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Substance abuse

Chapter 13

Legal and illegal drugsA drug can be dened as a substance that alters

the body’s physiology. Drugs may be used to treat

specic health problems, and this is known as

therapeutic drug use. There are also drugs that

people use to change their mood, such as caeine,alcohol, nicotine, cannabis and heroin.

Although all o these drugs can have benecial

eects in some circumstances, most o them also

have the potential to cause enormous problems

or their users and others i they are abused.

Drug (or substance) abuse means using the drug

in a way that causes harm, either to onesel or

to others. Misuse o drugs seriously damages the

physical and mental health o many people in

the Caribbean each year, as well as harming their

amilies and other members o the society in which

they live and work.

Many o the most harmul drugs are illegal.

However, the act that a drug is legal does not

mean that it is harmless. Most doctors agree that

alcohol, although it is a legal drug, does more

harm each year than any o the illegal drugs. It

has been suggested that, i alcohol was discovered

or the rst time today, it would immediately be

banned as being extremely dangerous to health.

In this chapter, we will look in detail at two legal

drugs which, between them, contribute to very

large numbers o deaths and serious illness each

year. These are alcohol and nicotine.

Drug dependencyMany drugs aect what happens at synapses, either

in the brain or elsewhere in the body. Postsynaptic

neurones contain receptors in their plasma

membranes into which the transmitter substance

used at that synapse precisely ts. Drugs that act at

synapses may do so by mimicking the action o the

transmitter substance; that is, they have the same

shape and aect the postsynaptic neurone in the

same way that the transmitter would. They may

prevent the breakdown o the transmitter – or

example, by inhibiting the enzyme that normally

does this. Or they may inhibit the action o the

transmitter itsel.

I the drug is taken over a period o time, then

the body may adjust to its use. For example, i

the drug blocks particular receptors at synapses,

then new receptors may be produced to make up

or the ones that are no longer in use. This means

By the end of this chapter you should be able to:

a discuss the meaning o the term ‘substance

abuse’, with reerence to legal and illegal

drugs;

b distinguish between psychological and physical

dependence;

c describe the short-term and long-term

consequences o alcohol consumption on the

nervous system and the liver, with reerence toatty liver, hepatitis, cirrhosis, cancer, impaired

nervous transmission, demyelination, and

dehydration o the brain cells;

d discuss the social consequences o excessive

alcohol use;

e describe the eects o the components o

cigarette smoke on the respiratory and

cardiovascular systems, including reerence to

passive smoking.

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Chapter 13: Substance abuse

270

that more drug has to be taken to have the same

eect. This is known as tolerance to the drug. An

increasing tolerance is an indication o increasing

dependence on the drug.

The ways in which people use mood-changing

drugs such as nicotine, heroin and alcohol are

sometimes classied according to how much

control a person has over their drug-taking

behaviour.

• Recreational use involves a person taking a drug

occasionally, in such a way that they do not

suer any health problems as a result, nor does

their use o the drug aect their behaviour in

ways that cause problems or anyone else. For

example, having a glass o wine or beer with

a meal would be classed as recreational use o

alcohol.•

Abuse occurs when the drug starts to damage

the health o the person taking it, or o people

around them or in their amilies. An example o

drug abuse would be a person drinking enough

alcohol to make them aggressive and cause them

to act violently.

• Dependency occurs when, as a result o changes

in the brain and other parts o the body, the

person can no longer manage without the drug.

Their lie begins to revolve around getting the

drug and using it.Dependency can be classied as physical or

psychological. This distinction is useul in working

out the best way to help a person to escape rom

the hold that the drug has over them. However,

there is no sharp dividing line between these two

types o dependency, and in the end they both

probably result rom changes that occur in the

body as a result o taking the drug.

