B1 Effects of drugs

What is a drug?

Learn this - 

A drug is a chemical substance that affects the central nervous system causing changes in psychological behaviour and possible addiction.

There are many different types of drugs so to make things easier they are classified into different groups.

1) Painkillers -  We feel pain when electrical impulses from a damaged part of the body are sent via sensory neurones to the brain. Narcotic painkillers, such as morphine, block some of these nerve impulses, so we feel less pain. These drugs can also make us sleepy.


2) Hallucinogens - These are drugs that change the way the brain works. These distort sense perception and so change how we respond to what we see, hear and feel. Hallucinogenic drugs like LSD can distort our senses of colour, time and space.

3) Stimulants - These drugs increase the speed of neurotransmission of nerve impulses across synapses. This speeds up reaction times so we use less time - we are quicker. Caffeine is a stimulant.

4) Depressants - These drugs slow down the activity of neurones in the brain and can help us relax. Alcohol is a depressant.

Some drugs are legal (like caffeine in fizzy drinks) and others are illegal like heroin. Some drugs are legal at certain ages to buy like alcohol whilst some illegal drugs like heroin are used in hospitals, but under very controlled conditions. Some drugs are recreational where they are used by people to feel in a certain way like alcohol. Other drugs are medicines to help against injuries or illnesses.

Most drugs are addictive which means that people become dependent on it and feel that they can't function properly without it.