IB DP Biology: SL复习笔记6.3.1 Skin


  • The skin and mucous membranes form a primary defence against pathogens that cause infectious disease
  • Skin is the largest organ of the body and is covered in microorganisms that usually cause no issues, as they can't enter the body. Skin provides:
    • A tough physical barrier that prevents entry of pathogens into our bodies
    • Cuts in the skin are sealed by formation of blood clots to prevent entry of pathogens
    • Chemical protection through the production of sebum from the sebaceous glands of the hair follicles
      • Sebum is a chemical responsible for maintaining a low skin pH which inhibits the growth of microorganisms
  • Mucous membranes are found lining vulnerable areas which may be a route for pathogens into the body
    • This includes the airways, areas around the reproductive organs (foreskin and vagina) and the digestive system
  • The membranes contain goblet cells which produce mucus containing glycoproteins
    • Microorganisms and particles become trapped by the mucus and are then either swallowed (into the stomach) or expelled, therefore preventing infection
    • Mucus also contains lysozyme enzymes which have antibacterial properties, providing more protection from invading microorganisms