connective tissue i like to think of connective tissue as the junk drawer of tissues you know how in most people's houses and if you don't have one you're entirely too organized and no one likes you but you know how in most houses there's a junk drawer and that drawer just kind of has a little bit of everything like ours has like light bulbs and old keys to cars we don't even have anymore not why we don't get rid of the keys old remotes to tvs we don't have anymore the point is it's kind of that go-to drawer when you need glue or a sharpie or something it's probably in the junk drawer connective tissue is kind of like that these tissues the previous picture uh see how it's all stringy looks like a stringy mess you have the dark pink a little bit thicker there those are the collagen and then you have those smaller kind of darker purpley strings those are the elastin so these are kind of the matrix if you look there's not a lot of cells in there i mean they're few and far between whereas epithelial tissue with cell cell cell cell cell all in a row connective tissue it's more about the matrix there are some connective tissues you won't even sell see the cells at all into the microscope so the collagen fibers were those big pink ropes on the previous slide the most abundant so you've got tons of these they're made of collagen protein they're very very tough so if you think about a rope if you pull on a rope it doesn't give that's the whole purpose of a rope whereas if you pull on a bungee cord it snaps back a bungee cord would be like elastin so elastin fibers were the like darker purple on the previous so if you think about what a bungee cord does or rubber band does how it needs to snap back you think about organs and tissues that do this like your lungs every time you take a breath you don't want your lungs to like wheeze out all slow you want them to snap back same thing with your skin if you pull on your skin you want it to snap back into place you don't want it to say stay all droopy like elephant skin and blood vessels when you get nice and angry and pissed off you want your blood pressure to shoot up you want those vessels to be able to adjust very quickly so collagen and elastin are crucial collagen for strength elastin for elasticity we want the best of both worlds like miley cyrus reticular fibers these are also called made of collagen collagenous and they surround blood vessels and some organs so they're just kind of a collagen that's in a different arrangement kind of like tying a rope in a knot it's still a rope but it has a different arrangement so the major cells of connective tissue that you'll see fibroblasts this is the most common so these guys make those proteins these guys make those collagen make those elastin so again blast means to build macrophages macro means large phage comes from my favorite science word that we had with cell parts phagocytosis so macrophages are large phagocytic cells that wander around they're kind of like garbage man they go around and like pack man up like the little pac-man used to do pac-man up foreign particles so they're garbage men and then mast cells release heparin and we're not too concerned about heparin does right at this moment but it prevents blood clotting and releases histamine and if you've ever heard of histamine you probably have if you have allergies or if you have some kind of inflammation so these are cells that have a very specific duty whenever we these things occur so if we look at this this looks like a creepy little alien moose head or something this is a fibroblast now this is with an electron microscope so we will never ever see this level of detail in our class but these guys are inside these connective tissues making those collagen and elastin fibers this is a picture of a macrophage so the bottom is the macrophage and look at the cell that he's eating you have to admire his spirit this macrophage is eating something like 10 times its size imagine eating a cheeseburger 10 times your size i mean i'd like to try a pickle would be like the size of a life preserver it'd be worth the effort but you got to admire the the the gumption of these cells it's like they really take on a lot they bite off more than they can chew see what i did there and a mast cell this is again for allergy response if you ever watch allergy commercials when they show kind of cartoons of the allergy response this is pretty much how they always draw a mast cell but structurally these are the big three that we care about and really just the top two for for lab identification collagen are the thicker ropes again when you pull on them they give you strength they don't stretch elastin kind of looks like the elastin in your underwear because its job is to stretch and then reticular fibers you can see they're kind of like they look like a mixture of the two but they're really just specialized collagen so they're also tough now vascularity with the epithelial cells we saw that epithelial tissue was not vascularized because we needed it to protect we didn't want to squirt blood everywhere but with connective tissue again kind of being like a junk drawer there's no hard and fast rule here all the tissues vary so you could have tissues connective tissues that are avascular not having blood poorly vascular having a little bit more and a very very bloody rich supply so it's just kind of all over the place as are their functions so because this is the junk drawer this is bone cartilage blood fat tendons ligaments i mean it's just ridiculous it does a ton of different functions so it forms the structural framework for the body if you're talking about bone and cartilage transports nutrients from waste