• Physical dependency occurs because there have

been changes in the structure and physiology o

neurones in the brain. I the person stops taking

the drug, they suer rom withdrawal symptoms

(abstinence syndrome). Withdrawal rom heroin

produces some o the very worst withdrawal

symptoms. The person will eel anxious,

restless and irritable. They will not be able

to sleep. Their eyes water and nose runs, and

they salivate excessively, and may vomit, have

abdominal pain and diarrhoea. The pupils o

their eyes dilate and they may eel pain all over

the body. These extremely unpleasant symptoms

start about 8 to 16 hours ater withdrawal

begins, and then can last or a week. The person

will eel cravings or the drug or many weeks

aterwards, as well as a general eeling o being

unwell and being unable to relax or sleep.

• Psychological dependency is also due to what

is happening in the brain as a result o taking

the drug, but the person does not experience

unpleasant withdrawal symptoms when they

stop taking it. They do, however, constantly

crave the drug. It seems as essential to them

as ood or water does to you when you eel

very hungry or very thirsty. They may have

begun taking it to help them to get through a

particular problem in their lives, and i thatsituation re-emerges they may start taking it

again. Their drug-taking may also have led them

to experience an environment that they enjoyed

– or example, injecting drugs along with others;

they may miss all the paraphernalia associated

with this environment and eel a tremendous

need to go back to it. Indeed, psychological

dependency may be harder to get over than

physical dependency.

AlcoholAlcohol – more correctly ethanol – has been used

by humans or thousands o years. It was drunk

in beer, wine and other drinks produced by the

ermentation o substances such as grapes by

yeasts. It was also widely used as a solvent in the

preparation o herbal remedies.

As you will see below, drinking too much

alcohol can cause serious damage to the liver, brain

and other parts o the body. Health proessionals

recommend that each person should stay within

daily alcohol limits (DALs) o no more than 2 or 3

units or a woman, and no more than 3 or 4 units

or a man. A ‘unit’ is explained on page 274.

How alcohol affects the body

Alcohol molecules dissolve very easily in the atty

acid tails o phospholipids that make up cell

surace membranes. This distorts the proteins that

orm channels in the membranes. In particular, it

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aects the shape o receptors in the membranes

o neurones in the brain that respond to a

neurotransmitter called GABA, which inhibits the

ormation o action potentials. Alcohol increases

and prolongs the eects o GABA.

Alcohol also aects another, stimulatory,

neurotransmitter called glutamate. This is the

commonest neurotransmitter in the brain, and is

responsible or much o the interaction between

neurones. Alcohol blocks the receptors on cell

membranes that glutamate would normally bind to.

So, alcohol increases the eect o the inhibitory

neurotransmitter GABA and reduces the eect o

the stimulatory neurotransmitter glutamate. Both

o these actions reduce or depress the activity o

the brain, so alcohol is a depressant. The eects

are especially great in the cortex o the cerebrumand in the cerebellum. As the activity o the cortex

is depressed, the person becomes less able to

think clearly and logically and to make decisions.

Inhibitions are reduced, and this helps some

people to relax and interact socially. Depression o

the activity o the cerebellum inhibits coordination

o movements.

I drunk in large amounts, alcohol can kill.

Inhibition o various areas o the brain causes

drowsiness and eventually unconsciousness. It can

cause coma. When the nervous stimulation o themuscles used in breathing is inhibited by alcohol,

breathing movements stop and the person may die.

Alcohol is broken down inside the cells

o the liver, the hepatocytes. The enzyme

that catalyses the breakdown o ethanol is

ethanol dehydrogenase, also known as alcohol

dehydrogenase. Ethanol is rst converted to

ethanal by this enzyme, and then to ethanoate by

aldehyde dehydrogenase. Ethanoate can enter the

Krebs cycle in mitochondria and be metabolised to

produce ATP (Figure 13.1).

I large quantities o alcohol are consumed on

a regular basis, then the tissues within the liver can

be damaged. You can see, in Figure 13.1, that the

breakdown o ethanol produces reduced NAD.

In its oxidised state, NAD is involved in oxidising

atty acids in the liver cells. I the NAD has been

reduced, then it cannot do this. The atty acids

accumulate and are converted to ats, which are

deposited in the liver. There is a strong correlation

between the amount o alcohol consumed and the

amount o at deposited in a person’s liver. The

at is stored in the hepatocytes, and can severelyreduce their e ciency at carrying out their other

unctions. This condition is known as atty liver

(Figure 13.2). (Alcohol consumption is not the

only cause o atty liver – other risk actors include

diabetes and obesity.)

