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integumentary system = skin
- -largest organ
- -7600 cm2
- -7% body weight
- -0.5-0.6 cm thick
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skin functions in protection
- -prevents dehydration (impermeable barrier)
- -regulates temp (sweat, blood vessels)
- -protects against microorganisms/pathogens (impermeable barrier, secretions)
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skin has 3 layers
- 1. epidermis
- 2. dermis
- 3. hypodermis
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epidermis
keranitnized stratified squamous epithelum
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kerantioncytes
- -are the great majority of epidermal cells
- -synthesizing keratin
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melanocytes
- -synthesize melanin
- -uv protection
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langerhans cells (dendritic cells)
- -macrophages
- -act in immune response against toxins, microbes, ect, that penetrate skin
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merkel cells (tactile)
-receptors for touch
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keratinization
- stratum basalis -> stratum spinosum -> stratum granulosum -> stratum corneum
- (this process takes 30-40 days)
then exfoliation occurs
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dermis
- papillary layer
- -looser CT
- -more elastic
- reticular layer
- -dense irregular CT
- -less elastic
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lines of cleavage (langers lines)
orientation of collagen bundles
(surgical cuts are made along these "langer lines" to reduce scarring and shit)
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friction ridges
elastic patterns in dermis (eg: finger prints)
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dermis also contains "accessory structures"
blood vessels, nerves, bases of glands, hair follicles, and arrector pili muscle (goose bumps!)
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hypodermis
- -adipose tissue
- -fatty connective tissue (high cell/ecm ratio)
- -blood vessels
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thermo-regulation
sweat glands + blood vessels
- -sweat: evaporative cooling
- -lose heat by vasodilation
- -conserve heat by vasoconstriction
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sweat glands
merocrine (eccrine), some apocrine glands
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sebaceous glands
simple alveolar glands
secretion into hair follicle or pours
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skin cancer
a disease of the epidermis
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basal cell cancer
- -malignant skin tumor involving cancerous changes of basal skin cells
- -caused from exposure to sunlight or uv radiation
- -95% cure rate when caught early
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squamous cell carcinoma
- -cancerous changes to middle portion of epidermis
- -malignant, more aggressive than basal cancer, but still relatively slow growing
- -more likely than basal cell cancer to metastasize
- -requires surgical removal
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melanoma
- -malignant skin cancer that involves the skin cells that produce pigment (melanocytes)
- -increases with age
- -number 1 cause of cancer death in women age 25-30
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1o burn
affected area: epidermis
-red, painful, dry (sunburn)
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2o burn
affected area: dermis + epidermis
-red, blisters, swollen, painful
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3o burn
- no pain!
- affected area: "full thickness"
- -epidermis + dermis
- -includes epidermal derivatives
-dry, leathery, black, white, brown, yellow, swelling
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