Transcript for:
Overview of the Integumentary System

so in today's lecture we're going to discuss the integumentary system this is the the very first organ system that we will be covering in a and p1 uh what we're going to focus on is the different layers of the integument uh talk about the characteristics of each layer what is the overall tissue type that you will see here and what are the different uh cells that are typically seen as well uh then we're going to go on to uh talk about some of the functions of the integument like how does it act as a physical barrier a chemical barrier a biological barrier several different appendages of the integument like the sweat glands are the sebaceous glands that produce oil or sebum we'll talk about the erector pulley muscle um we will talk about several different sensors a touch sensor and a pressure sensor so those that's what we're going to be really focusing on for today's lecture so let's kind of get started this is pretty straightforward material you'll see a lot of word slides i'll try to highlight the most important aspects and then of course focus on the figures to put all of those topics together okay all right so when you're looking at the integument it consists of two primary layers uh you have an epidermis layer and a dermis layer and right under the dermis okay i wanna talk about uh directionality okay so superficial would be towards the top and deep would be as you go further inwards or deeper into a particular space so starting with the most superficial region you've got the epidermis right underneath it you would start to see all the dermis layers and then even deep to the dermis is this supporting layer called the hypodermis all the superficial pressure this is a subcutaneous layer hypodermis is not considered part of skin so there's only two distinct layers making up the integument namely the epidermis and the dermis we'll talk about the characteristics of each of these layers for the hypodermis this is a supporting layer this is mostly adipose tissue so it acts like an insulator and it acts as a shock absorbent as you would expect in any lipid containing adipocyte tissue okay uh the hypodermis also is important for the structural stability of the integum so it helps to anchor uh the skin layers namely the epidermis and this and the dermis to any underlying structure so what you typically would see under all of this adipose tissue making up the hypodermis would be all of the muscles and then you know the nerves and and blood vessels and so on and so forth so make sure you understand what are the main regions of the of the integument and then what is the importance of the hypodermis as well so what we're going to do next is to start breaking this down layer by layer okay this is a very important schematic you will see this on your exam on your lecture exam uh you will need to identify the different layers and the different structures or the appendages associated with this uh organ system so everything that you see here on the top all of this brown part this is the most superficial layer of the integument called the epidermis right there everything underneath it that you see in this pink pot all of this is the dermis which is broken down into two sub layers okay uh the dermis has a very very thin region on the top which is called the papillary layer and then the majority of the dermis and you don't really see the distinction here but you kind of have to imagine this so as you can see with that little bracket there just this little portion here on the top is the papillary layer which is the the top layer of the dermis and then about 80 of the dermis so the majority of the dermis is this layer here called the reticular layer okay everything here on the bottom in yellow these are the adipocyte cells related to the hypodermis um that's a subcutaneous tissue we will also talk about uh different appendages associated with the with the skin or with the integument uh our focus will be on certain appendages like the hair follicle structure we'll talk about the sebaceous glands that kind of release sebum or oil into the hair follicle wall we will talk about these guys here these muscles these are smooth muscles um that you can see kind of attaches to the hair follicle and kind of connects upwards into the epidermis plays a very important role uh in first allowing for release of sebum but also helps to straighten this upward region which is the visible hair that you see outer to the epidermis which is called the hair shaft and what else do we have here okay there are two important sensors and only ones kind of shown in this schematic uh this here in yellow this is a this is a pressure sensor and notice this is much further deeper into the dermis so it's a deep pressure sensor called the pacinian uh or the lamellar or the lamellated uh corpuscle not shown here but if you can imagine there's another sensor kind of in these little um uh regions where you can kind of see the hills and the valleys okay up here these are this is typically where you would see the meissner's corpuscle which is a light touch sensor and then i am oh yes i forgot to mention these guys here these are the sweat glands these are the sudori first glands and the variety that is shown here is the akron sweat gland since i'm on this schematic i want to point this out a lot of what i'm discussing right now you will see some overlap between lecture and lab you are responsible for this information on a lecture exam but a lot of this you will also see on your lab exam okay uh here uh you will you will need to identify the sweat gland and this variety is called an accurant sweat gland because okay here's where the secretions are produced the sweat is actually produced that's a glandular portion of this wetland and it the sweat gets vented through this pore called the sweat pore notice that the sweat pore goes all the way through the epidermis and then penetrates outwards so the sweat directly is released through the epidermis and this particular variety is called an accurance wet gland now there are other sweat glands that are associated with the hair follicle like where uh the sweat gland attaches to the hair follicle wall like if you imagine a structure kind of feeding right there into the hair follicle wall now that is also a sweat gland but that's called the apocrine sweat gland and i'll talk to you a little bit more about that when we get to it now not to mention um i mean not to forget to mention that's kind of what i wanted to say was the epidermis this is all epithelial tissue and if you remember from lab epithelial tissue uh does not have any blood vessels it's an avascular tissue whereas all the blood vessels that you see here in red for the arteries and blue for the veins these are all different types of blood vessels um those blood vessels are seen here in this pink region so therefore the dermis has the vascular blood vessels okay so the dermis is mostly connective tissue and that's where you would see the blood vessels but the epidermis on the top this is epithelial tissue and you will not see any blood vessels there and this is important keep this in mind as we um move into our discussion of the epi of the epidermis now what i want to break this down into next is this the epidermis is yes it's one solid layer uh the most superficial layer of the integument but that really can be broken down into five different sub layers and you're going to see this here in a subsequent slide like this like right here okay so the epidermis can be broken down into five different strata or layers starting with the most superficial layer going all the way down to the deepest layer okay so you've got the corneium lucidum granulosum spinosum and the basal layer there's a mnemonic that helps you to remember the organization of the sublayers of the epidermis and so what you see here is i kind of have this mnemonic written up it's can live green snakes bite okay starting with the most superficial which means towards the top uh towards the top of the epidermis you have c c is for cornea l for lucidum g for granulosum s for spinosum and the deepest the the lowest layer of the of the epidermis that's b where's my pointer b for basal okay so that's how you kind of it's an easy way to remember the different uh sub layers of the epidermis um now this is also going to be relevant in uh in lab because you will be identifying all five sub layers of the epidermis and i'll show you how to do that hopefully i've got a histology view coming up here um or at least i can describe it for you um but you will need to know all five layers you should be able to identify let me back up you should be able to identify the entire region as the epidermis but also individually especially on a histology section be able to identify which layer is the corneum layer which one's the licitum which is the granulosum and so on and so forth okay we also want to discuss several different cell types that you would see within the within the integument at large um some of these cells like the keratinocytes that you see mostly in the epidermis you're gonna start to see as you go deeper down into the epidermis you're gonna start to see melanocytes uh you're gonna see a lot of your immune cells like these guys here called the dendritic cells now these are the policemen that are constantly patrolling the integument looking for pathogens that have invaded the integument if a dendritic cell identifies a pathogen it's going to flag that cell and then mark it for destruction by uh activating the immune system okay then you've got all of these different touch sensors or cells that are related to uh touch and these are called your tactile cells and i will go on a description of that here in just a little bit so keratinocytes uh this is the majority of your epidermis they are kind of modified cells uh they are packed on the inside within the cytosol they are packed with a fibrous protein called keratin uh so again like i said this is mostly the cell type that you see in the epidermis these curtain packed cells they are