if you're talking about blood provides protection if you're talking about bone cartilage and fat provides support and interconnection so your tendons and your ligaments and also these capitals that go across the joints and around your lymph nodes insulates and store energy and also makes the blood if you're talking about fat and bone marrow and contributes contributes to your body defenses and repair so your butt your blood because of your white blood cells your lymphatic system which is your immune system and dense connective tissue we're going to see that collagen kind of helps sow injuries back together so again this is an electron microscope more detailed than we've seen in lab but in lab we'll see these thick collagen fibers and these little stretchy elastin which are in yellow in this picture so your textbook and lab manual both kind of separate these into loose and dense i don't need you to know that for the lecture exam for the lecture exam i just need you to know the six types of connective tissue and they do have multiple names so this is areolar connective tissue or you can call it loose connective tissue or you can call it loose areolar connective tissue if you look at your anatomy list for lab this is one of the tissues that's on there so it kind of looks like a big stringy mess if you've ever seen like a jackson pollock painting it kind of looks like that it's just a big stringy random mess so if we look at this picture number one there is labeling the big thick collagen rope number two is labeling the little stringy elastin but you can see there's still a lot of space in between it's just a nice it's like a sweater that has a loose weave to it it's got a lot of holes in it then you can see the black circles everywhere those are the little cells so the matrix the the stuff around the cells is is crucial so this is everywhere in your body it wraps and cushions all your organs and it binds your muscles to other tissues so it's everywhere this is just showing it blown up a fibroblast now we don't see the details that we saw on that previous slide that look like a creepy moose head in lab we're just going to kind of see that this is a cell adipose adipose is fat one of my favorite tissues to look at under the microscope because it's so distinctive i think it looks like a bag of marshmallows all stuck in there so adipose is hard to miss fat has a lot of function in your body we saw that with chemistry that fat kind of gets a bad rep but remember you need two tablespoons of fat in your diet every day and so fat cushions your body is one of its big functions stores energy insulates your body keeps you warm so most of your organs have fat around them and most of um you know the area under your skin is going to have fat as well your eyeballs actually have big what they call orbital fat pads which i think sounds funny and so there are these big fat fat pads that cushion your eyeballs and somebody that suffers from severe severe anorexia or bulimia their body will actually feed on those fat pads for fuel and their eyes will sink back so that's always kind of an indicator that somebody's not eating properly so it again looks like a bunch of marshmallows reticular tissue this is one we are not iding under the microscope so you don't need to know too much about it because really it just supports other tissues it's just a specialized form of collagen so you can just see it's still collagen it's just a little thinner than those big ropes we've been seeing okay white fibrous connective tissue this is also dense connective tissue it has two names if you look at this the collagen is all running in the same direction so it looks like pink rivers so if you think about you know thousands and thousands of ropes all running in the same direction that's giving you a tremendous amount of strength these are your tendons and ligaments that connect your bones so the achilles tendon is one people are usually familiar with above the ankle that's what causes your foot to go up and down if you take your hand and press on that tissue especially if you're moving your foot up and down you can feel how rubbery that tendon is the patellar ligament which is the ligament beneath the knee that connects your knee to your tibia your lower leg bone again if you move your knee up and down and push on that you can feel how rubbery and tough this is but think about what we expect of our tendons and ligaments we are animals we move around like crazy and so these tissues get a lot of abuse so tendons attach muscle to bone and again i always think of the achilles tendon because he attaches your heel to your calf muscle ligaments are bone to bone so that's not crucial right now that'll be more important in our next unit when we start the skeleton for now we just need to see that tendons and ligaments are dense connective tissue and if you look at it it looks so strong but it's just strong in that direction it's kind of like a rope if you pull on rope from the ends it's very strong but if you pull from the middle you could fray your rope so if you took this tissue in this picture and pulled from right to left it would shred it would fray it's really only strong from top to bottom but if you think about tendons and liga tendons and ligaments they only have to be strong in that direction i mean my achilles tendon needs to be strong so i can lift my foot up and down and that's why it's so awful to be without it because your foot just kind of dangles there like if you've ever seen a good horror movie where somebody gets their achilles tendon cut ouch so dense connected connective tissue again we can just we need to know the three types so dense regular is the one we just