stimulants, seditives & painkillers

Drugs can affect nerves' impulses, reaction times and behaviour.

Stimulants

Stimulants include caffeine - found in cola drinks and coffee, cannabis and amphetamines. They increase the transmission of signals from one nerve cell to the next. This increases alertness, heart rate and breathing rate. However, in the longer term, they can produce 'highs' and then extreme 'lows' or even depression. They can be addictive because the body needs a constant top-up to maintain the effect.

Sedatives
Sedatives include alcohol and barbiturates - drugs prescribed by a doctor to help people sleep or to relieve the symptoms of stress. They slow down the nervous system and decrease reaction times.

Painkillers
Painkillers or analgesics include paracetamol, aspirin, heroin and morphine. They block nerve impulses from the painful part of the body, or block nerve impulses travelling to the part of the brain responsible for perceiving pain.

Paracetamol is an effective painkiller but an overdose is very dangerous. An overdose damages the liver and can cause death.

[ This page has been adapted from www.bbc.co.uk/schools/gcsebitesize/science ]