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| composed primarily of the skin and accessory structures. Those structures include hair, nails, and certain exocrine glands (glands that have ducts or tubes that carry their secretions to the surface of the skin or into body cavities for elimination) |
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| Sweat glands located primarily in the armpit and genital areas. |
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| Smooth muscle attached to a hair follicle that, when stimulated, pulls on the follicle, causing the hair shaft to stand upright. |
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| Finger-like projections extending upward from the dermis containing blood capillaries, which provide nutrients for the lower layer of the epidermis; also form the characteristic ridges on the skin surface of the hands (fingerprints) and feet. |
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| Thick, inner layer of the skin; if protective outer layer of skin is broken due to injury & microorganisms enter body, blood vessels in dermis help prevent microorganisms from reaching internal tissues by dilating/expanding which increases amount of blood flowing to area which brings more white blood cells & other protein factors to battle infection |
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| Body's most numerous sweat glands, which produce watery sweat to maintain normal body temperature. |
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| Thin, outer layer of the skin. |
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| Tissue that covers the internal and external surfaces of the body and also forms glandular organs. |
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| In animals and plants, any natural outer covering, such as skin, shell, membrane, or husk. |
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| Tough, fibrous, water-resistant protein that forms the outer layers of hair, calluses, and nails and coats the surface of the skin. |
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| White, crescent-shaped area of the nail bed near the nail root. |
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| found in the lower epidermis that produces the protein pigment melanin. |
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| Any part of the body formed of two or more tissues that performs a specialized function. |
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| oil glands; found in dermis all over body except palms & soles; secrete sebum (mixture of fats, proteins, fragments of dead fatproducing cells); most secrete sebum through ducts into hair follicles, others onto surface of skin; sebum is also forced out when arrector pili muscles contract to elevate hairs |
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| mixture of oily substances and fragmented cells secreted by sebaceous glands; function is to prevent drying of skin & hair; contains chemicals that kill bacteria present on skin surface |
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| cells that are flat and scale-like |
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| tissues between the dermis and the muscles |
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| Skin's two principal layers |
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| Epidermis (thin, outer layer); Dermis (thicker, inner layer) |
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| Beneath dermis lies subcuatneous (in between dermis & muslce) hypodermis (composed of adipose/fatty tissue) which anchors the skin to underlying muscles & contains major blood vessels that supply the dermis and houses many white blood cells |
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Definition
| Made of stratified (layered) squamous (scaly) epithelial tissue; basically many layers of thin, flattened cells that fit closely together |
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| a tissue composed of cells that line the cavities and surfaces of structures throughout the body; also forms many glands; lies on top of connective tissue; one of four primary tissues (connective, muscle, & nervous) |
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| Basal Cells (epidermis layer) |
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Definition
| inner/deepest cell layer; recieves nutrients from underlying dermis; basal cells constantly dividing & creating new cells daily which push older cells toward the surface; basal cells produce keratin (durable & water-resistant fibrous protein) |
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| found in lower epidermis; produces melanin (protein pigment that ranges in color from yellow to brown to black); amount of melanin produced determines skin color; freckles are result of melanin clumping in one spot |
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| Outermost layer (epidermis) |
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Definition
| 20~30 rows of tightly joined flat dead cells; cells only have keratin = waterproof layer; takes ~14 days for cells to move from inner to outer layer; remain on outer for 14 days before flaking of slowly/steadily |
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| second layer of skin; in between epidermis & subcutaneous layer (tissues between dermis & muscle); thicker than epi-; contains accessory skin structures: Hair, sweat glands, sebaceous (oil) glands are rooted in dermis; contains blood vessels & nerve fibers; nourished by blood and oxygen provided by these blood vessels = cells are alive; connective tissue forms dermis/bundles of elastic & collagen fibers blend into con- tissue & provide dermis w/ strength & flexibility |
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| finger-like projections that extend into epidermis called dermal papillae which contain blood capillaries (provide nutrients for basal cells); dermal papillae form looped & whorled ridges = finger- or toeprints, increase gripping ability of hands & feet |
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| unique to each individual; created by pattern of ridges/dermal papillae |
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| English scientist; first to devise a system of fingerprint identification |
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| further developed Galton's ideas by developing a more simplified fingerprint classification system |
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| for touch, pressure, heat, cold, pain; located within the dermis; specific receptors exist for each sensation: pain = free nerve endings, other = encapsulated nerve endings (have a cellular structure around their endings); #/type of sensory receptors determines sensitivity |
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| hair, nails, sweat, sebaceous glands |
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~5 million all over body; ~100,000 on scalp; entire body except palms, soles of feet, sides of fingers/toes, lips, & certain parts of outer genital organs is covered by hair;
each hair originates from hair follicle (tiny tubelike structure) that extends deep into dermis; often follicle projects into subcutaneous layer; capillaries & nerves attach to base of follicle providin nutrients & sensory information; inside follicle, epithelial cells grow/divide forming hair bulb/enlarged hair base; keratin, primary component of epithelial cells, coats & stiffens hair as it grows upward through follicle; part enclosed in follicle = hair root; once projected from scalp/skin, called hair shaft; older epith- cells forming hair root & hair shaft die as pushed upward from follicle by newly formed cells = hair shaft made of dead material/entirely protein |
