Individual health
WHO definition of health
A state of complete physical, mental and
social well-being, not merely the absence of
disease and infirmity
e.g. a person may not feel well although he is
not actually sick.
Health depends on how well your body
is functioning, how well you feel about
yourself and how well you fit with the society.
A balanced diet - why needed?
• A balanced diet is a diet that contains the right
proportion and quantities of different types of
food substances for our body needs
• We need energy for our daily activities and
maintenance of our body temperature. We need
to obtain sufficient energy-rich food substances,
i.e. carbohydrates, proteins and lipids.
• For body growth and repair (of worn out tissues),
we also need sufficient amount of proteins and
other nutrients such as fats, calcium and iron
• Our diet should also include various vitamins,
minerals, dietary fibre and water to keep the
body in healthy conditions
• If a body does not get a balanced diet, it may
result in malnutrition, overweight, deficiency
diseases or constipation
The food pyramid:
Improper Dietary habits
1. Eating at irregular hours and taking too much or
too
little food occasionally, esp. in people who are
always
busy in work, under strain, or eating in a hurry
This may affect the normal functioning of the
alimentary canal and lead to the development of peptic
ulcer.
2. Food preference on a restricted variety of food,
e.g.
avoids taking meat or vegetables.
This can result in malnutrition, e.g.
Lack of meat
iron-deficient anemia, becoming
pale- looking and fatigues easily
Lack of vegetables or fruits
constipation
3. Snacks between meals
May spoil a person’s appetite for normal meals if
taken too much and may lead to an unbalanced diet.
4. Excessive calorie intake, e.g. too much sugary food
May cause obesity or even tooth decay. A large
amount of fatty food, a likely source of cholesterol,
may lead to heart diseases.
5. Too much salty food
May result in hypertension
6. Too much stimulants in food, e.g. caffeine in coffee
Stimulates the nervous system and can cause person
to be easily exhausted and eventually addicted.
Prolonged drinking of coffee can result in anxiety, fast
or irregular heart beat and habitual inability to sleep
Not too useful Dietary habits
Taking tonics - to supplement the nutrient needs of
the body, but balanced diet can already supply all
nutrients needed.
1. Vitamin supplements
Excessive amount of vitamins A and D may be
toxic to the body. A high intake of vitamin D may
cause the formation of renal stones.
2. ‘Health’ drinks
They supposedly helps a person to recover from
fatigue instantly because they contain glucose or
particular minerals. Actually, a balanced diet can
supply enough energy and nutrients to the body and
there is no need to take in such ‘health’ drinks.
Value of suitable amount of exercise
(i.e. planned and repetitive physical activity)
1. Reduces the chance of heart disease, cancer and
other
diseases
2. Helps to prevent ulcers and other physical and
mental
disorders by relieving tensions
It also helps to achieve a feeling of well-being and
for enjoyment.
3. Increases the strength of skeletal muscles,
alertness
of movement, coordination and reaction
time.
i) regular training through exercise raises the
working
capacity of the skeletal muscles by
increasing the
size and strength of the muscles.
ii) With regular training , there is
improved
coordination between skeletal muscles so
that more
skilful movement can be developed.
iii) Exercise also improves muscle tone, allowing
the
body to respond more readily to sudden
demands
on physical responses
4. Improves body fitness and helps to maintain or
lose
body weight.
5. Regular exercise strengthens the respiratory
muscles
such as the intercostal, diaphragm and
abdominal
muscles, thereby increasing the vital
capacity of the
body.
6) Exercise also results in a stronger heart, so
that
number of heart beats can be reduced to
bring
about the same cardiac output.
Accordingly, the stronger heart of an athlete
can transport more blood to the muscles per unit
time, thus providing more oxygen and glucose for
the contracting muscles.
Exercise also leads to an increase in number of
red blood cells, thus increasing the oxygencarrying capacity of the blood.
Precautions to be taken in exercise
1) Follow proper instruction when performing any sport
or
exercise. Proper technique helps to prevent
injuries.
2) Do not perform any exercise when having a cold,
fever
or not feeling well.
3) Wear suitable clothing and shoes, and use
appropriate
instrument for the exercise.
4) Warm up the body for a few minutes
before
performing any sport.
5) Stop the sport and take a rest when the
following
happen: fatigue, pain, dizziness and vomiting.
6) Drink plain water to replace fluid loss due to sweating.
