Integumentary system is made of skin, hair, and nails. You can read about these in our book, starting on p. 893.

 Here are our notes, and pictures:

 A. Functions
  1. Waterproofing -- Keratin and sebum make skin tough and waterproof (in or out)
  2. UV Protection -- Melanin in the epidermis absorbs UV radiation
  3. Disease Prevention-- keep bacteria and chemicals out of blood
  4. Temperature Balance -- nerves sense temperature; sweat and increased blood flow when too hot, less blood in skin when cold

 B. Parts
  1. Epidermis -- layers of epithelial cells filled with keratin or melanin; top layers are dead, lower layers are alive and growing; no blood supply
  2. Dermis -- connective tissue, hair follicles & roots, nerves, blood vessels, sweat glands, oil glands
  3. Subcutaneous Tissue -- fat cells beneath the dermis