specific immune system

• what are antigens?

  • cell markers
  • body recognises them as self/non-self
  • foreign antigens stimulate an immune response, triggering the production of antibodies
• true/false? The specific immune system is faster than the non-specific responses

  • FALSE- the initial immune response is slow
  • but a secondary immune response activated by memory cells is indeed faster
• describe the structure of an antibody

  • specific to each antigen
  • made of two identical polypeptide chains called the heavy chains (longer) and the light chains (shorter)
  • chains held together by disulphide bridges and polypeptide itself is also held tgth by disulphide bridges
  • variable region- regions that binds to the antigen, variable shape on each antibody and gives antibodies their specificity
  • rest of antigen the same = constant region

  
• what is the term given to the binding of an antigen to an antibody?

  antigen-antibody complex
• describe the action of antibodies and how they defend the body

  1. antibody antigen complex acts as an opsonin so they tag the pathogens and are recognised easily by phagocytes to be engulfed
  2. most pathogens can't invade the host cells once part of an antigen antibody complex
  3. antibodies act as agglutinins- causing antigen antibody complexes to clump together, making engulfing multiple at the same time easier and preventing further spread
  4. act as anti-toxins- binding to toxins produced by pathogens and making them harmless
• why are B and T lymphocytes called B and T lymphocytes?

  • B lymphocytes mature in the bone marrow
  • T lymphocytes mature in the thymus gland
• state the names of the four types if T lymphocytes

  • T helper cells
  • T killer cells
  • T regulator cells
  • T memory cells
• what does each T lymphocyte do?

  • T helper cells- CD4 receptors, bind to antigens on APCs, produce interleukins that stimulate the activity of B cells, and attract macrophages to digest pathogens in antibody antigen complexes
  • T killer cells- produce perforins that perforate pathogen cell membranes, making them freely permeable which kills them
  • T memory cells- part of the immunological memory. If they meet an antigen a second time, they divide into T killer cell clones and rapidly kill pathogens
  • T regulator- stop immune response once pathogen is eliminated, prevents autoimmune response
• state the three types of B lymphocytes

  • Plasma cells
  • B memory cells
  • B effector cells
• describe the role of each B lymphocyte

  • plasma cells - produce antibodies to a particular antigen and releases them into circulation
  • B effector cells- divide by mitosis to form plasma cell clones
  • B memory cells - live for long and are part of immunological memory. Programmed to remember specific antigen and enable the body to conduct rapid response when that antigen on a pathogen is encountered again
• what is cell mediated immunity?

  where T lymphocytes respond to cells of an organism that have changed in some way by a pathogen (so an APC containing the antigens of a pathogen on their cell surface membrane)
• describe the process of cell-mediated immunity

  1. In non-specific defence system, macrophages engulf and digest pathogens and form APCs
  2. T helper cells recognise antigens as foreign and receptors on SOME of these helper cells fit the antigen.
  3. The helper cells with the complementary receptor become activated, produce interleukins to encourage more T helper cells to divide rapidly by mitosis
  4. form clones of the T helper cell carrying complementary receptor to bind to antigen
  5. These clones can- develop into T memory/T killer cells, produce interleukins that stimulate B cell division/phagocytosis

  
• what are the two different types of immunity in the specific immune response?

  • cell mediated immunity
  • humoral immunity
• what is humoral immunity?

  • Body responds to antigens directly found on a pathogen, eg on bacteria/fungi, AND APCs also
  • humoral immune system produces antibodies that are soluble in blood/tissue fluid which AREN'T attached to cells
  • B lymphocytes engulf the antigens and process them to become APCs
• describe the process of humoral immunity

  1. T helper cell binds to B lymphocyte with correct antibody which will bind to specific antigen- clonal selection
  2. interleukins produced by activated T helper cell which activate B cells
  3. activated B cells divide by mitosis producing cloned plasma and B memory cells- clonal expansion
  4. cloned plasma cells produce antibodies which bind to pathogens and disable them/act as opsonins/agglutinins. This = primary immune response
  5. some cloned B cells develop into B memory cells for quicker secondary immune response in which they'll divide into plasma cell clones

  
• what is mean by an autoimmune response?

  when the immune system stops recognising self cells/antigens on self cells and starts attacking healthy body tissue
• state an example of an autoimmune disease. What body part is affected and how is it treated?

  • arthritis
  • body part affected- joints- hands, wrists, ankles, feet
  • treatments- no cure. anti-inflammatory drugs, steroids, immunosuppressants and pain relief are effective treatments