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Chapter 5 (5-1 Describe the main structural features of the epidermis, and…

- - - - Pacinian Corpuscles
      - Vitamin D synthesis
        
        UV rays in sunlight activate its synthesis, Vitamin D is required for bone homeostasis
        
        Blood Reservoir
        
        The dermis houses about 10% of the body's blood vessels, Skin only requires 1-2% of the body's blood
        
        Immunity
        
        Langerhan's cells (macrophages), interact with T-helper cells in immune responses
- - - - Hemoglobin (HB) in dermal blood vessels = pink
      - lack of HB in dermal blood vessels = blue
      - Carotene may accumulate in S. Corneum = orange
      - inability to break down HB = yellow
- - - - Adds in absorption of calcium
        
        Weak and flexible bones without it
        
        Skin Cancers
        
        Nasal Cell Carcinoma
        
        Most common form of skin cancer
        
        Originates in stratum germinativum
        
        Squamous Cell Carinomas
        
        More superficial layers
        
        Malignant Melanoma
        
        Dangerous usually begins as a mole
        
        Metastasize thru the lymphoid system
        
        Prevention: Avoid mid-day sun and use sunblock
- - - - Papillary layer
        
        Composed of loose areolar CT
        
        Surface forms dermal papillae that form fingerprints in thick skin
        
        Meissner’s Corpuscles - sensory receptors for light touch
      - Reticular layer
        
        Dense irregular CT
        
        Bundles of collagen fibers
        
        Elastic fibers and reticular fibers which give skin its strength and resiliency
        
        Pacinian Corpuscles - sensory receptors for deep pressure
      - Main function: nourishment of epidermis
- - - - No odor in secretion
        
        Fuction throughout life
        
        Not associated with follicles
        
        Location: Forehead, neck, back
        
        99% water plus salts and wastes
- - - - Begin to function at puberty and continue through life
        
        Associated with hair follicles
        
        Location: armpits, groin
        
        Secretion: sweat above plus oil and cellular debris
- - - - Breast milk
- - - - Cuticle outer shingle like later
        
        Medulla inner layer, hard keratin
- - - - 2.5 million on body/500,000 hairs on the head
  - - - Cell in root=active mitosis
        
        Cells in follicle=maturing and accumulating keratin
        
        Cells in epidermis=dead epithelial cells; full of keratin=exposed hair or hair shaft
    - - Melanin decreases with age
        
        Genetically determined
        
        White/gray hair- Lackif melanin and air bubbles
      - Hair Papilla
        
        Peg of connective tissue
        
        Nerves and capillaries
        
        Arrector Pili Muscle
        
        A bundle of smooth muscle associated with every hair follicle
        
        Causes hair to stand on end when frightened or cold
- - - - Manipulation
        
        Protection of digit ends
- - - - Nail production by an epithelial fold
      - Lunula
        
        Pale crescent near nail root
        
        Cuticle
        
        Fold of stratum corneum
- - - - Conduction
        
        Convection
        
        Evaportion
        
        Hypothalamus
        
        Shivering
        
        Occurs and the tiny muscles contractions involved produce heat
        
        Hyperthemia
        
        2 more items...
        
        Heat loss varies, if heat increase our sweating increases, so we lose more heat by evaporating the sweat on surface of our skin
        
        Heat loss to surrounding air, increases as air movement increases
        
        Less heat lost, heat moved my physical contact, the reason the seat yousit on it more when you stand up
      - Most heat lost by this mode