B6 Preventing and treating disease

• What is an antigen?

  A toxin or other foreign substance that induces an immune response in the body

  
• What is a vaccine?

  A preparation of weakened or killed pathogens
• What does the MMR vaccine protect you against?

  measles, mumps and rubella
• Explain how a vaccination can help protect you against dangerous infections


  Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body.

  This stimulates lymphocytes to produce the antibodies needed to fight the pathogen. If the live pathogen re-enters the body in the future the white

  blood cells respond quickly to produce the correct antibodies, preventing infection.
• What is herd immunity?

  When a majority of a population are vaccinated against a disease. This means that even people who have not been vaccinated are less likely to get it because there are fewer people to catch it from.
• Explain the 2 advantages of being vaccinated against a disease

  Stops individuals becoming ill and may be cheaper than treating a very ill person.
• What is a painkiller? Name 2 examples

  Used to treat pain caused by disease but cannot kill the pathogen. E.g. aspirin & paracetamol
• Why can't you use disinfectants and antiseptics inside your body?

  Too poisonous to use in body
• What is an antibiotic?

  drug that kills bacteria
• Why can't you use antibiotics for viral infections?


  Extremely difficult to develop drugs that will kill viruses without damaging your cells and tissues at the same time.
• What are antibiotic resistant bacteria?

  Bacteria that are not affected by certain antibiotics
• Where is digitalis extracted from and what is it used to treat?

  Extracted from foxgloves and is used to treat congestive heart failure (CHF) and heart rhythm problems
• Where does aspirin originate from?

  Bark of willow tree
• Describe how Alexander Fleming discovered penicillin

  After returning from holiday Fleming noticed that lots

  of his bacterial cultures had mould growing on them

  (he had left the lids off). Around some of the moulds

  was a clear zone. Fleming realised that the mould had

  killed the bacteria.
• Describe the 4 characteristics that would describe a good medicine

  -Effective(must work)

  -Safe(not be too toxic)

  -Stable(able for use under normal conditions)

  -Successfully taken into and removed from your body(must reach its target and be cleared from system once use has been fulfilled)
• What are medicines tested on in the lab (pre-clinical stage)?

  Cells, tissues and live animals
• What are the tests in the lab designed to find out?

  If the drugs are toxic (safety) and if they seem to do their job (efficiency).
• Who is the drug tested on during the clinical trials?

  Healthy volunteers and patients
• Why are low doses used at the start of this stage?

  Very low doses given to healthy people to check for side effects.
• What happens once the drug has passed the clinical trials?

  If the drug passes all the legal tests it is licensed so your doctor can prescribe it. It's safety will be monitored for as long as it's used.
• What is a double-blind study and why is it used?

  neither researchers nor patients know who is getting treatment; to avoid bias
• What is a placebo and why is it used?


  A placebo gives the appearance of the actual manipulation but has no effect on the subject. (sugar pill) to think your contributing but there is no effect.
• What are monoclonal antibodies?


  Antibodies produced from a single clone of cells. Each

  type is specific to one binding site on a specific protein

  antigen.
• How is the hybridoma made? Why is it a combination of 2 different cells?

  Made by fusing a mouse B-lymphocyte with a tumour cell. Combination of 2 different cells so that the hybridoma cells can be cloned to get lots of identical cells.
• Describe the production of monoclonal antibodies

  A lymphocyte and a tumour cell are combined to make a hybridoma cell which then clones itself and divide, monoclonal antibodies are the separated, purified and can be used.
• Why are monoclonal antibodies useful?

  As they are all the same, they will only bind to one target molecule so they can be used to target a specific cell or chemical in the body
• Describe some uses of monoclonal antibodies e.g. pregnancy tests, diagnosing disease, measuring and monitoring hormone levels.

  Pregnancy tests- Monoclonal antibodies bind to the

  HCG hormone produced in early pregnancy. If the

  monoclonal antibodies find and bind to the hormone

  they cause a colour change.

  Diagnosis of disease- Monoclonal antibodies can carry

  markers that make it easy for doctor to see where the

  disease is in the body.

  Measuring and monitoring- Bind to hormones so that

  levels can be measured.
• Describe the 3 ways monoclonal antibodies can be used to treat cancer

  -Direct use to trigger the immune system to recognise, attack and destroy cancer cells

  -Using them to block receptors on the surface of cancer cells and so stop the cells growing and dividing

  -Can be used to carry toxic drugs or radioactive substances for radiation therapy
• Describe the advantages of using monoclonal antibodies

  -Can bind to the specific cells

  -Can be used to treat many conditions

  -Shouldn't affect healthy cells

  -Works really quickly

  -Once developed, they are cheaper
• Describe the disadvantages of using monoclonal antibodies

  -Has bad side effects e.g. nausea

  -Aren't as successful as expected

  -Expensive to develop

  -Animals harmed in process of testing