells and some other cells of the immune system as well all have fibers but the founders will vary based on the function of the tissue varying amount of Matrix again based on the function of the tissue um for the loose sometimes we're going to see lots of space between the fibers and the cells and kind of this like random scattered Arrangement so if you had a few uh rubber bands and pieces of rope and uh you just kind of threw them down on the ground that would be what a loose fiber is going to look like the dense they'll be packed and arranged in a certain order to help them do their function okay so let's look at the three loose types of connective tissue adipose or real R tissue in reticular adipose is fat tissue its job is support and protection because these are squishy oil-filled cells that are in and around your organs this is where we store extra calories to use um in the times when we are between meals it also helps to insulate us and conserve body heat and depending on how much fat stores you have it can be um you know somewhere between 20 and 50 of your body weight it has low Matrix because all right so each one of these is a cell and the fat cells are called adipocytes and they are just packed full of oil so here's like a brand new new one because the other ones got kind of full and then it'll eventually swell up um this is um real adipocytes under the microscopes they're so full of oil you can see the nuclear are squished up here these are more like balloons or beach balls that fill with oil so you can imagine the the organelles get squished over there to the sides um low amount of Matrix because their job is storage of energy so there's no need for us to have a lot of extra space we just cram them in there um we're going to see reticular and collagen fibers here so a little bit of like the stretchy kind of streaming stuff and a little bit of collagen in fact if you've ever um had the lovely privilege of looking at cellulite um the cellulite is when you have some of the fat coming kind of pressing through those collagen fibers a lot of the development of cellulite is genetic so don't stress out about that too much I mean eat well and exercise but sometimes it's just jeans lots of lots of blood vessels because if you think about that all the extra calories from the proteins and the carbohydrates are being transported to the adipose tissue and and loading up and transforming that into fat and um so we have to have the blood vessel then we break it down and send those calories back out when our body needs them and they're highly regenerative so as much as you would love to get rid of them even if you had liposuction where they go in and suck out some of the the subcutaneous fat we can just keep making more if if we're eating more calories than we need um where you store adipose on your body I put this in here because people always ask me this um in a in a live lecture um is based on hormones so testosterone versus estrogen is going to lead to different places where we store the fat we also can store the fat either subcutaneously so this is the just below your skin kind of what I call Squishy fat um like if you flex your abs whatever you could feel between your skin and your abs that would be your subcutaneous fat or you can have visceral fat um which is below your like abdominal muscles around your organ so we generally find the visceral fat so if you have a a big belly that's not squishy um we think that's a little bit less healthy because that fats around the organs um and when we look at Fitness we we've gotten away from looking at numbers on a scale or that weird calculation of BMI that really didn't do much for us being able to determine the health of an individual but we do look at how much of your body is fat versus the fat free Mass which is the bones in the blood and skin and all of that stuff and so we do have um some calculations on that so um like somebody who weighs 200 pounds could have a lot of fat and very little muscle or somebody who weighs 200 pounds could have very little fat and they are all like big bulky muscles so those the percentage of body fat and when where the body fat is located is far more predictive of longevity and risk of disease than any random number on a scale or that BMI number so you should start seeing your Physicians and all that moving away from the BMI um it's kind of quick and easy and their computers are set up to do it so it might take a while but um just know that um we have a body composition scale in um in the anatomy lab so if you're interested in seeing your fat to fat free Mass um we could do that for you okay so moving away from adipose now we're going to talk about a real R connective tissue this is the one that we call fascia the one that is connecting the skin the epithelials to the muscles we'll also see this wrapping around different muscle cells so if you are very active and you get those little kind of knots in your muscles or trigger points they call them with their really tender that is um that's occurring here in this fascia and we actually want to break that up so that your muscles can continue to move and be flexible this tissue like I said anchors epithelials to the the muscles it is stretchy this looks like under the microscope so here are your cells the fibroblasts and the white blood cells um there are very few of them you have all three kinds of fibers in this tissue the fat strong collagens the stretchy elastics and the tiny particular ones that these cells will kind of cling onto it is