08 Drugs

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- GCSE Bitesize - Drugs

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Science

Drugs

Drugs are chemicals that cause changes in the body. They

can be divided into legal and i llegal drugs. Drugs can also

be medical (drugs taken to cure illness) or recreational(drugs taken because they have pleasing effects). Some

drugs can be addictive more and more is needed to

achieve the same effect. Drugs can be separated into

categories solvents, painkil lers, depressants and

stimulants.

Types of drug

Drugs can affect nerves impulses, reaction times and behaviour.

Stimulants

Stimulants include caffeine - found

n fizzy drinks, tea and coffee,

cannabis and amphetamines such

as speed. They increase the

transmission of signals from one

nerve cell to the next, which then

ncreases alertness, heart rate and

breathing rate. However, in the long

term, stimulants 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 ordepressants include alcohol and barbiturates

(such as the prescribed drug amytal and the illegal GHB).

Sedatives are also drugs prescribed by a doctor to help people

sleep or to relieve the symptoms of stress. They slow down the

nervous system and reactions.

Coffee is a stimulant

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Painkillers

Painkillers oranalgesics 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.

Hallucinogens

Hallucinogens change the way our brains work, distorting our

senses. This changes our response to what we see, feel and

hear. LSD is an example of a hallucinogen.

Recreational drugs: tobacco

About 114,000 people die everyyear as a result of smoking-related

llnesses. All cigarettes sold now

carry a prominent health warning.

Smoking during pregnancy is very

dangerous as it reduces the amount

of oxygen available to the growing

foetus. This leads to an increasedrisk of:

miscarriage and premature

birth

low weight of babies at birth.

Cigarettes contain about 4,000 different chemicals, many of

which are harmful to the body.

Painkillers like paracetamol

and aspirin are available

over-the-counter' at

pharmacies.

Warnings such as 'Smoking

can cause a slow and painfuldeath' are used to deter

people from smoking

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Nicotine

Nicotine is the addictive substance in tobacco smoke. It reaches

the brain within 20 seconds and creates a dependency so that

smokers become addicted.

Carbon monoxide

Carbon monoxide combines with the

haemoglobinhaemoglobin : The red protein found in red blood

cells that transports oxygen round the body in red blood cells

and so reduces the ability of the blood to carry oxygen. This

puts extra strain on the circulatory system, and can cause an

ncreased risk of heart disease and strokes.

TarCarcinogens are substances that cause cancer. Tobacco

smoke contains many carcinogens, including tar. Smoking

ncreases the risk of lung cancer, mouth cancer and throat

cancer.

The images above compare a healthy lung to a smokers lung.

Tar deposits can clearly be seen clearly in the smokers lung.

Cigarettes and data

A healthy lung A smoker's lung, with tar

deposits visible

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There has been a lot of data

collected about the effects of

smoking. The graph shows the

correlation between cigarette

smoking and the incidence of lung

cancer. You may be expected to

nterpret graphs like this as part of

an exam question.

Recreational drugs: alcohol

The alcohol in alcoholic drinks -

such as wines, beers and spirits - is

called ethanol . It is a depressant,

which means it slows down signalsn the nerves and brain.

There are legal limits to the level of

alcohol that drivers and pilots can

have in the body. This is because

alcohol impairs the ability of people

to control their vehicles properly.

Short-term effects

Alcohol has short-term effects such as sleepiness and impaired

udgment, balance and muscle control. This leads to blurred

vision and slurred speech. Vasodilation occurs - blood vessels in

the skin carry more blood - leading to heat loss.

Long-term effects

The long-term effects of alcohol include damage to the liver and

brain. The liver removes alcohol from the bloodstream because

t's a toxic chemical. Over time, alcohol consumption can lead to

iver damage (cirrhosis).

Transplants

f an organ in the body has been damaged then it can be

A correlation between

smoking and lung cancer

Alcoholic drinks

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replaced by a healthy organ from a donor someone who had

healthy organs but very recently died from other causes.

A successful transplant has to have:

similar tissues from donor to patient

similar ages of donor and patient

similar locations as organs deteriorate quickly

Organ donation can be an ethical issue especially as the

supply of organs is limited. An ethical issue is one that has rights

and wrongs. In an exam you will be expected to discuss the

ethical issues involved in:

liver transplants for alcoholics

heart transplants for the clinically obese.

Now try a Test Bite.

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08 Drugs

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