so we keep talking about the tissues and our next type is the connective tissues we mentioned negative tissue connects there is a certain general structure okay like like Generic idea about the connective petition what it consists off any connective tissue would have the ground substance which is just a bunch of proteins cane that ground substance I'm gonna find fibers those fibers are made out of proteins like collagen elastin and a bunch of different proteins that form reticular fibers different tissues will have different proportions of collagen fibers elastic fibers and reticular fibers does that make sense now if this when this proportion changes obviously the structure of the tissue changes and the function of the tissue changes we clear fibers the ground substance together form extra cellular matrix okay of the connective tissue the fibers have also different features different properties which define the properties of the tissue they present for instance collagen provides tissues with the integrity structural integrity you can find a lot of collagen in surprisingly bones okay elastic fibers obviously provide tissue with a certain degree of elasticity the more elastic fibers there are the more elastic the tissues reticular fibers which pretty much can be found only one type of connective tissue they form somewhat like a mesh like a filter okay now cellular components the major cell of connective tissue is the fibroblast the role of the fibroblast is to produce ground substance and fibers pretty much we create connective tissue does that make sense those are fibroblasts and in addition to the fibroblasts connective tissue may house a bunch of immune cells and it does house houses a bunch of immune cells can be lymphocytes macrophages neutrophils all those cells lymphocytes macrophages neutrophils and you can see them in this picture to your left neutrophils and lymphocytes and star-shaped macrophages they are responsible for the innate for the different components of immunity okay that's all you have to know about those three I don't really care which one is for adaptive which one is for innate we didn't even talk about immunity yet yes yes so if I tell you you know this cell protect this cell found in the connective tissue is the immune cell that protects us from pathogens you know lymphocyte or neutrophil and macrophage that clear mast cells my cells are the bad guys my cells in the connective tissue responsible for allergic reactions and you have that ichinose or you have hives but because of the mast cell degranulation know that they are responsible for allergy another very interesting type of connective tissue cell is the fat cell a Depot site the Depot side represent here a Depot site is essentially a fibroblast [Music] that is terminally differentiated you understand what it is what I what I just said terminally differentiate it what does that mean cell is differentiated huh yes it's again yeah so so when fibroblasts become extremely specialized they can specialize in being fat cells obviously fat cells store energy in the form of lot and they also cushion that's actually really important functional cushion protect now there are probably their connective tissue has the most type so you know you will have to learn a lot types of connective tissue but as we mentioned during a first class how do you eat an elephant piece-by-piece one bite at a time so instead of trying to memorize all ten or eleven types of connective tissue that you need to know I suggest we will break connective tissue down to several classes and then we'll break each class further first of all in all those different kinds of a connective tissue we can isolate and highlight so-called connective tissue proper what do you think proper means when we say connective tissue proper okay good very good so when we say connective tissue proper I mean like real connective tissue true connective tissue okay it's not appropriate oh well tendon is yes then then is a true connection issue yes mixed up with with cartilage so there is a connective tissue proper and we're gonna talk about connective tissue proper first there are two subtypes of connective tissue proper lose and dense do you follow me so far and there are three types of each three types of loose connective tissue proper and three types of death the first tissue that we're talking about is the loose areolar tissue you can see it in this this micrograph right here you can see a bunch of loosely you know located elastic fibers loose fibroblasts thicker collagen fibers okay and the function areolar tissue can be found practically everywhere it wraps around pretty much every order its main function is to cushion there's an inflammation it's most likely the areolar connective tissue there is an infiltration of white blood cells areolar connective tissue does that make sense so again everywhere everywhere under epithelium is areolar connective tissue and we will look at different tissues during our next class it happens every time students take the slide with area our connective tissue and then tell me you cannot find it there's some dirt on the slide it is not dirt that's how aureole our connective tissue looks like like dirt it's very unremarkable okay adipose connective tissue is also lose that is fat you can see the micrograph of adipose connective tissue with a large Depot size that are filled with fat they are so filled with fat that nucleus is squished sorry nucleus is squished to the side obviously adipocytes can be found everywhere the response to kind of give you sort of sneak peak fats can be fun there are two major types of fat well counting breasts okay let's say three breasts is sort of a separate fat that's you know it pretty much forms most of the breast tissue now in general we have subcutaneous fat and we have abdominal fat what the subcutaneous mean what do you think under the skin so if you pinch your skin you pinch the fat as well another type of fat is abdominal it's the fat that surrounds your abdominal organs okay and if you will got someone and open up the belly we will see organ covered in fat you may often see people it's most common in men more common in men rather than women men you know they look pretty feet otherwise but they have this large bellies okay like really large extended bellies that is because