Transcript for:
Overview of Tissue Types and Functions

alright guys this is part one of the tissue lecture alright so when we think of tissues again we're talking about groups of cells okay they could be the same cell or there could be different cells I they're closely associated meaning that they're they're close to one another right and they're working together to provide a common function alright so for example if we take okay there's 210 different kinds of cells we take a little bit of this a little bit of that can't we put them together and they start doing something well then we have a tissue alright so based upon that definition okay it seems that tissues are just cells okay and the answer okay response to that is however rights well however dot dot dot so however tissues aren't just made up of only cells all right you also have it just the cells you have fibers you have fluid right you have stuff that's outside and in between the cells all right so what are the four major categories of tissues again right so we talked about okay epithelial tissue in lab okay we also talked about connective tissue in lab okay and we briefly mentioned muscle tissue and nervous tissue alright so if I'm gonna give a one word okay kind of explanation of what each one of these things do okay if I talk about epithelial tissue okay I'm gonna talk about covering alright or you can say lining so anytime I have to cover or line some part of my body you're gonna use an epithelial tissue alright so for example your skin is made up of an epithelial tissue called the epidermis so if you were to scratch your skin right now you're scratching the epithelial tissue part of your skin right the epidermis so covering the outside your body isn't everything covering okay the outside your stomach all right the organ the stomach covering okay or lining the inside of your stomach the lumen of your stomach alright so if I have to cover or line anything you're gonna use okay and epithelial tissue and epithelium the next one is a connective tissue and and comparing connected tissues with with the other three these are probably the most diverse in terms of what they do for your body all right so something as solid as bone as a connective tissue something as liquid as blood is also considered a connective tissue right so does lots of different things okay but if I want describe generally speaking what connected tissues do for you okay we think about binding okay other tissues or other organs of your body together we think about supporting okay other tissues or other organs of your body so binding and supporting would be a general function of connective tissues at the third one is nervous tissue so nervous tissue you think about for example neurons you think about supporting cells you've heard of a Schwann cell before okay you think about your brain okay you think about your spinal cord or do you think about nerves that come off of your brain and spinal cord alright so when you think about the nervous system you think about communication okay so if our body has to communicate from one part of your body to another v your body hey we're gonna use your nervous system hey we also have control if I want to control some aspect of our body okay for example voluntarily moving your hand or your arm alright involuntarily a causing your heart to beat right so we have what's called the nervous to the nervous tissue there and the last one is muscle alright and generally speaking we think about muscle we think about movement and there are different types of muscle tissue out there there's skeletal there's cardiac there smooth okay buddy regardless of what type of tissue we talk about in terms of muscle okay generally we're moving something alright so if you guys recall our hierarchy we started off at cells okay cells now we're talking about tissues in this chapter and ultimately okay we're gonna start taking these four tissues that we just saw in the previous slide and we're gonna start weaving them together okay to make the next level in our hierarchy known as organs okay so here in this figure we see a stomach all right and the stomach is an organ all right so we have for example an epithelial tissue that covers the outside of stomach that separates that stomach from the rest of the other organs in your peritoneal cavity okay here we have another epithelium lining the lumen your stomach right we then have muscle we have smooth muscle present in the walls of your stomach all right we have a nervous tissue that controls your stomach so here is an organ for example okay that has different tissues working together to vikon function well then by definition we call that an organ there all right so in lab okay when we talked about all the different types of tissues we specifically we concentrated on epithelial and connective well what you're doing in lab by studying those slides okay you are basically doing a branch of biology known as histology all right so chapter four okay it does talk about tissues talks about all four different types okay but its main concentration in terms of right giving a lot more detail okay we're gonna talk about epithelial and we're gonna talk about connective tissues right at the very end of this okay packet we're also gonna talk about nervous we're gonna time a muscle okay but in not so much detail okay and the reason for that is because right nervous okay has its own packet the nervous system packet and then muscle has its own packet the muscle system packet so when we reach those two packets later on in this in the term okay you're gonna then okay get more detail on both nervous and muscle tissue okay so we're gonna mention those two but our main concentration is gonna be epithelial connective okay so we're gonna off with part one of this video okay and then part two will be unconnected we're gonna be talking about epithelial tissue here alright now if you look at the title okay of this slide it says epithelia and glance alright epithelia and glands and the reason why we include glands here okay is because glands are derived from epithet okay if somewhere to ask you okay where do your glands come from where do where do sweat glands come from where do salivary glands come from where do mammary glands come from well they are derived from at the ethereal tissue all right now what is an epithelium okay epithelium epithelia referring to the same thing what is in episode well remember it's the tissue that covers or lines some part of your body okay so if it's gonna cover or line some part of your body okay we need to form a continuous sheet of cells right so imagine guys looking at a tiled floor all right so what's gonna make that floor isn't just one tile you need many tiles coming together connected to one another to produce a continuous sheet of tiles which is gonna then make a floor all right it's the same thing here you cannot make an entire epithelium with just one cell you need lots of cells come together that are joined to one another to form a continuous sheet of cells okay that now forms something that can cover or align part your body so think about we're gonna make a quilt we need individual patches to make this entire sheet of patches to make an entire quilt okay to make a lining to make a membrane all right so here for example let's say we took a cross-section of your small intestine which is a part of your your digestive tract all right and what we're gonna do really quickly just draw on our pseudo white board here okay we're gonna draw let's say a portion of your small intestine and let's say we're doing a cross-section of that small intestine okay so here's the cross section right here is what we call the lumen right this is where right the food would travel through this is the lumen all right this is the wall of your small intestine in white and then out here well this is the rest of your peritoneal cavity okay and in this peritoneal cavity you find the other digestive organs case your stomach would be out here right your large intestine would be out here your liver would be out here okay but here we're just looking at the small intestine right here alright and what we're gonna do okay is we're gonna highlight just a portion of the small intestine right let's just highlight for example and magnify this part right here okay so if we blow that up all right what is that gonna look like right so we're gonna see something okay and we're kind of carving it out like this oops let me do this one more time we're gonna just carve out the part right here okay where we can see this part that separates the wall of the small testing from the rest of the peritoneal cavity okay and then we have the lumen that's out here or in here okay so we're here would you expect to find an epithet something that covers or alliance well I'm gonna suspect lining the lumen okay this is gonna be an Epiphone all right so here okay that's an episode right here so this is gonna line the lumen okay where else would I find an epithelium here well I expect to find an epithelium right here all right separating the wall of your small intestine okay from the peritoneal cavity so this also is considered an epithelium all right so anytime I have to separate one environment from another for example I could separate the lumen from the wall of my small intestine you're gonna find it up a third if I have to separate the peritoneal cavity from the wall of my small intestine you're gonna find an epithelium right here all right so going back to that figure that we left off on okay here you can see the peritoneal cavity here's the lumen of your small intestine and we can see there is a sheet of cells each one of these okay columns you to see here for example right is an individual cell and each of the dots you see well those are the nuclei of these cells same thing here lining the lumen of your small intestine right is an epithelium a sheet of cells separating the lumen then from the wall with small tested alright so we did mention again glands on a sidenote gland or derive from epithelial tissue right so we're doing theater tissues okay do essentially well they they happen or occur at the interface again between two different environments from the lumen to the Walla small intestine with a peritoneal cavity to the wall or small intestine alright so because we find it an interface before this we find it separating two different environments alright what are some functions of an Epiphone well anytime okay that your body has to right absorb anything anytime your body has to give away anything okay remove it from the body absorption and secretion okay you must pass through an epithelium all right so if I'm talking about okay food traveling through the lumen of your small intestine again right cuz in the lumen of small test and this is where right the food would be okay the food would be here okay and in your food or nutrients okay and in the wallet