Excessive intake o alcohol may also cause the

liver to become infamed, a condition known as

hepatitis.

A combination o the excess storage o at in

the hepatocytes, plus the direct damage done to

hepatocytes by ethanol, can lead to a conditionknown as cirrhosis. The damaged hepatocytes

are replaced by brous tissue. The structure o

Figure 13.1 Detoxication o alcohol in the liver.

ethanolethanal

(acetaldehyde)

ethanoldehydrogenase

enters Krebs cycle

aldehydedehydrogenase

ethanoate(acetate)

oxidisedNAD reducedNAD oxidisedNAD reducedNAD

Figure 13.2 This is an MRI scan o a person

suering rom atty liver. The at deposits can be

seen as yellow patches in the liver.

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272

the blood supply is lost, so that some blood that

arrives in the hepatic portal vein simply goes

straight past and into the hepatic vein, without

ever passing through the channels between the

hepatocytes on the way.

A liver aected by hepatitis or cirrhosis cannot

carry out its normal unctions. The liver has a

very wide range o roles, involving many dierent

metabolic reactions, so damage to it has ar-

reaching eects on the body. For example, the

hepatocytes can no longer convert ammonia into

urea, so ammonia concentration in the blood

increases and can cause major damage to the

central nervous system. In severe cases, coma and

even death may result.

Long-term alcohol consumption also causes

high blood pressure which in turn increases the risko heart attacks and strokes. Alcohol can damage

the lining o the stomach. It increases the loss o

water in urine, so can cause dehydration. Brain

cells are especially susceptible to this. The neurones

in some parts o the brain also tend to lose their

myelin sheaths, a process known as demyelination.

This severely aects brain unction.

Alcohol is a major cause o cancer. People who

regularly drink large quantities o alcohol have a

greatly increased risk o developing cancer in the

mouth, oesophagus, liver, breast or bowel.Some people are able to drink large amounts

o alcohol without becoming dependent on it,

but others run the risk o developing dependency.

It is not understood why some people become

alcoholics (dependent on alcohol) while others do

not. Alcoholics experience unpleasant withdrawal

symptoms i they have to go or any length o

time without drinking it. I they wish to give up

drinking alcohol, they can be helped through these

withdrawal symptoms with the use o drugs such

as diazepam. However, a person who has once

been dependent on alcohol can easily all back into

the same dependency again, unless they completely

give up drinking alcohol or control their drinking

very rigorously.

Social consequences of alcohol abuse

Drinking and driving

Drinking alcohol increases reaction time, and

adversely aects judgment. Both o these eects

mean that a driver who has drunk alcohol is much

less likely to react appropriately and rapidly to

danger. A high proportion o accidents involve

drivers who have been drinking. They oten also

involve pedestrians who have been drinking.

Many Caribbean countries have laws that limit

the amount o alcohol that a driver can legally

have in their blood. In the majority, this is 0.08%

– that is, 80 mg o alcohol in every 100 cm3 o

blood. In Jamaica, the limit is higher than this, at

0.35%. In Barbados and Cuba, the limit is zero.

How can you judge your blood alcohol

concentration? Just going by how you eel doesn’twork, as people generally greatly underestimate

the eect that alcohol has on them. It helps to

think about ‘units’ o alcohol. One unit can be

considered to be hal a pint o low strength beer,

or just under one hal o a ‘regular’ glass o wine

with an ABV (alcohol by volume) o 13% (Figure

13.3). These each contain 8 g o alcohol.

Figure 13.3 Units o alcohol in some drinks.

To calculate the number o units in a drink,

multiply the volume o the drink in ml by its ABV,

and divide by 1000:

volume o drink × ABV

1000number o units =

On average, each unit increases blood alcohol

concentration by 15 mg per 100 cm3 (though this

may be higher in a small person, and tends always

one unit one unittwo units

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to be higher in women). The liver breaks down

about one unit each hour.

