salmon roe - good again in order 20 minutes in tenements at all times nice to the skin for 20 minutes and we're good with it skinnies were small it's not a big job group all those hormones [Music] the skin is a small chapter budsies the largest organ we have the integumentary external surface of our body yeah we can touch it we know that it has a few parts to it has an epidermis on top it's got a dermis underneath and it's called the soup subcutaneous fat layer below that or sometimes they call that also hypodermis hypodermis the epidermis is the top layer so if you touch your skin you talk to epidermis it is made of stratified squamous keratinized epithelium what then remember that stratified how many layers list epithelium in that's multiple layers we have simpler way of stratified squamous means it's fried egg looking things it's flat those are the flat tough now cube shape not too long nor say flat you don't want to give me your phone or shape sticking up there with a Buddhist ring and then we need new character but we did have a feeling that means it's an epithelial tissue the character NIH's the character is the protein that makes you be able to have as a leather jacket is prophy that makes the skin to hair in the nails hard and more improve so that's why a leather jacket is a is a helpful thing for us because that's basically skin and the skin there you go I like spongebob and that's definite when we look at the epidermis the top layer of the epidermis - don't think like when I do this themselves fall off so the top layers of cells are dead they're just flakes and that's great because when I bump into something I don't have to get injured these things could just fall off that that is actually a really good way of doing it so yes it has multiple layers because on the bottom right low deep fur this is the surface this is deep it cannot be dead cells because those cells have to be made so down here we have a base layer called them they call the layer straw to him strong to Basel they or German above tables and those cells constantly divide they always make more cells and in one of those cells the wall of the daughter cells goes up a little bit migrates upwards towards the surface and eerie in starts making keratin in there so we call that a stratum spinosum because because they look like a little pointy it can you see it on this picture but other pictures show or point you under the microscope and then as more cells get made from our own these things are pushed up further and further and began into a place called the stratum granulosum because now we have deterioration of those cells so they're slowly starting to die and they create granules in them and you can see those granules and that's why they call them strong term granules and then after that they're pretty much dead cells and they call that the straw - corneal at the top where the dead cells are the top layer and that's hard Cory means hard I'm in the pot the palms and the soles hands it's also the feet are a little bit different there's a little thicker skin there and we have one layer in between and a layer is known as the stratum lucidum in there if you need to know those words you look it up in the review you're starting what we do for the test okay make sure you try to understand as much as you can when I talk about so when you look at the cells in that in the epithelium we look at these cells that make the character that those are keratinocytes so those are the main cells then we have Auto cells and they include and a keratin I mean that and then we have ourselves some of them are nerve cells they're mechanoreceptors they make sure we can pick up touch or talk it's loud differentiate that so we know who's nice to us and it was not some of those are known as miracle cells not Angela Merkel cells just Merkel cells and they are mechana sensory cells and they're mostly found in sensitive areas those are actually the ones that are not the ones that are slappy those are the ones that can tell oh this is a corner the feed define tactile figure of otherwise I'm just also have no more juice not prepared all right and then be called melanocytes and that's that's the skin darkening so the melanocytes are interesting they are like at the bottom and have long cellular expansions into the cell extensions they will joke or on ourselves and sort of cover them a little cover their nucleus so their DNA doesn't get damaged by the UV rays radiation so we all have melanocytes is just are they active how active are they it's a question of how to order skins so in fair-skinned people go to solve they get a little round brown when people are they a little more brown and that's what that is it's not that one has it and one doesn't have it and ensuring anything else that people are talking about it about people call skin it's just are we using it or not that's the only thing and that's the melanocytes making melanin and then we got the long john cells longer arms means long johns homes means john and lung injuries long so those are the long johns and they are antigen presenting macrophages monocytes in the new system so I thought so Stefano size that goes to the tissue and lives there and in the skin we call them the lower homes themselves and that's what they do in the skin so they make sure that bad stuff comes in and we can eliminate it if it does and look at this nice picture there is all the layers there's different cells and so you just sort of have half an overview because then we go deeper and so one function that you've learned in epithelial tissue is it is not there's no vascularity to it is there's no blood vessels going to so this top layer is actually no blood vessels at all so if you caught yourself and you believe you know we called