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25 Cards in this Set
- Front
- Back
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Integumentary System(skin)
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Largest organ in body. Approx. 18 square feet and weighing 6-9 lbs. covers body and merges with mucous membranes near margins of body orifices(mouth, anus, nose).
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Composed of two layers-Epidermis
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Primarily stratified squamous epithelium. Five layers are basale, spinosum, granulosum, lucidum, corneum. Major cell type is a keratinocyte. Meloncyte is also found here, primarily located in basal cell layer. Meloncyte makes melanin which is brown, provides UV protection, and is made in response to light.
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First degree burns
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Involve epidermis only
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Melanin
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Granules in dermis. Everyone has same number of melanocytes, skin color is affected by how much melanin is produced. More granules, more brown color
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Composed of two layers-Dermis
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Composed of connective tissue. There is a papillary layer and a reticular layer.
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Papillary Layer of Dermis
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Loose CT. Composed of dermal papillae that is finger-like projections into epidermis. Epidermal ridges are opposite of dermal papillae.
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Reticular Layer of Dermis
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Dense CT. Tough, leathery, 3D arrangement of collagen fibers.
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Second degree burns
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Involve epidermis and dermis. Characterized by blistering
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Third degree burns
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Destroy both epidermis and dermis. Often require skin grafts.
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Functions of integumentary system
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Protection, prevents dehydration, perception of sensation, synthesis of vitamin D, regulates body temperature. waste excretion, fluid and electrolyte balance.
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Types of skin
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Thick skin(palms of hands, soles of feet, no hair, thick epidermis, 100 cells thick on average). Thin skin-(Everywhere else, hairy, 15-25 cells thick, corneum).
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Hairs
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Keratinized(keratin=fibrous, water proof protein) filaments that develop from invagination of epidermis called hair follicle.
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Erector pili muscle
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attached to connective tissue sheath of hair, contracts when cold to reduce surface area of skin.
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Structure of a hair follicle
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External root sheath(outermost part, downgrowth of epidermal cells). Deepest part forms bulb invaginated by connective tissue. 2/3 from bulb outgrowth froms sebaceous gland. Internal root sheath(formed from matrix which divides cells in bulb).
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Hair colors
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Depends on amount and type of melanin in cortex of hair. Pheomelanin and eumelanin is for blond and brown hair. Black hair just has eumelanin. Gray hair just has air.
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Sebaceous glands
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Secrete oily substance sebum. Holocrine secretion-entire bag of oil is released into hair follicle. Keeps hair and skin soft and waterproof and inhibits growth of bacteria. Excess production results in acne.
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Tarsal gland
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Modified form of sebaceous gland in the eyelids and ensures eyelids don't get stuck together.
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Sweat (sudoriferous) glands
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Function is to carry heat away from the body. Most numerous in palms and soles. Ciliary glands of eye are sweat glands and when blocked form sty. Mammary glands are modified sweat glands.
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Apocrine Sweat Glands
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Most active during emotional distress. Empty into hair follicle. Found in axilla, areola, nipple, external genitalia, and anus. Sex hormones lead to development of gland at puberty. High levels of proteins (steroids), mix with bacteria on skin and cause body odor. Responsible for pheromones in animals.
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Eccrine Sweat Glands
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Not associated with hair follicles. Much more numerous than apocrine. Secrete in response to increased body temp. (water, NaCl, urea, ammonia). Function in temperature regulation. Found on forehead, back, palms and soles.
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Nails
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Modified epidermis. Protective function. Keratinized plates.
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Eponychium
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This is the cuticle (dead skin) along proximal border of margin of nail fold.
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Hyponychium
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Located beneath free border of nail.
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Lunule
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Partially keratinized, white crescent distal to nail fold. Growth of nail takes place at the root of lunule.
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Nail plate
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Rests on nail bed. Consists of free edge, nail body and nail root.
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