small intestine this is we're gonna find the blood vessels that are gonna absorb those nutrients so how do I get now the food okay which is present in the lumen of my small intestine the nutrients okay how do I get it into my body how do I get it into my blood well it has to pass through an epithet okay and we call this absorption right at the same time all right what if I want to for example secrete something like sweat right so here's the surface of your body right here's an invagination a of that and let's call this thing down here this is a sweat gland right well here's my epithelium right here okay here's my sheet of cells okay that are covering my body well to get that sweat out of your body well you make the sweat here in the gland okay and then ultimately you have to pass through an epithelium so that the sweat that is secreted okay out of your body so this idea of either absorbing something or secreting something you have to pass through an epithelium okay so that's one of the functions guys right of an epithet secretion and absorption right protection would be another one why well we'll think about the epitome that's that's part of your skin so if you fall down on your skateboard or if you fall down okay and okay scrape your arm against nono right the counter you need something there that can now protect you from that abrasion so we have an episode that's not just a single hair cells on our skin we actually have an episode that is multiple layers of cells right you've ever script your arm and you weren't bleeding well the reason for that is because that you you you may be slopped away a couple layers of epithelium but down here the capillaries these weren't damaged that's why you weren't bleeding all right now parts where you did fall down and you were bleeding what happened well you probably burned through the whole layer of epithelium and then you started messing up then down in the connective tissue the blood vessels okay so protection is another function of Epiphone right sensory reception okay think about receiving touch think receiving right any type of stimuli okay a lot of those stimuli have to pass okay or be detected by an Epiphone all right and then filtration okay what's what's filtration yeah this isn't simply absorption and secretion and this isn't the idea of just diffusion what we're talking about here right in terms of filtration is we're dealing with blood vessels all right so let's say there's a blood vessel right here alright and let's say we have some type of molecule that's being carried inside your blood all right well there's pressure called hydrostatic pressure that is on the side of the arteries and what can happen is that pressure can now force things out of your blood vessels okay specifically out of your capillaries okay in this process of using pressure to force things across an epithelium okay and this in red that is an epithelium in red there okay the idea of using pressure to force things across epithelium well we call that process filtration all right so filtration a in terms of the epithelium is another function alright okay so what are some special characteristics of an epithelial tissue what are some special characteristics well number one okay is cellularity okay so when I think of an empathy is composed almost entirely of cells okay and the reason for that is because I have to form a sheet of cells right if I want to form something that covers or lines I can't have spaces or gaps between the cells in many cases right if I want to produce a nice floor okay you got to give me all the tiles I need to join together to produce one continuous floor okay and the tiles have to be pretty much one right on top of the other they got to be touching each other to form a nice tiled floor it's the same thing with an epithelium okay pretty much just composed entirely of cells okay cell after cell after cell after cell all right so if I wanted again to separate the two like say here is some type of okay outside environment okay here's some type of inside environment and wanted to separate the two well you better just make okay a continuous sheet of cells so here's one cell join to another cell join to another cell so forth and so on so by forming a nice continuous sheet of cells you have now just formed an epithelium here okay so I put the tissues are pretty much made up entirely of cells all right the second special characteristics are unique okay characteristic when epithelial tissue all right our cell contacts okay something has to be present that's joining the cells together right they're not just one night next few other nothing's holding them together alright so there's got to be something okay holding this cell next to that cell there's got to be something holding this cell with that so okay so that it forms a nice continuous sheet because the second these cells break apart well then there goes your epithelium there goes your your brain that separates one environment from another environment okay there must be something on the lateral sides of these cells that are holding them together okay they have special cell junctions all right the third thing okay if you look at it really quickly its polarity all right and we did touch upon this already in lab all right so when I think of an upper thames again okay it covers okay it separates two different environments from one another okay and one environment is gonna be what we call a free space okay this could be the outside your body this could be the lumen right of right of your stomach for example but this is a free space on the other side of epithelium right we are supported by a connective tissue okay I'll just previewed CT all right so one side when epidermis free space the other side is connected tissue okay what's your epithelium is not your epithelium is not like a magic carpet right when I think of a magic carpet like a Latin okay you're looking at space on one side of the magic carpet you can get free space on the other side okay and considering that the carpet is airborne right an epithelium okay one side is exposed to free space the other side is supported by a connective tissue all right so much like the analogy I gave with a tiled floor okay if you look at a tiled floor one side is exposed to the free space that part that you walk on okay but the other side of the tiled floor okay is supported by some type of foundation okay supported by concrete or supported by a piece of plywood down there okay so much like a tile floor this is the this is the top where you walk on this is the bottom part that's supported by the foundation okay we call that foundation the connective tissue alright so there's what we call polarity when we talk about an epithet polarity right so what does that mean well that means one side of the epithelium is different from the other side the side that is exposed to free space we call this the apical side of your epithelium okay the side that's supported by the connective tissue we call this the basal side of your empathy okay so there's dirty involved when we talk about an epithet right so that means we've tackled one too and we have pretty much as address cells okay there's got to be something holding these cells together special contacts all right there's number four okay we actually should this an order supported by connective tissue on the basal side right and because of that there's polarity there's an apical side supposed to than upper free space okay and then there's a basal side that's supported by the connective tissue alright number five a vascular but innervated alright so what does that mean a vascular but interview okay but you're never gonna find guys you're never gonna find blood vessels in epithelials up here okay down here in the connective tissue yeah okay there's gonna be blood vessels here alright so yes epithelial cells need blood so where did they get it from well they get it from the connective tissue so as stuff gets filtered out of the out of the blood here right out of the capillaries within your connective tissue those things then can be used okay to then support the epithelial cells again which do not have blood so when I say that epithelial tissues are a vascular we are saying that there are no blood vessels in epithet okay but it also says that blood cells are innervated okay so what does that mean well it's very possible okay you mind fine okay we cept yourselves okay present within an epithet all right for example the receptors for touch in your in your epidermis in your skin okay those receptors for touch are called Merkel cells which we'll talk about later right in Chapter five okay and these Merkel cells are present okay intermingled with all of the other epithelial cells okay so we say a vaster there's no blood vessels in up with them we say innervated okay to highlight the fact that you may find receptor cells present within an Epiphone all right and the last special characteristic okay it's high regenerative capacity okay and what does that mean okay it means that cells that are lost in an episode are easily replaced right so if I'm if I'm dealing with okay in this case an epitome that's not just one layer of cells let's say I'm dealing with an epithelium that is multiple layers of cells alright so if I have something for example I'm just doing it on this side of dip with them that looks like this alright and you go for a walk and you trip on something and you fall down right and you scrape your arm well what's probably gonna happen when you scrape their arm okay is that a couple layers of cells of your skin okay just we're lost okay so I fall down I scraped my arm I lose that say the top two layers of cells in my epidermis or am i epithet well what does that mean does that mean those two layers of cells are now completely lost forever okay and the answer is no right the reason why is because you have this ability now to divide and produce brand-new cells to replace the cells that were lost okay so all of a sudden boom okay those cells come back okay so we say that an epithelial tissue has high regenerative capacity it has that ability okay to replace any cells that are lost any cells that are old any cells that have been damaged alright so those are the six unique special characteristics of an epithelial tissue all right so again we did touch upon this in the in the tissue lab all right what we're gonna talk about it again in lecture all right because again when we when we test you guys for lecture and lab okay lecture lab are tested separately right so stuff that I teach you a lab or in the form of lab exams stuff that I teach you in lecture on the form of midterms quizzes or finals right so the fact that I touched upon this in lab means that it's up for grabbing lab on a lot of exam well the fact that I'm touching upon it again now in lecture well it just means that you have to also know this also for lecture okay all right so