Fighting Desease

• Antigens

  Unique molecules or parts of molecules that can elicit an immune response
• First-line defences (or barriers) that provide innate resistance against pathogens

  • Physical barriers (such as skin or bark)
  • Chemical barriers (such as the lysozyme enzyme in saliva and other body secretions)
  • Microbiological barriers, such a microflora
• First Line of Defence (Non-Specific)

  • Non-specific: they do not target a specific antigen
  • Rapid: occur within hours
  • Present in all animals
  • Fixed responses: they do not adapt
  • Do not lead to an immunological memory of the pathogen that caused the infection
• Viruses, unlike bacteria, contain a protective coating that allows them to more easily slip through the first line of defence
• Second Line of Defence (Non-Specific)

  1. Blood clotting: to stop infection through the skin

  2. Inflammation: increase the amount of blood cells reaching an infected area

  3. Fever: some pathogens cannot survive at high temperatures, so heating up the body is one way to destroy them
• Inflammation


  Increases the amount of blood reaching an infected area so that more white blood cells are able to attack the pathogen
• Fever

  37°C human body normal temperature – fever is anything above this
• White blood cells

  • Lymphocytes: main type of white blood cells and include natural killer cells, T cells, and B cells
  • Phagocytes (Greek for 'cells that eat'): deal with the non-specific immune response. They surround and absorb pathogens, destroying them in a process called phagocytosis
• Third Line of Defence (Specific)

  1. B cells: produce special molecules called antibodies, which specifically bind to certain antigens and stop them from invading

  2. T cells: recognise the same specific pathogens, attack and kill them

  3. Both B cells and T cells keep some memory cells alive just in case the pathogen tries to invade the body again
• Active Immunity


  • Your body making antibodies to a specific antigen
  • Natural: Antibodies made after exposure to antigen
  • Artificial: Antibodies made after injection or with killed or weakened pathogen
  • Memory cells produced
• Passive Immunity


  • Receiving antibodies from an outside source
  • Natural: Antibodies pass to baby across placenta or in mothers milk
  • Artificial: Injection of antibodies
  • No memory cells produced
• Immunity


  • Resistance to a particular disease causing pathogen
  • A person who is immune does not develop the disease
  • If a person is exposed to the antigen of a particular pathogen, they make antibodies against it
  • The next time they encounter that antigen, their response may be so fast and effective that they can resist infection
• Vaccination or immunisation

  The giving of the vaccine to produce a type of immunity called artificial immunity
• Many diseases controlled due to vaccinations – some rarely seen at all
• Analyse


  • How do we analyse?
  • What does it mean to analyse data?