saw all the collagen is going in the same direction parallel to the direction of the pole so very very strong tendons and ligaments dense irregular we'll see on the next slide the collagen is pulled in all kinds of crazy directions and so it's stronger and more than one plane it's not just strong in one direction it's strong all over and so we'll see you know places under your skin and your joints you need a little more power in every direction and then elastin is about stretchy stretchy snappy snappy so some of the ligaments between your vertebrae if you bend down and you expose your spinal cord you don't want to expose your spinal cord for very long so as soon as you stand back up those vertebrae snap right back together because of the elastic dense connective is like tug of war this is strong in this picture from right to left this would be strong in all directions so i picture this like if you tie a bunch of ropes to a rubber tire and pull in all directions it's like you wouldn't really get anywhere because everybody would be pulling in all directions you kind of just have have strength in all places and then elastan although kind of a blurry picture you can see it kind of looks like the elastic in your underwear so this is places where you need the tissue to be very snappy and here's a little bit better picture so this is highlighting that heart picture this is highlighting your aorta which is the largest artery in your body you get pissed off you need to send blood quickly to your body you need that guy to constrict and so we need it to constrict when we are pissed off but then relax when we go back to our normal blood pressure cartilage cartilage is avascular if you touch your nose and wiggle it that's cartilage so it lacks nerves if you've ever had a cartilage piercing a lot of people get the cartilage in their ear pierced or the cartilage in their nose pierced it doesn't hurt it'll hurt at first because you're going through epithelial tissue and some other connective tissues that may have more blood but by the time you hit the cartilage it doesn't hurt cartilage is 80 water that's why it can rebound after you squish it if you squish the tip of your nose and let go it bounces right back chondrocytes are the mature cartilage cells so for each one of the tissues you want to know the main cell players chondro like we had in the first lab means cartilage site means cell and then these cells are living in these little cavities called lacunae which we'll see on a picture there are three types of cartilage now in lab if you look at your list we're only id'ing hyaline cartilage elastic cartilage and fibrocartilage we still have to know details about for the lecture exam but as far as id'ing all we're ideing is hyaline cartilage so hyaline cartilage is charmingly called gristle if you ever eat meat that's got gristle in it it's the hyaline cartilage it's the most abundant in your body the matrix is pretty firm and it supports reinforces cushions and resists stress so we'll see in our next chapter that it's a big part of your embryonic skeleton it's also the like the ends of your joints like if you climb stairs and you can kind of feel your knee bumping and grinding it's got heart hyaline cartilage your costal cartilage which from the first lab costal meant rib nose cartilage your trachea which is your windpipe and your larynx which is your voice box so the point is you have this everywhere and one of its biggest job is to just cushion the bones as an animal you move around and we do not want bone on bone when bone grinds together it could wear down it could splinter causing excruciating pain cartilage prevents that so cartilage is almost like the rubber tires that are on your car to protect the rims elastic cartilage looks almost like hyland but it's got a lot of elastic in it so we'll see pictures here in a second but for me i think hyaline cartilage looks like jello under the microscope elastic cartilage looks like you have a bunch of hair in the jello nobody wants to eat that so this allows still some stretching and shape but it snaps back so like your ear if you take your ear and fold it and kind of bunch it up as much as you can as soon as you let go it goes right back to its normal ear shape the epiglottis the epiglottis is this little flap in the back of your throat we've all had a moment where we've eaten or drank something that goes down the wrong pipe as they say and so you cough really violently when things get down into your trachea when they were headed for the esophagus that shouldn't happen because you have this little flap of cartilage in the back your throat that when you're eating or drinking something it covers your windpipe but sometimes that little flap just doesn't close fast enough and then fibrocartilage fibro is the thickest in the sense that it has a lot of collagen in it so it's really really tough this hardly compresses it all it's kind of like tires on kids toys you know how hard plastic they are they don't really have any give so these are in your knee the cartilage in your knee and like your meniscus if you've ever heard of that and the intervertebral discs between your your spinal cord these take a beating think of what you do to your knees every single day so it's all about having like this thick cushion of fibrocartilage in that knee cavity so that way you know we don't we don't end up you know paralyzed by the time we're 10 years old from the abuse we put on our knees same thing with your back they always say lift with your legs not with your back your back takes a lot of pressure from your body all day long and we have to protect that spinal cord so this is a drawing of cartilage and i want you to