when I talk about an epithelial tissue alright you name it by giving it a first name and you name it by giving it a last name it has a first and last name looks like many of us right so the first name is based upon the changement or the relative number of layers present in the episode okay so we're gonna see that there are some up with them that are very thin consisting just of a single layer of cells okay we're also gonna see some examples of epithelium okay that are two or more layers of cells okay and that's the case if you're talking about something that has two or more layers of cells okay it's a thicker Epiphone it's a thicker membrane alright so first name arrangement how many layers am I talking about a single layer or two or more layers all right the second name we give tour up to him okay is based upon cell shape right so much like if you had Legos right there's different kinds of shapes of Legos that you can use to build whatever you're building it's the same thing here okay we're gonna have different types of cell shapes we can use to make our epithelium alright and we'll get into that right so let's talk about the first part the arrangement right so again if I'm dealing with a single layers of cells you call that a simple epithelium okay but if I'm dealing with now in this case one two three four five two or more layers of cells a thicker up with them we call that a stratified epithelia where you have stratified epithet for means single layer cells stratified means two or more layers of cells okay now the last name we give to an episode again is based upon this cell shape okay and there's only three types of legos right that we can use to make our structure in this case there's only three types of cell shapes that we can use to make our epithelium okay so we have cells that are very flat okay they're squished they're squamous cells so cells that are wider than they are taller right we call those squamous okay and then we have cells that are tall as they are wide alright we could make shaped like cubes we call these cuboidal cells okay or we can have cells that are taller than the are wider it's shaped like columns so then we call these columnar cells now if you notice the nuclei present in each of these squamous cuboidal and columnar cells okay they conform to the shape of the cell so for squamous cells the nuclei are flat okay for cuboidal cells they're pretty much spherical right for columnar cells they're elongated they're more oval shaped in this case now stratified epithelium okay we're gonna name them all right based upon their cell shape okay stratified something okay same thing was simple simple something so if I go back to this over here okay the fact that it's a single layer cells is this a simple epithelium or is this a stratified up with them well that is a simple epithelium okay well I need a last name I need simple something is this a simple squamous is this a simple cuboidal or is this a simple columnar epithelium well these are flat squamous cells well this would be an example of a simple squamous epithelium okay you can use your imagination what if this was just a single layer of cuboidal cells well then I would call this a simple cuboidal what if this was a single layer of columnar cells well then I would call this a simple columnar epithelium all right so simple epitome are easy to name simple single layer well then what's l-shape am I using alright for the last name now for stratified episode as in this example here okay you can have one layer that are shaped like cubes and then layers somewhere else that are shaped like squamous cells so this is a mixture now of both cuboidal and squamous cells in this stratified episode so how do i name a stratified episode do I name it okay based upon all the cells I see so this would be a stratified cuboidal squamous epithelial cells I see on the basal side the sales and that that I see in the middle or the cells that I see on the apical side well when you name a stratified epithelium okay you name that stratified epithelium according to the cell shapes found at the apical surface of the epithelial side so if I go back to this okay and I see flat squamous cells on the apical surface exposed to the free space right I would call this a what well this would be considered a stratified why because I'm live dealing with more than two layers stratified what well what's the cell shape on the apical side squamous this is a stratified squamous epithelium okay so again you name a stratified book theorem based upon the cell shape you see on the apical surface of that elephant alright so again polarity okay we discussed this already on our pseudo white board but here's another slide I added this okay so here is a simple columnar epithelial layer of columnar cells okay so let's say this is the free space on top this is let's say the lumen of your stomach okay and down here this is a connective tissue okay so free space on one side connected tissue out there so where's April goers basal all right well the side supported by the connective tissues basal the step outside open to the free space we call that ebook all right now again simple columnar okay here's a stratified up with them okay why because we're now dealing with two or more layers what would you name the stratified up at them stratified what well.when based the last name based upon the cell shape we see on the apical side so here on the apical side I see cuboidal cells okay so this would be considered a stratified cuboidal epithelium all right now there's also two less easily categorized types of epitome okay you have what's called pseudo stratified epithelium and he has something called transitional epithet alright so pseudo means what means false or fake okay so it's a fake stratified epithelia fake stratified so is it stratified well the answer to that is no right it's if it's not stratified it must be simple so the way that you kind of determine whether you're looking at a stratified epithelium or if you're looking at a simple epitome when you look under the microscope okay it's all you have to do is figure out how many layers of nuclei art there are right so if I see something like this right so I'm gonna make this a stratified epithelium we'll figure out stratified what later on okay I'm not gonna get too complicated here it's gonna make just two layers ourselves so this would be a stratified squamous why because I'm looking at the cell shape on the apical side okay I see flat squamous cells here okay so this is some type of free space okay this is the connective tissue on the basal side okay so when you actually see this under microscope okay if I seen out two layers of nuclei so this is one layer of nuclei and then I see a second layer of nuclei well then I say to myself well two layers of cells well this must be a stratified epithet all right now whoever first looked at pseudo stratified underneath the microscope okay they probably saw two layers of nuclei all right but upon closer examination and what they realized was that they were actually dealing with a simple epithet well what's going on there well it's because they were looking at an epithelium that consisted of cells that had different heights some were tall some were medium okay and some were short epithelium so when that happens when you deal now with an epithelium that has now cells that are tall medium and short what then happens to the nuclei in terms of what you look at them under a microscope well if I look at this now I see one layer of nuclei okay I see a middle layer of nuclei okay and I see a bottom layer of nuclei so if you don't look at this carefully you're you think it looks like this well you're gonna call this a stratified up a thing okay but the fact now okay that you look closer it's just a single layer of cells well what does that tell me well it's a simple episode that looks stratified so this is a pseudo stratified columnar epithelia now in many cases you're also going to find these little hairs coming off on the apical side we call these cilia okay so you may hear pseudo stratified ciliated columnar epithelia alright and these little cilia are little multi LaPenta jiz so if you have a layer of mucus up here okay what can the cilia do well this sylia then can propel the mucus right in whatever direction that they're beating okay so let's say we're beating the mucus in that direction right the other one is called transitional okay transitional is technically a stratified epithet okay transitional you're actually looking at multiple layers of cells here okay so I'll just make this one over here on the left that transitional put them so you're saying yourself why don't they call it stratified something then why are they calling it transitional well transition means to change okay so those of you that might have glasses that have transitional lenses well those are the lenses that turn very dark when you walk outside into the brunt side bright sunlight but then clear up when you walk indoors right so transition means to change okay you only find transitional epithelium where in your urinary system organs okay so for example lining the wall of your bladder you're gonna find transitional okay your your ITER's okay okay a portion of your wreath row okay he's gonna have a little bit of transitional right and transition up with them allows now these things to stretch okay so imagine your bladder filling with urine well now it's able to stretch so transitional epithelium when the bladder for example is empties around six cell layers thick okay this is in a empty bladder okay but when your batter is now full what happens okay it changes to around three cell layers thick okay so why is that because transitional okay when it's empty has kind of scalloped appearance kind of it kind of invaginate sin word right so here's here's the lumen of your bladder but as that bladder begins to fill what happens well then you start to stretch the walls of your bladder and this thing that about three six layers thick okay it thins out okay and become something around three cell layers thick so when your bladder is empty all right it's really thick it kind of looks like this right six layers thick but when your bladder now okay is full it has to stretch out okay and it then becomes around three cell layers thick and it's why we call it transition it changes all right all right so kind of a very quick summary guys of what we just talked about right we can have simple epitome dealing with a single layer of cells for example simple squamous simple cuboidal or simple columnar okay and you can have stratified uh paths on meaning that you can have multiple layers of cells okay so here I see one two three four five six I see seven layers of cells okay but on the apical most side of my epitome I see flat squamous cells so this is called a stratified squamous epithelial okay there's also stratified columnar that's