7) After exercise, take sufficient rest for the body
to
recover.
8) Do not take any steroids to improve the
performance
in sports. Many athletes use steroids
to increase
muscle mass and strength. Some of the
dangerous
effects of steroids include degeneration
of the
testes in the male, growth of dense hair on
the face
for the female, liver damage and clogged
arteries.
Importance of rest to healthy living
Continual activity, especially muscular activity, for a
long time may lead to accumulation of toxic waste
products and depletion of food reserve in the active
tissues. Under such conditions, the body can no longer
function normally and is said to be in a state of fatigue.
To recover from fatigue, the body has to take a rest
during which the exhausted cells remain relatively
inactive. When the toxic wastes are completely removed
and the food reserve is built up in the cells, they can
resume normal activity again.
We can rest by sitting down or sleeping. The quality of
sleep determines how much sleep we need.
Stress
A difficult situation that demands a person to adjust.
Examples:
Physiological - headache or sore throat
Psychololgical - inner fear of net living up to
standards or a conflict between a desire to please
parents and peer groups.
With external cause - examinations, dental visits,
a noisy and crowded environment, death in the
family, marriage, divorce, promotion or retirement.
Stress management
Necessary because if person cannot cope with too
much stress, he may develop abnormal behaviour and
become mentally ill although mild stress can help us grow
and develop to be more mature to prepare us for more
extreme kinds of stress.
How to deal with stress?
1) Talk to family members, friends or teachers to
help
clarify a problem, relieve emotions and find a
solution.
If they cannot help, seek professional advice
or
treatment from doctors, social workers
or
educational psychologists.
2) Try to analyse a problem calmly and realistically to see it
in
a better perspective.
This may reduce stress caused by the problem and
the
problem may not be as serious as they may seem
3) Engage in sports or other physical activities to
release
emotions that upset a person. Taking part in
community
services can also help him develop selfconfidence and
take a more positive attitude towards his
own problems.
4) Relax by developing healthy pastimes or participating
in
relaxation exercises such as yoga and tai-chi. This can
help
a person to cope with stress.
Undernutrition
This occurs when there is insufficient intake of food. The
body requires a certain amount of energy to work properly.
This energy comes from the breakdown of food. The total
amount of energy used varies according to age, sex, body size
and occupation. If insufficient food is eaten to supply this
energy, the body uses its stored fat and then body proteins.
The effects of undernutrition also depends on the stage of
life and the kinds of nutrients lacking.
A child undernourished before birth may be born with one
or more body defects. If serious undernutrition occurs during
the first 2 years of life when brain growth is at is peak,
mental retardation may result. Inadequate nutriton during
childhood and adolescence may interfere with or even stop
growth spurts as well as intellectual development.
Effects of a low protein diet
This results in a disease called Kwashiorkor which occurs
most commonly in young children who have stopped breastfeeding after the first six months and turn to a diet rich in
starch.
Symptoms:
swelling of the belly, cracking of skin, and damage to the
liver and pancreas.
Overnutrition
When a person takes in more food than he needs,
the excess food may be stored in the body as fat and
this leads to overweight or obesity.
Overweight people are usually not as healthy as
slim people. They have a shorter life span and an
increased risk of illness, including heart diseases,
diabetes and high blood pressure.
Uses of food additives
Food additives are chemical substances added to commercial
food products for various purposes
1) as preservatives to prevent spoilage, i.e. to prevent
the
growth of microorganisms that cause food-borne
illnesses
and are hence hazardous to health, e.g.
a) salt to preserve meat and fish
b) sugar used in canned and dried fruits and in jams
and
jellies
c) vinegar for preserving vegetables
d) nitrite to preserve sausages
2) as antioxidants - to prevent oxidation when food is
exposed
to air, as oxidation causes changes in colour,
appearance or
flavour or even nutritional value of food,
though they are
not hazardous to health, e.g. Vitamins C
and E.
3) as nutrient additives - to improve the nutritional value
of
foods, e.g. iodine is added to table salt, vitamin A and D
are
added to dairy products and vitamin C is added to
fruit
drinks
4) colourants to make food pretty, sometimes using dyes
from
natural sources (e.g. beta-carotene added to food
products
such as margarine, cheese and macaroni to give a
yellow,
red or orange colour).