very vascular it regenerates a lot and because it's located here between the muscle and the skin and has all this space this tissue is what will hold and soak up extra fluid so when you have edema if you have a trauma like a sprained ankle and your your ankle gets swollen that that um The Matrix in the a real or connective tissue acts kind of like a sponge and soaks that up that fluid up it also if you have high blood pressure or you know you're still for a while and you you see that your hands or your feet or your lower legs get kind of puffy that's where um the edema exists is in this a real R connective tissue all right in particular remember this is the one that looks like cherry trees um it is has reticular fibers and lots of them in this fine delicate mesh we find reticular connective tissue in your lymphatic structures your back is is um our organs that function in immune defense like your spleen your lymph nodes and your bone marrow and because we have a lot of cells in this tissue that are dueling remember that I said this is like a filtering tissue so fluid is is running through it and these cells kind of hold on to those reticular fibers I'm saying like they're a white blood cell and then if they recognize something that hey that's a germ it's not supposed to be there they kind of let go and then go after it and like the macrophages and then go out gobble it up and destroy it so that we don't get um sick it has more Matrix than adipose but less than the areolar only the reticular connective or fibers it has the fibroblasts that make the fiber the white blood cells the macrophages which are the Cookie Monsters and those mast cells from the immune cells highly vascular highly innervated all right so now we're going to go to the other kind of the connective tissue proper the dense and dense member is going to relate to the um the fiber arrangement so we're going to see dense regular fibrous connective tissue so that means dense lots of fibers regular means they all go in the same direction and you're going to see that has to do with its function you're going to see mostly collagen fibers in this dense regular so this is a very strong tissue a little bit of stretch with the elastic but because all of the cells and fibers are going in the same direction we're going to see that it's strong and stretchy but only in One Direction so this is what we're going to see like in your tendons and ligaments tendons attach your muscle to the Bone remember we talked about muscle contracts only one way um and so it makes sense that the tendons would only move one way for strength and stability same thing for ligaments ligaments attach bone to bone so you've got multiple ligaments you've probably heard of your ACL and your PCL and your MCN your LCL those are all the ligaments that wrap that knee joint but they only go from the femur to the tibia from your top leg bone to your lower leg bone they don't go sideways because we want to stabilize that joint and that that's their job strength and stability we're going to see fibers fibroblast cells in there this tissue is avascular and that is because it is mostly fibers and cells that make fiber so it's just it's like remember the collagen fibers are like the ropes so these are like just strong ropes um this is why if you get an injury in your tendon or ligament it takes a really long time to heal because uh there's not a lot of blood flow here we have to rely on uh diffusion slow generation and healing so just to be clear here this top one is the regular dense where all the fibers are going in One Direction This Is The Irregular which is the next slide coming up so but I wanted you to be able to see dense all these little white threads going in the same direction this irregular they're going in many directions and that is because the stretch for these kind of fibers is going to be not just two-dimensional it's going to be um three-dimensional if you pull a little bit of your skin up away from the muscle or the bone you'll see that it comes in many directions that's because um the connective tissue underneath the epithelial underneath the skin is this dense irregular connective tissue that goes in many directions um so here oh sorry let me go here because we just talked about this and we'll flip back to elastic so dense irregular is this one down here on the bottom same kind of collagen elastic but multi-directional in many ways vascular this one heals relatively quickly because it's vascular remember dense regular is avascular so if you uh tear your Achilles tendon it's going to take forever to heal but if you cut through the epidermis uh your your epithelial lining into the dermis you might get a little bit of blood but it's also going to heal relatively quickly all right let's go back here so the elastic fibers are what you would think lots of stretchy fibers All in One Direction we find them in your lungs right tissue that is constantly expanding and Contracting with every breath that you take and um in your large arteries that's like your aorta coming off of your heart because those vessels have to also expand and contract in relation to some hormones that are going to dictate that to maintain blood pressure and things like that um the elastic connective tissue is avascular which means it's going to be slower in generation all right so now that was all connective tissue proper now we're going to go to the second category of connective tissue that is supporting supportive tissue which includes the subcategories of bone and