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Integumentary system is comprised of:
- skin
- hair
- nails
- sweat and subcutaneous glands
- blood vessels
- sensory receptors
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Function of skin
- protective shield against heat, light, injury and/or infection
- regulates body temperature
- stores water, fat and Vitamin D
- senses painful and pleasant stimulation
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Skin consists of 3 layers:
- epidermis
- dermis
- subcutaneous
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Epidermis
- outer layer or skin
- stratified or layered squamous cell epithelial cells (continually sheds dead keratinocytes)
- differentiated keratinocytes (produces keratin)
- basal layer (continually divides)
- basal cells (produce melanin to protect against sun rays)
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Dermis
- middle layer of skin comprised of:
- blood vessels
- lymph vessels
- hair follicles
- sweat glands
- fibroblasts
- sensory receptors (pain and touch)
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Subcutaneous
- deepest layer of skin
- consists of a network of collagen and fat cells that help conserve body heat and protect organs from injury by acting as a "shock absorber"
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Diagnostic procedures for skin diseases
- visual exam
- blood and urine tests to exclude underlying disease
- microscopic exam of skin scrapings
- biopsy (punch, shave & exisional)
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Punch biopsy
done with a round-shaped knife ranging in size from 1-8 mm
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Shave biopsy
- also: incisonal
- for removing a small sample of a potential tumor tissue
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Total excisional biopsy
removal of an entire lump or suspicious area including normal tissue
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Skin lesion classifications
- macule (freckle)
- wheal (hive)
- papule (pimple)
- nodule (large papule)
- vesicle (blister)
- bulla (larger vesicle)
- pustule (filled with pus)
- ulcer (erosion)
- eczema
- psoriasis
- fissure
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Epidermoid and pilar cysts
- smooth, round lumps beneath the skin, usually harmless and self-contained
- filled with air, infected fluids and/or sebum
- usually asymptomatic
- pain may occur with cyst found in genital skin folds or next to either finger or toe nails
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Treatment of epidermoid and pilar cysts
- incise and drain cyst
- oral antibiotics if infected
- surgical excision
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Epidermoid cyst
- formed from cells in epidermis and filled with sebum
- affects ~1-5% of population
- may occur due to injury or blocked hair follicles
- may be asymptomatic; rupturing can result in significant discomfort
- develop on face, neck, chest or upper back
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Risk factors for epidermoid cyst
- age
- gender (men 2x more likely than women)
- history of acne
- traumatic or crushing to the skin
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Pilar cyst
- fluid-filled growth that forms from cells in the bottom of hair follicle
- affects 5-10% of population
- more common in middle-aged women
- smooth and mobile
- filled with keratin
- may or may not be tender
- usually occurs in clusters on the scalp
- may proliferate forming pilar tumors that are usually benign; very rarely pilar cysts become cancerous
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Drug eruptions
- adverse drug reactions manifest more often on the skin that any other organ system
- ~2-5% of patients suffer from cutaneous drug reactions
- may involve the entire body surface or a limited area
- may appear as pink -to-red rashes, wheals, red patches and/or pustules
- may also cause photosensitivity and/or anaphylaxis, shock or death
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Medications causing drug eruptions
- antibiotics
- NSAIDs
- narcotic analgesics
- anticonvulsants
- psychotropic medications
- diuretics
- iodine
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