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chapter 5 (Intro (FUNCTIONS (chemical barrier (protection) (pH or 5-6,…

- - - - epidermis
        
        (outermost layer), keratinized stratified squamous
      - dermis
        
        inner layer
        
        keratinized epithelium (hair follicles)
        
        glandular epithelium (sweat and sebaceous glands)
        
        dense irregular CT (collagen)
        
        smooth muscle tissue (arrector pili muscles)
        
        nervous tissue (meissners and pacinian corpuscles)
        
        blood vessels
      - subcutaneous layer
        
        adipose tissue, beneath skin
        
        also called hypodermis
  - - - physical barrier from:
        
        water loss
        
        injury
        
        chemicals and microorganisms
    - - pH or 5-6
      - prevents microorganism growth
    - - langerhans cells
        
        epidermis
      - macrophages and mast cells
        
        dermis
    - - urea
      - uric acid
    - - light touch detection + meissners corpuscle
        
        egg shaped
        
        located in dermal papillae
        
        populate areas in the fingertips, palms, soles, eyelids,tip of tongue, nipples, clitoris, tip of penis
- - - - fat
      - cellular material
  - - - merocrine glands
        
        2-5 million glands
        
        structure
        
        coil in deep dermis
        
        duct in dermis
        
        pore at surface
        
        characteristics
        
        respond to elevated temp/ exercise
        
        no odor in secretion
        
        function throughout life
        
        not associated with hair follicles
        
        location
        
        forehead
        
        neck
        
        back
        
        aka merocrine glands
        
        99% water plus
        
        salts and wastes
      - apocrine glands
        
        structure
        
        ducts terminate into hair follicles
        
        characteristics
        
        respond to stress/ emotions
        
        odor in secretion
        
        begin to fuction at puberty & continue through life
        
        associated with hair follicles
        
        location
        
        armpits
        
        groin
        
        secretion
        
        sweat above plus
        
        oil & cellular debris
        
        modified apocrine glands
        
        ceruminous glands
        
        is external, ear secretion, earwax is cerumen
        
        mammary glands
        
        breasts, milk
- - - - prevents moisture loss (waterproof)
      - prevents injury by penetration
      - prevents microorganisms/chemicals entry
- - - - people of different races have essentially the same # of melanocytes
      - amount of melanin produced varies (determined by DNA)
  - - - accumulate in s. corneum = orange
    - - in blood vessels = pink
    - - yellow (jaundice)
- - - - most common form of skin cancer
      - originates in stratum germinativum
    - - more superficial layers
      - metastasis seldom occurs for above cancers
    - - dangerous, usually begins as a mole
      - metastasize through lymphoid system
    - - avoid mid-day sun and wear sun block
- - - - keratinized stratified squamous epithelium
    - - stratum corneum
        
        outmermost layer
        
        composed of dead epithelial cells filled with the protein keratin
      - stratum lucidium
        
        translucent layer separating corneum & granulosum
        
        extra layer only in thick skin of soles and palms
      - stratum granulosum
        
        3-5 layers of flattened granular cells
      - stratum spinosum
        
        many layers of spiky cells with large nuclei
      - stratum basale
        
        innermost layer above basement membrane
- - - - two layers
        
        papillary layer
        
        20% below epidermis
        
        composed of loose areolar CT
        
        surface forms dermal papillae that form fingerprints
        
        meissners corpuscles
        
        sensory receptor for light touch
        
        reticular layer
        
        80% dense irregular CT
        
        bundles of collagen and elastic fibers
        
        these fibers give skin strength and resilency
        
        pacinian corpuscles
        
        sensory receptors for deep pressure
    - - nourish epidermis
- - - - adipose tissue and blood vessels
    - - insulation
- - - - hair root in deep dermis
      - follicle throughout dermis
      - hair shaft
        
        cuticle
        
        outer shingle like layer
        
        cortex
        
        middle layer
        
        flexible soft keratin
        
        medulla
        
        inner layer
        
        hard keratin
    - - grows for 2-5 yrs
        
        new cycle pushes old hair out
      - 0.3 mm per day
      - 2.5 million on body
        
        500,000 on head
    - - cells are epithelium
      - cells in root
        
        active mitosis
      - cells in follicle
        
        maturing & accumulation keratin
      - cells in epidermis
        
        dead epithelial cells
        
        full of keratin
        
        exposed hair or hair shaft
    - - melanin decreases w age
      - genetically determined
      - white/gray hair
        
        lack of melanin and air bubbles
    - - peg of connective tissue
        
        nerves and capillaries
    - - a bundle of smooth muscle associated with every hair follicle
      - causes hair to stand on end "goose bumps"
- - - - covers nail bed
    - - nail production by an epithelial fold
      - lunula
        
        pale crescent near nail root
      - cuticle
        
        fold of stratum corneum
- - - - mostly a by-product of cellular metabolism
    - - controlled by regulating dermal blood flow
      - vasodilation
        
        increases dermal blood flow which also increases heat loss
      - vasoconstriction
        
        decreases derma blood flow wich decreases heat loss
      - 4 methods for heat loss
        
        radiation
        
        most heat loss by this mode
        
        infrared heat rays move from area of high head to low heat
        
        conduction
        
        less heat loss
        
        heat moves by physical contact
        
        the reason the seat you sit in is warm when you stand up
        
        convection
        
        heat loss to surrounding air
        
        increases as air movement increases, this is why turning on a fan cools you off
        
        evaporation
        
        heat loss varies
        
        if heat increases our sweating increases, so we lose more heat by evaporating the sweat on the surface of our skin
    - - hypothalamus
        
        signals for sweating to decrease and dermal vasoconstriction
        
        usually brings body temp back to normal
    - - heat must be produced
      - shivering occurs and timy muscle contractions produce heat
  - - - elevated body temp
      - 2 causes
        
        humid air decreases evaporation
        
        air temp exceeps body temp, heat is gained not lost
    - - low body temp
      - very dangerous if core of body drops below 94 degrees
      - limbs can withstand about 65 degrees bc no organs are there
- - - - step 1
        
        inflammation
      - step 2
        
        scab, stem cells, phagocytes, and granulation tissue
      - step 3
        
        stem cells move over mesh work from fibroblast, scab is disintegrating
      - step 4
        
        scab is gone and shallow depression is left
  - - - epidermis only
      - reddening due to increased blood flow
      - mild pain
      - common in sunburn
      - heals in few days- 2 weeks
    - - epidermis and some dermal damage
      - reddening and blistering by blood vessel damage
      - moderate pain
      - common to physical contact with hot objects
      - heals in 2-6 wks w/o scars unless infected
    - - epidermis, entire dermis, and potentially subcutaneous damage
      - dry, leathery tissue with red or black color
      - severe pain
      - caused by prolonged heat or chemical contact
      - healing rarely occurs due to lack of surviving skin cels, skin replacements (grafts) are usually needed
        
        autograft
        
        transplant from yourself
        
        homograft
        
        temporary transplant from cadaver
    - - estimated by rule of nines
- - - - epidermis thins and connective tissues more common
    - - less macrophages (langerhan cells)
    - - decline in vitamin D3
    - - melanocyte activity declines
    - - sebum and perspiration delcines
    - - melanocyte and stem cells actiity declines
    - - dermis is thinner, elastic fibers decease
    - - number of sweat glands
      - capillary beds in the skin shrink
    - - young adult 3-4 weeks to heal blister
      - takes elderly 6-8 weeks to heal blister