very good for for strength okay so it gives the epidermis the toughness that's required to act as a barrier a physical barrier to prevent things from entering but also gives it the the toughness that's required to protect yourself from abrasion and constant friction okay okay the next important cell type that you see in integument are these guys called the melanocytes uh this is about 25 of the of all of the cells this is seen much deeper down in the epidermis as you get into the stratum spinosum and the basal layer now these are super important cells they produce a completely different pigment uh protein called melanin and the melanin is important for different things one important for skin color which we will talk about later but from a biological perspective the melanin is important to protect your cell protect you the integument from excessive uv rays from the sunlight um so it protects you from damage and can prevent cancer as well but of course overexposure too much exposure to excessive sunlight uh can result in skin cancer and we'll talk about that last uh dendritic cells and a different immune cell here called macrophages are important as part of the immune system and of course your sense uh your touch sensors are your tactile or your markle cells so let's go ahead and talk about the five different uh layers of the epidermis so the stratum corneum remember this is the most superficial layer of the epidermis so starting from the top the outermost layer you've got the corneum and then underneath it you should see the licitum the granulosum the spinosum and the deepest layer is the basil make sure you know those five different layers okay so let's start with the most superficial layer and this is the stratum cornea okay so this is uh got a lot of layers to it about 20 to 30 layers but notice this it says these are all dead cells so when you and me uh are looking at each other right everything that you see on the surface of your integument this is all the stratum corneum which is part of the epi the superficial part of the epidermis this is all dead cells um beauty is only skin deep okay so uh and i'll tell you why these cells are dead cells in just a little bit it'll make sense to you um but even though they are dead okay they are not useless they do perform very important functions because uh they can help with protection from abrasion and penetration from other biological agents chemical agents like any chemicals uh that you expose your integument to constant trauma like physical assaults of course from the biological perspective um this is going to prevent any microbes like bacteria and viruses from constantly entering into the integument so it gives the toughness to the epidermis okay so even though they're dead they play a very important role now why are they dead okay now if you remember from a previous slide i told you um that the epidermis is epithelial tissue um and so epithelial tissue does not have any blood vessels the the the ease the the source of blood vessels is from the layer underneath it namely the dermis now these cells being so far away from the dermis the nutrients like glucose and other amino acids and of course oxygen they cannot reach these cells of the epid of the stratum corneum and this is why because they do not get those nutrients they are mostly dead okay and i'll tell you where that transition occurs uh in just a little bit okay now i want to introduce to you the concept of thick versus thin skin uh remember those five layers of the epidermis where you had the cornea and the lucidum the granulosum spinosum and the basal layer you're gonna see all five layers in thick skin like um the palms of your hand the soles of your feet and towards the back region the the dorsum uh now thin skin has only four layers what it's lacking is this layer here which is the the lucidum stratum lucidum so no stratum lucidum in thin skin okay so if you see the stratum lucidum you know that you're looking at thick skin okay this is a very transparent almost like a ghost-like looking layer when you're looking at this under the microscope when you're looking at histology again these are all still those dead keratino sites okay okay now this is where it gets a little interesting okay this is where i'm going a little further down into the epidermis this is the third sub layer which is the stratum granulosum for reference i've kind of drawn a little schematic here okay so starting so this is the epidermis the most superficial layer of the epidermis that's a stratum corneum remember this is really about 20 to 30 layers of all dead keratinocytes all up here okay uh what i kind of have here in like almost transparent like a like a silver color this is like about a single maybe two layers of uh what we call the stratum you see themselves remember this is only seen in thick skin you will not see this in thin skin okay now right underneath this stratum lucidum is shown here in purple is the stratum granulosum this is about three or four layers maybe up to about six layers of cells the granulosum layer you should easily be able to see this distinction uh in a histology image because you will see the color changing it's a much more uh like a deeper purple or a or a darker appearance okay so your cell appearance changes here because remember pretty much everything from the granulosum layer upwards these this is where the cells start to die okay everything from the granulosum layer downwards so within the spinosum layer and the stratum basil layer all of these guys here are cells that are alive the reason being what's under the epidermis so if this entire region is the epidermis all of this that i have in gray that's the dermis layer this is where you have the dermal blood vessels so all those capillaries they kind of invade into these uh regions here you can kind of see these little little little hills if you will right uh these are called the dermal papillae which is kind of like the boundary between the dermis and the epidermis above it within these dermal papillae right here this is where you expect to see the dermal blood vessels and this is all a passive process you guys you know what passive process means right movement of like for example oxygen um across from a high concentration to a low concentration so if you think thinking about diffusion of oxygen yes it's going to diffuse upwards into these layers but as it goes further and further up it is too far away to reach it that's why all of these cells here within the spinosum of course the basal and towards the lower part of the granulosum for all practical purposes we say basil and spinosum all of those nutrients are able to reach those layers so they are living cells but grad granulosum upwards too far for those nutrients to reach by the process of passive diffusion this is why all of these layers are all dead cells okay so coming back to the granulosum layer you should be able to identify this by looking at the the cell appearance and how it changes okay this is where a very important process called carbonization starts where you start to accumulate a set of granules called character hyaline granules this is where these granules get packed with keratin and then gets pushed upwards into these all of these cells of the stratum corneum allowing them to be distinguished as keratinocytes there's also another type of granule called the lamellar granules this is a this is a glycolipid that is water resistant which means it's going to slow down water loss from the epidermis so it definitely prevents dehydration as you walk outside on a really hot day like today okay um so just remember keratinization begins at this layer granular stratum granulosum what are the two different types of granules that you see here what's the importance of these granules make sure you understand that everything about the granulosum towards the corneum all of these guys are dead cells everything under the granulosum so the stratum spinosum layer which is all of this white part here basically and the stratum basil all of these guys all of this portion are the living cells okay because they have access to the blood vessels uh from the dermis okay so now let's talk about this next layer which is a stratum spinosum okay this is really where you're gonna start to see your um uh you see a lot of your dendritic cells here you will also see your melanocytes here so a lot of melanin being produced here uh the the most important feature of the stratum spinosum layer is that this is where you have anchoring of your cells of the spinosum to each other to where you have an intact layer this is good uh if you remember to your chapter 3 when we talked about cell junctions you're going to see a very specialized type of junction here called desmosomes which acts like a rivet kind of junctions allowing you to anchor one cell to the next cell to the next cell which is really important because you do not you want integrity of the epidermis you don't want uh every time you walk past an object or a surface and you don't want the the abrasion or from that that friction causing tearing of the f the epidermis what prevents that these guys here the desmosome junctions okay and the last layer of the of the epidermis this is the deepest layer of the epidermis closest to the dermis right this is called uh the stratum basal layer okay this is very very important this is only a single row of cells these are all actively dividing stem cells that are rapidly undergoing mitosis and you should be familiar with mitosis this is where one cell a parent cell divides into two daughter cells of uh identical genetic information okay so these are your actively dividing stem cells now why is that the case let me back up to this schematic that i had here remember i said all of these cells here the stratum corneum these are all dead cells they are constantly getting sloughed off every time you uh again brush up against a surface in fact there's a lot of loss of cells that's occurring um thousands of cells that are lost every day now think about this remember we said this was about 30 