A drug is defined as any substance that alters the normal running of the body. Some drugs such as aspirin and paracetamol are useful when used according to the manufacturers instructions but when  these are not followed a helpful medicine can become very harmful. Alcohol and other substances can also affect the way your body works. This leads at best to impaired reactions and at worst can kill you.  In some cases this can be the first time you try it.

If you eat a balanced diet and exercise regularly then you will be far healthier.  What this will actually mean to you is that you will be able to play all your sports and run around without getting tired.  You won’t get ill as often and you will feel good in yourself.

The growth and reproduction of bacteria and the replication of viruses can affect health.  These can be minimised when high priority is put on cleanliness at the personal and community level as this will help prevent the spread of diseases.

Some diseases are caused by bacteria such as cholera or tuberculosis and some are caused by viruses such as influenza (flu) or HIV  (which can go on to cause AIDS).

The body's natural defences can be supplemented by artificial methods. These can be in the form of vaccinations or other medicines

These 3 videos are about 8 minutes each. they make um an animated cartoon about the tetanus bacteria and how immunizations work.

Micro-organisms are living organisms that are often too small to be seen, and they may be beneficial or harmful.

We are not the only species on the planet that matters and our advanced intelligence puts on our shoulders the responsibility to  conserve and protect the other living things and their environment.

Dr Jane Goodall is an eminent scientist who did groundbreaking work with chimpanzees.