How does a medicine or drug act on the body?

Read the new words:

• защита организма от заболевания

• сокращать

• становиться стойким

• контролировать при помощи чего-то

• ухудшать, усиливать

body’s defenses against disease

to reduce

to become resistant

to control by something

to aggravate

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There are many different diseases and medical conditions and thousands of medicines and drugs have been produced to help people who need treatment. Each has its own way of working and we each react differently so the process is very complex and difficult to understand. Here are some examples of ways in which medicines and drugs work:

1 Aspirin

Enzymes are large protein molecules which control the chemical reactions in our bodies. When cells are injured, an enzyme makes substances called prostaglandins which aggravate inflammation, fever and pain. Aspirin works by blocking the action of the enzyme which makes the prostaglandin and at the same time relieving the pain and inflammation in other ways.

2 Antibiotics

As part of the body's defence against disease it produces antibodies to invading bacteria, but if these are not able to combat the disease, medicines may have to be taken as well. Penicillin and other antibiotics kill invading bacteria by weakening the bacterial cell wall and causing the bacteria to swell and burst. Human cell membranes have a different chemical structure from the bacteria and are not damaged by these drugs.

Penicillin also helps to reduce the bacterial cell division, and this slowly helps defeat the invading bacteria.

The correct dosage of the antibiotic must be taken and the whole course of treatment followed. This is because problems can arise if antibiotics are not used according to a doctor's instructions. The bacteria can become resistant and so the drug gradually becomes less effective.

3 Drugs for incurable diseases

Some medicines and drugs are used to treat chronic conditions which have no cure, such as diseases of the central nervous system. By controlling or reducing the symptoms of the disease, medicines and drugs can improve the sufferer's quality of life. For example, Parkinson's disease affects over 100,000 people in Britain, most of them elderly. It causes muscle stiffness and severe shaking. The drug Levodopa reaches the brain through the blood system and helps to improve balance and reduce the shaking. Sometimes drugs which act on the central nervous system have unwanted side effects on the person's personality and emotional state. Some people feel depressed and 'not themselves'. However, these side effects can usually be controlled by using other drugs and for most people relief from the symptoms of the disease is the most important effect.

Answer the following questions after reading the text.

1. What were many drugs and medicines produced for?

2. What controls chemical reactions in our bodies?

3. How do antibiotics work?

4. Are there any drugs for incurable diseases?

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