of the abdominal fat inside of the abdominal cavity and I've heard several medical students that when they first saw the autopsy of the person who has a lot of abdominal fat it's shocking how much fat is wrapping around the intestines it's like an apron made of fat interestingly enough subcutaneous fat and abdominal fat different features for instance if you would compare the body composition of a woman and a man men have less subcutaneous fat may have less subcutaneous fat than females females in general have more body fat but most of their body fat is subcutaneous fat in terms of the health implications abdominal fat is bad you know how well and you I'm gonna give you a certain number and I want you to keep it in mind two thirds of the US population are overweight third of the US population are obese so half of overweight people and not just over there are B's and obesity brings with that a lot of health problems you know hypertension hypercholesterolemia cardiac problems metabolic problems mostly sugar metabolism problems but it is pretty interesting that abdominal fat it makes the biggest impact on your well-being subcutaneous fat is often considered a healthy one okay so women have more healthy fat than men men accumulate abdominal fat much faster we don't know the exact mechanisms maybe it's hormonal maybe something else we don't know why it happens also women have born on average women have more fat than men huh babies so what what what about babies huh from what there you go it stores energy because look man I dispensable seriously you know after the conception you can get rid of them females have to carry the baby and give birth to baby I'm talking about completely biological standpoint don't take me wrong I'm not suggesting to eliminate all humans so women have to provide for baby so their survival is more critical and that extra fat provides extra energy in case of hunger that make sense well you're talking about this each single case but in general from the evolutionary standpoint having extra fat sort of provide sort of a savings account and insurance for survival over time that make sense so that that is one of the reasons why female well main reason why females on average have higher body fat content than males lose reticular connective tissue okay it can be found exclusively in the lymphoid organs and you can see here there's bunch of white blood cells in a bunch of reticular fibers so lymphoid organs meaning lymph nodes spleen okay now what happens in that reticular reticular connective tissue and lymph flows through the say lymph nodes this reticular fibers form a mesh that filters out all different kinds of crap okay this different kinds of crap stays in the lymph nodes and your immune system now has time to respond to it does that make sense so we've got three types of loose connective tissue proper Arriola adipose then reticular no the location nor the function clear let's move on dense dense connective tissue proper also three times regular a lot of collagen fibers remember what I told you about collagen collagen provides mechanical resilience to the tissues so this collagen fibers that can be found in the regular dense regular connective tissue they are oriented sort of in the same direction okay they are parallel does that make sense you're gonna find them in different types of tendons and ligaments okay if you would look at Arnold right there you can see the large assemble of ligaments in the front of the knee same goes with Arnold's right there that's dense regular connective tissue you see there on the right side of his head the white covering oh that that model that female figure on the right the white covering that's called aponeurosis it's also tendon okay tendons and ligaments now if you think about it they are very resilient to the force that is applied along the fibers that make sense I mean if you try to rip my hand out of the glenohumeral joint it's going to be pretty hard tendons will hold it you will probably dislocate it but raining attendant requires a lot of force but if you apply this force knock along the fibers but at an angle you can just rip it make sense so they withstand a lot of tension along one direction okay one direction well that is an irregular dense connective tissue okay it has collagen fibers that are oriented somewhat chaotically right so it will form structures that must withstand forces pulling on it in all possible directions for instance joint capsules fibrous capsule of the joints okay but it's in the shoulder joint like here elbow joint those capsules have to withstand pooling forces in every direction interestingly enough one of your skin layers is also composed of the dense irregular connective tissue because if you think about it your skin withstands pooling forces in all direction doesn't really reap my clear boss skin one of the layers in the skin specifically it's the reticular layer of the dermis is your dense irregular connective tissue because your skin withstands pooling forces right like muscles expand and skin starts to be pulled in all directions all at the same time it has within those forces it has not to be ripped apart okay finally elastic well the name kind of explains itself so done elastic connective tissue is elastic contains a lot of elastic fibers okay and the most two most important locations that I want you to be aware of are stretchable dilate able cubes the bronchi and large arteries think about this the bronchi can dilate and can constrict your arteries can dilate and can constrict that connective tissue that can be found in the walls of both arteries and bronchi first gives them enough mechanical resilience and an addition to that allows them to expand and contract because it's elastic does that make sense now before we move on to cartilage so far we have covered three types of loose connective tissue proper areolar adipose and reticular and three types of dense connective tissue proper regular irregular and elastic cartilage is another example of connective tissue classification wise it is now not a connective tissue appropriate sort of it's a little bit farther still connective tissue but it forms it leaves in its own right okay so there are three types of cartilage we're gonna start with a hyaline which is the most abundant a lot of collagen fibers you cannot