5) as artificial flavours and flavour enhancers to improve
taste
or texture, e.g. used in ginger bread, sausage, icecreams,
ice-sticks, candies and jellies. Also, monosodium
glutamate
(MSG) is widely used in restaurants.
General effects of food additives
Certain additives may cause allergies such as asthma,
headaches, behaviour problems in children, damage to the
kidneys and liver, and certain cancers. And, in general,
children are more at risk than adults.
Need for control of food additives
Due to the possible harmful effects, food additives,
before being released for public consumption, must be
tested in animal studies to determine if they are safe
enough. The minimal amount of them must also be used to
provide the expected effect, such as protection against
disease-causing microorganisms.
Major groups of Drugs
- chemical substance that alters the way the body
works, including not just dangerous drugs like opium 鴉
片, heroin海洛英 or LSD迷幻藥 but also substances
used daily by most people (e.g. tea and coffee)
a) Narcotics 麻醉劑- opium and other drugs made from
it,
e.g. morphine 嗎啡, methadone & heroin
b) Stimulants 興奮劑 e.g. caffeine & cocaine可卡因
c) Depressants:
i) Sedatives鎮靜劑, e.g. barbiturates, the
essential
components of sleeping pills or
ii) tranquillisers鎮定劑- drugs prescribed by
doctors
to anxious or psychotic people to relieve
anxiety.
d) Hallucinogens迷幻劑, e.g. LSD
Effects of Drugs
a) Narcotics
They act on centres of the cerebrum which perceive
pain, producing drowsiness and sleepiness. Some of them
are prescribed by doctors as analgesics (pain-killers) to
relieve pain after operations or in severe illnesses. However,
they can easily lead to dependence and are therefore known
as ‘hard’ drugs.
b) Stimulants
They keep a person awake by stimulating body
processes such as heartbeat and basal metabolic rate. They
make the user ignore his body’s natural warnings to rest and
as a result he becomes excessively fatigued. Constant use
of stimulants may cause nervousness and confusion,
poor judgment or even hallucinations or mental illness.
Students using stimulants to keep themselves awake
at night to prepare for examinations can keep awake but
will not be able to concentrate, leading to a state of
confusion.
c) Depressants
Sedatives cause relaxation, drowsiness and sleepiness
by depressing the activity of the cerebrum and cerebellum.
As a result, the user’s judgement and coordination become
poor, his reaction time is slow, and his vision and
concentration are also affected. Abuse of the drugs lead to
physical and psychological dependence and the use may
easily take an accidental overdose.
Tranquillisers act on regions of the cerebrum that
are concerned with emotional reactions. People habitually
taking tranquillisers appear to become less alert.
d) Hallucinogens
These drugs affect the normal function of the
synapses at the nerve endings and produce
hallucinations. The user hears sounds and forms
visions that exist only in imagination. Very small
amounts of LSD can cause effects lasting for hours
and hallucinations can occur again months after the
user has stopped taking the drug.
These drugs are dangerous because their effects
are unpredictable. They may produce pleasant or
horrifying illusions. Judgement may become so poor
that the affected person may jump off a high
building in the belief that he can fly.
Possible causes for people to start taking Drugs
1) Most young people probably start from curiosity,
or
because their friends are doing it and they want to
be
a member of a group of similar friends who smoke.
2) Others like taking risks, particularly if they know
their
parents or other adults would not approve
3) Some do so to try to relieve boredom
4) Some because they don't get along with their parents
5) Others because they are depressed, worried
about
school, work or family problems or as a 'cry for
help'
to attract attention.
6) Still others do so because they say it is stimulating,
or
it relieves tension.
This is because some drugs make you feel good.
They can relieve your anxiety, elevate your mood,
energize you, even change your perception of reality.
They can also numb feelings of mental pain and
enable you to avoid dealing with the problems in your
life.
Consequences of drug abuse
1) Drug abuse diminishes a person's ability to learn and act.
2) It alters mood and impairs judgment.
3) It lessens the person's ability to cope with life's
problems
and meet basic needs, often destroying selfesteem and
increasing the potential for suicide.
4) Some drugs create dangerous hallucinations. For example,
a
person under the influence of drugs might imagine
hearing
threatening voices and react violently to these
imagined
voices.
5) Drug abusers tend to focus more on maintaining their
drug
habit than on maintaining relationships. As a result,
they may
suffer loss of friends and family, loss of jobs, loss
of respect
from non-drug users, loss of a legitimate way of
life.
