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I. Introduction
II. Main functions for homeostasis
     A. Serving as a barrier
          1. Microorganisms
          2. Chemicals
          3. Water
          4. Light
          5. Trauma
     B. Providing information
     C. Temperature regulation
     D. Vitamin D production
III. The epidermis - components and functions
     A. Keratin and keratinocytes
     B. Melanin and melanocytes
     C. Immune function and Langerhans cells
IV. Age changes in the epidermis
     A. Keratin and keratinocytes
          1. Thickness
          2. Structure
          3. Replacement
     B. Melanin and melanocytes
     C. Immune function and Langerhans cells
V. Epidermal accessory structures - components and age changes
     A. Hair - formation and functions
     B. Age changes in hair
     C. Nails - formation and functions
     D. Age changes in nails
VI. Dermis
     A. Foundation material
          1. Fibers
          2. Cells
               a. Fibroblasts
               b. Defense cells
          3. Gel
          4. Age changes in the foundation material
     B. Blood vessels - structure and functions
     C. Age changes in dermal vessels
     D. Sweat glands - structure and functions
          1. Types
          2. Age changes in sweat glands
     E. Sebaceous glands - structure and functions
          1. Sebum
          2. Age changes in sebaceous glands
     F. Nerves
          1. Sensory neurons
          2. Motor neurons
          3. Age changes in sensory neurons
               a. Numbers and functioning
               b. Significance
          4. Age changes in motor neurons
VII. Boundary between epidermis and dermis
     A. Structure and functions
     B. Age changes in the epidermal-dermal boundary
VIII. Vitamin D production
     A. Normal vitamin D production
     B. Age changes in vitamin D production
IX. Subcutaneous layer - structure and functions
     A. Loose connective tissue
     B. Fat tissue
     C. Age changes in the subcutaneous layer
X. Miscellaneous cosmetic changes
XI. Abnormal changes
     A. Reasons
     B. Effects of sunlight
          1. Cells
          2. Fibers
          3. Glands
          4. Prevention
          5. Treatment
     C. Effects from heat
     D. Bedsores
          1. Causes
          2. Effects
          3. Prevention
     E. Neoplasms
          1. Contributing factors
          2. Benign skin neoplasms - types and effects
          3. Malignant skin neoplasms - types and effects

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