B6- preventing and treating disease

• What is vaccination

  Introducing small quantities of dead/inactive forms of pathogen into the body which cannot lead to disease
• how do vaccinations work

  • white blood cells are stimulate to release antibodies to fight dead/weak pathogen
  • The white blood cells divide by mitosis to produce lots of cells with antibodY recognition
• What is herd immunity

  • if enough people are vaccinated it also protects unvaccinated people
  • The unvaccinated person cannot catch the disease if nobody around them can pass the pathogen
• bacterial diseases

  Salmonella and gonorrhoeal
• when was the first antibiotic discovered

  • 1940s
  • Penicillin
  • Alexander Fleming
• How do antibiotics work

  • kill infective bacteria in human body
  • Don’t harm body cells
• what is antibiotic resistance

  • certain antibiotics are no longer effective against certain bacteria
  • antibiotics are overused
  • bacteria are evolved and no longer killed by antibiotics
• Key points about antibiotics

  • doctors have to use specific antibiotics to treat specific bacteria
  • Antibiotics cannot kill viruses, only bacteria
• what is prescribed for virus

  • painkillers
  • Treat symptoms by relieving pain
  • Do not kill pathogens
• Why is it difficult to develop viral drugs

  • virus’ reproduce in cells
  • Difficult to develop drugs that don’t damage cells
• Drugs extracted from plants

  • Foxglove used to extract heart drug digitalis
  • painkiller aspirin extracted from willow trees
• where does penicillin come from

  microorganism - mould penicillium
• How are most new drugs discovered

  • synthesised by chemists in pharmaceutical companies
  • Often chemicals extracted from plants
• Why are drugs tested

  • to check toxicity
  • Check whether it is effective
  • Work out best dosage
• stages of drug testing

  • preclinical testing - cells, tissues and live animals
  • Clinical testing - humans
  • In first stage of clinical testing very low dosages are given to healthy volunteers - check safety
  • If its safe testing continues to find optimal dosage
• what is a placebo effect

  • a tablet of injection with no active drug
  • some patients will get better with placebo - belief they are getting treated
• what are double blind trials

  • test group receive active drug
  • placebo group receive dummy drug - looks identical to test drug but has no active ingredient
  • Neither patient or doctor know who receives active drug
  • Stops bias in case doctors pay closer attention to active drug