phagocytosis

• What is the body's first line of defense against pathogens?

  Physical or chemical barrier
• What happens if the first line of defense fails?

  The next line of defense is white blood cells
• What are the two types of white blood cells?

  Phagocytes and lymphocytes
• What is the role of phagocytes?

  Ingest and destroy pathogens
• What process do phagocytes use to destroy pathogens?

  Phagocytosis
• What do phagocytes do when they encounter a pathogen?

  Engulf and destroy it
• What is the process of phagocytosis?

  • Pathogen is attracted by chemicals
  • Phagocyte recognizes and attaches to pathogen
  • Pathogen is engulfed into a phagosome
  • Lysosomes fuse with phagosome
  • Lysozymes hydrolyze the pathogen
  • Breakdown products are absorbed into cytoplasm
• What are the attractants that cause phagocytes to move towards pathogens?

  Chemical products of pathogens or damaged cells
• What do phagocytes have on their cell-surface membrane?

  Receptors that recognize pathogens
• What is formed when a phagocyte engulfs a pathogen?

  A phagosome
• What happens when lysosomes move towards the phagosome?

  They fuse with it
• What enzymes are present within lysosomes?

  Lysozymes
• How do lysozymes destroy ingested bacteria?

  By hydrolysis of their cell walls
• How is the process of phagocytosis similar to digestion?

  Both involve hydrolysis of larger molecules
• What happens to the soluble products from the breakdown of the pathogen?

  They are absorbed into the cytoplasm
• What are the steps involved in phagocytosis as summarized in the study material?

  1. Chemical attraction to pathogen
  2. Attachment to pathogen by phagocyte
  3. Engulfment into phagosome
  4. Fusion of lysosomes with phagosome
  5. Release of lysozymes into phagosome
  6. Hydrolysis of bacteria
  7. Absorption of hydrolysis products