all right let's look at accessory wardens so the main accessory organs are going to look at our hair and nails but we're going to look at some other smaller organs that we have in our skin as well so hair nail just let you know are made of a hard keratin while skin is made of a soft character so let's take a look at hair so hair is in a hair follicle so this is the hair itself the follicle is the tissue around the inner so this is a tube like depression in the skin in which the hair develops now if we look at distribution and types we have about 5 million hairs on the human body most of which are on the general service 98% or on the general surface meaning not the head so we have about a hundred thousand hairs on our head well some of us have more than others so looking at types of hair one type is called Bellus hair that's a typical body here so what we find on our body next is terminal hair in turmoil hair is hair on the head eyebrows eyelashes and after puberty we'll get in other areas so we'll get in the axillary and pubic hairs axillary armpit male facial hair and some hair of the trunk and limbs last type of hair that we can produce is called lanugo and Luco is a fine downy unpigmented hair that's found on a fetus and it's found in the last three months of development and then it falls off alright you can see lanugo typically on a premature baby but not a fully a baby that is going full term so let's take a look at the structure of hair and the follicle so down here so that's shown the hair so down here at the bottom of the hair this is where we find the hair bulb so this is swelling at the base and that's where the hair originates so the root is the remainder of the hair that's in the follicle and the hair shaft is the portion of the hair above the skin's surface now the root and the shaft both contain dead hair dead skin cells next is a haircut pillow and this is the hairpin pillow right there so this is a bud of vascular tissue there and that provides nutrients for the hair all right so let's take a look so the hair matrix right there within the bud that's the hairs growth Center so let's take a look at the hair cross-section so this is shown the hair and the follicle and cross-section alright so the first is the medulla so this kind of if you follow this that inner portion oh kind of that lighter blue area there that is medulla so whenever we have say that we have a medulla the module is the inner portion we have a cortex the cortex is the outer portion so the medulla is a corps of loosely arranged cells and air spaces it is found in thick hair it's absent in thin here around that and that purplish area in there is the cortex and so this is a layer of keratinized cuboidal cells and then outside of that shown here brown is the cuticle which is the surface there alright let's take a look at some structures we got here so structures associated with the hair follicle the first are hearing receptors so you can see this yellow is trying to show nerve fibers wrapping around the follicle so those hair receptors these are nerve fibers that respond to hair movements so if I move the hair that's gonna move the hair in the follicle and that's gonna be sensed by those hair receptors and this for a large reason is why we still have hair on her body is to feel things that might get on our body oh we humans had a reduction in hair in our body because it helps our evaporative cooling we sweat more easily and lose heat more easily having less hair on her body next is erector pili muscle so this erector pili muscle here this is smooth muscle that causes the hair to stand on end so you know we can track the rector peel eye muscles when we're cold and that makes the hair stand on end you also are going to contract that when you're scared also causing the hair to stand on in now erector pili muscles are the pseudo organs for humans so a vestige organ is an organ that was functional and ancestor but no longer function functional in the current organism alright so by pausing hairs to stand on end when you're cold that creates the air just hair to stand up and creates a lot of air pockets between the outside air and your skin and by creating those air pockets air is a poor insulator and so poor conductor of heat I should say and so this helps keep your you're warmer so that's why dogs and cats and so on will do that so you'll also can track this when you're scared now if you've ever seen a scared cat its back its arched tails in the air hair standing on and it's trying to make itself look more intimidating and bigger alright and so if you get scared same thing will happen to you but once again that function is lost on humans because you do not look larger and more intimidating alright let's take a look at hair texture in color so texture so we're gonna take a look at the texture and looking at the differences in cross-section so if you have straight hair like these two ladies here your hair is oval in shape alright if you have weight I'm sorry so your hair is circular right as round in cross-section sorry about that if you have wavy hair here your hair is oval in cross-section and if you have curly hair your hair is relatively flat and a picture of that one so if we look at color color if you have Browns black hair you have high levels of you Oh melody alright if you have red hair you have low levels of eumelanin and high concentrations of pheomelanin if you have blond hair you have intermediate amounts of pheomelanin and very little you in your hair you have gray hair basically when you get gray hair you have a mutation so you stop production of the the melon here so with gray hair you have little melanin and you get air in your medulla if you have white hair you have no melanin so once again you also have air in the medulla if we look at hair growth gonna go back to this picture here hair growth is similar to skin growth so we have a stratum basale there and basal makes the new care to the sites and those characters sites are pushing to the matrix and so as those cells move up as new cells remain underneath those those cells will begin to die so same kind of process in there the difference is is that hair grows in cycles so the first phase is called an antigen phase and that's where we have hair growth occur right the second phase is called the cabbage and phase and that's where the base of the hair does all right so the base of the hair dyes and lastly is the telogen phase and that's where the hair rests in the fall so after that hair dies the hair can just rest in the follicle no now the hair may fall out at the cabbage in more telogen phase so once the the base of the hair dyes and the cabbage in things the hair could fall out or can rest in there in the telogen phase for a little while before it falls out hair growth in most parts of the body is two three months so the length of the anagen phase determines how long the hair is going to be okay so if it grows or you know two months it's going to be pretty short hair three months gonna be a little longer hair on the head can has an antigen phase of six to ten years and that's why hair in the head also male facial beards or facial hair can grow very very long you lose about 50 hairs on your head per day which means 50 new hair start to grow per day hair functions one is a sensation with touch there all right hair on the head a couple functions two guards against heat loss probably not as much as you ever heard it's basically the surface area body that's how much heat lost you would restrict from then okay so you know that's why and a winner you know me being somebody doesn't have hair I always have a hat on because my head gets cold Herod your head also protects you against sunlight so think about like if you've ever been underneath you know an umbrella during this you know sitting outside on a patio and you know there's a table umbrella there it blocks the Sun directly hitting you it helps keep you cooler your hair does the same thing to your head alright we also have hair in our nose and ear canals and that's going to help prevent entry of foreign objects okay let's move on to nails nails are protective coverings at the ends of fingers and toes so what we see here and nail growth is similar to skin growth so we have new character the sights made we have new keratinocytes made here and as they are made they push the older ones further further up and so on it and so that kind of follows the same progress here let's uh get glands in the skin the first are surah first glance also know the sweat glands and we have two types of sweat glands we have eccrine or merocrine sweat glands and the other are apron sweat glands now the Mariner echoing sweat glands they produce a watery perspiration so we use this for temperature control and these are found all over the body and I'll just let you know because this opens up in a poor we actually lose about 500 milliliters of water off our skin per day and this is known as insensible perspiration and those come out of our sweat glands next our African sweat glands so the deeper down larger here these produce a thick milky perspiration these are found in the pubic anal region axillary areolar and beard of males and supposedly they secrete an odor that is attractive to the other sets next are sebaceous glands so this is a sebaceous gland here so these produce an oily secretion known as sebum and these are associated with hair follicles alright so see if it lubricates the hair growth and hair as it grows and it also moisturizes the hair in the skin next is shermanus glands not shown here but sir - glands secrete cerumen which is earwax so these are found in our external ear ear canal or center of auditory meatus ensure cerumen is really a combination of sebum in dead skin cells lastly our mammary glands mammary glands produce milk and they are actually modified sweat glands