not shown right and then you have transitional which is a type of stratified up at them but again we call transitional this is the one okay found in the walls of your year in your system organs okay and then another type of simple epithelium called pseudo stratified you can actually see in this figure here right cells have a columnar cells that are tall called ourselves that are medium and then Cullen ourselves they're short that I give again give that staggered nuclei okay appearance okay making it seem like it's stratified but in actuality it's a simple epithet all right so why do we have different kinds of times of episode and the answer to this is the very first time that I gave you guys a lecture structure determines function okay the reason why we have different types of episodes in purses stratified simple squamous versus simple cuboidal like it's because of function right if depending on what's going on in that particular region of your body that you're covering or lining you're gonna find a different type of epithet all right so let's first tackle guys the simple up with them okay so these ones here they are very thin okay you can have simple squamous which is the thinnest you have simple cuboidal okay which is a little thicker made up of little chunkier cells and then you have a simple columnar okay consisting you move even bigger cells so if you really take a wild guess guys okay based upon that statement structure determines function okay what do you think is gonna happen at a simple up with them hey and this is where I typically tell my students this okay there's a lot of material right and we're gonna be covering everything from cells all the way to the entire body okay and that's why people consider this class hard is because just the vast amount of tear of material that you guys have to learn okay and in many cases memorize right and it's that last word that I said memorize that makes this cause really really really hard okay so if you have to memorize all of this stuff it's gonna be tough all right as opposed to understanding the material all right and then kind of figure it out without memorizing so if I'm telling you structure determines function okay and I just talked about simple epithelium as being just a single air cells can you guess before I even teach you guys this stuff what do you think okay is the function of simple epithelium after I just described its structure to you okay do you think this is gonna be involved in protection yes or no just a single layer of cells do you think this is involved in protection the answer is no all right if I just have a single layer cell separating one environment from another okay it's gonna be very easy to bust through that one layer cells so I'm not gonna put a simple episode where I need to protect something like if I fall off my my skateboard and scrape my arm on the sidewalk right do you think some puppet um is involved in allowing things to pass easily the answer is yes if I wanted to get something from once okay from a free space and this on my body from up forth from the inside of my body to some type some type of free space I don't have to go through multiple layers cells give me just one layer cells to get through okay to pass through this episode so that's a good example guys of either memorizing I can tell you this you can memorize all these functions or you can just make sense of it you can understand what you're dealing with and then figure it out all right and that's Mike you know people that actually really get this class and do very very very very well are people that make sense they understand the material and they use that information to kind of figure out the problem as opposed to simple up with filtration diffusion write a simple cuboidal secretion absorption having no idea what they're memorizing okay they're just blurting out facts so when this class is done and they asked them the professor asks the students again what is a simple episode oh uh I forgot because you just memorized the crap alright so understand the material as opposed to just memorizing stuff okay simple epithet okay single layer cells okay so if I'm gonna guess this is probably involved in something that's gonna allow things to easily pass through my ipython so here's simple squamous okay it's the thinnest of all the different up a thumb that we're gonna talk about so the function for this is passive diffusion and filtration passive diffusion and filtration all right so what's the difference between diffusion and filtration again all right so when I think about diffusion it's this idea of things going from a high concentration right to a low concentration okay and this happens passively you don't need energy for this to occur right things will move from high to low on their own so if I'm talking about diffusion okay as the mechanism by which I'm passing my up at them well you better give me a very thin epitome for that to occur okay we're gonna use simple squamous for that okay so this is diffusion well what's filtration well filtration is this idea of using pressure again right so let's say okay this is okay a Kapler okay and it's on my capillary is blood well what kind of epithermal guys do you think you're gonna be finding here okay separating the lumen of your blood vessel from this connective tissue outside of this capillary okay this blood vessel well you're gonna find a simple squamous epithelium in the wall of this capillary okay so not all your blood vessels are lined with simple squamous capillaries okay our line was simple squamous so that what happens well then here's your heart beating okay and your heart creates something called hydro static pressure okay and what that hydrostatic pressure does is it takes the stuff that's in your blood okay and it pushes it through and across that simple squamous epithelium so if I'm pushing things across up at them you better not give me a very thick stratified up with them yours making it harder on me okay you better give me a nice okay spin up with them okay in this case the finish we got is simple squamous alright so hopefully you guys understand now the difference between diffusion and filtration now places where you find a simple squamous you find it an endotherm case all lining okay slick lining in the hollow organs so one thing about simple squamous is that it's a very slick and slippery okay so for example lining the inside of your blood vessels is an endothermic okay you don't want blood getting stuck on the walls okay of your of your blood vessels okay that's gonna cause blockages in clots right okay so you actually want nice a nice slip and slide going on in the lumen of your blood vessels so we're gonna line it with a simple squamous very slippery slippery slippery and slick all right you also find Amy's oath in you guys remember serosa right so serosa there was a visceral serosa that covers your organs your wrists organs there is a parietal serosa that lines your cavity walls okay and we also said one of the functions of that was what well it reduces friction hey we secrete in lubricating fluid that then when the organs rub up against one another or if they rub up against the walls of the cavity that they're housed in okay we have a nice slippery surface well that's serosa that we talked about in lecture and in lab that serosa is actually made up a simple squamous epithelia okay alright so we're gonna move from simple squamous now okay and we're gonna now talk about right simple cuboidal right and simple columnar a simple cuboidal and simple columnar okay so here we're just showing you blood vessels that I drew my pseudo whiteboard that's where you would find simple as mom's all right simple cuboidal epithelial cells okay and this simple columnar would be a single layer of columnar sauce all right now notice the function is not defeat infiltration the function for simple cuboidal is secretion and absorption the function for simple columnar is secretion and absorption all right so secretion and absorption versus diffusion and filtration for simple squamous so why the difference so what is secretion and absorption then so if diffusion is simply going from high to low no energy required and filtrations idea of pushing things across because of hydrostatic pressure okay what would secretion be well it's this idea right where let's say here is my epithelium simple cuboidal epithelium right and here's connective tissue down here and this is some type of free space this would be the lumen let's say of your digestive tract so secretion involves right taking stuff from your blood all right packaging in these cells okay producing it in these cells and then giving it off okay something like this now we talked about when we did the cell this idea of exocytosis right well that would be an example of secretion all right as opposed to absorption would be what well absorption would be taking stuff let's say from that free space that's out there okay and doing the opposite bring it into your body so that we can get into the blood that's down here in the connective tissue so there's something out here we're gonna then do endocytosis so that thing now is containing a vesicle okay and then we're gonna exocytosis it okay so now that thing is down here so now it can now hitch a ride in your blood okay so one thing I felt to mention over here is that the all these things that we're going to secrete we also have to package them in vesicles and do exocytosis so why is simple squamous diffusion and filtration whereas simple cuboidal and simple columnar are secretion and absorption well do you think this is gonna require do you think secretion absorption is gonna require energy do you think it's gonna require ATP for example yeah so I'm gonna need what are you gonna need that organelle we talked about in chapter 2 called the mitochondria so I need a lot more mitochondria do secretion absorption right now what what about this whole thing about endocytosis exocytosis you're gonna need lots of vesicles now okay so which one of these two cells a flat squamous cell okay a cuboidal cell and a columnar cell okay which one has more cytoplasm to house the necessary mitochondria to do secretion and to do absorption well cuboidal and columnar are gonna have more cytoplasm so you can house more mitochondria to do secretion absorption right well which one of these is gonna have more space for vesicles for endocytosis and exocytosis well cuboidal saw anna come to our cell number exocytosis and what starting translation on a free ribosome going to an attached ribosome on the rough ER from the rough ER going to the Golgi apparatus and then Golgi apparatus pathway one okay to do all that you better give me a cell that has enough cytoplasm to do that whole process so for secretion absorption more energy requiring processes and requires more of that free to attach to exocytosis you better give me a cell that has