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25 Cards in this Set

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Integumentary System(skin)
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).
Composed of two layers-Epidermis
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.
First degree burns
Involve epidermis only
Melanin
Granules in dermis. Everyone has same number of melanocytes, skin color is affected by how much melanin is produced. More granules, more brown color
Composed of two layers-Dermis
Composed of connective tissue. There is a papillary layer and a reticular layer.
Papillary Layer of Dermis
Loose CT. Composed of dermal papillae that is finger-like projections into epidermis. Epidermal ridges are opposite of dermal papillae.
Reticular Layer of Dermis
Dense CT. Tough, leathery, 3D arrangement of collagen fibers.
Second degree burns
Involve epidermis and dermis. Characterized by blistering
Third degree burns
Destroy both epidermis and dermis. Often require skin grafts.
Functions of integumentary system
Protection, prevents dehydration, perception of sensation, synthesis of vitamin D, regulates body temperature. waste excretion, fluid and electrolyte balance.
Types of skin
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).
Hairs
Keratinized(keratin=fibrous, water proof protein) filaments that develop from invagination of epidermis called hair follicle.
Erector pili muscle
attached to connective tissue sheath of hair, contracts when cold to reduce surface area of skin.
Structure of a hair follicle
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).
Hair colors
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.
Sebaceous glands
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.
Tarsal gland
Modified form of sebaceous gland in the eyelids and ensures eyelids don't get stuck together.
Sweat (sudoriferous) glands
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.
Apocrine Sweat Glands
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.
Eccrine Sweat Glands
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.
Nails
Modified epidermis. Protective function. Keratinized plates.
Eponychium
This is the cuticle (dead skin) along proximal border of margin of nail fold.
Hyponychium
Located beneath free border of nail.
Lunule
Partially keratinized, white crescent distal to nail fold. Growth of nail takes place at the root of lunule.
Nail plate
Rests on nail bed. Consists of free edge, nail body and nail root.