layers or so in thickness if you keep losing cells from the stratum corneum because they're getting sloughed off all those dead cells are getting sluffed off right like um like skin dry skin kind of get stuff sloughing off occurring well if all of those cells get lost and you have no way to regenerate the stratum corneum and you don't because that's important for protection right if there was no way to regenerate it then you would basically break down the entire entire epidermis to the point where you do not have an epidermis that is not good obviously so this is why you have these actively dividing stem cells here within the stratum basal layer and what it does is okay every time one of these cells divides it divides into two daughter cells one daughter cell stays behind so that you're going to keep the basal layer intact the other daughter cell gets pushed upwards and that's why you're constantly regenerating uh the corneum layer now that's an important feature of the of the epidermis it has excellent regenerative potential because of the fact that it can undergo rapid mitosis okay okay so the mitosis is happening where in the stratum basal layer that's where you've got the stem cells okay now also you will see other melanocytes within the stratum basal layer okay so let me quickly talk to you about cell differentiation so i told you at the kind of midway through the epidermis where you have the stratum uh granulosum this is where characterization is occurring this is also kind of where the place where you will start to see changes in the structure of the cell and that's why it's starting to look different okay uh so if you're looking at all the different top layers of the of the epidermis going from the corneum all the way to the stratum basil you're gonna see that the cells look different okay by the way the entire epidermis the entire thickness consisting of all those five sub layers that entire thickness is i've already told you this is epithelial tissue what type of epithelial tissue this is has multiple layers so it's a stratified variety right uh it's uh it's a stratified uh squamous epithelium okay okay so when you're looking at the different strata or the different layers and then you go through the different sub-regions you're going to see a differentiation process that's occurring this is actually a specialized form of cell death called apoptosis this is where okay going from basal to spinosa and those are all living cells once you get to granulosum the cells start dying they go through an active apoptosis process once you clear the granulosum and go upwards into uh of course the lucidum and the mostly the corneum these are all dead cells so this process this is like cellular suicide okay this so when you're actually looking at the cells um in the quantum layer this is where you don't really have uh a nucleus they're dead cells no dna okay uh there's no cellular organelles there because you don't have any ribosomes making new um proteins you don't have the golgi you don't have the endoplasmic reticulum uh you don't have you don't have any of that okay all it is doing is that it is packed with this curtain which allows for a great amount of uh friction resistance and and to allow for a strengthened structure okay so like i said the stratum corneum layer uh these cells slough off as dandruff and dander about i was on the low end uh when i was talking about this a while ago more like 50 000 cells are shed every minute okay again i hope you understand the importance of this if you're losing that many cells from the stratum corneum every minute this is a problem if there was no way to regenerate the thickness and keep the integrity of the epidermis and this is where the stratum basal layer is going to be important because that's that's its job is it's actively dividing and it's going to keep pushing up new daughter cells upwards to keep the the thickness of the cranium layer intact okay all right now that we've talked about the epidermis let's move on to the layer that you see underneath the epidermis okay so this is also a lot of the anatomy that i'm going to describe here and then we'll move on appendages where you'll start to see a little bit more of the physiology so the dermis that is right underneath the epidermis this is all connective tissue this is broken down into two different layers that you see here in red on the bottom towards the upper part of the dermis about 20 percent of the dermis is a layer called the papillary layer and the remainder of the dermis which is the majority is uh the reticular layer okay there are different types of cells here um fibroblast cells and if you again think back to your uh unit one of the lab component where we talked about the different tissue types you will see a bunch of different uh cells within the connective tissue depending on what connective tissue you're discussing but this is a classical areola connective tissue and uh which is what you see in the papillary layer and uh like your dense irregular connective tissue which is what you typically see in the reticular layer so you're going to see a lot of fibroblast cells here which is normally what you see in traditional connective tissue your defense cells like your macrophages you also have mast cells and other white blood cells all defense mechanisms okay now remember the dermis is where you're going to see your blood vessels okay it is in a it i'm sorry it is vascular associated with the blood vessels you also have lymphatic vessels they're important for drainage of any excess fluid so that it doesn't start to pile up or doesn't start to accumulate within the interstitial spaces therefore preventing edema okay so that's the role of the the lymphatic vessels of course you're gonna have a lot of nerve endings here so it's definitely innovative because you feel pain uh when you uh uh prick yourself or you have a tear in the integrity all right so let's break this down even further and yes uh like someone just pointed out yes here is where the dermal papillae are is labeled but i want to kind of orient you to uh the different layers again everything here on the top and brown all of that is the epidermis okay now remember what type of tissue the epidermis is made this is important for both your lecture exam and your lab exam okay the epidermis is a stratified squamous epithelium okay everything in pink is the dermis uh where you break it down into the papillary layer the top 15 to 20 percent this is all loose areola connective tissue the majority of the dermis which is about 80 or so this is the reticular layer where you're going to see dense irregular connective tissue don't forget to identify the hypodermis which is the adipose tissue okay so what i'm going to be focusing on now is this right here the dermis what's the differences between those two layers uh what are the different types of features and characteristics of those layers let's start with the topmost layer of the dermis this is the papillary layer you gotta know this areolar connective tissue you're gonna see a lot of collagen fibers and elastic fibers here remember this is where all of those let me back up right quick all of those blood vessels um they basically end up right there in those little uh those little peaks that you see there which like i pointed out just a while ago was the dermal papillae all of your dermal blood vessels the smallest general blood vessels which are any blood any small blood vessels called a capillary these guys the capillaries typically end up right there okay and this is important because diffusion of oxygen and nutrients from those capillaries occurs at that region and it diffuses upwards okay and this is why these lower layers of the epidermis consisting of the basal and the spinosum they get those nutrients because they're closer to those blood vessels but the upper layers of the epidermis which is like the corneum too far away and that's why those are all dead cells okay okay so make sure you know this know the importance of collagen and elastic fibers uh this was discussed again in lab collagen great for uh for tensile strength um so its collagen is more like a rope-like structure so it has a lot of strength to it um so it prevents like twisting forces and all of that elastic fibers on the other hand not so much for strength but a lot of give so it's like a rubber band so it has a lot of stretch and recoil which is gives a little bit of flexibility okay collagen not so flexible it can only have a little give after that it snaps okay that's why you have sports injuries where you can tear ligaments and uh sprains and things like that okay um we already talked about the dermal papillae so these are those peg-like projections so these are actually extensions of the papillary layer of the dermis as it projects upwards into the epidermis let me show it to you right quick so these dermal papillae these are as you can see these are upward projections off the capillary layer of the dermis but they're kind of pushing upwards into the epidermis okay i like to think about it as literally the boundary between the epidermis on the top and the dermis below it okay okay in association with the dermal papillae okay again we talked about this is where you see all of those dermal capillaries uh but in association with that you also see a very important touch sensor called uh the meissner's corpuscle i also call it tactile corpuscle uh you see a lot of different pain receptors here and friction ridges okay so this is you can see friction ridges associated with the dermal papillae this is going to allow you to be able to grasp surfaces uh much much better okay so again contributes and the pattern of those friction ridges uh is unique to each individual and contributes to fingerprints okay that's the dermal papillae going deeper down into the dermis okay so this is where the majority of the dermis is the reticular layer and this is a different type of connective tissue okay so remember the papillary layer on the top was loose areola connective tissue the reticular layer okay i don't want