Many people, however, think that the best rule is

not to drink at all i you are going to drive (Figure

13.4). There really is no ‘sae limit’ or drinking

and driving. Young people on an evening out oten

appoint a ‘designated driver’, who doesn’t drink

alcohol at all, and gets all o his or her (non-

alcoholic) drinks paid or by the rest o the group.

Violence

Some people become aggressive and violent when

they have been drinking alcohol. They may be

almost unaware o this eect on them, thinking

that they are just behaving normally and like

everyone else. However, this kind o behaviour can

have very severe eects on others who get caught

up in it. Alcohol-uelled violence happens not only

out in the streets, but also within the home. Family

members may suer at the hands o a drunken

parent or partner. Each year, many amilies break

up as a result o aggressive behaviour caused by

drinking alcohol.

Crime

We have seen that drinking alcohol damages

judgment and weakens inhibitions. In some people,

this can lead to them committing crimes such as

thet, which they would not commit i they were

not drunk.

Figure 13.4 The amount o alcohol in the breath

is directly related to the concentration o alcohol

in the blood.

SAQ

1 The graphs show the number o people who

were admitted to hospital in one part o the

USA in the year 2000 or drug-related illnesses.In all cases, the drug was being abused and was

a direct cause o the need or admission.

a Describe the pattern o alcohol abuse that

resulted in hospital admission, amongst men

o dierent ages.

b Compare the pattern you have described in a

with that shown by cannabis.

c Compare the pattern you have described ina with the pattern o admissions or alcohol

amongst women o dierent ages.

d Explain why these data do not give useul

inormation about the percentage o people

who were using these dierent categories

o drugs.

femalesmales

N u m b e r o f a d m i s s i o n s / t h

o u s a n d s

100

200

0

300

400

0

100

200

300

400ages

40+

<20

20–29

30–39

alcohol

opiates

cocaine

other

stimulants

cannabis

alcohol

opiates

cocaine

other

stimulants

cannabis

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274

SmokingTobacco smoke contains many dierent chemicals.

These include:

•tar – a mixture o substances, some o which

can cause cancer;

•nicotine – the addictive substance in cigarette

smoke; it aects the brain and other parts o

the nervous system, and also the cardiovascular

system;

•carbon monoxide – a gas, produced by

incomplete oxidation o some o the substances

in tobacco, which reduces the oxygen-carrying

capacity o the blood;

•particulates – tiny particles, mostly o carbon,

that cause irritation in the lungs and airways.

Each o these substances is potentially harmul

to health. Compounds ound in cigarette smokeare the direct cause o serious lung diseases, and

increase the risk o developing CHD or suering

a stroke. Even breathing in someone else’s

cigarette smoke – passive smoking (Figure 13.5) –

signicantly increases the risk o developing these

health problems.

Lung diseases

Lung diseases are a major cause o illness and

death. They include:

•chronic obstructive pulmonary disease (COPD)

– this includes many related diseases, such as

emphysema, that prevent the normal fow o air

through the gaseous exchange system;

•lung cancer, where cells in the lungs divide

uncontrollably and orm a tumour;

•illnesses caused by inectious organisms

(pathogens), such as bronchitis.

Chronic obstructive pulmonary disease

COPD is an illness in which the airfow into and

out o the lungs gradually and progressively

becomes more and more obstructed. COPD

happens to everyone to a certain extent as they getolder, but it is hugely accelerated and worsened

by smoking. It is thought that around 600 million

people worldwide suer rom COPD, and that 300

million die rom it each year. Somewhere between

80% and 90% o these cases are caused by smoking

cigarettes.

Cigarette smoke contains a wide range o

dierent chemicals, many o which stimulate

neutrophils – a type o white blood cell (Figure

13.6) – to come to the scene. Neutrophils

are an important part o the body’s deenceagainst inectious disease, but here they behave

inappropriately and actually cause illness.

