Cells And The Immune System

• What do cell-surface membranes contain that act as antigens?

  Proteins
• What do cell-surface membranes contain that act as antigens?

  Proteins
• What is the role of antigens in the immune system?

  They help distinguish 'self' from 'foreign' cells
• What are molecules that can generate an immune response called?

  Antigens
• What are foreign antigens?

  Antigens not normally found in the body
• What are pathogens?

  Organisms that cause disease
• How does the immune system respond to pathogens?

  It identifies them as foreign and destroys them
• What type of cells have abnormal antigens that trigger an immune response?

  Cancerous or pathogen-infected cells
• What are toxins?

  Poisonous molecules produced by bacteria
• What happens when you receive cells from another person?

  Foreign antigens trigger an immune response
• What is phagocytosis?

  Engulfment of pathogens by phagocytes
• What happens if donated blood contains A or B antigens not recognized by the recipient?

  It generates an immune response
• What type of white blood cell carries out phagocytosis?

  Phagocyte
• How does a phagocyte recognize a pathogen?

  By identifying foreign antigens on it
• What is the process of phagocytosis?

  1. Phagocyte recognizes foreign antigens.
  2. Phagocyte engulfs the pathogen into a vesicle called a phagosome.
  3. Lysosomes containing hydrolytic enzymes (lysozymes) are released.
  4. Lysosome fuses with phagosome, releases the lysozymes which digests the pathogen.
  5. Phagocyte presents antigens to activate other immune cells.
• What type of white blood cell carries out phagocytosis?

  Phagocyte
• What happens to the pathogen after it is engulfed by a phagocyte?

  It is contained in a vesicle called a phagosome
• What do T-cells bind to?

  Complementary antigens presented by phagocytes
• What fuses with the phagosome to break down the pathogen?

  A lysosome
• What do helper T-cells release to activate phagocytes?

  Chemical signals
• What do phagocytes present after destroying a pathogen?

  The pathogen's antigens
• What is the role of cytotoxic T-cells?

  They kill abnormal and foreign cells
• What is the role of T-cells in the immune response?

  They bind to antigens and activate immune responses
• What do B-cells have on their surface?

  Antibodies
• What happens when a B-cell's antibody binds to a complementary antigen?

  The B-cell is activated
• What is clonal selection in B-cells?

  • Activation of B-cells when antibodies bind to antigens.
  • B-cells divide into plasma cells.
  • Plasma cells secrete specific antibodies.
• What are B-cells also known as?

  B-lymphocytes
• What do plasma cells secrete?

  Monoclonal antibodies
• What do antibodies do?

  They bind to antigens to form complexes
• What is agglutination?

  Clumping of pathogens by antibodies
• What is clonal selection in B-cells?

  Activation of B-cells by binding to antigens
• What is the general structure of an antibody?

  Proteins made of amino acid chains
• What do plasma cells secrete?

  Monoclonal antibodies
• What determines the specificity of an antibody?

  Its variable regions forming binding sites
• What is agglutination?

  Clumping together of pathogens by antibodies
• What are the two types of immune responses?

  • Cellular response: Involves T-cells and phagocytes.
  • Humoral response: Involves B-cells and antibodies.
• What is the general structure of an antibody?

  Proteins made of amino acid chains
• What is the primary immune response?

  The initial response to a first-time antigen
• Why is the primary response slow?

  There are few B-cells to produce antibodies
• What do memory cells do after exposure to an antigen?

  They remain in the body for a long time