so as we have established connective tissue comes in many forms and many types these different types and subtypes can be classified based on the connective tissue cells present as well as the amount and distribution of ground substance and protein fibers in the coming slides we will discuss the make up of each connective tissue type and subtype and how this makeup contributes to its function so taking a broad look at connective tissue and connective tissue can be classified into two general types connective tissue proper which is further divided into loose and dense connective tissue depending on the ratio of ground substance to protein fibers and specialized connective tissue which is further divided into cartilage bone and blood and which each contain a specialized connective tissue which is specific to that type of connective tissue only but coming back to look at each of those types individually and first looking at loose connective tissue and the fibers of loose connective tissue are Loosely arranged between cells in other words there is a high proportion of ground substance with relatively fewer protein fibers arranged in between it there are three subtypes of loose connective tissue these are areola connective tissue adapost tissue and reticular connective tissue and although each have that loose arrangement of fibers within the ground substance they are all structured slightly differently so looking at each of the loose connective tissue subtypes and arola tissue is one of the most widely distributed connective tissues it consists of collagen elastic and reticular fibers arranged in a random pattern around several kinds of cells including fibroblasts macres plasma cells osit mass cells and a few white blood cells all embedded in a semifluid ground substance arola tissue is found in and around nearly every body structure and that's why it's sometimes called the packaging material of the body it can also be found in the layer of tissue deep to the skin and around blood vessels nerves and organs the function of arola tissue is to provide support strength and elasticity to the structures adapost tissues uh contain cells called eposides or fat cells which are specialized connective tissue cells for the storage of triglycerides or fat with weight gain a fat cell will fill up with a single large triglyceride droplet in adults most of our adapost tissue is white this is the adapost tissue that contains one single triglyceride droplet per cell and it functions to serve as an energy store and for insulation and protection of different organs and Joints acts a little bit like a cushion in babies and infants and in very small amounts in adults we have brown adapost tissue this adapost tissue contains many triglyceride drets per cell it's also highly vascularized so has lots of blood vessels which is what gives it its brown color it also contains many mitochondria which help serve its major purpose which is to generate heat which happens as a byproduct of producing energy retic connective tissue is a fine interlacing network of reticular fibers and reticular cells cells our reticular cells are the specific type of fibr blast that produces reticular fibers reticular connective tissue uh forms the supporting framework of soft organs such as the liver spleen and lymph nodes as well as the basement membrane which is like the bottom layer of epithelial tissue and also layers surrounding blood vessels and muscles so taking a look at those connective tissue subtypes and we have our areola tissue on the left so with our thick collagen fibers some thinner branching elastic and reticular fibers we have our adapost tissue in the middle here so you can see this is a a white adose tissue this is one site or fat cell which fills up with triglycerides or fat with the increasing need to store energy and then we have our reticular connective tissue on the right so these dark bits here are our reticular fibers the purpley bluish dots are our reticular cells which is what produces these reticular fibers now with all of these images don't freak out that I'm going to provide you with a microscope and some slides and ask you to identify any of these particular subtypes I definitely won't be doing that I just wanted you to see what these tissues look like because then otherwise all of this information is just words so coming back to this figure and the other type of connective tissue proper that's found within the human body is dense connective tissue and dense connective tissue contains more fibers than loose connective tissue and they're more CL closely packed together with less ground substance in between within dense connective tissue we also have three subtypes these are regular connective tissue irregular connective tissue and elastic tissue so looking at those subtypes and dense regular connective tissue forms a shiny white extracellular Matrix made up mostly of collagen fibers arranged regularly or in parallel in bundles so nice and neatly or lined up next to one another this arrangement of mostly collagen fibers forms our tendons our ligaments and our apine Neurosis which are like sheetlike tendons that attach either muscle to muscle or muscle to Bone our regular connective tissue provides strong attachment between various structures and although this tissue is very strong when pulling along the line of the collagen fibers it can be prone to breakage when the line of force or the tension comes in from another angle our dense irregular connective tissue is also made up of primarily collagen fibers but this time arranged in an regular fashion it's often found in sheets such as the fascia or the tissue beneath the skin and around muscles surrounding the heart and surrounding the outer layer of bone also like dense irregular connective tissue uh sorry like dense regular connective tissue our irregular connective tissue provides strength to the tissue however because of that irregular arrangement of the fibers so they're not all only in one line it can actually provide strength in many directions which is important for structures like our skin our heart bone or gastro intestinal tract which can be pulled in all directions our elastic connective tissue as you would expect is made up mostly of elastic fibers for this reason elastic tissue is found within