through the entire epidermis because you've got to have to cut one of these blood vessels down the endodermis so the dermis gives the skin resistance so when you pull it it doesn't come off and it's flexible it helps you not tear and it gives it so plasticity so yeah it can be deformed we'll go back to the regular shape afterwards it has a lot of collagen and all of elastic fibers the top layer of the dermis is known as the papillary layer and you see those little peg like structures that go up here they go through the whole thing so there are three dimensional fingers that stick up and they anchor the epidermis to the deeper structures those peg light projections increase the surface area high number depends on mechanical needs of an area and it also through that common close to the surface as your proper nutrient that nerve supplies to the epidermis remember it's a vascular and and all that layer we have a deeper reticular layer and that anchors the darkness into the subcutaneous fat layer and that's the owner needs to skin fat them yeah that's a very good protection we need some of that it's a good insulation layer so that's basically the dermis not too much about the dermis but that it brings us to the function of skin well the skin has protective function it protect us against mechanical damage radiation and chemical damage protein here is two key ingredients also we talked in immune system the skin is the first line of defense it doesn't let the crap go in it stays outside so that's the new function right there and anyhow just temperature constriction dilation of the vessels in the skin determines the amount of red heat radiation from the skin if you get a lot of like I have a lot of what Riley Gordon that radiates off so that gets rid of heat in the body also it is cool cold just bring the heat away from it begin more pale and that is also temperature regulation also protects the horses from not getting too cold water balance at the dermis prevents water loss it's not just the water going in it's also the water going out that's not happening well that's good what is that oh we have to sweat as part of that cooling off system and it mentioned that and then it's very salty it has ions electrolytes in it and that then influences many body functions so if we sweat too much we gotta make sure we take some electrolytes back in and have something salt the body just get rid of it I worry about too much I'm over about the deficiency I mean unless it's Gatorade and then is just sugar water just back to that right I mean that's part of the problem with it then it also sensory function the skin contains receptor of pain well yeah you feel pain thank God you feel pain when you hit something not did you like it we also have touched temperature pressure in this and we can communicate skin washing or turning pale that's a communication tool that we can have this to the skin not that we maybe want to use it but it just shows up unannounced and then from there we have a couple of appendages we have some glad to have sweat glands these are these little Wiggly things antennae go up to the skin up to the surface and then we have sebaceous gland and sebaceous glands are these on the side here they go into every hair and they secrete an oily substance rich in fatty acids that helps our skin pliable provides well Ciera who provides clothes here so that the sebum is like your lotion gland that's your swagg plan that's your lotion plan let's declare the two different plants we have up there and then of course we got hair - hair provides teeth and talk sensation for the body the hair shaft right here so that's a hair shaft that's it close by hair follicle that's the outside portion of it hair follicle and then a sebaceous gland where did they write the sebaceous gland I guess right here the small little wiggle here feeds into it as well also attached to the hair is a muscle known as the erector pili muscle and then when the hair comes out at a 45 degree angle you can see it this doesn't go out of straight is it Elaine and so when it's cold for example or when a cat is endangering these to make itself bigger the hair stands up and gets four feet that happens to cut those and then the muscle stands to hair up and it pulls on the skin against what we get goosebumps so that's the goose bump down interesting how the hair ball forms the hair at the deep end over here pillow blah blah blah so down here the hair ball is you know like the bulb of a plant that you put in the ground that's where the flame comes from that's where the hair comes from and then at the bottom we have to fulfill under fulfill is distinct sticking up a little bit and that's where we have nerves and blood vessels coming into it all right good I think that's it Oh nails oh you know of course we can't have no nails you know what nails are really weird I mean they're great to paint on to start with but they're they're very specialized epidermal formations but they help us with well actually let's just consider you you have to pick up something and you don't have this nail here and it's just four feet fluffy and all we have in the middle is a bowl he's really gonna be hard to do stuff with and so it helps us give us the backstop against the pressure can go against and then we can grab stuff easier and so we can pinch stuff easier so that's kind of cool that's the nail bed where the nail comes from here anchors to nail and then we have epithelial sure and Elton Grover you know is thinking roles like that at epithelial tissue especially as it comes to the outside surface and then limb protects the terms of phalanges that's the ball for the finger of the finger of the toes and informs that backstop which is what we just talked about cool cool I think that's it