more okay cytoplasm to do that type of function okay all right so that is simple cuboidal that is simple columnar alright simple columnar you can have ciliated forms okay like you see here use little sis little silly on the apical side or you can have non ciliated forms meaning that okay it doesn't have any cilia like this one here on its april-b surface alright and then we have pseudostratified guys we did draw this already so here it's actually a simple epithelium we're dealing with columnar cells of varying hearts some of them are tall some of our medium some of them are short right a lot of pseudostratified up with them okay is ciliated game meaning that for example okay on the apical side you see this little hairlike processes can't good example where you fight pseudo stratified ciliated columnar pathan is actually in your trachea okay cuz your trachea has a layer of mucous lining the lumen and let's say you're breathing air in and it's not that clean and that dust gets trapped on that mucus and the trachea well then we have the ability to beat that dirty mucus away from your lungs and back towards your throat so that you can actually swallow that dirty mucus okay you'll also find non ciliated forms for example in the ducts of some male reproductive organs alright and also present in some large glands alright so we're gonna go from a simple epithelium now to a stratified epithet okay a simple epithelium to a stratify so now we're looking at something that has not just a single layer of cells we're now looking at something that has two or more layers of cells all right so the thickest and the most protective epithelium that we have in our body okay is a stratified squamous epithelium the whole thing about memorizing versus understanding right okay this is your thing right you guys are entering the science field this is not a GE course for you guys okay this is not something where I gotta just get it done because I want to graduate I'm actually an English major no this is your life this is your occupation at this point so don't be just blowing this stuff off alright saying well I'm gonna memorize it and then the next class I have them just in toilet forgetting this is the foundation of your clinical practice you guys will be working on human beings I assume right well you better know human anatomy so if I'm gonna take a wild guess all right in terms of what a stratified epithelium does without memorizing just understanding two or more layers of cells what do you think the general function is of a stratified epithet two or more layers a thicker episode the function probably is protection all right in all cases when we think about shad will try to fight up with them okay pretty much we're dealing with protection here all right so the most protective and the thickest of the stratified episode that we have okay consisting now there's just two layers cells but many layers of cells okay we call this a stratified squamous up with them so here's a figure of satify squamous here is actually shadowfied squamous so I see this wavy boundary so this is actually connective tissue this is the basal side of my stratified squamous this is free space up here this must be the apical side of my stratified squamous epithelia the figure you see the cells on the apical side are very flat squamous cells that's what we call it stratified squamous because I see flat squamous cells on the apical side of my epithelium alright so many layers of cells so why would we consider these very protective well if you fall down and scrape your arm again okay yes you may get rid of these top layers of cells but you still have layers of cells that are now separating the outside environment from the inside of your body all right this is while the blood vessels are me become ever epithelia are avascular okay so if you scrape off this many layers you're not gonna bleed yet okay the times that you bleed is when what when you burn through all the different layers of that stratified squamous epithelia in the connective tissue all right now for stratified squamous yes it's protection and there's two different forms of stratified squamous you can have care tonight's keratin is a protein they're very tough very fibrous protein okay that will actually will make your epitome okay very strong or you can have a non keratinized stratified squamous so and when we take a wild guess right do you expect your epidermis which is the outermost layer of your skin to be a keratinized stratified squamous okay or a non keratinized stratified squamous it's the whole idea of memorizing versus understanding well I expect it to be keratinized my epidermis is a keratinized stratified squamous why because there's I expect that to undergo lots and lots of abrasion alright well what about the inside your mouth okay there's abrasion in there right when you eat food okay but compare the abrasion the abrasion that the skin is subjected to versus that okay abrasion that the mucosa that lines your mouth is subjected to well its abrasion but not that much not going overboard here right so inside your mouth for example lining your esophagus lining your throat you have a non-keratinized right stratified squamous epithelia the more proximal portions of your esophagus okay lining your mouth line your esophagus okay lining the vagina okay would also be a non keratinized stratified squamous alright stratified cuboidal epithelium with okay in this case two layers of cells okay and this is connective tissue this beige site this is free space and this apical okay and where on the apical side we see cuboidal cells okay so this must be some type of duct right so I see closely in this micrograph I could see one layer of nuclei I can see two layers of nuclei so I know this ratified okay but I wanna look closer here I look on the apical side okay on the free space side okay I see cells that are shaped like cubes well this must be a stratified cuboidal epithelium sweat glands forms the ducts of mammary glands and also your salivary glands and now the rarest okay type of episode of fide columnar so in this figure here I see one two I see three layers of nuclei okay some cases I see four okay we're on the apical most side though I see cells that are calling ourselves so I see one I see two I could see three I could see four layers for example but on the apical most side here I see a cell that shaped like a cone no this is connective tissue this is basil this is the free space this is apical alright so this is the rarest one found in male urethra and also the large ducts of some glance right in the last stratified up a theme that we're gonna discuss alright its transitional episode so again yes it is stratified but the name would give to it we give it transitional all right so it stretches it's found where what's found in your ureters urinary bladder a part of the urethra okay it allows distension allow stretching to occur all right so when the bladder is empty is around six layers thick right so this looks like an empty bladder to me right but then when this bladder is fill picture stretching this out stretching that way of stretching this way okay that's gonna spin out basically around the three so layers thick all right now someone walks up the street and says well I heard your tech and doctor buys anatomy class all right I heard whoever it graduates and passes that class really knows their stuff can you tell me what we're glands come from yeah and we're doing salary glands coming for where do you sweat glands come from what do mammary glands come from well they come from epithelial tissue okay glands are derived from epithelial tissue right so why is that so let's go to our pseudo white board here okay so the reason why we say that glands are derived from epithelium is because of this right so let's say this is some type of free space up here's okay and this is gonna be connective tissue down here right and here's my epithet separating the two environments from one another so this is April go that's basal right we talked about glands all right we're looking at an invagination of the epithet so we see something that looks like this an invagination of that epithelium right here all right so let's just do this very so I don't have to worry about drawing a stratified up with them all right so here's my epithelium okay can we see that invaginate that invagination of that epithelium producing our gland okay and we'll get specific here this is gonna make sense to you pretty soon we're gonna call this an EXO crin I'm glad alright now one part of this gland okay has cells that actually make the product that we're actually gonna secrete and produce okay I'm gonna highlight it in red I'm not gonna need me though okay and there's another part of the gland that's gonna make up the duct all right so let's say I make a product alright so these cells here think of free ribosome right attached ribosome and Golgi apparatus and then pathway one exocytosis case we exocytosed a product okay and that product X ends up in the lumen of our gland okay and then we use this duct okay and that product now ends up where well that product ends up on the apical surface of our epitome okay this be outside your body that could be a sweat gland that edges true okay this could be some type of mucous glands so now there's new kiss lining the inside your stomach right so this process of saying that a gland is derived from epithet atissue why because it's an invagination of an epithet it's an invagination of that membrane alright so what we're gonna do okay it's just talk about the Glenn so some some glands are made up of one cell some glands are made up of multiple cells again they secrete a product okay and might the picture that I drew on my suit a whiteboard that product was the green dot right it could have been sweat it could've been milk it could have been saliva right and the products of a gland are typically aqueous meaning that whatever we make we mix it with water so we produce a watery product okay and we'll say aqueous so where did we get all that stuff from right these cells that I drew in red okay they must have gotten their stuff okay from blood okay so I'm connect the tissue there's blood vessels over here all right the blood vessels carry things all right and then we use those okay to produce whatever product we make that we ultimately secrete all right so there right from blood now we're gonna take our glands and we're gonna classify them based upon two things two criteria okay number one well where do we release our product okay is our product released externally could be the outside your body could be the inside of your stomach it could be the inside of right the urinary system where do we really sit okay if we really sit externally we call it an exocrine gland if we release it internally we call it an endocrine gland all right and the second we're gonna classifier glands okay is how many