y'all to make this mistake it is the reticular layer is not reticular connective tissue reticular connective tissue is only seen in immune lymphoid organs like lymph nodes for example the reticular layer of the dermis does not contain reticular connective tissue it contains dense irregular connective tissue and from what you recall of um any kind of dense tissue you have a lot of fibers that's why this is a dense tissue and the dense regular or the dense irregular has a lot of collagen fibers okay collagen like i said in the previous slide great for strength uh not so much give though okay now i want to point out here something called cleavage line so how how are these collagen fibers these bundles of collagen fibers how are they organized within the dense irregular connective tissue that you see within the reticular layer of the dermis there's actually a specific organization to these bundles of collagen and you can kind of see it here in this schematic so most of the times you will see that the collagen fibers run parallel to the overall structure uh especially like in the upper limbs and the lower limbs it's almost parallel um that you see on the inner side now what you're seeing here is deep right it's underneath the uh the surface it's it's within the the dermis layer you don't actually see this visibly uh on the outside but this is exactly how the collagen is is arranged and you can see how it has a very specific arrangement in different parts of the body now this is really important for a surgeon okay who if you wanted to do any kind of invasive surgery where you have to make a cut in the integument if you were making a cut like you want to make sure that it is parallel to where to how those collagen fibers are associated in that particular region this is going to prevent or will not prevent but it's going to reduce the amount of scar tissue that's formed when the tissue starts to heal okay uh so that's the that's the best way to make a cut if you were going to make an invasive cut this is the preferred way okay so again this is important for for surgeons all right all right in association with the dermis let's talk about some homeostatic imbalances here striae okay these are stretch marks this is because of dermal tears uh because of extreme stretching and oftentimes you see stray if you uh very enthusiastically start hitting the gym and start lifting weights and start working out you also see striae females see this in the case of pregnancy you see these silvery white scars start to show up in the in the abdomen region as the uterus expands over nine months and as that baby grows that's going to cause some really um quick expansion in that particular region causing extreme stretching and therefore this resulting in tearing of the dermal tissue so that that's an example of striae blistering okay so remember the dermal purpley which is like between the epidermis and the dermis uh if if there's fluid that starts to accumulate in pockets um in the general papillae this is because of um burns for example like so heat excess heat or like chemical uh kind of burns a lot of this can cause blistering and this is basically a fluid-filled pocket separating the epidermal and the dermal layers in the vicinity of those dermal papillae okay so now that we've talked about the different layers of the integument uh the epidermis and the dermis and what are the different types of cells that you see within these different layers we're going to kind of talk about something slightly different focusing a little bit on skin color let's talk about the different pigments that contribute to skin color these are the three most important pigments a lot of this is just mostly um characteristics and a description of these topics uh so a lot of it will be kind of highlighted on the slides themselves so i'll try to stick to the most important uh aspects of that topic absolutely need to know this what are the different pigments for skin color melanin is the most important uh contributor to skin color right behind it carotene and hemoglobin so let's break this down melanin sorry um there are two different forms of melanin and really so we talk about skin color so depending on the uh the type of melanin pigments or varieties that you have you would have the overall skin color depending on the proportion of those pigments like for example so depending on the proportions of the pigments either reddish yellow or brownish black you would have your overall skin color so the more brownish black pigments the darker your your skin color the more the yellow pigmentation and less of the brownish black are the lighter your skin color okay okay um the this melanin this pigment is produced by specialized cells within um the deeper part of the epidermis and in the dermis which is called the melanocytes so yes melanin does play a role in overall skin color but remember melanin also plays another important uh role uh towards the integument this acts as um kind of like a shield to prevent you from being exposed to too many i mean too much uv sun rays okay so too much exposure to uv sun rays can cause skin cancer and we will get to that part here towards the end of this set of slides the other important skin uh pigment for color skin color is carotene this is more of a yellow yellowish orange kind of pigment this is actually kind of formed or it can be converted into vitamin a so this is something that you can accumulate in your body based on the diet based on certain foods that you eat so it does play a role for you know vision and those purposes but also for overall epidermal health and of course plays a huge role in along with uh melanin it plays a role in skin color okay uh hemoglobin okay this is uh the least significant pigment when it comes to overall skin color contribution this is mostly a a player in people with much lighter skin again hemoglobin is a protein that you see packed within rbcs your erythrocytes within the plasma and the hemoglobin is able to bind the oxygen and allows you to transport that oxygen throughout your body and just lighter skinned individuals the the pinkish hue of the hemoglobin in oxygenated blood kind of shines through a little a little bit more obviously and that's why this plays a role in overall skin color but again mostly for lighter individuals the most important pigments for skin color would be melanin followed by carotene and then lastly hemoglobin okay this is a very very important slide you can use skin color for diagnostic purposes in the clinic okay and you're going to need to know all of these different examples as listed here cyanosis okay if you see blue coloration of your skin or kind of becoming more bluish uh this is because of low oxygenation levels so you're not carrying enough oxygen not delivering enough oxygen to certain tissues and that that's where that bluish skin color starts to appear so this is something that you can see externally and this is a good indication of what's happening as a marker of what's happening inside of the body okay erythema this is redness this is often seen during inflammation hypertension fever or an allergic reaction this is again a redness overall redness of the skin pallor or blanching this is due to low blood pressure anemia uh also anger fear things like that jaundice this is actually a liver disorder this is because of accumulation of bilirubin which is not being broken down efficiently as it starts to accumulate in the cells you can see an overall kind of a yellowish pigmentation to the skin this is what we call jaundice often seen in new bonds okay that uh do not have the ability just yet to break down that bilirubin effectively okay bronzing this is a specific condition that is associated with addison's disease this is because of inadequate or low production of corticosteroid hormones from uh from a gland called the adrenal gland which is located on the top part of the kidneys so when you have lowered levels of cortisol or aldosterone which are all examples of corticosteroid hormones this can result in like a darker coloration of the skin where it appears more brown or darker and this is what we call bronzing of course everybody's familiar with this blue and black black and blue marks which is bruising that's occurring because of clot formation underneath the skin okay so make sure you know this if i give you a description of that particular uh condition you should be able to associate it with the clinical um term okay um now let's talk about some of the most important appendages of the skin and our focus is going to be on the hair follicle structure i am not going to discuss nails uh and then i'm going to talk about two different types of glands the sadoriforous glands which are also called the sweat glands and the sebaceous clients called the oil glands now you're going to identify from the anatomy point of view you're going to identify a lot of this on your lab exam so make sure on your lab exam when you're identifying a sweat gland don't say sweatland make sure you're identifying it as a sadoriforous gland there's two varieties you may have to be specific uh on your lab exam where you're saying this is the akron pseudoreference clan or the apocrine pseudorefresh plan and don't call it the oil gland it is the sebaceous gland okay so i just want to point that out because there is some crossover here in the material between lecture and lab all right so let's start with the hair structure okay now if you remember the skin uh structure the upper layers of the epidermis the superficial layer which is the stratum corneum has these dead cells that are all packed with this really uh there's this pigment called keratin except that that was soft keratin and that's why it causes sloughing off of those those keratin pack cells those keratinocytes now you don't see the same thing happening with hair because the overall hair the overall hair might drop off and i'll give you an an explanation of that in a little bit but you don't see the external layers of the the hair structure kind of slough enough the reason being the type of