Fighting Disease - Vaccination and Drugs

• Human body's features for fighting disease

  • Skin acts as barrier, secretes antimicrobial substances
  • Hairs and mucus in nose trap particles
  • Trachea and bronchi secrete mucus to trap pathogens
  • Trachea and bronchi lined with cilia to waft mucus up
  • Stomach produces hydrochloric acid to kill pathogens
• Immune system's ways of attacking pathogens

  • Consuming them (phagocytosis)
  • Producing antibodies
  • Producing antitoxins
• Antibodies


  Proteins produced by white blood cells to lock onto and destroy specific invading pathogens
• Vaccination


  1. Injecting small amounts of dead/inactive pathogens to cause body to produce antibodies

  2. If live pathogens later appear, antibodies can rapidly mass-produce to kill them
• Pros of vaccination


  • Helped control many communicable diseases
  • Can prevent epidemics if large percentage of population vaccinated
• Cons of vaccination


  • Vaccines don't always work
  • Can sometimes have bad reactions
• Painkillers


  Drugs that relieve pain but don't tackle cause of disease or kill pathogens
• Antibiotics


  Drugs that kill or prevent growth of bacteria causing a problem, without killing body's own cells
• Antibiotics don't destroy viruses as they reproduce using body's cells
• Use of antibiotics has greatly reduced deaths from communicable diseases caused by bacteria
• Bacteria becoming resistant to antibiotics

  1. Bacteria mutate to be resistant

  2. Resistant strains survive and reproduce when treated with antibiotics

  3. Resistant strain can cause serious infection
• To slow development of resistant strains, doctors should avoid over-prescribing antibiotics
• It's important to finish whole course of antibiotics and not stop once feeling better
• How some drugs originally came from plants

  • Plants produce chemicals to defend against pests/pathogens
  • Some of these chemicals can be used as drugs
  • Many current medicines were discovered by studying traditional plant-based cures
  • Some drugs extracted from microorganisms like penicillin
• Nowadays drugs are synthesised by chemists in labs, but process may still start with chemical extracted from a plant