L3.3: Integumentary System

• CONSISTS OF:

  • Skin (cutaneous membrane)
  • Maintains body’ boundary
  • Keeps water and other precious molecules in the body
  • Keeps excess water out
  • Pliable yet tough
  • Allows us to take constant punishment from external agents
  • Skin Appendages
  • Sweat glands
  • Oil glands
  • Hair Nails


  Integumentary system
• • Insulates and cushion deeper body organs
  • Protects the entire body from:
  • Mechanical change (bumps and cuts)
  • Chemical damage (acids and bases)
  • Thermal damage (heat or cold)
  • Ultraviolet (UV) radiation (sunlight)
  • Microbes (bacteria)
  • Desiccation (drying out)
  • Aids in loss or retention of body heat as controlled by the nervous system
  • Aids in excretion of urea and uric acid
  • Synthesizes vitamin D


  Functions of the integumentary system
• Physical barrier contains keratin, which toughen cells, and both pressure and pain receptors, which alert the nervous system to possible damage. Fat deep to skin cushions deeper structures


  protects from Mechanical damage (bumps)
• Has relatively impermeable keratinized cells; contain pain receptors, which alert the nervous system to possible damage


  protects from Chemical damage (acids and bases)
• Has an unbroken surface and “acid mantle” (skin secretions are acidic and thus inhibit microbes, such as bacteria and yeast). Phagocytes ingest foreign substances and

  pathogens, preventing them from penetrating into deeper body tissues

  protects from microbe damage
• Melanin produced by melanocytes protects DNA from UV damage


  Ultraviolet (UV) radiation (damaging effects of sunlight or tanning beds)
• Contains heat/cold pain receptors


  protects from Thermal (heat/cold) damage
• Contains a water-resistant glycolipid and keratin


  protects from Desiccation (drying out)
• • Heat loss: By activating sweat glands and by allowing blood to flush into skin capillary beds so that heat can radiate from the skin surface
  • Heat retention: By not allowing blood to flush into skin capillary beds


  Aids in body temperature regulation (controlled by the nervous system)
• Contained in perspiration produced by sweat glands


  Aids in excretion of urea and uric acid
• Modified cholesterol molecules in skin converted to vitamin D in the presence of sunlight


  Synthesizes vitamin D