really see them so yes so we have wait we have three types of loose connective tissue proper it's areolar adipose and reticular three types of adipose and reticular and three types of dense connective tissue proper regular the regular and elastic okay good now we go into cartilage and we talked about hyelin one first of all the cells that produce ground substance and you know extracellular matrix in general in cartilage are not fibroblasts they're special types of cells that are called chondroblasts or chondrocytes chondroblasts the different shade become conscious sites you can see chondrocytes in the empty pockets inside of the cartilage those printers or empty pockets called lacunae so there are a lot of collagen fibers in there and the extracellular matrix and the cartilage is pretty dense functionally cartilage sometimes can expose supports beause reinforces cushions okay hyaline cartilage is sort of a jack-of-all-trades so it's pretty decent in terms of you know withstanding tensile forces it's pretty decent in terms of withstanding pressure but keep in mind that I used the adjective pretty decent okay jack of all trades master of none so embryonic skeleton starts as the hyaline cartilage and this cartilage skeleton or suffice becomes you know turns into the bone not directly it covers the ends of the bone if you would look at Marvin right in that corner like the ends of the bones that form joints for instance the proximal end of the humerus and shoulder discovered in hyaline cartilage okay distal end of the humerus discovered in hyaline cartilage - okay ribs are connected to the sternum by the hyaline cartilage trachea to a large extent racquel cartilage is what actually forms four key if you would look at trachea it's the cycles of cartilage the Adam's apple right here it's a thyroid cartilage which is also highly okay that make sense Adam's apple is the highly it so the name anatomical name of that particular structure that you feel here is thyroid cartilage type wise it's highly that make sense now elastic cartilage is guess what elastic contains a lot of elastic fibers okay you can find it in essentially three locations one two and I cannot show you my epiglottis okay it's the little fragment of the cartilage that closes your larynx when you swallow preventing food from getting into the langston in turkey does that make sense those are only three places in human body where you can find elastic cartilage fibrocartilage so this has a lot of thick collagen fibers okay much smaller lacunae right and this type of cartilage fibrous cartilage of fibrocartilage can resist the pressure very well in withstands enormous pressure forces there are very few types very few places in the human body where you can see a lot of feel a lot of pressure first and foremost intervertebral discs if you would look at those those models of vertebral column in the side especially right one you see those great blueish discs between the vertebrae those are interpretable discs the pressure that they can with that withstand is pretty significant those of you who exercise no heavy lifting you can only imagine how much weight the lumbar portion of your vertebral column have has to carry when you stand with the weight all this all this weight all this pressure goes on those vertebral discs and they can withstand it pretty well you I don't think you can possibly lift the weight that would destroy that one if you do it wrong way that's a different story but you just stand straight they can withstand enormous that's another place you just mentioned so I was going to say meniscus of the knee okay now meniscus well Marvin is too far and how we gonna call this this whoa this gentle what's-his-name well that's Marvin let's call them Melvin Melvin okay so if you look at Melvin here meniscus is the layer of the cartilage they're two mini sigh okay the medial knee nice and lateral mini site that provide additional feet of the condyles of the femur and condyles of the tibia make sense now when you do lifting and start sort of shaking in your knees instead of going perfectly proper this movement the lateral movement may damage the meniscus and may tear the meniscus and then the knee gives up okay it's so it's knees are pretty pretty stable but any for vertical load but any lateral blow me well medial blood can hardly imagine but lateral blow will just kill them okay lateral movement they're not designed for lateral movement does that make sense so we've got intervertebral discs got mini site third place quite surprisingly is right here between your hip bones okay you cannot see it in this picture but now if I can live Melvin but here your few bones if you think about it the weight of your entire upper body relies on the hip bones that pressure pushes them together okay and that joint called pubic symphysis is where you can find fibrous cartilage as well because there's a lot of pressure there does that make sense yes good great question it is connected but it's a little stretchable the he bones during the delivery they they do not separate but they stretch somewhat and but they come back together okay make sense moving on so we've got three types of cartilage hyland elastic and fibers bone another type of connective tissues please bonus connective tissue it's not a separate type of tissue it is connective tissue right a lot of collagen actually it looks somewhat like a cartilage okay you can see the individual cells the osteocytes located in the lacunae okay bone is pretty heavily vascularized actually those openings here called central canal that's where the blood vessels are okay and the extracellular matrix consists of collagen fibers but the ground substance which contains proteins by itself is calcified mineralized that's why your bone is so hard okay the salts of calcium is what makes you bone hard so what what's gonna happen if you don't have enough calcium in your diet osteoporosis well in the earth usually it's called mostly osteomalacia because when what steel process is the disease that affects primarily females males to a lesser extent and is associated with hormonal changes with age it can be prevented by elevating calcium and the diet but not completely but if you are adult and you try to completely abstain from calcium your bones will become not only brittle they become