1. TYPES OF DRUGS

2. How do drugs affect the body? Nerves (neurones) carry information for the nervous system. There is a gap between two nerves called a synapse. Information crosses these gaps as impulses. Drugs affect the speed at which these impulses cross the gaps.

3. How a synapse works Chemical moves across the gap Impulse moves this way When one impulse reaches the end of a nerve (neurone) a chemical is produced. The chemical moves across the gap and when it gets to the next neurone it starts another impulse

4. How do drugs affect the synapse? Caffeine, cocaine and amphetamine are stimulants They work by increasing the speed by which impulses cross the synapse. Faster impulses can cause faster heart rate and breathing. Using drugs like cocaine and amphetamine can lead to addiction.

5. Sedatives Sedatives are drugs which slow down the speed of the impulses as they cross the synapse Barbiturates and alcohol are sedatives These increase reaction times (it takes a longer time to do something)

6. Analgesics Some drugs are given to relieve pain. These are called analgesics They include paracetamol, ibuprofen heroin and morphine. These work by blocking the impulses at the synapses in parts of the brain that deal with pain

7. Taking too much Paracetamol is a mild pain killer and it is a safe drug if the correct dose is taken. If more is taken it is called an overdose and can damage the liver. Morphine and heroin are very strong pain killers. People who take them for a long time can become addicted.

8. Solvents Chemicals in glues, aerosols, spray paint and lighters are called solvents. These are very dangerous. Solvents are breathed in and they enter the lungs. They then get into the blood stream and reach the brain. They slow down breathing and heart rate. Some people die because solvents cause heart failure. Solvents also cause damage to the nerves, brain damage and memory loss.

9. Now try these exercises Exercise 7 Exercise 7 - Matching Exercise 8 Exercise 8 - Cloze