lung tissue bronchioles vocal cords and blood vessels elastic connective uh tissue allows organs to stretch but more importantly to recoil and to return to its original shape after being stretched so again taking a look at what these tissues actually look like and on the left we have our regular connective tissue so you can really clearly see those large numbers of collagen fibers that are all arranged in nice neat parallel lines this tissue in the middle is our irregular connective tissue so kind of looks the same but those lines are not all nice and neat the the collagen fibers are kind of all arranged all over the place and then the tissue on the right is our elastic fibers oh sorry our elastic tissue which is full of elastic fibers and you can see quite clearly here that this wavy structure will allow that tissue to stretch but then also recoil we then move on to our specialized connective tissue and the first type of specialized connective tissue is Cartage and cartilage consists of a dense network of collagen and elastic fibers firmly embedded in a gel-like ground substance cartilage can endure more stress than loose and dense connective tissue with its strength attributed to the higher proportion of collagen fibers and its resilience or its ability to bounce back after it's being compressed due to that gel-like um consistency of the ground substance now cartilage differs slightly from other connective tissues and it has a very low or very poor blood supply and for that reason the ability cartilage to heal after it's damaged is quite low and quite slow so the first subtype of cartilage is elastic Cartage an elastic cartilage is made up of condra sides so our cartilage cells within a threadlike network of elastic protein fibers elastic cartilage is found in your epig glotus which is that flap of cartilage which covers your trachea or your windpipe when you swallow as well as the external part of your ear so the bit that you can kind of feel on the side of your head and the tubes that then lead into your brain or sorry into your skull elastic cartilage provides strength but also a high degree of elasticity to a structure and so it helps maintain the shape of certain structures that that are nonweightbearing Highland Cartage is made up of fine collagen fibers prominent condra sites and a resilient gel-like ground substance it appears Bluey white and really shiny within the body and it's actually the most abundant cartilage so this is the the greatest um type of cartilage within the body Highland cartilage is found at the end of a long bone the external portion of your nose the Brony and bronchioles within your lungs and then also the embryon called the fetal skeleton so at the ends of long bones Highland cartilage provides a really smooth surface for your joints so that your bones don't rub up against each other when we move it provides flexibility and support in the nose the Brony and the embryonic skeleton until that skeleton is then calcified and becomes hard however this type of carage is the weakest type of cage and it can actually be fractured if it's exposed to trauma lastly we have fibro Cartage which is made up of conicit among real really thick bundles of collagen fibers fibro cartilage is found in regions that bear weight so this could be the pubic symphysis which is where your two hipbones meet at the front the intervertebral discs which sit in between the vertebrae in our spine and the meniscus which is that pad of cartilage in in the knee which sits between the fe uh the FEMA sorry and the tibia fibro cartilage supports and join structures together and its strength and rigidity mainly due to those thick bundles of Collen fibers make it the strongest type of cartilage once again taking a look at those subtypes of cartilage and on the left here we have our Highland cartilage with that gelike ground substance and then the prominent condra sites there aren't as many cells or fibers in this type of cartilage so it can be quite thin like at the end of a long bone this middle image is our fibro cartilage so you can see all those long lines of Collen that's nice and densely packed in together so it gives us um a nice amount of strength on the right we have our elastic Cartage and all of these dark purple lines are our elastic fibers surrounding those white bits which are our condra sites our next type of specialized connective tissue is bone and I'm not going to go into too much detail about bone because the sceletal system and Bone tissue will be the focus of the next series of modules and recordings however bone has two subtypes compact bone and spongy bone so bone tissue supports soft tissues it protects delicate structures and it works with sceletal muscle to generate movement bone stores calcium and phosphorus it houses red bone marrow which produces blood cells and it contains yellow bone marrow which is a storage site for triglycerides or for fat bone tissue can be classified as either compact or spongy with compact bone being made up of oans which are these circular structures here which all form in quite close proximity to one another to form quite a compact and dens looking bone it sits on the outside of all of our bones spongy bone is made up of tracula which is this kind of like branching network of bone here there's more space between the branches of tracula which makes the bone more flexible and light but red bone marrow forms Within These spaces which is where our blood cells are produced both types of bone tissue are made up primarily of collagen fibers which give it its strength the ground substance of bone tissue is also mineralized or calcified which adds to its hardness finally the last type of specialized connective tissue is blood and again like bone I'm not going to cover blood in too much detail as it's covered um in Blood and the cardiovascular system in a number of other units however blood is a special type of liquid connective tissue which has a liquid extracellular Matrix this liquid extracellular Matrix is made up of blood plasma suspended in the blood plasma are formed elements so namely red blood cells white blood cells and platelets so we have our red blood cells here our white blood cells and our platelets blood is the only type of connective tissue which does not contain any fibers