cartilage bone is sometimes called osseous tissue so if you see that that means the same it functions in support and protection right our skeleton holds this up protects the vital organs bone has a solid Matrix so there's no liquid surrounding these cells it is actually the minerals like calcium phosphorus magnesium those kind of things that are mineralizing the Matrix for strength that helps the bone do its job it contains mostly collagen fibers for strength right bones don't flex very much so mostly collagen and um we are going to see three different kinds of bone cells so we see an osteocyte right site mean cell Osteo means bone that is a mature bone cell they kind of hang out and direct things like saying hey we you know deposit that calcium over here or take it out of here send it to the blood those kind of things the osteoblasts remember blast means they build or create things so these cells are the ones that are laying down the minerals and making the bones stronger the osteoclasts I always think of class like the cleanup crew they are um breaking down bone to liberate the minerals to take them to the blood to do whatever they need to do in the body we have two forms of bone tissue that we'll see the compact bone and spongy bone which is so sometimes compact bone is called cortical bone because it's on the outside um we have cancellous bone that's sometimes called spongy bone sometimes it's called trabecular bone I know it's crazy you have three all these different names from the same tissue all right compact bone looks like this under the microscope so it makes these things called osteons which look like these tree trunks and so they this is a blood vessel here and some nerves coming in here these are the blood cells the osteocytes the mature cells so once they the osteoblasts have surrounded the osteocyte with all this mineral then it becomes this osteocyte this mature cell we find compact bone on the outer edges of bone so your skull bones we haven't studied bones yet but your skull bones are what we call Flat bones they're like a sandwich we've got this hard uh layer of compact bone that has all these tree trunks really close to each other here two layers of that like the bread on a sandwich and then like the guts of your sandwich the spongy bone is in there you can see there's lots of spaces in the spongy bone we'll talk about that in just a second compact bone on your long bone this is a femur bone which is your upper leg bone but really all of your bones of your arms and legs are the long bones except your wrist and ankle bone sorry about that um and this outer shell is the compact or cortical bone but in the ends of the bone we're going to see the spongy bone here and here and then we're going to see this like cavity in the middle okay so the spongy bone this part here in the middle and then in the ends of the long bone looks like this so it's not like um the osteon it's gonna you're gonna have these little needle-like bones here but big spaces and the big spaces are where the bone marrow lives and um bone excuse me blood cells are made in the bone marrow so bone marrow exists in the spongy bone um in the ends of long bones and in between the middle layer of the sandwich of the skull and flat bones okay cartilage is our other kind of supporting tissue it is tough but it's more flexible than still pretty strong but it's more flexible again for its function and that is because it's going to have this like rubbery squishy gel Matrix so um watery but thicker than the fluid in the other tissues but not solid like bone um all cartilage has different kinds of fibers we'll look at that um it's going to have chondrocytes so chondro is your prefix for cartilage so these are sites that make cartilage where we had fibroblasts in some of the other tissues in cartilage we're going to see chondrocytes of all cartilage is a vascular that is why cartilage injuries take forever to heal um they don't hurt so much and unless you damage the tissue other tissues around them but the cartilage doesn't have any nerves in it at all slow generation after an injury and we have three sometimes that we'll look at next year so Highline cartilage is okay so this is your shoulder the end of your shoulder and this is the um end of your scapula um so your this is your upper arm bone and this is the Bony tissue here but at the end this smooth white shiny stuff is this hyaline cartilage if you've ever eaten uh like chicken or turkey and seen at the end of the bone you have that white shiny stuff that's the same Highline cartilage it looks like these beautiful purple bubbles under the microscope and that is because its job is to reduce friction we will find Highline cartilage where all bones touch another bone so when a bone touches another bone we call that articulating or a joint is an articulation and we don't want our bones rubbing toughly on us we want our bones to move smoothly and so at the end of each bone we have this smooth and shiny High Line cartilage it also makes up uh the flexible part of the end of your nose your larynx which is your voice box um if you feel in your throat the little ridges that keep your trachea your airway open those are made of hyaline cartilage hyaline cartilage attaches your ribs to your sternum they're in the growth plates of Bones of kids and um your fetal skeleton starts out all as hyaline cartilage and then slowly the bone deposits in there we don't we have fibers they're just very few and dissolved in here because again this is less of a strong tissue