Infection and response

• White blood cells have a nucleus.
• The role of platelets is to clot the blood when a blood vessel breaks 
• Platelets do not have a nucleus.
• The role of blood plasma is to carry substances and cells around the body
• Dissolved substances in urea:

  Glucose

  Amino acids

  Fatty acids

  Glycerol

  Carbon dioxide 

  Urea 

  Antibodies 

  Hormones 
• The painkiller aspirin originated from the bark of willow trees. It is now used to reduce pain, and lower fevers. 
• The drug digitalis originated from plants known as foxgloves. It is used to treat heart conditions such as heart failure. 
• Penicillin was the first discovered medicine.
• Efficacy - How well a drug produces the desired effect 
• Toxicity - How harmful a drug is e.g. how many side effects 
• Dosage - How much of the drug is required to give the desired effect
• 1. Stage 1 - Test the drug on human cells and tissues.
  2. Stage 2 - Test the drug on live animals.
  3. Stage 3a - Test the drug on healthy volunteers to find the maximum dosage before side effects occur.
  4. Stage 3b - Test the drug on patients that suffer from the relevant disease, to find the optimum dosage. 
• Importance of testing drugs:

  To make sure they are safe to use

  To make sure they are an effective treatment

  To determine the optimum dose
• In a double blind trial, only the researcher is given the trial drug and placebo.
• Double blind trials are done:

  To avoid any bias by the patients and/or researchers

  If patients know they received the drug they may be more likely to report side effects

  If researchers know who has been given the real drug then they may pay closer attention to those patients