keratinized cells that you see in the hair even though these are the same as what you see in the integument the only difference is you actually have hard curtain as opposed to soft curtain that you see in in in the integument okay so this is just kind of giving you examples of the functions of hair i'm going to let you all kind of look at that this is pretty straightforward physical trauma and things like that hair pigments very similar to uh skin color pigments you still have melanin but there's different varieties of melanin in this case and again depending on what proportion of melanin you have you may have more lighter colored hair like be more blonde versus you may have reddish hair that's actually a special pigment hair pigment um and then of course you could have the darker melanins like the brown and the black hair okay now why would you see uh your your hair turning gray or white this is because of reduced melanin production as you age unfortunately and this is really where the melanin as those levels have to drop uh it gets replaced by air bubbles in the shaft or the hair shaft and this is where you see your loss of your natural hair color and it turns more gray silver white okay all right so i'm going to what i'm going to do next is to talk about the overall hair structure i'm going to discuss the hair follicle structure and this is mostly an information slide i want you all to pay attention to the next slide i believe where we've got the schematic of the entire structure i'll talk to you about the hair bulb region where's the matrix located what's the function of the erector pulley as well as the papilla region so this is a very important schematic make sure you can identify the different regions of the hair follicle structure using a picture that kind of looks like this so let's start with the top here uh everything here on the top all of this is the epidermis layer and of course you would expect to see the dermis here on the inside okay now the epidermis the the outermost part of the hair structure that extends beyond the epidermis is the hair shaft uh the hair shaft then continues downwards okay and this part is called the hair root as you can see here so external to the epidermis it's the shaft what continues downwards into the epidermis and the rest of the entire human this is the hair root this then the hair root by the way is surrounded by all of this lighter brown structures of this peach looking regions this is the hair follicle wall and then as you get to the bottom of this hair structure there is a there's an expanded region to as you can see here with that box that's the hair bulb region on the very center of the hair bulb towards the core of the hair bulb is where you would see the hair papilla so let me go ahead and explain uh what this would look like in cross section if you were viewing this under the microscope with a histology slide okay so okay so your hair root is all of this here on the inside all of this darker pink region that you see kind of on the outside all of this is going to be the hair follicle structure uh this expanded portion here on the very bottom this enlarged part this is the the bulb the hair bulb and the very center the core of the hair belt this is where you would see the hair papilla and notice all of this here on the outside this is all the dermis region right this is all surrounded by the dermis all over here this is where you would see the blood vessels so all of the nutrients from the blood capillaries within the dermis they kind of invade into this hair papilla region okay so therefore all the nutrients to this newly developing hair uh is seen within the hair papilla region right above this region is one layer of cells very similar to the stratum basal cells of the epidermis so this re this layer here is called the the hair matrix region so this is the mitotically dividing stem cells which allows for growth of new hair okay now i want to point out here every time you lose hair you are basically losing just that internal region right that just the hair but everything else is remaining intact which means when that particular hair follicle comes back to life emerges from uh bring dormant if you will uh then you've got the nutrients here you've got the basal i'm sorry the the mitotically dividing stem cells over here so with with both of that you're good to go you can regenerate a new hair used in the same outer follicle structure okay um the only other thing i did not mention here is this guy this is the erector pili muscle this is a smooth muscle so it attaches on one end to the hair follicle wall to the outer wall and the other end of this erector pulley connects directly to the epidermis when this muscle smooth muscle contracts it's going to make the hair shaft erect as in what you would experience if you were going if you had goose bumps okay now the other importance of this structure is associated with a hair follicle you have this uh this glandular tissue this is this sebaceous gland which releases an important secretion called sebum or oil so when the erector pulley contracts the sebaceous gland is able to release sebum that sebum then enters into the hair follicle wall that then nourishes and kind of lubricates the the hair structure okay so those are some of the important uh uh anatomical features of this particular advantage namely the hair follicle and the associated erector pillion sebaceous gland okay so let's talk about the growth of hair there's different types of of hair that you typically see on your body um children and adult females have very uh fine hair uh called b less hair but terminal hair is what's what you see as more coarse hair like uh hair that you see on your scalp your eyebrows and then when you hit puberty in specific regions where terminal hair development occurs especially in the armpits the underarm areas the axillary regions and of course in the pubic regions of both males and females okay okay uh regardless of what type of uh hair structure we're talking about we need to discuss growth cycles okay follicles go through different phases there's an active phase and there's a regressive phase so the regressive phase is when it goes into dormancy when it kind of uh takes a break okay so if the hair was in the act oh sorry if the hair follicle was in the active phase then you have a a hair that is constantly growing in length when it shuts down from the active phase and transfers over to the dormant or the regressive phase this is where that hair is lost so you lose that hair and the entire structure kind of shrivels up the matrix shrivels up and it goes into dormancy so every hair follicle will go between alternative active and dormant or regressive phases okay now there are certain hairs like uh terminal hair that you see on the scalp like your hair external scalp hair that has much longer active cycles and shorter regressive cycles this allows the length of that hair to continue to grow out longer and longer you don't see the same thing happening in the eyebrow hair right it doesn't keep growing to the same length as what you see on the scalp the reason for that is you've got shorter active cycles and in this particular region but longer regressive cycles or rather what's more important is that it has shorter active cycles so it grows to a certain length and then it goes into a regressive phase so that hair falls out and then it again kicks back into active phase to grow out a new eyebrow okay so that's the difference between active and regressive phases uh make sure you know the differences between the two different uh hair varieties as well so now that we've talked about the hair follicle i'm going to discuss two different types of glands now the first type of gland is the sweat glands the sadoriforous glands where we will talk about two main varieties acronym and apocrine and this is not very easily distinguished on a schematic like in your textbook or on any of these slides but you see this much more readily visible on a model like a lab model and so when you're reviewing this material with practice anatomy lab uh you will you will find the differences but i will describe it for you here using my schematic as best as i can okay let's start with equine sweat glands the most important thing here is like i said there's a glandular tissue uh that produces the sweat that's the secretion of the sweat gland uh what's the composition of sweat it's kind of listed over here i'll get back to that then that sweat is released through a sweat pore the sweat pore if it connects directly to the external epidermis this would be an eccrine sweat gland if the sweat pore uh connects to the wall the follicle wall of the hair follicle uh then that would be an apocrine sweatpant it's really just where the sweat pore ends up okay or where does it connect to that distinguishes between the akron and apocrine structurally functionally they have very different roles the most important type of sweat glands are the akron sweat lines and why is this important because they play a huge role in thermal regulation okay okay uh i will use um a sub a subsequent slide to explain how the sweat glands play a role in controlling your overall core body temperature but for right now let's talk about the secretion the sweat secretion and what is it made up of any um fluid that you see in your body is predominantly water i've already talked to you about this when we discussed the chemistry chapter most of the blood volume that's water uh sweat urine um cerebrospinal fluid uh all mostly water okay so again sweats no different 99 water there are many antibodies and there are many microbe killing um well kind of properties associated with with sweat which is really important for you to know this is really important derm sit in this helps to pretty much kill quite a few microbes so this is like kind of an important defensive mechanism and where are these sweat glands within the integument so if there are any microbes that uh invade into uh the integument because you have a tear or you have a cut on your skin uh well there's many