and more of a smooth reducing friction tissue fibrocartilage is um is a shock absorber cartilage it's kind of like like if you remember those big pink erasers you used to have in school kind of that consistency where um it can compress and so that will find it between bones that take a lot of shock so thinking if you're jumping up and down um all of your vertebrae in your back have a disc of fibrocartilage between them so that they're not rattling against each other and they're um not touching each other your pubic symphysis is where your hip bones come together in the front there's a lot of flex um and shock in that joint um we'll find them in the labrum of your hips and shoulders so again where your leg bone comes into your pelvis and where your arm bone comes into your shoulder we'll have a little cup of fiber cartilage to absorb some of the shock there and we have fibrocartilage in our knees we call that the meniscus if you know anyone who had a meniscus tear it usually takes forever to heal because again they're avascular if you wear out your meniscus it's going to hurt because you're not you're going to feel all the shock you don't have anything to absorb the shock um elastic cartilage is our third and final kind of cartilage it is elastic so it's got mostly elastic fibers it is stretchy and um it is found in areas that can bend and they will flip back right to their other uh shape um if you fold your ears forward and then let them go they go back exactly the way they're supposed to go because they're made mostly of elastic cartilage we also find elastic cartilage in your eustachian tubes those are the tubes that are in your ear that equalize pressure if you've ever been in an airplane or driving up a mountain and your ears are popping and cracking that is that elastic tissue stretching and recoiling to equalize the pressure and your epiglottis so I just remember this e for elastic and these three e places your epiglottis is the flap that covers your Airway um and when you swallow Foods your Airway to your lungs is always open except when you swallow and gets covered up on this little flap if you've ever been laughing or something when you're eating and uh food goes down the roll and probably you start kind of choking a little bit it's probably because it got stuck in there on that epiglottis and tried to go to your lungs instead and this is just a map that shows you different color codings of um the cartilage so here's all of your you can't really see um so you see there's a high line cartilage where these bones come together but also in that hip socket we're going to have some Fiber cartilage you can't really see but it's in here between if you've ever heard somebody who has a degenerative disc um that is a erosion of or slipping of this little disc of fiber cartilage we got it in your knees here all the red is the Highline articular cartilage there uh this is another picture um of it to show you the number of cells and how they're spread out okay and our last connective tissue is the fluid kind and that we have blood and lymph so blood is found in your blood vessels your arteries veins and capillaries its job is to transport gases oxygen and carbon dioxide nutrients right so the the food carbohydrates and fats and all that are going to go in there and your waste blood helps to regulate your body temperature and pH and is a place that um the immune cells can circulate and functions in defense there is a lot of Matrix so all these little red these little tiny red circles those are your red blood cells the white is the Matrix that we call plasma these kind of unique pink and blue cells are in this purple one right here those are we have different kinds of white blood cells those are immune cells and the little teeny tiny purple flecks right here those are platelets which are little um sticky fragments that we use for blood clotting the fancy word for red blood cells is erythrocytes a fancy word for white blood cells are it's leukocytes and the fancy word for platelets is thrombocytes you do want to learn those root words erythro leuko and thrombo we'll see those again throughout the course lymph is fluid that circulates through your body kind of like blood in in vessels kind of like um veins but there are no red blood cells and no platelets in lymph it is just tissue fluid so the lymphatics are what drain the extra fluid from your tissues and take it back to the circulation so if it didn't get um and about 15 is not reabsorbed in the tissue level like when it goes from artery or red blood to Blue Blood if you will and so these lymphatics are kind of one-way vessels that carry that tissue fluid back to the regular circulation it has lots of Matrix has lots of um red blood cells um excuse me not one let me take that back lots of white blood cells but no red blood cells or platelets um the other thing I forgot to tell you back here in blood is that like all connective tissue blood does have fibers but those fibers are dissolved in the plasma and they only show up when a chemical shows up and says hey we need this Blood to climate we've had an injury and then those fibers come out of the solution and then make the little mesh of a clot so that we can stop flow blood to places we don't want it to go lymph is the same way with the with the fibers that are dissolved okay you made it through connective tissue there was a lot there so make sure that you can reorganize those notes and charts and concept Maps so that you really understand the difference in those tissues