cells make up the glend okay is it two or more cells or is it just a single cell that makes up with a glimpse okay so let's talk about the side of release first okay we're gonna jump this one we'll come back to that okay let's talk about exocrine glands so extra clean lands are externally releasing okay which means what well we're able to now release it onto the apical surface of an epithet and the only reason why we can do that is because these glands have retained their duct alright so right here okay in green is this thing called a duct and because we still have that duct we have the ability to now take our product and release it onto the external surface of an F of M we're able to release it into this free space okay and again this could be the outside of your body and we just made with Sweat right or this could be the lumen right of some type of organ this could be the inside your stomach all right but anything in case we externally released our product well then we call this gland because we've retained our duct we call it an exocrine gland all right now would you say that the product that I drew in blue is a locally acting product meaning that it acts really close to where it was made or do you think that okay this is what I drew in blue would be a far acting product mean that it acts not here but it acts somewhere else far away in your body well when you thing about the product of an extra glands they are locally acting okay so this is sweat well this is where the sweat is acting if this was saliva well this is where the saliva is acting right so extra cream glands externally Singh why because they still have the duct product locally acting the second type of Glenn okay based upon site of release okay is called an endocrine gland alright an endocrine glands okay they have lost their duct these are the ductless glands okay so if I go to my suit a whiteboard and draw an endocrine gland for you well I got extend this a little bit all right so let's extend our epithelium now endocrine glands are also derived from Epiphone but they've just lost their duct all right so here is this duct less gland here's my endocrine gland right so these ones also okay have cells that produce a product right but the fact that I don't have a duct anymore what does that mean can I can I take my product and can my product be now released okay to the outside of my body well the answer is no okay because I don't have the ability to get out here so where's my product gonna be released well my product is gonna be released now into the surrounding connective tissue okay and since I am now internally releasing this product well you call this an endocrine gland and call it an endocrine gland so what does that mean does that mean that these purple dots are gonna stay here or are they gonna go somewhere else well before I even do that if I talk about endocrine glands well what are these purple dots what is the product I make okay when you make okay something with an endo convent well you just made something called a hormone okay that is a hormone right there enter cream glands make hormones and what happens to hormones do they do they just act here or did they go somewhere else in your body well they can get picked up right they can get picked up by part of your own lymphatic system okay they can get picked up by your cardiovascular system okay so here is a blood vessel and your connective tissue again and we can pick up these hormones so ultimately all right this emphatic system this goes ultimate to your blood okay this one's already directly in your blood and where does your blood go your blood goes everywhere all right so your blood now goes somewhere far away from your body okay so if I go over here now alright and here's just a different part of your body and here's that capillary and here's that hormone that we made all the way over there but now we're over here okay and we have this process called filtration okay that now filters this hormone out into this round and connect the tissue right and now here is your hormone okay so what happens now when we come in contact with other cells so here's another cell in your body here's another cell in your body and we talked about this when we did cells what do these cells have to express on the surface well they better Express receptors so let's say this here looks like it's gonna receive something triangular this cell here okay we'll call cell B and this is cell a okay so B it's gonna be something sent shaped like a sphere well it looks like cell B's the target cell okay the quote-unquote target cell of this particular hormone why because it has the proper receptor so what happens the hormone binds hey the cell then responds okay there's some type of response that occurs okay because of that hormone binding okay so that's how to classify them okay there's side a release either external releasing EXO Krim okay so things like salivary glands mammary glands what else can there be the pancreas is technically an extra time be discreet digestive enzymes right into your into your small intestine right external releasing exocrine endocrine glands well those are the the hormones right we think about the pancreas is also an endocrine gland it secretes insulin and glucagon right the testes in the ovaries okay yes they produce the male and female gametes the sperm in the egg but they also release hormones testosterone and estrogen and progesterone and you have the adrenal glands we talked to talked about okay epinephrine we talked about okay adrenaline any the thymus and this is where right we mature right your your t-cells so so thymus in and thymoma eaten and then you have your parathyroid glands the parathyroid hormone yeah your thyroid glands the thyroid hormone calcitonin okay pineal glands melatonin pituitary gland whole master hormones secreted by the pituitary so these are all lost their duct okay and they secrete cake hormones that are for acting alright so the second way we now classify our glands is how many cells make up our glad okay is it is it one cell that makes up a gland we would call those unicellular glands or is it to a more like two or more okay cells that make up your your Glenn we call those multicellular events okay so the line I drew okay on our picture the ones that have ducts those would be the ones that we consider multicellular okay so I drew on the pseudo whiteboard an example of a multicellular good now in terms of unicellular there's only one unicellular Glenn that we're gonna talk about this term okay and those that gland is called a goblet self okay and the reason why they call the Goblet sound here's a figure of a goblet cell is that people who ever saw this looks like it's a goblet okay so something that you drink out of like a little chalice that you drink out of okay during the medieval times all right so I've kind of thought well maybe some of you guys haven't been to point a Parkin in to medieval times yeah or maybe Excalibur in Las Vegas well who else kind of uses goblets okay that's that's somewhat relevant okay he's on his way out I think okay I think he's on some type of Travelocity commercial hey but little John all right Little John used to walk the red carpet with his with his goblet right with his little energy drink right there yeah right so when you think about unicellular exurban glands okay the one that we're talking about our goblet sauce so if I look at this it has a nucleus it has a rough ER so what's probably happening here we're making now membrane-bound proteins all right you guys can see here's a Golgi apparatus okay and coming off of the trans Golgi apparatus coming off the shipping side of our golgi apparatus you see all of these vesicles and all these vesicles contain protein okay waiting to what waiting to be exocytosed so the question is what what is this goblet cell producing what's in all these vesicles waiting for exocytosis well it's producing a glycoprotein called Newson all right and mucin mixes with water that's out here in this free space and when you take Newson and water well then you make mucus so goblet cells make mucus basically so if I see an episode that has a goblin saw well then I can say okay that that epithet probably has a layer of mucus on this apical surface okay so if I go back to the picture here and they stick a unicellular goblet cell right here okay so it's a it's a it's a gland that's actually embedded with the nepo thumb as opposed to multi seller which is this imagination okay goblet cells are actually just part of the epithet okay and all they do is they secrete mucus so I would see then on the apical side of whatever epidermis is I would see a layer of mucus there okay so again this would be a goblet so okay so that's our one example of a unicellular exocrine gland alright multicellular extra can glance okay these women still have their duct okay so these produce a product and they secrete their product okay onto the apical surface and epithet I'm using their duct so they have two basic parts the secretory unit and the epithelium walled duct right so the secretary unit and the episode and walled up so if I go here okay you actually can see all right this epithelium walled duct right here so everything that I drew I'm seeing everything okay not wealth duct but secretory you know sorry okay so the secretory unit should ok Secretariat is that part of your extra cream gland that makes and produces the product okay and then you have the duct that allows you to take that product onto the apical surface of the upper throat all right so we're gonna classify our multicellular extra can glance based upon the structure of the duct right so if the duct is not branched okay for example the the duct is in yellow here right and here's my secretary unit okay in purple right if the ducts not branch we call it simple okay however if my duct branches for example branches to that secretary to unit it branches the second unit and branches to this Secretariat well then we call that branched when we called it a compound okay so if it's branched like this or if it's unbranched like this well then we call it okay either simple or compound all right the next way we're gonna do is we're gonna categorize them based upon the structure of their secretory unit okay so you can have sector two units that are shaped like tubes okay if that's the case we call this tubular alright or you know secretory that are shaped like grapes right the ones that are shaped like grapes we call these alveolar okay so either have tubular secretory units or you have alveolar secretory ins okay now you might see some that are a combination that have both tubular and alveolar what we call those then two below alveolar alright so let's look at this figure and I'll tell you right now you guys better know this figure for your midterm all right okay you may see this again so the secretory unit is in red and then the I'm in the