Exam 3 Review Skin bone axial skeleton on exam 3 Chapter 5 Integumentary system 1 Integumentary System Basic Components a Composed of i skin hair nails and glands embedded in skin 2 Skin a Skin is a giant sense organ it is the largest one b Functions i Protection of underlying tissues and organs 1 First defense against pathogens 2 3 Water resistant 4 ii Excretions of salts water organic wastes iii Maintenance of body temperature 1 Hypodermal regulation 2 Sweat and Goose Bumps iv Production of melanin and keratin v Synthesis of vitamin D3 1 Absorbs sunlight and synthesizes vi Storage of lipids vii Detection of touch pressure pain and temperature 3 Skin Layers a Epidermis stratified squamous epithelium i Avascular no blood vessels ii Basement Membrane Impenetrable bacteria can only get in if there is a cut of some sort Immunity may have enough macrophages to kill off pathogens that try to enter 1 Bottom of epidermis We are building up from the bottom 2 Melanocytes sit right on basement membrane a These synthesize a pigment called melanin i Deliver melanin to other layers of the epidermis b Disperses the pigment throughout the skin c Skin color differs based on how much melanin is released d Located about the nucleus and are used to shield the by the melanocyte nucleus from the sun i Tanning damages skin ii More melanin is produced to protect the nucleus from rays of the sun e Skin color depends on melanin production not the number iii Stratum basale of melanocytes 1 Sits directly on the basement membrane 2 Cells are constantly growing and dividing and producing daughter cells 3 Contains keratinocytes they are not yet keratin Just keep adding more growing and growing a b Most plentiful kind of cell in epidermis c Keratin is what eventually makes your skin tough and water tight d Melanocytes are in this layer e Deepest layer single cuboidal or columnar 4 Basal cells germinate cells stem cells 5 Merkel cells hairless skin respond to toch 6 Melanocytes contain pigment 7 Epidermal ridges finger prints iv Stratum spinosum 1 As cells in the stratum basale age they start to enter the stratum 2 This is a spiky looking shape 3 The keratinocytes are still alive but not nearly as mitotically active spinosum layer as they used to be 4 This is what creates the swirls in fingerprints 5 Langerhans cells are found here dendritic cells 6 8 10 layers of keratinocytes 7 Dendritic Langerhans cells active in immune response v Stratum granulosum 1 Older keratinocytes are in this layer a They are filling up with grains b Get a granular dark appearance 2 The keratinocyte grains are precursors to keratin 3 Cells get old and start dying no longer making new cells 4 Cells are filling up with keratin which is what causes them to die a Too much keratin 1 Thin clear zone only in thick skin 2 Extra fifth layer vi Stratum lucidum vii Stratum corneum keratinized cells keratinocytes let each other ago 1 Cells are filled with keratin and are dead these are fully 2 All cells are dead as they get closer to the surface the a No longer hold on to each other no more tight junctions 3 These will soon be dust 4 There can be a minimally keratinized type of skin a Only occurs in places that need moisture i Cavities that lead to inner body like mouth ear nose vagina b Dead cells aren t sloughing off 5 15 30 layers of keratinocytes 6 Water resistant shed every 2 weeks viii Surface basale 1 Cells fall off when they reach the surface ix Order of skin layers corneum lucidum granulosum spinosum x Hair follicles form when the layers of epidermis are modified and dig into the skin and the hair follicle then fills that empty space 1 No hair follicles in thick b Dermis connective tissue partially loose and partially dense tissue i Papillary layer Immediately underneath the epithelium 1 2 Areolar loose layer of connective tissue It runs in a ridge or hill type shape 3 ii Reticular layer 1 2 Mostly dense irregular connective tissue 3 Some reticular fibers and some elastic Underneath the papillary layer iii Vascular blood vessels and nerve fibers iv Directly under the epidermis 1 Tactile corpuscle sensory nerve ending a End immediately on the basement membrane b Associated with the sense of touch 2 Merkel cells sit right on top of tactile corpuscle a Allow you to feel touch b Merkel disk is when merkel cell sits on top of the sensory nerve ending v Glands are in the dermis 1 Sweat glands used for thermoregulation sudoriferous gland a Most common are eccrine glands apocrine glands b Some places only have i not for thermoregulation ii found in genital groin armpit regions 1 not used to release heat they secrete a thicker fluid 2 secrete when you are scared sexually excited or stressed iii don t work until you hit puberty i Secrete oil into hair follicles c Sebaceous gland oil d Ceruminous gland In outer ear canal i ii Secretes cerumin 1 Ear wax 2 Helps flush out pathogens and bacteria vi If you bleed when cut you have cut down to the dermis c Subcutaneous layer hypodermis not part of the skin i Located underneath the skin made of adipose tissue ii Vascular superficial region contains large arteries and veins d Hair Follicles i Hair 1 Hair is seriously compressed keratinocytes 2 Hair doesn t grow what s underneath the hair is what grows ii Hair bulb small amount of tissue that contains actively dividing cells 1 Little tiny piece of tissue and it s called hair papilla a Living part of hair follicle b Produces keratin filled dead hair iii To get rid of hair you have to kill the papilla iv Most sebaceous glands coat the follicle which is why hair is oily v A little muscle attaches about midshaft that contracts 1 Attaches to edge of epithelium 2 Called the arrector pili muscle a When this contracts it pulls the hair straight this is why our hair raises when you get cold 4 Nails a Compressed keratinocytes similar to hair b Extend from a modified epidermis at your fingertips c Has a root at the end d Only a few mitotically active cells that cause it to grow the rest is dead e Eponychium i Buildup of epidermal cells in a tough deposit where the nail comes out f Hyponychium i Under your nail at the very tip of it ii Tough epidermal cells 5 Healing process for cuts a Inflammatory phase i A series of chemicals are released to create a barrier from bacteria ii Blood starts to coagulate 1 Fluid part of ground substance becomes thicker and gelatinous iii Dry clotted blood will form a scab on top of the skin iv Blood fills up the space in between the