Cell recognition and immune system

• What happens if a pathogen gets past the body's barriers?

  The immune system responds with white blood cells
• What are the two types of responses white blood cells have?

  Specific and nonspecific responses
• What type of white blood cells are phagocytes?

  They are nonspecific responders
• What is another name for phagocytes?

  Macrophages
• What do phagocytes do during phagocytosis?

  Engulf and destroy pathogens
• How do phagocytes recognize pathogens?

  By binding to chemicals or antigens
• What happens to a phagocyte after it engulfs a pathogen?

  It forms a vesicle called a phagosome
• What is the role of lysosomes in phagocytosis?

  They fuse with phagosomes to release enzymes
• What enzyme do lysosomes release during phagocytosis?

  Lysozyme
• What does lysozyme do to pathogens?

  Hydrolyzes and destroys them
• What happens to the soluble products after a pathogen is destroyed?

  They are absorbed and recycled by phagocytes
• What do phagocytes become after presenting antigens?

  Antigen presenting cells
• How do phagocytes respond to different types of foreign particles?

  They respond the same regardless of type
• What is the significance of phagocytosis in the immune response?

  It is a nonspecific mechanism to destroy pathogens
• Where can phagocytes be found in the body?

  In blood and tissues
• What attracts phagocytes to pathogens?

  Chemicals or debris released by pathogens
• How does the process of phagocytosis contribute to the immune response?

  It eliminates pathogens and presents antigens
• What are the steps of phagocytosis?

  1. Phagocyte detects chemicals from pathogens.
  2. Phagocyte binds to the pathogen.
  3. Phagocyte engulfs the pathogen, forming a phagosome.
  4. Lysosome fuses with the phagosome.
  5. Lysozyme is released to destroy the pathogen.
  6. Soluble products are absorbed and recycled.
  7. Antigens are presented on the cell surface.
• What are the key features of phagocytosis?

  • Nonspecific immune response
  • Involves macrophages (phagocytes)
  • Engulfs and destroys pathogens
  • Uses lysosomes and lysozyme
  • Antigen presentation occurs post-destruction
• What is the difference between specific and nonspecific immune responses?

  • Specific responses target specific antigens.
  • Nonspecific responses act against all non-self cells.
• What type of cells are B lymphocytes also known as?

  B cells
• Where are B cells made and matured?

  In the bone marrow
• What does the humoral response involve?

  B cells and antibodies
• What does the term "humor" refer to in the context of the humoral response?

  Body fluids
• Why is the humoral response named so?

  Because antibodies are soluble in body fluids
• How many different lymphocytes are approximately present in the body?

  10 million
• What do B cells create antibodies against?

  Particular antigens
• What happens when a B cell collides with a foreign antigen?

  It takes in the antigen by endocytosis
• What activates a B cell after it presents an antigen?

  Collision with a helper T-cell receptor
• What is clonal expansion in B cells?

  Creation of large numbers of identical B cells
• What do some B cells differentiate into after clonal expansion?

  Plasma cells and memory B cells
• What is the role of plasma cells?

  To produce antibodies
• How do memory B cells respond to a re-infection?

  They rapidly produce plasma cells
• How long can memory B cells live in the body?

  For decades
• What is the primary response in B cells?

  The first activation by an antigen
• What happens during the secondary response to an antigen?

  Rapid differentiation into plasma cells
• What is the significance of the antibody concentration graph?

  It shows antibody production over time
• What are antibodies classified as?

  Proteins
• What is the structure of antibodies?

  Four polypeptide chains
• What is the variable region of an antibody?

  The part that changes shape for antigens