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Skin Glands
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Group of specialized epithelial cells & usually associated w/ hair follicles.
holocrine glands; cells produce globules of a fatty material that accumulate, swelling, bursting cells. |
Sebrum
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Fatty material from skin glands & cellular debris
secreted into hair follicles; keeps hairs & skin soft, pliable, & waterproof |
Sebaceous
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Simple branched areolar gland
scattered thruout skin, not on palms or soles; some regions include lips, corners of mouth, etc. open directly to surface of skin |
Sweat Glands
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Widespread in skin; gland consists of tube (originates as ball-shaped coil) in deeper demis.
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Eccrine
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Most numerous sweat glands; respond thruout life to a temp. elevated by environmental heat or physical exercise.
common in forehead, neck, & back. produce profuse sweat on hot days. fluid is carried by duct opens up at surface |
Apocrine
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Secretion; develop scent as they are metabolized by skin bacteria
become active at puberty |
Cerumious & Mammary
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Ear wax glands; modified apocrine glands
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Epidermis
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Outer layer; keratinized stratified squamous epithelial; four cell types, five distinct layers
surface layer (kerantin); waterproof, resist surface evaporation, prevent excessive water loss. protective barrier against UV light, bacteria, chemicals & abrasion |
Dermis
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2nd layer (thinner layer), thicker than epidermis, made up of connective tissue (collagen elastic fibers, smooth muscle tissue, nervous tissue, & blood)
has basement membrane anchored |
Stratum Basale
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Deepest epidermis layer, 1 row of cuboidal-columnar, stem cells that divide rapidly to produce new keratinocytes.
melancocytes (synthesize pigment melanin); merkel cells found too |
Stratum Spinosum
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8-10 layers thick; keratinocytes contain thick bundles of immediate filaments.
Langerhans cells most abundant in layer |
Stratum germinativum & stratum spinosum
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Adjacent to dermis; only layer to receive nourishment
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Stratum Granulosum
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Kerantinization process begins, cells die; contains granules (precursor of keratin)
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Stratum Lucidum
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Found in thickened areas of epidermis (sole of feet); cells appear clear due to accumulation of keratin precursor; cells begin to degenerate
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Stratum Corneum
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Outermost layer composed of dead, flat keratinized cells
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