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| outer layer of hair shaft; consists of a single layer of flat, overlapping cells |
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| inner layer of hair shaft; made mostly of keratin |
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| Hair shaft size, shape, color |
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| size varies depending on where located on body; oval-shaped hair shafts = wavy hair, flat = kinky/curly, perfectly round = straight; different types of melanin produced by melanocytes at follicle base combine to create hair color (with age production of melanin decreases & hair turns gray) |
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| Arrector pili muscle (hair) |
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Definition
| attached to each hair follicle; smooth muscle; when stimulated, muscle contracts & pulls on follicle causing hair shaft to stand upright |
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| ends of fingers/toes; produced by nail follicles; nail root is portion embedded in skin lying near bone of fingertip (cells produce a stronger form of keratin than is found in hair); New cells formed = older cells pushed forward, forming nail body/visible portion; free edge is portion that extends over tip of finger/toe; protect exposed tips of fingers/toes from physical injury; fingernails also aid in picking up of small objects |
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| tissue beneath nail body; live cells; blood vessels running through nail bed give nail a pink color; near nail root blood vessels are obscured = white crescent/lunula |
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| >2.5 million distributed over most surfaces of human body |
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| more numerous than apocrine; found all over body; numerous on forehead, upper lip, palms, soles; glands are coiled tubes that originate in dermis; a duct extends from the gland to the skin's surface where it opens into a pore; produce sweat/perspiration (clear secretion that is 99% water); some salts, traces of urea, & vit C form 1% |
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| armpits, around nipples, groin; coiled tubes found in dermis; usually larger than eccrine glands & ducts empty into hair follicles; do not function til puberty (begin to release odorless cloudy secretion that contains fatty acids & protein); if secretion remains on skin for any length of time, bacteria on skin break down fatty acids & protein for their growth creating unpleasant odor associated with sweat; activated by nerve fibers during periods of pain/stress; theorized to act as sexual attractants |
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| Functions of Integumentary System |
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Definition
| Homeostasis; protects underlying tissues and organs from infections and injury; prevents loss of body fluids |
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Definition
| skin/glands help maintain normal body temperature as they recieve ~1/3 of blood pumped from heart/minute; works as mini-excretory system (secretes salts, water, & wastes in form of sweat); skin cells use sunlight to create vit D (necessary for bone growth & function); contains sensory receptors |
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| outermost epidermal layer is a barrier between internal environment of body & external world; keratin waterproofs the body (w/out it, handling household chemicals, swimming, or taking a shower would be disastrous to underlying cells of body); keratin also keeps water in |
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| spilled drop of dimethyl mercury which permeated through her latex glove & soaked into her skin; once in the body dimethyl mercury seeps from bloodstream into brain tissues causing damage to central nervous system/brain (loss of motor control, numbness in arms/legs, blindness, hearing, speech loss); Wetterhan felt effects 6 months after accident, w/in 3 months she was dead |
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| Slight-permeability (skin) |
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Definition
| skin allows vit's A, D, E, & K to pass through; vit's are absorbed in capillaries in dermis; steroid hormones (estrogen & chemicals such as nicotine) also pass through/are absorbed |
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| Hair (protective function) |
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Definition
limited; protects scalp from damaging UV radiation; cushions head from physical blows; insulates scalp (to a degree); eyelashes prevent airborne particles & insects from entering eyes; in nostrils/external ear canals perform similar function as eyelashes;
when stimulated by cold or 'fear,' arrector pili muscles contract (in animals, adds warmth by adding layer of insulating air; in humans, doesn't really serve a purpose...) |
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| Melanin (protective function) |
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Definition
| accumulates within cells of epidermis; absorbs UV radiation before radiation can destroy cells' DNA; increased exposure to Sun causes melanocytes to increase production of melanin (temporary result is that skin becomes darker/tanned & is able to withstand further exposure to UV rays); protection by melanin is limited: prolonged exposure to UV radiation damages skin by causing elastic fibers in dermis to clump = skin becomes leathery; overexposure can result in melanoma (tumor composed of melanocytes) |
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| 98.6°F<-if this temp varies, life-threatening changes occur; when boy temp rises due to phys. ed. or environmental conditions, hypothalamus signals eccrine glands to secrete sweat which carries large amounts of body heat with it when it evaporates on skin surface, cooling the skin; blood flow regulates body temp: warm conditions, hypothalamus tells vessels in dermis to dilate/expand to increase blood flow & carry excess heat to body surface; cold conditions, eccrine glands stop secreting sweat & vessels constrict to reduce bloodflow to surface so heat is kept within core of body |
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| Excretion & vit D formation |
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Definition
| sweat contains salt & urea, but amounts of these wastes are slight |
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| cells in the lower layers of epidermis contain a form of cholesterol that when exposed to UV radiation, changes into vit D which body uses to absorb Ca & phosphorus from food in small intestine (these 2 minerals are used to build & maintain bones & teeth) |
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| in dermis; provide brain with info about external world & effect on skin; touch rec. are most sensitive; pain rec. need a stronger stimulus; once receptor info is interpreted, brain directs body to respond = Sensation is function of brain/nervous system |
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