The neutrophils secrete an enzyme called

neutrophil elastase. This enzyme is a protease and,

as its name suggests, it breaks down elastin, which

orms the elastic bres in the tissues o the airways.

Usually, there are inhibitors present that prevent

this enzyme rom doing very much harm. But, in

a smoker, the balance between the concentrations

o the protease enzymes and inhibitors tips too ar

in avour o the enzymes. The proteases gradually

break down the elastin tissues in the lungs, causing

irreversible damage.

One o the eects o this tissue damage is that

the walls o many o the alveoli are broken down.

Instead o millions o tiny alveoli, separated rom

blood capillaries by exceptionally thin walls, the

lungs become lled with larger spaces, much more

widely separated rom the blood capillaries. What’sFigure 13.5 Passive smoking.

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more, many o these capillaries also disappear.

The total surace area or gaseous exchange is

thereore greatly reduced. This condition is called

emphysema (Figure 13.7). Not surprisingly,

someone with emphysema has great diculty in

getting enough oxygen into their blood.

The progressive damage to the lungs causes

them to lose their elasticity, while damage to the

airways causes their walls to thicken. This happens

because the attempts by the tissue to repair itsel

cause it to become brous. Both o these changes

make it more dicult or air to move into and out

o the lungs.

The damage to the airways also involves the

ciliated cells and the goblet (mucus-producing)

cells, which normally help to keep the lungs clear

o dust, bacteria and other oreign particles in the

air that is breathed in. In smokers, the goblet cells

oten prolierate, producing much larger numbers

than in a non-smoker. The production o large

Figure 13.6 The development o emphysema.

b Neutrophils rom the blood make pathways throughalveolar walls by digesting elastin and, ater manyyears o this destruction, the alveoli do not deflatevery much.

Inspiration

Inspiration

elastin fbre

alveolus

Expiration

Expiration

a Healthy alveoli partially deflate when breathingout due to the recoil o elastin fbres.

Figure 13.7 a Photomicrograph o lung tissue

rom a person with chronic emphysema, showing

large spaces where there should be many tiny

alveoli, b photomicrograph o normal lung tissue.

a

b

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276

numbers o ‘extra’ cells is called hyperplasia. As

a result, more mucus is produced, but the cilia

do not beat and so there is nothing to carry the

mucus up and out o the bronchi and trachea.

Instead, mucus accumulates in the airways,

where it provides a breeding ground or bacteria.

People with this condition thereore tend to suer

rom bacterial inections o the bronchi, called

bronchitis. They may have a chronic cough, as they

attempt to clear the mucus rom their lungs.

There is not really a great deal that can be done

to help a person who has COPD. Once the tissues

have been damaged, it is very dicult or them to

recover. Usually, the best that can be done is to

prevent the disease rom getting any worse.

The rst thing that anyone with COPD will be

told to do is to stop smoking. This will almostimmediately produce a reduction in the requency

and severity o inections, and may also reduce the

cough. Ciliated cells and goblet cells can recover

to a certain extent. But it is unlikely that large

improvements will be made in the breathlessness

that is caused by emphysema. Emphysema appears

to be irreversible.

Many patients may be helped a little by drugs

called beta agonists, which dilate the airways by

causing the smooth muscle in their walls to relax.

As the patient ages, and the symptoms getworse, they may need to breathe oxygen on a

regular basis. This can be done at home, where the

patient has an oxygen cylinder and breathing mask

that they can use whenever they need to. In the

advanced stages o the disease, even walking a

ew steps becomes impossible without getting out

o breath.

Lung cancer

While COPD causes about 15% o smoking-

related deaths, lung cancer causes almost double

that number. Smokers are almost 20 times as likely

to die rom lung cancer as are non-smokers. Lung

cancer is one o the most dicult cancers to treat

successully.

Cigarette smoke contains several chemicals

that are carcinogenic. Carcinogens are substances

that damage the control o cell division. Cells

may begin to divide much more than they should,

As the tumour grows, it displaces other tissues.

