5.2 - Phagocytosis

• What are the 2 types of white blood cell ?

  Phagocytes and lymphocytes
• What’s phagocytosis ?

  A non-specific defence where phagocytes ingest and destroy the pathogen
• Where are white blood cells made ?

  Bone marrow
• 5 steps of phagocytosis ?

  Chemotaxis (pathogen releases chemicals that attracts phagocyte), phagocyte recognises pathogen as non-self and binds to the pathogen, phagocyte engulfs the pathogen (endocytosis) and the pathogen is now in a phagosome, a lysosome containing hydrologic enzymes called lysozymes fuses with phagosome to form a phagolysosome, lysozymes digest and destroy the pathogen
• How do lysozymes kill pathogens ?

  Weaken the cell wall of the pathogen or hydrolyse and damage the proteins
• 2 types of phagocytes ?

  Neutrophils and macrophages
• What step occurs after the pathogen has been destroyed that makes the phagocyte and antigen presenting cell (APC) ?

  Antigen presentation, presents antigens on the surface to initiate adaptive response
• What type of phagocytes are APCs ?

  Macrophages
• What type of phagocyte aren’t APCs ?

  Neutrophils
• What happens to neutrophils after they’ve destroyed a pathogen ?

  It dies