branch but the duct is in yellow or orange okay so here okay this one is shaped more like a tube okay I would actually probably call her these ones a little more red too right more like a tube so we call these a tubular the duct is not branch so this is simple okay so this is a simple tubular Glenn simple alveolar gland alright now you're looking at this is this a simple okay or is this a compound okay is the duct branch towards a duct unbranched compared to this compare that to that okay this is actually a simple duct okay we just have three separate or units feeding into one duct okay so we actually call this a simple branched tubular so a simple tubular simple branch tubular simple alveolar simple branch to help you learn okay so it's a single duct multiple secretory in is feeding into one duct okay you seen yourself well how is it in that compound that looks branch to me well then compare it with this here's my duct in yellow going this way going this way and going this way so this duct is branched okay so because it's branch we call this now compound compound what well all the sector joining us with like tubes this is compound tubular right duct is branch and that's compound all the sector Turnus look like grapes well this is compound alveolar here I see a mixture of both alveolar secretory Ness and tubular Secretariat's well this is a compound okay to below alveolar glad okay so hopefully that makes sense for you guys alright so shown in this figure we see an epithelial cell just one cell okay only one tile of a tiled floor only one epithelial cell of an empathy all right now let's just give you guys some directionality here right so this is the apical side it must be free space up here this is the basal side so this there must be connective tissue down here okay we call this in these the lateral sides of our epithelial cell okay you have the apical side the apical membrane you have the basal side the basal membrane okay and you have the lateral sides the lateral membranes of our epithelial cell again you see the nucleus you see a Golgi apparatus there alright so we're gonna be concentrating right now okay on what type of structures we would find on the lateral sides of our epithelial cells okay what kind of structures would I find on the lateral sides of our epithelial cells okay basically what's gonna hold this cell to that cell right what's gonna hold this cell to that cell so one of the things that holds them together okay are adhesion proteins there are sticky proteins okay that stick the cells to one another on their lateral membranes okay you also find wavy contours okay between two adjacent cells so instead of having something that looks like this okay so here's one cuboidal cell next to another cuboidal cell where their boundary is basically just parallel to one another okay instead of seeing that you're gonna see something that looks like this and your racists actually okay so instead of seeing this okay where I have two cells just adjacent to one another okay you're gonna see wavy contours between adjacent cells all right you see something that looks like that right where know they Jason cell looks like this so why is that why wavy contours versus just straight up and down like we see between these two adjacent cells why wavy contours well number one okay it holds the cells in place better together right when you when you when you're a kid or maybe even now maybe you're into puzzles right the puzzle pieces okay they interlocked with one another okay you see something that looks something that looks like that right so that the next adjacent piece when it fits into it okay it fits perfectly right into that right other structure with that other piece okay you don't see puzzles where one piece is this okay and another piece is that okay these two puzzle pieces aren't gonna stick together one another yeah you move that around this is gonna fly apart so by having now wavy contours between two adjacent epithelial cells it allows them to hold them together right another could be surface area if I want exchange now things between this on this how there's more connection okay there's more surface area between this and this then there is this and that okay but the main one the reason why we have the wavy contours is it holds the cells tightly to one another prevents the epithet for being easily torn apart right and the third thing okay the one that we're gonna spend pretty much the majority hey discussing what how do these cells hold on to one another is number three special cell junctions okay and the first one we're gonna talk about the special cell Junction we gonna talk about are called tight junctions alright and these tight junctions okay are a belt like junction that goes around the periphery of the epital along the lateral sites okay so you don't find them on the top you don't find the bottom they're found on the lateral side but more towards the apical side okay you're not gonna find them down here towards the basal side okay more towards the apical side going all the way around on their lateral surfaces okay so what do tight junctions do so let's go to our pseudo white board over here alright so let's draw a simple columnar epithelial wavy contours but there are wavy contours again between these epithelial cells right so here is my simple columnar epithelia pouco side again connected tissue is down here okay more towards the apical side you're gonna see that lateral membranes fuse with one another okay erase a portion of this of this okay you're gonna see the membranes fuse okay and by fusing okay it closes off the exerciser space between the two cells alright so let's say this is the lining of your large intestine okay well one of the things about your large intestine is there's bacteria out here in the lumen this is the lumen of your large intestine okay let's say here's a bacteria and there's a bacteria can we know okay pass through the epitome and let's say there's blood vessels down here in the connective tissue alright can we now simply pass right through the epithelial cell that possible no because this is a boundary right we know there's a plasma membrane there okay we know that there's something that separates this environment from that environment well can I pass okay in between the cells can I go like this okay well the answer is no why because you have a tight Junction they're blocking off the extra shelter space between the two epithelial cells now if you had something where there was no tight junctions okay let's say between these two epithelial cells here there was no tight Junction well then yeah okay you can now simply simply pass through that epithelium all right passing in between the two cells but because there are tight junctions okay you cannot do that okay that's one structure you find on the lateral surface of your epithelial cells right so the next structure we find on the lateral surface are called adherence junctions okay so these are right below the tight junctions so these are found looking more towards the apical site okay and what you're gonna find here are linker proteins that attach to your cytoskeleton they attach to the microfilaments and they bind the cells together all right so if I go and back to our whiteboard here alright we're gonna draw now these tight junctions right below okay let me have these adhere instructions right below our tight junctions okay so you have these proteins that are embedded in the plasma membrane okay and they link to one another so these proteins okay from adjacent cells they link to one another and by linking to one another they basically bind the two cells together all right now what's supporting them okay is here on the cytoplasmic side you find actin microfilaments remember microfilaments are a part of your cytoskeleton all right these microfilaments they attach to the proteins which attach then to the protein which attached to them sounds good so essentially what's happening is that the cytoskeleton of this cell is connected to the cytoskeleton of that cell okay we are holding these cells together so that we don't simply okay break apart from one another now if I talk about the tight junctions and dad here in junctions if I talk about them together okay so sprite yellow and line cane lemon in line together okay well together you call that whole thing tight junctional complex you call it the tight Junction 'el complex okay all right and the third thing you find okay on the lateral sides of these cells okay are the main things that really hold a two adjacent cells together on their lateral surfaces okay these are the main things that kind of keep them together okay we call these desmosomes all right so what do what desmosomes okay where do you find them we find them throughout the entire lateral surface so not just on the apical side you actually find the desmosomes on the basal side okay okay again some of the lateral surface right now we're not gonna find desmosomes here or desmosomes here okay I'm saying where specifically would you find it what we find on the basal lateral surface and also in the middle lateral surface and also the apical lateral surface right here okay all right so going back to our pseudo whiteboard let's draw some desmosomes on these cells now can you find them all throughout the lateral surface I'm just gonna draw them where I have space to draw now right so one thing that you find is a cytoplasmic plaque okay so cytoplasm on this side of plasma membrane okay so there's one cytoplasmic plaque okay over here on this cell you have another cytoplasmic plaque and extending inward right you have these linker proteins that pass through the plasma membrane right so linker proteins from each desmosomes from opposite cells they linked to one another all right so again you're gonna find desmosomes on both sides lateral side so I'll put a desmosomes over here desmosomes here since we have this cell already let's put a desmosomes okay on these lateral surfaces okay so again linking these cells together you have these linker proteins okay that now hold the desmosomes together on every side right okay now again you find these all up and down okay you would find them all up and down the lateral surface now if I were to take my finger okay let's say I'm a really small person okay tap my finger and I were to pull this cell that way okay and I would increase the force okay is it possible to rip this cell from this cell okay is it possible to rip cell one from cell two okay if I were to now okay pull really really really hard right in this direction yeah okay because all that's kind of holding them together would be again right the hair in junctions and all the desmosomes found up and down the lateral side if you pull hard enough there's enough tension place between cell one and two you can rip cell one from the rest of the epithet right now desmosomes aren't simply isolated by themselves on