Vaccines and Medicines

• Non-specific defences:

  • Skin (acts as a barrier)
  • Stomach acid (HCl destroys pathogens)
  • Tears (Contain enzymes which destroy pathogens near our eyes)
  • Mucus (Produced in respiratory system, traps particles and bacteria entering our respiratory system)
  • Platelets (seal wounds)
• Should the pathogen pass the non-specific defences, the immune system is activated. This is made up of different white blood cells, which have different functions:

  • Phagocytosis - Finds pathogen and engulfs it.
  • Antibodies - White blood cells recognise foreign antigens and produce antibodies specific to this antigen.
  • Antitoxins - Neutralises the toxins released by bacteria, preventing harm.
• Antigens are found on the surface of a pathogen. White blood cells can recognise this (memory cells) and produce antibodies, specific to the type of antigen. This clumps the pathogens together, allowing other white blood cells to engulf them easier.
• Monoclonal antibodies are produced from clones of cells, and are complementary to 1 type of antigen.
• Producing monoclonal antibodies

  1. A mouse is injected with the chosen antigen.
  2. The mouse's immune system responds by producing lymphocytes that produce the particular antibody.
  3. The lymphocytes are extracted from the mouse and fused with tumour cells to form hybridoma cells.
  4. The tumour cells grow rapidly, so lots of clones of the antibody is made.
  5. These antibodies are collected, purified, and then can start to be used to target specific cells and chemicals.
• Uses of monoclonal antibodies:

  • Pregnancy tests
  • Pregnant women produce a hormone called HCG.
  • Monoclonal antibodies bind to this hormone.
  • If the urine contains HCG, the monoclonal antibodies bind and show that the women is pregnant.
  • Treating disease
  • Monoclonal antibodies can bind to targeted cells.
  • Once bind, drugs can be given directly to the tumour.
  • Will not affect other tissue, due to only targeting one antigen.
  • Identify chemicals in the blood
  • Usually bind with a fluorescent dye, and so when they clump together, the molecules are highlighted.
• Common side effects of monoclonal antibodies:

  • Fever
  • Vomitting
  • Sneezing
• Vaccination

  1. Inject a dead pathogen.
  2. Immune system recognises antigen.
  3. Antibodies produced.
  4. Some white blood cells remain as memory cells.
• Antibiotics treat bacteria. The may destory the cell wall of the bacteria, to stop it replicating.
• Alexander Fleming discovered Penicillin.
• Antivirals treat viruses.
• Antiseptics prevent microbe infections.
• Criteria for testing drugs:

  • Dose - How much?
  • Efficacy - Does it work?
  • Toxicity - Is it safe?
• Preclinical testing is done in laboratories, on human cells, lad-grown tissues and live animals to test the drug.

  If the drug passes these tests, they need to be tried in larger doses. Drugs will then be tested on volunteers, to see if they are safe.
• Placebo effect

  When someone is given an alternative and begins to feel better, because they expect to be, even though they haven't been given the real drug.
• Double-blind test

  Neither the doctor nor the patient knows which patients are taking a placebo.
• Microorganisms can be grown as colonies on an agar gel plate.
• Bacteria multiply via binary fission.
• Joseph Lister discovered antiseptics,