definitions

• What are agglutinins?


  chemicals (antibodies) that cause pathogens to clump together so they are easier for phagocytes to engulf and digest
• What are antibiotic-resistant bacteria?

  bacteria that undergo mutation to become resistant to an antibiotic and then survive to increase in number
• What are antibiotics?

  a chemical or compound that kills or inhibits the growth of bacteria
• What is an antigen?

  an identifying chemical on the surface of a cell that triggers an immune response
• What is an antigen-antibody complex?

  the complex formed when an antibody binds to an antigen
• What is an antigen-presenting cell (APC)?

  a cell that displays foreign antigens complexed with major histocompatibility complexes on their surfaces
• What are anti-toxins?


  chemicals (antibodies) that bind to toxins produced by pathogens so they no longer have an effect
• What is artificial active immunity?

  immunity which results from exposure to a safe form of a pathogen, for instance by vaccination
• What is artificial passive immunity?

  immunity which results from the administration of antibodies from another animal against a dangerous pathogen
• What is autoimmune disease?


  a condition or illness resulting from an autoimmune response
• What is an autoimmune response?


  response when the immune system acts against its own cells and destroys healthy tissue in the body
• What are B effector cells?

  B lymphocytes that divide to form plasma cell clones
• What are B lymphocytes (B cells)?

  lymphocytes which mature in the bone marrow and that are involved in the production of antibodies
• What are B memory cells?


  B lymphocytes that live a long time and are responsible for remembering and recognizing specific pathogens or antigens that the immune system has encountered before.
• What is cell signalling?

  A complex system of intercellular communication
• What is clonal expansion?

  where activated T or B lymphocytes undergo mitosis to form many clones, which then differentiate
• What is clonal selection?

  a process where specific T or B lymphocytes are selected for replication
• What are clostridium difficile?

  a species of gram-positive bacteria that is resistant to most antibiotics, found in the digestive tract
• What are communicable diseases?

  diseases that can be transmitted from one organism to another, of the same or different species
• What are cytokines?

  Cell-signalling molecules produced by mast cells in damaged tissues that attract phagocytes to the site of infection or inflammation
• What is direct transmission?

  Direct transmission refers to when a pathogen is transferred directly from one individual to another by direct contact (body fluids, skin-to-skin, or via faces)
• What is endocytosis?

  Endocytosis is the process by which cells take in external materials by engulfing them with their cell membrane or

  the bulk transport of materials into cells via invagination of the cell-surface membrane forming a vesicle
• What is an epidemic?

  when a communicable disease spreads rapidly to a lot of people at a local or national level (widespread outbreak)
• What is a fomite?

  an inanimate object (non-living) that can transmit pathogens indirectly, e.g the fungus that causes athletes foot can be transferred from an infected to a healthy individual on a towel (the fomite)
• What are glycoproteins?

  extrinsic membrane proteins with attached carbohydrate molecules of varying lengths and shapes
• What are gram-negative bacteria?

  bacteria with cell walls that stain red with gram stain
• What are gram-positive bacteria?

  bacteria with cell walls that stain purple-blue with gram stain
• What are histamines?

  chemicals produced by mast cells in damaged tissues that make the blood vessels dilate (causing redness and heat) and the blood vessel walls leaky (causing swelling and pain)
• What is the immune response?

  a biological response that protects the body by recognising and responding to antigens and by destroying substances carrying non-self antigens
• What is immunity?

  when an organism's immune system has the resources it needs to kill a pathogen before it can cause damage/symptoms
• What are immunoglobulins?

  Y-shaped glycoproteins that form antibodies
• What is indirect transmission?

  Where a pathogen is transferred indirectly from one individual to another via vectors, fomites or (droplet infection)
• What is inflammation?


  a biological response of vascular tissues to pathogens, damaged cells or irritants, resulting in pain, heat, redness and swelling
• What are interleukins?

  a type of cytokine produced by T helper cells
• What are lymphocytes?

  white blood cells that make up the specific immune system
• What are lysosomes?

  specialised vesicles that contain hydrolytic enzymes for the breakdown of waste material within a cell
• What is MRSA (methicillin-resistant Staphylococcus aureus)?

  a mutated strain of the bacterium Staphylococcus aureus that is resistant to the antibiotic methicillin
• What is natural active immunity?

  immunity which results from the response of the body to the invasion of a pathogen
• What is natural passive immunity?

  the immunity given to an infant mammal by the mother through the placenta and the colostrum
• What are Opsonins?


  chemicals (e.g antibodies) that bind to pathogens and tag them so they are recognised more easily by phagocytes