Eventually, this can lead to the blockage o the

airways or other parts o the lungs. The person

may nd it dicult to get their breath, and may

have a chronic cough, sometimes bringing up

blood. They may experience pain or tightness in

the chest. As the cancer progresses, they may lose

weight.Cancerous cells may break away rom the

primary (original) tumour and begin to orm

secondary tumours in other parts o the body.

I this happens, survival rates are very low.

Some o the carcinogenic substances enter

the bloodstream in the lungs, and are carried

all over the body. It is thereore not surprising

that smoking signicantly increases the risk o

developing cancers in almost every part o

the body.

Smoking and the cardiovascular system

Smoking increases the risk o developing CHD.

Nearly everyone who develops CHD in their 30s

or early 40s is a smoker. Smoking can cause high

blood pressure. A smoker with high blood pressure

has a 20 times greater risk o stroke than a non-

smoker who does not have high blood pressure.

Figure 13.8 Micrograph showing a tumour

(darker purple) in a human lung (×16).

orming a lump o disorganised cells called a

tumour (Figure 13.8). The tumour can be almost

anywhere in the gas exchange system, but most

requently grows where the trachea branches into

the two bronchi, or at other branching points.

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Nicotine

One o the culprits is the nicotine in cigarettes.

Nicotine is a neurotoxin – a chemical that damages

the nervous system. It is used as an insecticide.

Nicotine is extremely addictive, and this is the

reason why smokers nd it so dicult to give up.

Nicotine molecules are relatively small, and they

easily move out o the blood and into every part o

the body, including the brain. Nicotine increases

the levels o a transmitter substance called

dopamine in the parts o the brain that are known

as ‘reward circuits’. Activation o these circuits

gives eelings o pleasure, and this is why people

enjoy smoking.

Nicotine also causes the release o adrenaline

into the blood. Adrenaline increases the rate o

heart beat, blood pressure and breathing rate.Nicotine is a vasconstrictor – it causes the

smooth muscle in the walls o arteries and

arterioles to contract, narrowing the lumen and

thereore making it harder or blood to be pumped

through. This, too, tends to increase blood pressure

and the risk o blood clots orming (page 250).

Carbon monoxide

Carbon monoxide diuses rom the alveoli into

the blood in the lung capillaries. Here it combines

with haemoglobin, orming a bright red compoundcalled carboxyhaemoglobin. It holds on tightly;

haemoglobin has a very high anity or carbon

monoxide. With a proportion o the haemoglobin

tied up in this way, there is less available or the

transport o oxygen. Smoking thereore reduces

the delivery o oxygen to the tissues, including the

heart muscle. Smokers have less energy available to

their muscles when they exercise.

The body may respond to the oxygen shortage

by producing larger numbers o red blood cells.

A hormone called erythropoetin, produced by

the kidneys, is secreted in larger amounts when

the amount o oxygen in the blood is low. This

hormone stimulates the production o red blood

cells by the stem cells in the bone marrow. and

smokers usually have a higher red blood cell

count (the number o red cells per unit volume o

blood). This might seem to be a good thing, but it

can sometimes cause problems such as dizziness,

weakness, headache and joint pain.

Hypertension, CHD and stroke

We have seen that nicotine increases blood

pressure, which can increase the risk o developing

atherosclerosis and CHD (Chapter 12). It is not

only the coronary arteries that are aected –

atherosclerosis can develop in any arteries in the

body. Smokers run a higher risk than non-smokers

o atherosclerosis developing in blood vessels that

supply the brain. This greatly increases the risk o

suering a stroke (page 254).

Smokers tend to have more viscous blood than

non-smokers. This can increase the risk o blood

clots orming inappropriately, which once again

increases the risk o stroke.

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278

Notes:1 ‘ratio total chol : HDL-chol’ is

the ratio o the total amount o cholesterol in the blood to theamount o cholesterol transportedin high density lipoprotein in theblood.

2 A ‘cardiovascular event’ inthis table is reerring to newlydiagnosed angina, myocardialinarction, death rom CHD or stroke.

