Ch 16 The integumentary system

• functions of skin


  1. provides protective membrane
  2. skin glands lubricate and cool the skin
  3. receptor for sensations
  4. helps maintain body temperature
• function of producing sweat

  sweat glands produce a watery secretion that evaporates and cools
• function of producing sebum


  sebaceous glands produce an oily secretion that lubricates the skin and hair
• function of receiving sensation


  pain, temperature, pressure, and touch
• function of thermoregulation


  interprets message from heat center in the brain
• epidermis


  outermost, thin cellular membrane
• dermis 


  middle layer, dense fibrous, connective tissue
• subcutaneous tissue (hypodermis)


  thick, fat-containing tissue
• accessory organ: hair


  cells are filled with keratin

  • hair follicles = shaft that holds the hair
  • 5 million hairs on body and 100k on head
  • melanocytes at the root form the color
  • grows 0.5 inches a month
  • cutting does not affect growth
• accessory organ: nails 


  made of hard keratin plates covering the toes and fingers

  • lunula (crescent at base of nail)
  • cuticle (by nail bed)
  • paronychium (skin around nail)
• accessory organ: glands 


  either sebaceous or sweat

  • secrete oily sebum into the hair follicle to lubricate
  • sweat in pores moistens and cools
  • both subject to bacterial growth