Biology - B2 - Keeping Healthy

  • Created by: Niamh
  • Created on: 14-05-11 19:26

You should know :

- Diseases are caused by some microorganisms, and by a person's lifestyle, for example, smoking, poor diet.

- Natural barriers help to stop harmful microorganisms entering the body.

Tears, sweat, skin, stomach acid.

-These microorganisms may reproduce very quickly in good conditions, damaging cells or producing poisons which cause symptoms of disease.

Potentially once every 20 minutes. They release toxins which is what you should be referring to, as opposed to just poisons.

- White blood cells are part of the immune system to fight infections.

- White blood cells can destroy microorganisms by digesting them or producing antibodies.

The antibodies stick to the MO's markers, but it usually takes about 17 days to develop the new antibody.

- Different antibodies are needed to fight every different microorganism.

Different 'keys' for different 'locks'

- Once you have made one type of antibody you can make it again very quickly, so you are immune to that disease.

- Vaccines trigger the body to make antibodies before it is infected with a particular microorganism.

Uses a dead/inactive/unharmful version of the MO so it causes no harm, although sometimes you will feel ill because of how your body reacts to it.

- Vaccines contain a harmless form of the microorganism.

- No action can be completely safe, including vaccinations and other medical treatments.

Thinking about why in England it is not compulsory, but in other countries it is. Benefits vs. Risks.

- Why a very high percentage of people must be vaccinated to prevent an epidemic.

Herd immunity, usually at about 94%. This means that so many people in a population are immune, that the chances of two unvaccinated members of the population meeting


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