MenNon-smoker Smoker ratio total chol : HDL-chol

WomenNon-smoker Smoker ratio total chol : HDL-chol

180/105160/95

140/85

120/75

180/105

160/95

140/85

120/75

180/105

160/95

140/85

120/75

180/105160/95

140/85

120/75

Age 70–79

Age 60–69

Age 50–59

Age 40–49

B l o o d p r e s s u r e / m m H g

4 44 45 55 56 66 67 77 78 88 8

Risk – 5 yr cardiovascular fatal+ non-fatal events

Events preventedper 100 treated for 5 yrs

very high

high / moderate

mild

>30%

25–30%

20–25%

15–20%

10–15%5–10%

2.5–5%

<2.5%

>10

9

7.5

6

42.5

1.25

<0.8

SAQ

2 The chart below is used to work out how likely a

person is to have a heart attack or stroke.

a Use the chart to nd the predicted risk or:

• a 56-year-old woman who smokes, has a

blood pressure o 160/95 and whose total

cholesterol : HDL-cholesterol ratio is 5

• a 45-year-old man who does not smoke,

whose blood pressure reading is 160/95 and

whose total cholesterol : HDL-cholesterol

ratio is 8.

b What could each o these people do to reduce

their risk o having a heart attack or stroke?

c Suggest how a risk calculator like this could

be produced.

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Summary

•Substance abuse is the misuse o a drug or other substance, so that it causes harm to the user or to

other people.

•Although alcohol and nicotine (in cigarettes) are legal drugs, their use can cause serious health

problems.

•Physical dependency on a drug occurs when the structure and physiology o the body is changed

by the drug use, so that withdrawal symptoms are experienced when the drug is no longer taken.

Psychological dependency occurs when the person eels they cannot manage without the drug, even

i no withdrawal symptoms are experienced. There is no sharp dividing line between physical and

psychological dependency.

•In the short-term, alcohol aects the neurotransmitters GABA and glutamate in the brain, which

together causes the activity o the brain to slow down. It is thereore a depressant. Inhibitions are

reduced, coordination is lost and nervous transmission is slowed, lengthening reaction time. I so

much alcohol is drunk that the breathing muscles are inhibited, the person may die.

•Alcohol is broken down in the liver by the hepatocytes. Long-term excessive consumption o alcohol

oten leads to atty liver, hepatitis and cirrhosis and also greatly increases the risk o developing

many types o cancer.

•Alcohol consumption is a causative actor in many vehicle and other accidents, in incidents involving

violence and aggression, and in petty crime.

•Smoking cigarettes, and the inhalation o smoke rom other people’s cigarettes, causes a very wide

range o serious health problems. These include COPD and lung cancer, CHD and stroke.

QuestionsMultiple choice questions

1 Drug abuse is:

A the use o a drug or personal gratication, causing damage to health.

B the compulsion to use a drug on a periodic or continuous basis to avoid discomort rom its

absence.

C the need or increasing quantities o the drug to produce the same eect.

D the occasional use o the drug to lessen pain.

2 Which o the ollowing best describes ‘physical dependence’?

A the emotional changes i the drug is withheldB the need or an increasing dose o the drug to produce the same eect

C when a drug or one o its metabolites has become necessary or the continued unctioning

o the body

D a mild orm o dependence that does not produce withdrawal symptoms

continued ...

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280

3 Which o the ollowing is not a consequence o long-term use o alcohol?

A the development o swollen cells with wispy cytoplasm in the liver cells

B the accumulation o at in the liver cells

C the constriction o blood vessels in the liver

D the development o brous tissue in the liver

4 How many grams o absolute (pure) alcohol does one ‘unit’ o alcohol contain?

A 7

B 8

C 15

D 25

5 Fat accumulates in the liver when alcohol is consumed regularly because:

A at absorbs alcohol and helps detoxiy it.

B alcohol is used to synthesise at molecules in the liver.

C liver cells use alcohol instead o at as an energy source.

D alcohol prevents liver cells rom secreting at molecules.

