module 4 - 12.6 the specific immune system Flashcards
how is the specific immune system different to non-specific responses?
- specific immune system is slower than non-specific
- immune memory cells react much quicker if second invasion of same pathogen occurs
what are antibodies?
Y-shaped glycoproteins called immunoglobulins which bind to specific antigen on pathogen/toxin that has triggered immune response
what are antibodies made up of?
- 2 identical polypeptide chains - heavy chains
- 2 shorter identical chains - light chains
- chains are held together by disulphide bridges & disulphide bridges within polypeptide holding its shape
why is the binding site known as the variable region?
- binding site is area of 110 amino acids on both heavy and light chains
- different shape on each antibody - specificity
why is the rest called the constant region?
rest of antibody molecule is always the same
what is formed when an antibody binds to antigen?
antigen-antibody complex
how do antibodies defend the body?
- antibody of antigen-antibody complex acts as opsonin so complex is easily engulfed & digested by phagocytes
- most pathogens cant invade hist cells once part of complex
- antibodies act as agglutinins, cause pathogens carrying complexes to clump together - helps prevent them spreading through body
- antibodies can act as anti-toxins, binding to the toxins produced by pathogens
which white blood cells are involved in the immune response?
- B lymphocytes - mature in bone marrow
- T lymphocytes - mature in thymus gland
what are the main types of T lymphocytes?
- T helper cells
- T killer cells
- T memory cells
- T regulator/suppressor cells
what are T helper cells?
- have receptors on cell-surface membranes what bind to surface antigens
- produce interleukins - stimulate activity of B cells, increasing antibody production, attracts and stimulates macrophages
what are T killer cells?
- destroy pathogens carrying antigen
- produce chemical called perforin - kills pathogen by making holes in cell membrane so is freely permeable
what are T memory cells?
- live for long time, part of immunological memory
- if they meet antigen a second time, they divide rapidly to form a huge number of T killer cells and destroy pathogen
what are T regulator/suppressor cells?
- suppress immune system, control & regulate it
- stops immune response once pathogen has been eliminated
- makes sure body recognises self-antigens and doesn’t set up autoimmune response
what are the main types of B lymphocytes?
- plasma cells
- B effector cells
- B memory cells
what are plasma cells?
they produce antibodies to particular antigen and them release into circulation
what are B effector cells?
they divide to form the plasma clones
what are B memory cells?
- provide immunological memory
- programmed to remember specific antigen & enable body to make rapid response when pathogen carrying that antigen is encountered again
what happens during cell-mediated immunity?
(happens inside cells) - T lymphocytes respond to the cells of an organism that have been changed by antigen processing or by mutation
what is the first stage of cell mediated immunity?
- in non-specific defence system, macrophages engulf & digest pathogens in phagocytosis
- they process antigens from surface of pathogen to form antigen-presenting cells
what is the second stage of cell mediated immunity?
- receptors in some of the T helper cells fit the antigens
- T helper cells are activated & produce interleukins - stimulate more T helper cells to divide (mitosis)
- form clones of identical activated T cells that carry correct antigen to bind to pathogen
what 4 things may the clones T cells do
- develop T memory cells which give rapid response if pathogen invades body again
- produce interleukins that stimulate phagocytosis
- produce interleukins that stimulate B cells to divide
- stimulate development of clone T killer cells, specific for presented antigen then destroy infected cells
what happens during humoral immunity?
body responds to antigens found outside the cells
- humoral immune system produces antibodies that are soluble in blood and tissue fluid & are not attached to cells
where do B lymphocytes have antibodies?
on cell surface membrane
what happens when a pathogen enters the body?
- carries specific antigens
- produces toxins that act as antigens
- B cell with complemetary antibodies will bind to antigens on pathogen or free antigens