notice kind of the purpley matrix that's like a jello substance again if you wiggle your nose you can kind of feel it the chondrocyte is labeled at the top that's just referring to the entire cell with its little nucleus there and then if you look there's that little lacunae which is either a little space out to the side or a space around the cell itself lacunae is space so if this these are living cells so if you think about the room you're sitting in right now if the ceiling were to open up and fill the room with jello you would drown because you need oxygen and you need to get rid of your carbon dioxide well these cells are the same they are living breathing cells they have to have oxygen and carbon dioxide so if i filled the room with jello but i gave you a straw to like reach the window or you know out the top of the room so you could still breathe you'd be able to survive for a little bit being colored covered in jello so these guys are able to survive because they get this little this little encasement around them called lacuna so this picture is what we've seen probably at this point you've seen in lab the hyaline cartilage so it's that costal cartilage so if you look at the rib cage let's shown in this picture here you have cartilage there this allows you to be able to expand your rib cage for breathing gives you a little bit of flexibility so again we've got a nucleus we have the lacunae the little space and then we have that jello matrix so this is hyaline cartilage i think under the microscope it looks like a bunch of eyeballs staring at you so again just another drawing of it elastic cartilage we do not have to id in lab but it's really easy to id i guess we just don't have the slides right now so you just have cartilage with it looks like a bunch of hair in it so that's elastin cartilage so for example in your ear again like you bend your ear it snaps back into place fibrocartilage we do not have to id and i'm glad because if we've done the tissue lab already this could be confused with a lot of other things dense connective or even maybe smooth muscle but you can see the difference between the first two it's not about really the matrix it's about the it's about the matrix but not the jello i guess it's more about those crazy collagen ropes so you can see by looking at this with the collagen in there these guys are really really strong osseous tissue you can just call it bone but it is osseous is the appropriate term for bone so bone supports protects and provides a framework for your body so the location the bones duh vascularity bone is very very bloody those of you that broke a bone usually end up with horrific bruising afterwards because bone is so bloody there's also a lot of nerve supply if you've ever broke a bone which i haven't knock on wood i'm gonna be 40 soon and i've never broke a bone but i've seen it done it does not look like a good time it doesn't sound like a good time it's bloody and extremely painful because this tissue is very very vascularized but think about how important that is bone heals really really quickly cartilage really doesn't i still have piercings in my ears from when i was two years old and i hardly ever remember to wear earrings but i can still feel the little hole in that cartilage now sometimes when i decide to wear earrings i have to kind of pierce through the epithelial tissue that's grown over the hole but otherwise that hole pretty much stays in there because cartilage is a vascular it doesn't heal very well so those little cartilage cells have to rely on diffusion to feed themselves so they have that little lacunae that little space that oxygen can diffuse in and carbon dioxide can diffuse out but that's no way to heal it's a very slow process like i've said before sitting there waiting for somebody to feed you isn't as efficient as just going and feeding yourselves so bone tissue has a blood supply so it heals really really fast in fact sometimes after a break the bone starts to heal back like immediately there are people that actually have to go and get their bones rebroke because they knitted back together so quickly and not really properly so lots and lots of blood so bone is made of collagen so we're still going to see those big big protein ropes and also a lot of mineral salts calcium carbonate calcium phosphate makes the matrix so bone tissue is arranged in cylinders that surround central canals central canals are where the blood is so bone matrix gets deposited in these concentric rings around the central canal kind of like tree rings we call these lamella you don't really have to know that word but we'll see it a lot in anatomy because it's just kind of this ring-like structure so a central canal is the blood is the hole the lamella are the rings one of those is an osteon which will make more sense when we see a picture we're still going to see lacunae we're still going to see little cavities that contain the osteocytes so osteo means bone site means cell the mature bone cells are osteocytes and then caniculi are these little canals that connect the osteocytes so again if we look at this picture it makes more sense so this is bone bone i think under the microscope looks like tree rings or barnacles it's very pretty so if you look at the picture below we have that red and blue little artery and vein running through that central canal which they've labeled haversian canal i think central canal is a lot easier so blood is life it's kind of like water if you look at the map of the united states and you look at where major cities are there's you know new york la chicago they're all next to water because that's how we ship and still ship how we shipped and still ship a