6 Which component o tobacco smoke causes an increased risk o lung cancer?

A nicotine

B carbon dioxide

C carbon monoxide

D tar

7 How does nicotine in cigarette smoke increase the risk o cardiac disease?

A by reducing the diameter o arterioles

B by attaching to haemoglobin

C by stimulating the sino-atrial node directly

D by orming plaque in blood vessels

8 Which o the components o tobacco smoke lowers the capacity o haemoglobin to

transport oxygen?

A carbon monoxide

B nicotine

C tar

D carcinogens

continued ...

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9 The images below are enlarged views o alveoli rom a non-smoker and a smoker.

Why may a smoker have to consciously contract his muscles to breathe out?

A increased mucus production by goblet cells

B paralysis o the ciliaC excess tar in the alveoli

D loss o elasticity in the alveolar walls

continued ...

Structured questions

10 a What do you understand by the ollowing terms?

i drug

ii drug abuse

iii drug dependence

iv drug tolerance

v abstinence syndrome (withdrawal symptoms) [10 marks]

b Distinguish between:

i physical and psychological dependence

ii legal and illegal drugs. [5 marks]

11 The ollowing drinking guidelines have been developed or people over 18 years o age,

based on medical advice.

MenIt is recommended that men drink nomore than 3 to 4 units o alcohol aday and no more than 21 units over the course o the week.

WomenIt is recommended that women drinkno more than 2 to 3 units o alcohola day and no more than 14 unitsover the course o the week.

alveoli o a non-smoker alveoli o a smoker

3 day14 week

4 day

21 week

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282

a What do you understand by the term ‘unit o alcohol’? [1 mark]

b Why are the recommended units given in both units per day as well as units

per week? [2 marks]

c Why are the recommended units per day o alcohol or men and women dierent? [4 marks]

d Alcohol is absorbed quickly rom the gastrointestinal tract into the blood.

What properties o alcohol acilitate the ast absorption rates? [2 marks]e Recently the Trinidad and Tobago Government introduced breathalyzer testing in

order to reduce road accidents.

i Copy and complete the table below which shows the eects o drinking and

blood alcohol concentrations on driving behaviour.

Blood alcohol

concentration / g 100 cm−3

Efects o alcohol on

driving

0.02 – 0.05

0.05 – 0.08

[4 marks]

ii The legal limit or drinking in Trinidad and Tobago is 0.08 g per 100 cm3 blood.

Explain why a breathalyzer test can be used to determine whether a driver is

above this limit. [2 marks]

12 a Name three main constituents o cigarette smoke that are harmul to the body. [3 marks]

Diagram a below shows the alveoli o a smoker and non-smoker during expiration,

and image b shows the coronary artery o a smoker.

b Identiy the alveoli o the smoker and the non-smoker. Give a reason or your answer. [3 marks]

c i Name the disease that is characterised by the alveoli o the smoker. [1 mark]

ii Explain why the smoker would have diculty in breathing. [2 marks]

d i Identiy structure III in image b. [1 mark]

ii Name the disease that is characterised by image b. [1 mark]

iii State our symptoms that might be experienced by a person whose artery has

been narrowed as shown in image b. [2 marks]

iv Explain how cigarette smoking may account or the appearance o the artery. [2 marks]

continued ...

b

I

II

III

a wall o artery

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13 Explain the ollowing terms using alcohol and the components o cigarette smoke

as examples.

a physical dependence

b psychological dependence

b toleranceb abstinence syndrome (withdrawal symptoms) [15 marks]

14 Cigarette smoke contains many substances that are harmul to the body and which

cause disease. Explain how the components o cigarette smoke increase the risk o

developing the ollowing diseases.

a coronary heart disease

b lung cancer

c chronic bronchitis

d emphysema

e hypertension

strokes [15 marks]

15 a Briefy describe the short-term and long-term consequences o alcohol

consumption on:

i the liver

ii the nervous system. [9 marks]

b Discuss the actors which aect blood alcohol level. [3 marks]

c Discuss the social consequences o excessive alcohol consumption. [3 marks]

Essay questions

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CAPEc13