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Chapter 5 (Introduction (Cutaneous sensation (Light touch detection…

- - - - Physical Barrier
        
        From water loss
        
        from injury
        
        chemical and microorganisms
      - Chemical Barrier
        
        PH or 5-6
        
        Prevents microorganisms growth
      - Biological Barriers
        
        Langerhan's cells (epidermis)
        
        Macrophages and mast cells ( Dermis)
    - - Urea
      - Uric acid
  - - - Messner's corpuscle's
- - - - cuticle outer shingle like layer
      - cortex middle layer, flexible soft keratin
      - medulla inner layer, hard keratin
- - - - UV rays
      - Chemical
      - Drugs ( antihistamines & antibodies)
  - - - carotene may accumulate in S. corneum = orange
      - 2.hemoglobin in dermal blood vessels= pink
      - lack of KB in dermal blood vessels = blue ( cyanosis)
      - inability to breakdown HB ( liver problems) = yellow (jaundice)
- - - - Sebum keeps skin & hair soft, pliable and virtually waterproof
    - - Acne ( hypersecretion of sebum; duct clog & inflame
      - Seborrhea ( hyperproduction of sebum; oily scales)
  - - - coils deep in dermis
      - duct in dermis
      - pore at surface
      - Characteristics
        
        respond to elevated temperatures/ exercise
        
        no odor in secretion
        
        function throughout life
        
        not associated with hair follicles
      - Location
        
        Forehead
        
        neck
        
        back
      - secretion
        
        salts
        
        waste(urea and uric acid )
  - - - ducts terminate into hair follicles
    - - respond to stress/ emotion
      - odor in secretion
      - begins to function at puberty & continues through life
    - - Armpits
      - Groin
    - - oil
      - cellular debris
    - - ceruminous gland
        
        external ear
        
        secretion= earwax; cerumen
      - Mammary gland
        
        breast milk
- - - - most common form of skin cancer
      - originatesin stratum germinativum
    - - Dangerous usually begins as a mole
      - meastasize thru the lymphoid
    - - avoid did day sun & where sun block
- - - - Keratinized stratified sqamous epithelium
    - - Outermost layer
      - Composed of dead epithelial cells filled with the proteins keration
    - - translucent layer cells seperating corneumform s. granulosum
      - Extra layer only in thick skin of soles & palms
    - - 3-5 layers of flattened granular cells( filled with keratin granules)
    - - composed of many layers of spiky cells with large nuclei
    - - Innermost layer
      - directly above basement membrane
      - Composed of single row mitosing cuboidal epithelial cells
      - Composed of melanocytes
      - Specialized cells that produce the pigment melanin
    - - Prevents moisture loss ( waterproof)
      - Prevents injury by penetration
      - prevents microorganisms/chemical entry
    - - Determines skin color
      - is produced by melanocytes in stratum basale ( germinativum)
- - - - composed of loose areolar CT
      - surface forms dermal papillae that form fingerprint in the thick skin
      - meissner's corpuscles ( sensory receptors for light touch )
    - - bundle of collagen fibers
      - elastic fibers
      - reticular fibers which gives skin its strength and resiliency
      - pacinian corpulses - sensory receptors receptors for deep pressure
- - - - manipulation
      - protection of digit ends
    - - nail body covers the nail bed
      - nail root
        
        nail production by an epithlial fold
        
        lunula; pale crescent near nail root
      - cuticle
        
        fold of stratum corneum
- - - - mostly a by-product of cellular metabolism
    - - vasodilation- increases dermal blood flow, which also increases heat loss
      - vasoconstriction - decreases derma blood flow which decreases heat loss
    - - radiation
        
        most heat loss by this mode
        
        infrared heat rays move from area of high heat to areas of 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, tha is why turning on a fan cools you body
      - Evaporation
        
        heat loss varies
        
        if heat increases our sweating, so we lose more heat by evaporating the sweat on the surface of our skin
    - - the hypothalamas signals for sweating to decrease and dermal vasoconstriction
      - usually this brings body temperature back to normal
      - If temperature is to low after above action
        
        heat must be produced
        
        shivering occurs and tiny muscles contractions involved produce heat
    - - hyperthermia - elevated body temperature
        
        humid air decreases evaporation
        
        air temperature exceeds body temperature, thus heat is gained not lost
      - hypothermia- low body temperature
        
        very dangerous if core body temperature drops below 94 F
        
        limbs can withstand about 65 F because they contain no vital organs
- - - - the number of sweat glands
      - capillary bed in skin shrinks
    - - young adults 3-4 weeks to heal blister
      - elderly 6-8 weeks to heal a blister