lot of our project or a lot of our products we had to have access to water also water is life i mean you don't see a lot of people setting up shop in the dead of arizona unless they have a water supply we can't survive without water so if you think water is life well so is blood so if i'm a bone cell i want to be as close to that blood supply as i can or you think about a party anytime i'm at a party i want to be close to the bar because i don't like to be thirsty so if i get to where i'm so far away from the bar i might as well go to a new party and that's kind of how these cells are they will lay themselves down in concentric rings around that blood till they get so far away they might as well find a new blood vessel to settle around and so this picture's a little bit better so they've labeled a whole osteon i think of an osteon as like if you look at a case of soda or a case of beer from the top you have the holes where the beer comes through and then you have the rest of the metal lid so if you look at this it kind of looks like that kind of looks like the top of a soda can where the osteon is the hole where the liquid goes through and then the lamella are these concentric rings that the bone cells get laid around so again the farther you get from the blood you're not going to get as much oxygen eventually you're going to get so far away that you won't get served just like getting too far away from the bar so it's best to just find a new bar find a new central canal now those osteocytes are inside those tiny little lacunae those tiny little black dots everywhere so we will never see an osteocyte you have to have a com or you have to have a much more high powered electron microscope to see an osteocyte our little compound microscopes will never see them but we know that they're there and then if you look at those faint lines that are kind of running everywhere connecting all of those osteocytes in their lacunae you see they're labeled caniculi think of these like driveways every house has a driveway to ultimately connect it back to a larger road in this case all these osteocytes have coniculi so that can ultimately connect them back to that central canal so they can get their blood and get rid of their waste so this is showing an illustration of an osteocyte we will never see because they're just too small but we know that they're there blood blood is a connective tissue it always seems really strange to me that blood is a connective tissue because blood is liquid but remember a tissue is just a group of cells a bunch of cells working together so blood is a bunch of cells working together so it fits the description even though it's a liquid so the matrix here is the plasma the plasma is the watery portion of the blood that's the majority of your blood then we have erythrocytes which are the red blood cells these are the most abundant so when you look at a blood smear there's tons and tons of red blood cells because they carry the oxygen and the carbon dioxide but mammals have lost their nuclei so our cells don't have nuclei and the benefit to that is there's more room to carry oxygen and carbon dioxide by kind of dumping that dead weight now leukocytes for amp1 we just need to know that leukocytes are white blood cells and they fight infection but for amp2 you will have to know the five different types and what they do so that's listed there is kind of an fyi at this point but we will be getting into those details i mention it only because these five look very different under the microscope so if you look at a blood smear the large kind of pinkish purple that are everywhere those are the red blood cells the erythrocytes so they carry oxygen and carbon dioxide when you look at them under the microscope they look like they have a clear center that's because they are biconcave they cave in on both sides like one of those if you've ever had one of those cream saver lifesavers that don't have the hole in them but they kind of have a thin center or one of those lifesaver mints that has the mint stuff on the inside that's kind of what our red blood cells look like so they're very thin in the middle so when you shine a bright light behind them like a microscope they look like they're transparent in the middle when they're really not they're just bi-concave then you notice that large dark purple guy up at the top that's a white blood cell the reason why a white blood cell stains so differently from a red is because it has a nucleus now a lot of other animals have nuclei we've as mammals we've lost ours birds still have theirs reptiles still have theirs amphibians still have theirs but mammals have lost theirs so we can carry more oxygen which makes us better but these white blood cells they stain differently because as that previous slide said they have different functions so they look different under the microscope but they're dna stains so at a crime scene they have to have at least a dimes sized amount of blood to get enough dna to do a dna test sometimes there's not enough blood to have enough white blood cells to get enough dna if you look at the little tiny tiny purple dot that's labeled on the bottom left at the bottom platelets platelets are for blood clotting and so those are kind of you know just tiny tiny tiny little bits of cells that you'll see but we'll get into their importance when we get into blood clotting and then the white background is the plasma it's mostly water so you need to be able to identify those four things for the lab practical erythrocytes the red blood cells leukocytes the white blood cells platelets the little chunks of cells and the plasma the white background but again we'll get into the specific types