12.7 Preventing And Treating Disease

Question 1

What is natural active immunity?

Answer 1

This is when you become immune after catching a disease, this is due to T and B memory cells

Question 2

What is active immunity?

Answer 2

The type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen. There are two different types of active immunity: natural and artificial

Question 3

What is artificial active immunity?

Answer 3

This is when you become immune after you’ve been given a vaccine containing a harmless dose of antigen

Question 4

What is passive immunity? What are the two types?

Answer 4

This is the type of immunity you get from being given antibodies made by a different organism - your immune system doesn’t produce any antibodies of its own. Protection is short term as memory cells aren’t produced.

1) natural passive immunity- when a baby become immune due to the antibodies it receives from it mother, through the placenta and breast milk
2) artificial passive immunity- this is when you become immune after being injected with antibodies from someone else e.g. through blood donations

Question 5

What are antibiotics?

Answer 5

Chemicals that kill or inhibit the growth of bacteria without damaging human body cells

Question 6

Why does antibiotic resistance arise? Why is this a problem?

Answer 6

• genetic mutations make some bacteria naturally resistant to an antibiotic. The bacterium with the antibiotic resistance gene is able to survive the selection pressure of an antibiotic being present and can then reproduce, passing on the antibiotic resistant gene to the next generation. Whereas the other bacteria, without the advantageous mutation, do not survive against the selection pressure applied by the antibiotic.
  Over time with continued selection pressure, the number of antibiotic resistant bacteria in the population increases.
  This has happened with MRSA and C.difficile (antibiotic resistant bacteria)
  MRSA causes serious wound infections and is resistant to several antibiotics including methicillin
  C.difficile infects the digestive system, C.difficile produces a toxin which causes sever diarrhoea, fever and cramps
  Problems:
• we are less able to treat some bacterial infections

Question 7

How can we reduce antibiotic resistant infections?

Answer 7

• minimise the use of antibiotics and ensure that every course of antibiotics is completed
• good hygiene in hospitals and in general

Question 8

Explain the importance of maintaining biodiversity for the discovery of new medicines

Answer 8

If we dont maintain biodiversity there is a risk of some sources of drugs going extinct before we can even study them. Even organisms that have already been studied could still prove to be useful sources of medicines as new techniques are developed for testing compounds

Question 9

What is meant by personalised medicine and synthetic biology?

Answer 9

Personalised medicines: tailored to an individuals DNA as doctors can use your genetic information to predict how you will respond to different drugs and only prescribe ones that will be most effective for you

Synthetic biology: involves using technology to design and make thing like artificial proteins, cells and bacteria. Using the techniques of genetic engineering we can develop populations of bacteria that would otherwise be too rare, too expensive or not available

Question 10

Describe and explain the use of vaccinations

Answer 10

• vaccines contain a small/safe dose of antigens (could be free or attached to a dead or weakened pathogen)that cause your body to have an immune response and produce memory cells against a particular pathogen, without the pathogen causing disease
  So you become immune without getting the symptoms of disease
• vaccines may be injected or taken orally. Disadvantage of taking a vaccine orally is that it could be broken down by enzymes in the gut or the molecules of the vaccine may be too large to be absorbed into the blood
• sometimes booster vaccines are given later on to make sure that more memory cells are produced, to increase the time you are immune to a disease
• if most people in a community are vaccinated, the disease becomes extremely rare.
  This means that even people who haven’t been vaccinated are unlikely to get the disease, because there’s no one to catch it from
  This is called herd immunity — it prevents epidemics (mass outbreak of disease on a local or national level)
  A pandemic is when the same disease spreads rapidly across a number of countries and continents

Question 11

Why do vaccination programmes constantly need to be changed?

Answer 11

Pathogens can change their surface antigens, so you are no longer immune as your memory cells can no longer recognise the antigens on the surface of the pathogen

E.g. influenza (flu) vaccine changed every year, as the antigens on the surface of the virus change regularly, forming new strains of the virus
The strains are immunologically distinct