soft and if you would look if you google severe osteomalacia you will see people that pretty much squished by the gravity they bones the deformed they they buddies i deformed okay in kids have you heard about rickets so rickets often and some physicians just that rickets effects every kid to a different extent because when they grow the age of two three four they grow so fast that they physically cannot acquire sufficient amount of calcium from the diet it's inevitable they will have certain degree of softness in the bones okay make sense well functionally supports protects stores minerals houses bone marrow which produces blood cells all kinds of does that make sense that's about also connective tissue what is connective tissue itself there's a lot of cells the ground substance for the blood is essentially plasma so this is your ground substance and it has a lot of mewn cells well red blood cells then the fibroblasts or anything and it's similar to it but tell me that it doesn't connect it connects everything every organ your body is connected to all other work is by a blood make sense so question good not in this class if you want test your blood types come to my microbiology class we're doing that okay we're doing a lot of other fun stuff as well like she's simply now to sum up with a connective tissue connective tissue proper let me do something here I don't know if it's gonna work but we'll try it doesn't make me any smarter the Smart Notebook come on come on dude I shouldn't have done that I just want to kind of make a sketch with you so you can see how you can draw it and classify it okay I mean how long will it take screw that I want it to be in the YouTube video so that's that's the only reason what is it blowed that many pages there we go okay so we've got connective tissue right so we have proper which can be what two types lose and dance loose can be ru or adipose and reticular dense can be regular irregular and elastic does that make sense you have cartilage which can be highly elastic and fibers you have blood and you have both remember I told you about drawing things that's sort of an example what I suggest you do okay so just you can do it look I mean I I understand it's unfair I know but you can do it in like a couple of minutes on the like piece of paper on the napkin on the paper towel okay you can throw it away just practice and then if you want you can take a larger piece of paper and just start writing and you know functions and whatnot does that make sense it kind of gives you a perspective it it gives a structure to your to your concepts right it's all in the YouTube don't worry about it muscle tissue the three types skeletal which is the only voluntary controlled muscle type and well to certain Excel we can vouch for nervous system also being voluntarily controlled but it's the only voluntarily controlled muscle skeletal responsible for movement movement I mean body movement locomotion okay striated you can see those little stripes on the surface of the muscle it's striate they called striations okay cells are multinucleated because they are multiple cells that a certain point have used together and the cells are straight unbranched fibers does that make sense skeletal muscles contract fast if you think about your movements it's really fast contraction Adam I'm not gonna tell you where they are look where skeletal muscle is located it's located in the skeletal muscle clear cardiac contraction is slower and it is of course in voluntary control cells of the cardiac muscle are branched you can see the branching and they generally have one nucleus they are also striated a skeletal are that make sense a Bisley cardiac muscle can be found in the heart and smooth muscle cells are known striated shape like a spindle each cell has its individual nucleus and you can find smooth muscles around kind of tubes not only there but mostly okay like stoma or intestine or ureter or walls of the bladder or gall bladder does that make sense everywhere you need the contraction of the tube everywhere you need propulsion smooth muscles contract slowly now before we move to the last type of tissue summary for the muscles skeletal fast contracting voluntary striated unbranched long cells and the only way you can stimulate skeletal muscle is by nerves cardiac involuntary contractions branch cells also striated can be stimulated by nervous stimuli hormonal stimuli chemical stimuli mechanical stimuli not only nervous okay which pretty much means you can rip the heart out of someone and it will still beat okay and its contractions are slower finally smooth muscles involuntary controlled non striated each cell has its own nucleus contract slow can be stimulated by nerves hormones chemicals mechanical stimulus okay for muscles control stimulus nervous or more than that and structural features striations yes or no number of nuclei branching does that make sense okay the last one nervous that's easy obviously I'm not gonna ask you where it's located on the exam that would be just giving you a question for free it's located in the nervous system nerves brain spinal cord okay now there are two major types of cells in the nervous system so neuron you can see the neuron here okay and glia you see the nuclei of the glial cells those little tiny dots neurons have sort of extensions on them some extensions are called dendrites let's breathe in neurons receive the signal some extensions called axons that's through which they relay the signal you don't have to know dendrites and axons yet it's the next topic the nervous system but so far understand that you know neurons are responsible for the signal transmission does that make sense by clearing that okay glio if neurons are responsible for the signal transmission what the function of the glial cell that it's like how many people are in Metallica there are four how does they to look like a bunch of busses why many people that help them to kick ass right so glial cells help neurons to kick ass real cells make sure that your ins function properly they maintain the you know they nourish them they protect them some types of glial cells insulate them electrically some types of glial cells protect them from pathogens glial cells is the supporting stuff okay neurons are they top performers am i clear I'm going to wrap it up now