the lateral side you also have what are called intermediate filaments you guys remember what those do before I tell you cuz we did talk about the cell and we talked about microfilaments we talked about microtubules we also talked about intermediate filaments can someone tell me okay mentally Ryan you're gonna tell me through the computer hey what do intermediate filaments do for yourself yeah well we know that they resist pulling forces they resist tension okay so what I drew in green here joining a desmosomes on one lateral surface cell to a desmosomes on the opposite lateral surface of cell i drew intermediate filaments okay so intermediate filaments again help resist pulling forces so if I'm up here now pulling and tugging on cell one well that it that pone force now gets distributed okay through these intermediate filaments right which then gets distributed to the next cell through the intermediate filaments which is distributed to the next cell to its influence and so forth and so on so this pulling force here okay isn't now just between cell 1 & 2 this pulling force now is between right this cell and all the cells in this episode okay that pulling force is now is transmitted throughout all of the cells in our epitome here so we're picking on someone like we're bullies uh-huh uh-huh okay and then cell 2 so 3 cell 4 go what's up okay why you messing with our boy saw one so by having now the desmosomes linked together okay by these intermediate filaments okay the pulling force is now distributed out through the entire epithelium okay so not just right this salt one and two but the entire episode is now receiving this pulling force all right okay those are desmosomes all right the next one doesn't necessarily link the two cells by holding them together it allows two cells that are adjacent to one another epithelial cells okay to communicate with one another all right you use what are called gap junctions so president between this cell and this cell is this little tunnel okay these little tunnels are made up of proteins called connects ons all right so if I were a self if I was this episode of cell and I wanted to communicate with that up and through cell well what would I have to do if there were no such thing as gap junctions well if there was no such thing as gap junctions what would have to happen right is you would have to do this okay you would have to have let's say I wanted to get this red is easy to see okay you would have to take whatever this red dot is put it in a vesicle okay have the process of exocytosis so now it's out here in that extra cellar space have endocytosis okay and then get in vesicle and cell 2 okay and that just seems like a lot of work just to get something from sell one to sell - all right sone actuality you actually have what we're called gap junctions okay so what I'm gonna do here is I'm gonna put a gap junction between cell 3 and cell 4 alright and gap Junction again I'm a proteins called connects ons right and these gap junctions have little tunnels that run through them so if I'm this red dot now and I want to go from self 3 to self or okay all you have to do now is use that gap Junction and now you've gone from one cell to another cell okay so it eliminates this tedious process of having to do an exercise followed by endocytosis okay we can simply go from one to another now we'll talk about gap junctions later on okay in Physiology we'll also talk about these okay when we talk about cardiac muscle right and in your heart you actually have cardiac muscle cells that link to one another by gap junctions why so if I generate electrical signals that say in cell 4 okay those electrical signals can simply pass to the next cell and depolarize the next one yeah all right so I believe that's the end of structure we'll talk about right on the lateral surface of our cell okay it starts talking about structures we find okay on the basal surface of our epithelial cells okay so down here again it's connective tissue so this is the basal side of my simple columnar epithelial side of my simple clump of them okay so we're conscious ran out of stuff we find on the basal side here okay so one thing unifying is this thing called a basal lamina okay so our our epithelial cells rest on something called the basal lamina okay it's the border between the epithelial tissue on top and the underlying connective tissue on the bottom right so what exactly is the basal lamina well the basal lamina is a non cellular sheet consisting of proteins secreted by the epithelial cells okay so the basil lemon is produced by the epithelial cells okay it's a supportive sheet it's a filter determining what molecules for example from the capillaries they end up here okay up in the connective tissue so one it supports the growth of these epithelial cells and two it acts as a filter regulating what can pass between the connective tissue up okay to the epithelial tissue now since it doesn't consist of cells is the basal lamina life well it is not a life okay so it comes again from the epithelial tissues now in terms of a type of clinical application alright we can talk about the basal lamina and how it's affected individuals that have diabetes alright so for normal people again lining your capillaries you have a simple squamous up with them okay okay what's the function for simple squamous diffusion filtration right so here's my simple squamous epithelium lining my capillary all right and through the process of filtration okay because of hydrostatic pressure we're able to push things out across that simple okay squamous epithelium hey and then nutrients for example okay end up out here so if i'm a sell-out here and i get nutrients well I'm happy all right now the basal lamina okay that's here is a very thin basal lamina okay I don't want to have to interfere with diffusion filtration so I'm not gonna put a thick base on I'm gonna there okay even over here is gonna be a thin basal lamina now the problem here is okay is that people with diabetes okay they have a thicker basal lamina okay so on one side I'll put a thick basal lamina in purple on the other side I'll keep it normal alright I'll keep it as it as it would be okay so this side is normal I'll put an N okay over here this is the person that is a has diabetes I'll put a D so through the process of filtration okay because I have a thin simple squamous because I have a thin basal lamina okay filtration is gonna easily okay push stuff out of your blood into the surrounding interstitial fluid okay which will reach your cells and your cells will be happy on the other hand okay if I'm talking about someone with diabetes okay and now I have a thick basal lamina well what happens okay is the process of filtration okay gonna be okay helped or is it gonna be impeded it's gonna be harder to filter stuff out of your blood or is gonna be easy to feel stills your stuff out of your blood by having a thicker basal nominal well you're gonna do what well you're going to impede it okay it's gonna be hard to filter so if i'm a sell-out here now okay with some with diabetes okay I'm not getting the stuff that I need I'm gonna be pretty sad yeah again cells can't be sad right guys right but you know I'm saying well they're not gonna get we need positive these cells can die all right okay so that's a clinical application of that basement membrane there now so the basal lamina okay is produced by all right we have authority issues on top okay you also have these reticular fibers down here which are provided by the connective tissue okay so the reticular fibers provided by the connective tissue and then the basal lamina provided by that but the tissue together okay we call this the basement membrane okay so a lot of times people will use these interchangeably with them up with one another okay they'll say basal lamina they'll say basement membrane okay they're actually replying to basically the same thing okay but in terms of your your midterm well you're gonna learn basal lamina is specifically that non-cellular sheet produced by the epithelial cells on top okay in addition to the reticular fibers okay provided by the connective tissue on the bottom we call both of those together we call that the basement membrane all right so that's this that's the basal surface okay what about the apical surface of our epithelial cells well the apical surface can be flat okay or we can have these little extensions here okay so the one we see here these are called micro villi okay so these are non-mo Tyl extensions right so what these do is they all they do is they increase the surface area right of your epithermal so if I wanted to absorb new today this was the lining of my small intestine right hey what a cell that is flat or a cell that has micro villi have more interaction with the lumen of your small intestine thereby absorbing more nutrients into your body well obviously cells that have micro villi have more surface area more interaction okay so if I want to now have more interaction with the outside surface in this case the lumen well I'm gonna put micro villi here okay well what do I see here well these aren't micro villi these are cilia these are motile appendages right these are the ones that ya are have the ability to propel things why because at their core they have these microtubules alright and what they do is they now whip they have this little whip like motion where they do a power stroke okay so we're propelling the mucus from left to right okay we power stroke so the mucus now goes in that direction okay but instead of like a windshield wiper and just going in the opposite direction which then would cause the mucus to go backwards we then do what's called the recovery stroke so we streamline ourselves okay and then we power stroke again okay we streamlined ourselves and then we power stroke again so that the mucus goes only in a single direction okay so if these are micro villi I'm sue Michael but if these are cilia and at the core have micro tubules what organelle would I find right here right underneath the apical surface of these epithelial cells where do where do all microtubules originate from what's the name of that organism organ oh well that organelle again is called okay a Centro soma all right so the centrosome okay along with the centrioles right that are present in that central soul all right here's another motile appendages since we're talking about motile appendages okay also found at the core of the flagella of a sperm cell you'll also find okay those microtubules so I expect to find a centrosome okay where those microtubules yeah so we'll stop there guys this is part 1 of the chapter 4 tissue lecture okay we're the next one we will continue with part two okay we're gonna move from epithelial tissue we're gonna now talk about a brand new type of tissue called connective tissue okay so have a good day guys I'll see you on the next lecture bye