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integumentary system
consists of skin, hair, nails and associated glands
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dermatology
study of the skin
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skin
- functions:
- --regulates body temp
- --produces vitamin D - bone growth (sunlight required for vitamin D synthesis)
- --blood reserve
- --excretion (perspiration)
- --immunity
- --protection
- --receptors for touch, pain, temp
- covers 20 sq. feet
- 3 layers: epidermis, dermis, subcutaneous
- 3 glands: sudoriferous, sebaceous, ceruminous
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sudoriferous gland
- sweat gland
- regulates temperature
- 2 types: eccrine, apocrine
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eccrine gland
- sudoriferous gland
- secretes on forehead, hands, feet
- produces watery sweat under stress
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apocrine gland
- sudoriferous gland
- secretes in armpits, groin
- produces odorus sweat
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sebaceous gland
- produces sebum
- sebum lubricates skin, kills bacteria
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ceruminous gland
- modified sweat gland
- produces wax
- only found in ear
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epidermis
- outer layer of skin
- made of keratinized stratified squamous epithelium
- 4 types of cells: keratinocytes, melanocytes, merkel cells, langerhan cells
- 4 or 5 layers (bottom to top): stratum basale, stratum spinosum, stratum granulosum, stratum luicdem, stratum corneum
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keratinocytes
cells that make keratin
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melanocytes
cells that produce melanin (pigment)
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merkel cells
touch receptor cells
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langerhan cells
cells that produce chemicals to boost the immune system
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stratum basale
- bottom layer of epidermis
- made of simple cuboidal
- all cells living
- area of constant mitosis
- contains keratinocytes, melanocytes, merkel cells
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stratum spinosum layer
- fourth layer of epidermis
- made of 10 layers of squamous and cuboidal cells
- contains anchoring junctions that allow for stretching
- mostly melanocytes, langerhan cells
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stratum granulosum layer
- middle layer of epidermis
- made of 5 layers of living squamous cells
- keratin is first produced here
- contains keratinocytes
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stratum lucidem layer
- second layer of epidermis
- made of several layers of flat dead cells
- layer not present in thin skin
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stratum corneum
- top layer of epidermis
- made of 30 layers of flat, dead keratinized cells
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dermis
- middle layer of skin
- made of adipose and areolar tissues
- vascular
- contains base structures of hair, oil, sweat glands
- 2 layers: papillary, reticular
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papillary layer
- top layer of the dermis
- contains the dermal papilla
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dermal papilla
ridges that produce fingerprints and footprints
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reticular layer
- bottom layer of the dermis
- attaches dermis to subcutaneous
- composed of dense regular, adipose, elastic fiber
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subcutaneous
- bottom layer of skin
- aka hypodermis or superficial fascia
- adipose
- attaches skin to underlying structures
- contains pacinian corpuscles
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pacinian corpuscles
pressure receptors
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skin color
- determined by the amount of melanin (genetic)
- carotene: yellow pigment
- hemoglobin: pink pigment
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vitiligo
isolated patches of no pigment
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albino
total absence of pigment
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freckles
isolated tiny melanin patches
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hair (pilli)
- covers entire body except lips, nipples, palms, soles, parts of external genitals
- made of dead, keratinized cells
- 3 layers: cuticle, cortex, medulla
- attached to hair follicle
- surrounded by arrector pilli muscle
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cuticle
outer keratinized layer of hair
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cortex
- middle layer of hair
- dark hair: contains melanin
- blond/gray hair: contains air
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medulla
- inner layer of hair
- filled with air
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hair follicle
hair attachment location
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bulb
- surrounds the hair follicle
- contains blood and nerves
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arrector pilli muscle
- surrounds each hair
- allows hair to stand on end
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root hair plexus
makes hair sensitive to touch
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nails
keratinized extensions of the epidermis found on fingers and toes
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