B1 - infection and response

• What are pathogens?


  Microorganisms that can cause disease
• What do pathogens include?

  • bacteria
  • fungi
  • protists
  • viruses
• How can we stop disease from spreading?


  Hygine

  • washing hands
  • cleaning cookery items / keeping food production and distribution sanitary

  Vaccination

  • (if you can’t catch the disease you can’t pass it on)

  Isolate / Quarantine

  • (no contact with other people)

  Kill the vectors

  (organisms that transport the pathogen)

  • mosquitoes
  • (with) insecticides
• What is Phagocytosis?


  The process that white blood cells engulf pathogens

  (done by) :

  • tracking
  • Binding
  • Engulfing - (which destroys them)
• What do the anti-toxins that our white blood cells produce, do?

  • bind and counteract toxins released by pathogens, so they can’t do us any harm.
• What are antigens?


  Substances that our immune system detects as being foreign. (Bacteria / viruses)
• What are antibodies?


  Proteins that our white blood cells produce that lock onto antigens, which act as signals - to tell our white blood cells to destroy them.
• Each of our Antibodies are…

  Specific for each antigen (and won’t be able to bind to any others)
• What are the 3 functions white blood cells do to protect us against pathogens?

  • phagocytosis (engulfing them)
  • produce anti-toxins
  • produce anti-bodies
• The cells that line the trachea, bronchi, and bronchioles have tiny hair-like projections that waft pathogens away from the lungs. What are they called?

  Cilia

  
• What does a vaccine against a specific pathogen do for us?

  Practice producing the correct antibodies so we become immune.
• what are the pros of vaccines?

  • protection from disease
  • control of common diseases - (polio, smallpox, measles)
  • prevent outbreaks (epidemics)

  which kill lots of people
• What are the cons of vaccines?

  • don’t always work

  (don’t grant full immunity)

  • can cause side effects
• What is herd immunity?


  When a large amount of the population have been vaccinated

  (because the pathogen has so little people to spread to, it can’t find them easily enough and dies out)

  So the whole population become immune too
• What can antibiotics only kill?

  (bacteria or virus)

  Bacteria
• What are the 2 types of drugs in medicine?

  The ones that relive symptoms - eg:

  • aspirin
  • paracetemol
  • painkillers

  The ones that treat the disease

  (kill the bacteria) eg:

  • antibiotics
• medication drugs used as painkillers include:

  • aspirin
  • paracetamol
• What is it called when bacteria evolve so antibiotics can’t kill them?

  Antibiotic resistance
• What do we need to keep in mind when testing / developing drugs


  Efficacy

  • how well it works

  (does it do the effect you’re looking for)

  Toxicity

  • how harmful it is

  (does it damage cells or have side effects)

  Dosage

  • how much, and what concentration should be given?

  (the more we give, the more effective it will be - but the more side effects it will cause)
• Testing Stage 1


  • Use human cells and tissue
  • Can be grown in a laboratory
  • Can cheaply test lots different substances
• Testing Stage 1 Downsides


  • Doesn't tell us how it would effect an entire organism / organ
• Testing Stage 2


  • Use live animals
  • Because we are also mammals, our bodies Are relitivley similar
  • This would give us a good idea of the efficacy and toxicity
• Both Stage 1 and Stage 2 are 'preclinical' - they do not test on humans
• Clinical testing Stage 3


  1. Give to healthy volunteers at a low dose

  2. Slowly increase dose, while doctors keep an eye out for side effects

  3. Find the maximum dosage without side effects

  4. Give to people suffering from the illness

  5. Slowly increase the dose

  6. Look for the optimum dosage (the efficacy is maximised and toxicity is minimised)
• What do we need to do in drug testing? - to get ‘valid results’

  • use a placebo
  • do the test blind
• Why is it important for medical trials to be double-blind?

  • to avoid bias patients and / or researchers
  • if patients know they received the drug they may be more likely report side effects
  • if researchers know who has been given the real drug they may pay closer attention to those patients