The immune system

• What is the role of harmless bacteria in the gut?

  Help in absorption of nutrients
• What is a pathogen?

  A microorganism causing disease
• How do pathogens damage host cells?

  By entering and reproducing inside cells
• What happens to host cells when pathogens leave?

  Host cells are lysed
• What do pathogens produce that damages host cells?

  Toxins
• What are the main transmission methods of pathogens?

  1. Contaminated food or water
  2. Airborne
  3. Sexual intercourse
  4. Blood to blood contact
  5. Mother to fetus
• How do immune cells detect pathogens?

  By binding to foreign antigens
• What are antigens?

  Molecules that cause an immune response
• Where are antigens located?

  In cell membranes of pathogens
• What types of cells have antigens on their surface?

  Viruses, cancer cells, and transplant tissues
• What are the two types of immune responses?

  1. Non-specific immune response
  2. Specific immune response
• What are the components of the non-specific immune response?

  • Barriers to pathogens
  • Phagocytosis
• What is the function of the immune system?

  To enable the body to resist disease
• What physical barrier protects the body from pathogens?

  Skin
• What role does Vitamin C play in the immune system?

  Maintains strong connective tissue
• What is phagocytosis?

  Engulfing of bacteria by phagocytes
• How does stomach acid protect against pathogens?

  Kills many bacteria with low pH
• What happens during phagocytosis?

  Phagocyte encloses bacterium in a vacuole
• What do lysosomes release during phagocytosis?

  Hydrolytic enzymes
• What is the role of skin flora?

  Compete with pathogenic bacteria
• How does the ear prevent pathogen entry?

  Hair and wax trap pathogens
• What is the function of the respiratory lining?

  Traps dust and germs
• How do cilia in the airways help protect the lungs?

  They sweep dust and germs up to throat
• What is the role of good bacteria in the intestines?

  Prevent harmful pathogens from being eliminated
• What occurs during inflammation?

  Capillaries become leaky, allowing white blood cells out
• What is the result of inflammation in the affected area?

  It becomes red and swollen
• What is the first response of phagocytes to an immune system trigger?

  Engulf pathogens
• What happens to pathogens inside a phagosome?

  They remain until digested by enzymes
• What is displayed on the phagocyte's membrane after digestion?

  Bacterial antigen
• What triggers the immune response after antigen display?

  Other immune cells recognize the antigen
• What are the four surfaces of viruses mentioned?

  Found on cells, tissues, or organs
• What initiates the cancerous immune response?

  Antigens or toxic products from pathogens
• What are the two types of immune cells mentioned?

  Phagocytes and lymphocytes
• What is the role of macrophages in the immune response?

  Engulf pathogens via phagocytosis
• Where do T cells mature?

  Thymus gland
• What is the function of Helper T cells?

  Activate specific B cells
• What are mature B cells called?

  Plasma cells
• How do T cells become activated?

  When antigen binds to receptor proteins
• What do T cells have on their surface that makes them specific?

  Specific receptor proteins
• What is the structure of antibodies?

  Four polypeptide chains held by disulphide bonds