The Immune Response

• What happens to the cytoplasm of the phagocyte during the immune response?


  It moves around the pathogen to engulf it
• What is contained within the phagocytic vacuole?

  The engulfed pathogen
• What is the first stage of the immune response?

  A phagocyte recognizes the antigens
• How does a phagocyte respond to a pathogen?

  It is attracted to the pathogen's antigens
• What role does the lysosome play in the immune response?

  It fuses with the vacuole to break down the pathogen
• What enzymes are contained in the lysosome?

  Lysozymes
• What happens after the pathogen is broken down?

  The phagocyte presents the pathogen's antigens
• What is the function of the phagocyte as an antigen-presenting cell?

  It activates other immune system cells
• How does the phagocyte present the antigens?

  By sticking them on its surface
• (1)What are the main stages of the immune response involving phagocytes?

  1. Phagocyte recognizes antigens on pathogen
  2. Cytoplasm engulfs the pathogen
  3. Pathogen contained in phagocytic vacuole
  4. Lysosome fuses with vacuole to break down pathogen
  5. Phagocyte presents antigens to activate other immune cells
• What is a Phagocyte?

  It (macrophage) is a type of a white blood cell that carries out phagocytosis( engulfment of pathogens).
• Where are phagocytes found what do they do?

  They are found in the blood and the tissues and are the first cells to respond to to an immune system trigger inside the body.
• What is a T-cell?

  It is another type of white blood cell. It has receptor proteins on its surface that bind to complementary antigens presented to it by phagocytosis.
• What activates the B-cells?

  T-cells.
• Different types of T-cells respond in different ways.
• What are the type of T-cells?

  Helper T-cells and Cytotoxic T-cells.
• What do Helper T-cells do?

  They release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells.

  
  

  They also activate B-cells, which secrete antibodies.
• What do Cytotoxic T-cells do?

  They kill abnormal and foreign cells.
• What are B-Cells?

  They are a type of white blood cell. They are covered with antibodies. They have receptor proteins that bind to the signalling molecules released by the Helper T-cells.
• What are antibodies?

  They are proteins that bind to antigens to form an antigen-antibody complex.
• Each B-cell has a different shaped antibody on its membrane, so different ones bind to different shaped antigens.
• Antibodies bind to antigens because they have a complementary shape- like a lock fits a key.
• What is Clonal selection?

  Process where an antibody on the surface of a B-cell meets a complementary shaped antigen, it binds to it. This , together will substances released from helper T-cells, activates the B-cell. The activated B-cell divides into plasma cells.
• What process does the B-cell divide by?

  Mitosis
• Why do B cells divide by Mitosis?

  So that all the cells are genetically identical. This means that they all produce identical(monoclonal) antibodies specific to the pathogen.
• In Antibody production, Plasma cells are identical to the B-cell( they are clones ). They secrete loads of antibodies specific to the antigen. They are called monoclonal antibodies.
• Monoclonal antibodies bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes.
• What is agglutination?

  This is when an antibody bind to two pathogens at the same time.
• An antibody has two binding sites, so can bind to two pathogens at the same time.
• Antibody Production

  Plasma cells are identical to the B-cell(they are clones). They secrete loads of antibodies specific to the antigen. These are called monoclonal antibodies. They bind to the antigens on the surface of the pathogen to for lots of antigen-antibody complexes.

  An antibody has two binding sites, so can bind to two pathogens at the same time. This is called agglutination

  Phagocytes then bind to the antibodies and phagocytose many pathogens at once. This process leads to the destruction of pathogens carrying this antigen in the body.
• Antibodies are proteins- they are made of chains of amino acids.
• What is the specificity of an antibody?

  It depends on its variable region, which form the antigen binding sites.
• Why does the B-cell divide by mitosis?

  So that all the cells are genetically identical. This means that they all produce identical (monoclonal) antibodies specific to the antigen.
• Each antibody has a variable region with a unique tertiary structure that is complementary to one specific antigen. This is so because of the different amino acid sequences.
• The immune response is split into?

  Two types
• What are the types of immune response?

  Cellular and humoral response
• Describe the Cellular response?

  The T-cells and other immune system cells that they interact with. e.g, phaogocytes form cellular response.
• Describe the Humoral response

  B-cells, clonal selection, monoclonal antibody production. They form the humoral response.
• What activates the immune system when an antigen enters the body for the first time?

  The primary response
• Why is the primary response slow?

  There aren't many B-cells to produce antibodies