different things that will kick in to help with defense or to eliminate that undesired microbe and sweat can contribute towards it because it has dermcidin in it okay and there's also other antibodies that can help mount an immune response so structurally if you were looking at this in lab this is what it should look like all of this structure here is an example of the sodory first gland um what you're seeing here is mostly the glandular portion here on the bottom this is these are the this is where the sweat is produced okay you don't you don't really see the the sweat or not in this cross section remember this is a very thin section across this particular structure so what this looks like is a set of coiled tubes almost kind of collapsed one on top of the other that's what it that's what it looks like under the scalp and this is where the sweat is produced okay the apocrine sweat glands okay this is less understood if you will okay uh it kind of has a similar composition yes it does produce sweat but it has a lot of other things in composition um okay it if it reacts with bacteria especially this can this is what results in uh body odor okay and this is confined to very very specific regions like the genital areas and the axillary regions okay what is its main function we actually do not know uh we're still trying to figure that out we do know what role apocrypha clients play in other species not so much in humans though in other species this is mostly used in uh in mating between male and female so it kind of acts as a like a chemical attractant between the male and the female allowing for reproductive purposes okay in the fee in humans we know that the apocrine secretions um are elevated during um times when you are aroused for example or during intercourse but the exact role is really not understood we do know of specific modified apocrine glands let me get that pointer back up here okay uh examples of modified apocrine glands are listed here the kuruminous glands these are seen within the uh the ure canal the external ear canal and it produces earwax mammary glands breast tissue okay are also modified apocrine glands and yes in this case it produces milk that's important for lactation purposes okay the next gland that i want to quickly talk about are the sebaceous or the oil glands now remember these are associated with the hair follicle um it it releases oil or sebum has a lot of back antibacterial properties and most important thing is it acts as a lubricant helps to soften uh hair and skin okay now that we've talked about all of the appendages so remember uh we started off with the with the hair follicle and we talked about the erector pulley muscle associated with the hair follicle um then we discussed the sebaceous glands the sodoriferous glands and that pretty uh that pretty much wraps up all of the different appendages of the skin i did not talk about nails although it is also classified as an appendage of the skin okay uh now let's move on to the main functions of the integumentary system this is all pretty straightforward i'm just going to quickly go over the distinction between the different functions this is all fair game on a lecture exam you will need to know what the main functions of the integumentary system are let's start with let's start with protection and work our way down the list okay so protection there's three different levels of protection that's offered by the integument it can act as a chemical barrier a physical barrier and a biological barrier so what are some of the chemical barriers remember we just talked about dermcidin which is has an anti-microbial property which you see in when in sweat well that is an example of a chemical barrier overall uh skin secretions like sweat are maintained at a much lower ph yes yes i know i said i was not going to talk about chemistry but you've got to think back to that chemistry chapter very quickly okay very briefly remember the ph scale goes from 0 to 14 right 7 being neutral so everything below 7 6.99 downwards to zero all of this is acidic territory skin secretions tend to be lower ph meaning they have they have more of an acidic functionality that's why this is called the acid mantle okay bacteria do not like low ph conditions they do not do not like acidic environments it uh prevents bacterial proliferation it prevents the it kind of retards or slows down the growth of bacteria so that in itself is a deterrent so if bacteria invade your integument the integument all the secretions from the integrand being maintained at a lower ph is kind of like your first line of defense if you will kind of slowing down the growth of these bacteria now don't forget you've got all of those immune cells like those dendritic cells macrophages all of them will then flag the bacteria and then mount an immune response and and mount other more specialized cells of the immune system to go fight and destroy that bacteria or that virus or whatever that microbe is okay uh sebum produced by that oily secretions produced by the sebaceous gland also has antibacterial uh substances uh defensins natural antibiotics that are seen within any of the sebum or the the sweat secretions remember we talked about melanin just a while ago okay this is also produced by melanocytes it plays a role in protecting against excessive uv rays so that's uh a chemical barrier physical barrier well remember the the in the epidermis has the uppermost layer of the epidermis is called the stratum corneum layer remember those were all dead cells about 20 to 30 layers of dead cells all packed with this really tough protein called keratin which acts as a physical barrier in itself preventing uh unnecessary penetration by microbes and um and pathogens okay uh glycolipids these guys uh those those granules will help to prevent uh dehydration and excessive water loss there's very limited number of things that can actually penetrate the skin and um here are some examples of what can penetrate the skin okay uh certain lipid-soluble substances organic solvents like acetone this is why when you're using uh when you're working with paint thinners and things like that you want to have gloves on your hands so that because all of that can penetrate easily through the skin from the outside and can cause damage uh certain plant based uh pathogens or all your resins like poison oak poison ivy all of that can penetrate skin some of us have been unfortunate enough to experience that right um salts of heavy metals uh mercury lead all of that can also penetrate from the outside certain drugs like uh topical ointments that are designed that way for penetration from the uh from the outside especially in certain sex-related uh kind of conditions or to treat certain disorders related to reproductive organs um as a biological barrier okay so this is where uh we've got different immune cells dendritic cells which are typically your immune cells of the epidermis uh macrophages that are seen deeper down in the dermis all of these together all they do is that they identify uh a pathogen dendritic cells they just recognize a pathogen they flag that cell they put like a red flag on it if you will and then tells the immune system now it's your turn you go ahead and destroy that target macrophages go a little further they are part of their immune system as well so they actually have the capability of engulfing say a bacteria or a virus and then they're going to release those very hydrolytic enzymes on those um bacteria or whatever that pathogen is and destroy kind of chop up that pathogen so they can eliminate the the pathogen in itself dna that you see within the cells of the epidermis specifically plays a huge role in absorbing excessive uv radiation what it does is that it's able to convert this radiation into heat and this is what well heat is good because it helps to maintain your core body temperature okay other functions of the integumentary system let's talk about that thermoregulation now okay this is where i'm going to bring in uh the sodoriferous glands okay those the door refresh plants that play a huge role in body temperature uh regulation um okay so on a normal day if you are not perspiring too much everybody perspires to a certain extent the the most the minimal amount of perspiration that's produced is called insensible perspiration okay but what if your body temperature becomes elevated this could be in response to external triggers like um [Music] it's a it's a hot day okay um so when your body temperature rises how does your body uh bring that back into homeostasis so remember this is classic negative feedback mechanism my variable here is body temperature my problem the stimulus is a rise in body temperature how would i counter it the response should be based on a negative feedback system is here's a problem too much too higher temperature the response would be to go in the opposite direction and lower the body temperature so as to bring your body back to homeostasis and how exactly is this accomplished i'm going to explain that to you but when you actually actively perspire by increasing sweat production for example that's called sensible perspiration okay so we're going to discuss two conditions or two uh scenarios what happens if your body temperature rises and the second scenario what happens if your body temperature drops okay both are examples of negative feedback mechanism so i'm going to work on the first scenario here okay so here's homeostasis this is where you want your normal body temperature to be this is your normal operating range so the problem is what if this range becomes too low or if the range becomes too high okay so we're going to start with one scenario what if this is outside of range it becomes too high so the stimulus in this case is increased body temperature this is a homeostatic imbalance we've got to correct this problem because you don't want increasing body temperature again thinking back to your chemistry chapter what happens when the internal core temperature becomes too high like if you strike a a fever right when your temperature