Immune responses

• What are the physical barriers to infection in the immune response?


  • Skin: tough barrier made of keratin
  • Stomach acid: kills bacteria
  • Gut and skin flora: competes with pathogens
• What is the role of antigens in the immune system?


  • Antigens are proteins on cell surfaces.
  • They identify cells as self or non-self.
  • The immune system responds to non-self antigens.
• What are the non-specific immune responses to infection?


  • Inflammation: vasodilation and increased blood flow
  • Lysozyme action: enzymes that kill bacteria
  • Interferon: prevents virus spread
  • Phagocytosis: engulfing and destroying pathogens
• What is phagocytosis?


  A process where white blood cells engulf and destroy pathogens.

  
• What is the specific immune response and its components?


  • Antigen-specific response
  • Involves B cells (humoral response) and T cells (cell-mediated response)
• What are memory cells in the immune system?


  Cells that replicate when exposed to a pathogen and remain in lymph nodes.
• What do B effector or plasma cells do?


  They produce antibodies.
• What is the function of T helper cells?


  They stimulate B cells and T killer cells to divide.
• What do T killer cells do?


  They destroy pathogen-infected cells.
• What is the structure of antibodies?


  • Made of four polypeptide chains
  • Y-shaped structure
  • Complementary to a single antigen
• How do antibodies function in the immune response?


  • Form antigen-antibody complexes as markers for phagocytes.
  • Agglutination: clumping cells together for easier identification by phagocytes.