Immune System (Defences Against Pathogens)

• What is the primary function of the human body's defense system?


  To protect us against pathogens
• What are the two main components of the human body's defense system?

  • Physical and chemical barriers
  • Immune system
• What acts as a physical barrier to pathogens in the human body?


  Skin
• How does skin contribute to the body's defense against pathogens?


  It acts as a barrier and secretes oils and antimicrobial substances
• What are the two main entry points for pathogens if they cannot penetrate the skin?


  Nose and mouth
• How do the nose's adaptations help prevent pathogen entry?


  It has hairs and mucus that trap pathogens and particles
• What are the two tubes that pathogens must pass through after entering the throat?

  Trachea and esophagus
• What is the role of mucus in the trachea and bronchi?


  It traps particles and pathogens to prevent them from entering the lungs
• What structures help move mucus in the respiratory system?

  Cilia
• What happens to the mucus and trapped particles in the respiratory system?


  They are moved to the back of the throat to be swallowed
• What is the pH level of the stomach contents due to hydrochloric acid?


  About 2
• How does hydrochloric acid contribute to the body's defense?


  It kills most pathogens due to its strong acidity
• What are the three important functions of white blood cells in the immune system?


  1. Phagocytosis (engulfing pathogens)
  2. Producing antitoxins
  3. Producing antibodies
• What is phagocytosis?


  A process where white blood cells engulf pathogens
• What do antitoxins do?


  They bind and counteract toxins produced by pathogens
• What are antigens?


  Substances detected as foreign by the immune system
• What are antibodies?


  Small proteins made by white blood cells that bind to antigens
• How does the immune system remember pathogens?


  It produces antibodies specific to the pathogens and remembers them for future attacks
• What does it mean to be immune to a disease?


  It means the body can quickly produce antibodies to destroy pathogens before they can develop
• How does the human body defend against pathogens daily?


  • Physical barriers (skin)
  • Chemical barriers (mucus, hydrochloric acid)
  • Immune response (white blood cells)