PHAGOCYTOSIS

• What is the first line of defense against pathogens?

  Chemical and physical barriers
• What is an example of a physical barrier?

  Skin
• What is the role of white blood cells in the immune system?

  They respond to pathogens
• What type of response do phagocytes conduct?

  Phagocytosis
• What is another name for phagocytes?

  Macrophages
• How do phagocytes respond to non-self cells?

  They respond the same regardless of the cell
• What do phagocytes engulf?

  Pathogens and debris
• What attracts phagocytes to pathogens?

  Chemicals released by pathogens
• What happens to the shape of a phagocyte when it binds to a pathogen?

  It changes shape to engulf the pathogen
• What is formed when a pathogen is engulfed by a phagocyte?

  A phagosome
• What fuses with the phagosome to destroy the pathogen?

  A lysosome
• What enzyme is released by lysosomes?

  Lysozyme
• What is the function of lysozyme?

  To hydrolyze and destroy pathogens
• What happens to the soluble products after a pathogen is destroyed?

  They are absorbed and recycled
• What does a phagocyte become after presenting an antigen?

  An antigen presenting cell
• How do phagocytes respond to different types of foreign particles?

  They respond the same way
• What type of mechanism is phagocytosis?

  Nonspecific mechanism
• What is the role of lysosomes in phagocytosis?

  To release enzymes that destroy pathogens
• Where can phagocytes be found in the body?

  In blood and tissues
• What are the steps of phagocytosis?

  1. Phagocyte detects chemicals from pathogens.
  2. Phagocyte changes shape to engulf the pathogen.
  3. Pathogen is contained in a phagosome.
  4. Lysosome fuses with phagosome.
  5. Lysozyme is released to destroy the pathogen.
  6. Soluble products are absorbed and recycled.
  7. Antigen is presented on the cell surface.
• What are the characteristics of phagocytosis?

  • Nonspecific response to pathogens
  • Engulfs various foreign particles
  • Involves lysosomes and lysozyme
  • Results in antigen presentation
• What is the significance of phagocytosis in the immune response?

  • Destroys pathogens
  • Presents antigens to activate other immune cells
  • Initiates the adaptive immune response