becomes too high this really affects protein structure proteins need to be maintained in this perfect uh three-dimensional configuration as either a tertiary or a quaternary structure because that preserves the functionality of the protein if you increase your body temperature this presents a problem because it brings about denaturation of the proteins which means it starts to unravel into a more simplistic linear form then it becomes non-functional which means to the point of depth okay so therefore how do you correct this problem as your body temperature increases this stimulus this input is sent to the control center also called the integration center the control center in this case as you can see here that's the brain okay there's a very specific region in the brain shown here in purple called the hypothalamus so the hypothalamus there's a two centers in the hypothalamus that control uh temperature regulation um so because your body temperature is rising becoming too high you're going to activate the heat loss center within the hypothalamus okay now so now this is the control center that has made sense of this problem namely an increased body temperature and it's then going to interpret that condition and send out a set of directives to these guys here these are the effectors that will then carry out the instructions from uh the hypothalamus which is the integration center in this case so what are the two directives let's look at number one remember uh blood vessels are seen within the dermis layer of the integument uh the smallest blood vessels the capillaries become dilated meaning they so when you're thinking about a blood vessel uh the innermost part that's the lumen that's the lung for the flow of blood um if you expand if you increase the diameter of the lumen this is what we call vasodilation okay so what's the problem here increased body temperature right if you open up these blood vessels if you vasodilate these blood vessels then what do you think happens to the amount of blood flowing if you open up the the diameter if you make the blood vessel larger right where there's more room obviously there's going to be more blood flowing into that region now remember this is in the dermis right so you're allowing more blood to flow into that region this is warmer blood because of increased body temperature so this can cause basically radiation of that heat from the integumentary surface and as that heat is radiated it is lost from the integument and so what does that bring about cooling right dropping your body temperature which is the response it's the appropriate response so this is an example of a negative feedback mechanism because the stimulus the problem was an increase in body temperature the response was to move this variable in the opposite direction by decreasing the body temperature okay now that's just one part of the story here's the second part the sweat glands uh when the heat loss center is activated the sweat glands also get activated because you know this when you start overheating what happens is you start sweating right so your echoing sweat glands get activated by a very specific region sorry division of the nervous system called the sympathetic division just keep that in mind later on in the semester as we talk about it this will start to make sense what do the sweat glands do these acronym glands are going to start to increase sweat production and again as that sweat is released from the body all the excess heat trapped in that sweat is also released therefore bringing about cooling so that's a response okay now what i'm going to talk about next is the bottom half of this uh scenario right here which is what if the stimulus is a decrease in body temperature which is still going outside of homeosta homeostatic balance still a problem so here's my stimulus a drop in body temperature so if you're kind of looking ahead right through that loop if the problem is a drop in body temperature negative feedback would correct that problem by basically increasing that body temperature that's the response how is this brought about same integration center same hypothalamus region within the brain except you don't want the heat loss center you the body temperature is decreasing you don't want to lose any more heat so you don't want to activate the heat loss center instead you want to activate the heat promoting center in other words this is going to conserve body heat okay how are we going to do this the same dermal blood vessels uh instead of vasodilation you can bring about vasoconstriction which is right the opposite if you narrow down the diameter of the blood vessel there's less blood flowing into that region which means there's less radiation of heat meaning there's more trapping of heat which helps you to elevate your overall body temperature and the second thing as you feel cold like with reduced body temperature you start shivering this is nothing but your skeletal muscles going into some vigorous contraction and as they contract vigorously one of the byproducts is heat so that excess heat that is generated causes uh causes a buildup of that heat in the body therefore increasing your body temperature so the problem here the stimulus here was a decrease in body temperature and using a different center in the hypothalamus namely your heat promoting center i'm sending two directives to two different effectors the dermal blood vessels bringing about vasoconstriction the skeletal muscles going through rigorous contractions therefore releasing heat both of these mechanisms release heat and conserve heat in the body thereby increasing your overall body temperature so that's your response okay so that's a an explanation of thermal regulation in the body which is a very important aspect of the integrity so we've been discussing the functions of the integumentary system uh how it acts as a protective barrier um protection for in a biological sense protection is like a physical barrier as well as a chemical barrier and then we also went ahead and talked about how the integumentary system plays a role in thermoregulation and maintaining a fairly stable body temperature or core temperature so let's review a few other functions of the integumentary system uh cutaneous functions or cutaneous sensations so there's several sensory receptors which plays a huge role in detecting changes in temperature touch and pain these could be just nerve endings or these could be more encapsulated kind of corpuscles so receptors that are more specialized like the pacinian corpuscle um and then of course the the the tactile or the meissner's corpuscles so they all play a role in cutaneous sensations uh metabolic functions of the integumentary system um they play a role in the synthesis of vitamin d and can also activate some hormones okay blood reservoir um the integument holds up to five percent of the total volume of blood uh contained in the body so it can be used uh to divert blood to other critical organs if necessary so for example if you were exercising okay and uh your skeletal muscle is needing to generate a whole bunch of atp in order to facilitate that contraction and relaxation process so to gen to generate that atp uh your skeletal muscle cells will go through a process of cellular respiration and uh the oxygen required for this process obviously has to be carried by the blood okay and delivered to those exercising skeletal muscles so the integumentary system could help by bringing about vasoconstriction of the dermal blood vessels in other words restricting the amount of blood flowing into the dermis and into the integument region and diverting or shunting the majority of the blood to critical organs like the skeletal system uh so normally the the dermal blood supply acts as a reservoir to where you can shunt this blood as needed to different regions of the body okay the integumentary system also plays a role in excretion um this is of nitrogenous waste and especially through sweat okay all right so let us now discuss some of the homeostatic imbalances associated with the integumentary system one of the most important uh conditions here is skin cancer so i'm going to discuss three different types of skin cancer as listed here in blue okay so basal cell carcinoma squamous cell carcinoma and melanoma so i would like for you to know the basic characteristics of these different types of tissue uh sorry different types of cancer um how aggressive they are especially with melanoma i would like you to understand something called the abcd rule okay so how does cancer come about uh in particular here we're talking about skin cancer most of the underlying causes of skin cancer is because of overexposure to uv radiation this causes mutations in the dna and this could debilitate certain uh tumor suppressor genes to where it becomes uh it gets suppressed or down regulated okay um so we're going to talk about all three different types of skin cancer let's start with basal cell carcinoma this is the least malignant uh this is associated with uh over proliferation of the stratum basal cells remember where we talked about stratum basal this is the um deepest layer of the epidermis right there at the boundary between the epidermis and the and the dermis remember this is also the layer where you have those um very highly active mitotically dividing stem cells so if these cells lose control of the mitotic process and start to over proliferate then this is the basis for this particular kind of skin cancer namely basal cell carcinoma okay normally you would see basal cell carcinoma in areas that are raised and more exposed to the sun's uv radiation so it typically shows up as structures like that this kind of looks like a nadio kind of shiny and has elevation to it the good news about basal cell carcinoma is that this this is the least malignant meaning it can it has a very good prognosis so therefore it can be cured uh most of the time by just surgically excising that nodule okay the second type of skin cancer is uh screen cell carcinoma this is related to a different layer in the epidermis namely the stratum spinosum uh involving the kernel sites within that layer okay this appears as a more of a red kind of a scaly structure that's the appearance of this type of carcinoma typically seen on the hands the ears the scalp and so on and so forth does not metastasize um also has a very good prognosis if you can treat it by many different therapeutic interventions using like radiations for example or it can be surgically remote the last kind of skin cancer is melanoma so this is related to cancer of the melanocytes remember these are the cells that produce melanin okay this is the most dangerous kind because melanoma is extremely aggressive um so before oftentimes it um it avoids detection if you will so it goes from something really small to something really large and uncontrolled in a short amount of time that's why it is so aggressive it is also highly metastatic so therefore it can easily spread to other distant sites or remote locations it's really hard to treat this type of cancer because it is resistant to most chemotherapy can be treated by excision also by immunotherapy uh this is super important key to survival is early detection and we need to know this rule the abcd rule before i get there this is what it should look like typically a melanoma specimen um where it typically has um okay so it's a it's a very um um it's a structure that does not have much symmetry to it and if you're looking at the different colors um of this particular tumor you will see multiple colors and different shades of browns reds black purple and so on and so forth so what does the abcd rule indicate a stands for asymmetry meaning if you if this is not a perfect circle uh or an oval or anything like that if you're looking at the overall shape of this melanoma uh you're going to see that the the left side is very different from the right side so it looks it's asymmetrical okay b for border irregularity so if you are scanning the outer periphery of this structure of this melanoma it's going to have a very lacy appearance so it's going to have a lot of curves to it so it's it's not a it's not a smooth uh water so it's very lazy and that's the border irregularity okay see i kind of already mentioned this this is for color if you're examining a melanoma specimen you're going to see different colors within that one specimen so you're going to see different shades of browns black purple and red in some cases so you're going to see a variation in colors d stands for diameter anything greater than six millimeters uh it's too far gone in most cases it's really hard to treat that you want to be able to detect melanoma while it is still within uh or less than four millimeters so that is melanoma so make sure you understand all three types of of cancer especially focusing on melanoma uh and its particular uh characteristics and make sure you know what abcd rule is okay the next homeostatic imbalance that i want to talk about to wrap up our discussion of the integumentary system is burns so this is tissue damage that's done because of excessive heat electricity radiation or this could be a chemical burn as well what this does is it denatures proteins because remember if this is excessive temperature for example this can denature proteins which obviously kill cells the most immediate threat this is really important for you to know um when tissue gets burned you have compromised the epidermis which means you do not have that outer protective covering acting as a physical chemical and biological barrier so therefore this can cause um of course you're prone to infections okay all kinds of infections but also um you remember you've got glycolipids within the cells of the epidermis that helps to slow down water loss and it helps to trap water content and prevents dehydration well without that protective barrier and with all of those cells being burned away uh dehydration becomes the most immediate threat in the case of uh burn victims um this would result because we're talking about water balance here this ultimately also causes an imbalance in electrolytes like sodium especially okay because water always follows salt and when you start to see an imbalance with the water that's going to ultimately affect even other electrolytes in the body can definitely impair renal function causing renal shut down and as you get dehydrated um overall throughout your body this is going to reduce the overall blood volume or the plasma volume and typically when blood volume drops um this would also drop blood pressure so blood pressure decreases dramatically putting you into circulatory shock so those are all consequences of burns you can classify burns depending upon depending on the severity of the burns so you could classify them as partial thickness or full thickness within partial thickness you've got the first and the second degree burns so first degree is always only damage to the um outermost epidermal layers so this is going to cause redness swelling and pain obviously second degree burns is all of the epidermis plus the upper dermal layers blistering is going to occur here uh in in full thickness burns this is where the entire epidermis gets burned the dermis everything gets burned all the way down to the bone so this is going to cause in this particular case this is a really severe degree of burn normally in full thickness burns skin grafting is necessary because remember those immediate threats uh that you're prone to all sorts of infections because you do not have that protective covering plus dehydration becomes a problem which can put you in renal failure and problems with the cardiovascular system so circulatory shock all of that you do not have time to allow for what would you call it mitosis to occur and to allow for a normal regenerative potential of the epidermis to uh to actually regrow that tissue first of all all the epidermis has been kind of eliminated so you don't have the the stem cell population and you have a you have bare uh bone and there's nothing protectoring protecting it so in such a um full thickness burn in such a severe case of a third degree burn uh time is of essence and typically the best way to to uh help these patients is to to do skin grafting normally you take a skin graft from a different region of the patient's body to graft over this area that has been damaged okay here's examples of partial thickness and full thickness burns uh so what you're seeing here this would be an example of a first degree burn where you just see some redness okay and some swelling in a second degree burn you can clearly see the blistering right there so that's where the epidermis and the top layers of the dermis have been um impacted and here's an example of a third degree burn where this is basically completely burned all the way down to the muscle and the and the and the bone uh tissues so uh the last part that i want to talk about related to burns um it is typically considered critical if greater than 25 of the body has second degree burns if it is 30 degree burns then anything greater than 10 containing third degree burns is considered critical generally speaking any burns to the extremities the face the hands and the the feet when they have third degree burns this is this is a problem um because scar tissue formed in joints within the hands and the feet can really limit mobility or even completely restrict mobility which is a problem anything related to the face is also critical because of airways and and passages so that can cause airways to to kind of swell up and and can cause all collapse which prevents your ability to breathe so causing respiratory distress treatment in the case of critical conditions like this or just about any condition especially if it requires uh skin grafting this is typically the process that's followed first you've got to remove all of the burned tissue you've got to clean the area um and get it ready for a graft uh there's a lot of antibiotics that are applied and of course you uh you want to be on a severe regimen of antibiotics because you want to be able to counteract all these infectious agents and microbes that have now free entry into the body you always want to place a temporary covering uh for a short amount of time to kind of prepare the area for uh if needed come in with a skin graft okay so that in essence is our discussion of homostatic imbalances related to the integumentary system so in this video we've covered the integumentary system uh we talked about the basic anatomy the structural uh layers the the the features and the characteristics of the integumentary system make sure you understand the epidermis and the dermis all the different sub layers the tissues the different cell types and what do they do their functions all of that then make sure you can pinpoint and also know the functions of the different appendages associated with the integument starting with the hair follicle structure and what does it do the erector pulley muscle and then um what else um we talked about the glands so that we we discussed the pseudoiphas the sweat glands as well as a sebaceous glands um and then after that we really went on to our discussion of the overall functions of the integumentary system make sure you understand the negative feedback mechanisms involved in thermoregulation within the body what would happen if the stimulus was an increase in body temperature versus or what would you expect to see if you see a drop in body temperature so all of that is definitely important and then the last things that we talked about here was two examples of homeostatic imbalances associated with this organ system namely cancer skin cancer where we talked about three different types of skin cancer and the last thing that we discussed was burns so that is a summary of the integumentary system i hope it made sense to you uh keep reviewing the material till it all sinks in um the next video that i will be um making will be a discussion on the skeletal system and uh emphasize a little bit on join so i hope this made sense and i hope it was helpful to you thank you