6) Increasingly isolated, drug abusers are forced to deal
more
and more with other people who take illegal drugs,
thus
entering a potentially violent subculture.
7) In order to assure a steady supply of drugs, the person
may
be drawn into crime. Many addicts become
prostitutes,
trading sex for drugs and spreading sexually
transmitted
diseases - gonorrhea, syphilis and the AIDS
virus.
Risks of drug abuse to the foetus
Depressants can retard development of the foetus
and cause limb deformities. LSD can result in
chromosomal anomalies and deformed babies whereas
narcotics such as heroin and morphine can cause
death of baby before it is born.
Excessive alcohol intake
All alcoholic beverages contain alcohol formed by fermentation
of sugar by yeast cells. Alcohol is toxic and causes various
effects in the body. Alcohol does not need to be digested.
After drinking, it is absorbed directly into blood through the
walls of the stomach and small intestine within about 2
minutes and carried to all parts of the body. Its most
important effect is on the brain, esp. those areas which
control judgement, motor coordination and speed.
Alcohol is absorbed fairly slowly in the stomach and more
quickly in the small intestine. When a person drinks alcohol
with an empty stomach, alcohol passes more quickly into the
small intestine and therefore more quickly absorbed into
blood. A stomach full of food, however, slows down alcohol
absorption and the effects of alcohol on the person will be
less severe.
Effects of alcohol
Immediate
1 ) Alcohol slows down the passage of nerve impulses. A
likely
explanation is that the alcohol affects the synapse. A
slowing
down of nerve impulses explains the slow reaction
times.
2 ) Even in moderate doses, alcohol interferes with motor
skills,
slowing down your control of your nerves, muscles,
and
senses. It results in poor muscular coordination,
unsteady
walking and slurred speech and it causes confusion
and
disorientation (losing one‘s perception of time, place or
even
one’s personal identity) as it distorts your perceptions
of
speed, depth and space.
3 ) Alcohol causes drowsiness. It may help you fall asleep
faster
but it can also cause you to awaken at intervals
throughout
the night.
4) Drinking too much also can result in stomach upset,
causing
nausea or tendency to vomit
Long-term
1 ) Excessive dribnking reduces appetite and so the person
does
not have a balanced diet. This leads to malnutrition
and
weakens the body’s resistance to diseases.
2 ) Too much alcohol causes the liver to swell and become
yellow
with fat. The liver may finally shrink and harden.
3 ) Excessive drinking can also lead to mental illness. The
heavy
drinker may experience terrifying hallucinations and
his body
may shake with convulsions. These effects are
caused by a
damaging action of alcohol on the nerve cells.
4) Alcohol drinking may shorten a person’s life
expectancy.
Poor health and judgement due to alcoholism
makes a
person more likely to be involved in an accident. Even
small
amounts of alcohol affect a driver’s vision and hearing
and
make his reflexes slow.
Risks of alcoholic consumption to the foetus
during pregnancy
Expectant mothers should not take any
alcoholic drink because some damage is caused
to the foetus. In severe cases foetal alcohol
syndrome is produced. The babies have growth
deficiencies, such as small heads and abnormal
facial characteristics, and they often have
subnormal intelligence.
Social consequences of alcoholism
1 ) More car accidents on the road result from heavy
drinking
than from any other cause. This is because alcohol
slows
down reflexes, interferes with concentration and
distance
judgement, and increases risk-taking, which may
make you
more likely to run yellow lights, for example.
2) alcohol can increase hostile or violent behaviour
3 ) crime - many murders and assaults are associated
with
excessive drinking
4 ) unhappy home life since alcoholics lose concern about
their
families and friends
5) poor work
6) absenteeism from work
7) illness
8) depression
Harmful chemical substances in tobacco smoke
1)
Carbon
monoxide
400
times
that
of
safe
industrial
exposure - reduces oxygen content in blood,
causing
heart to beat faster in order to increase the blood
flow to
various body parts.
2) Nicotine - slows down nerve impulse transmission at
the
synapse and gives the smoker a feeling of relaxation. It
is
responsible for the development of dependence on
the
smoking habit.
3) Tar - mixture of hundreds of chemical substances
condensing
to form dark, sticky substance on lung surface.
They cause
cancer & irritate the respiratory system, causing
coughing and
damage of the lung tissue. They also paralyze
cilia which
protect the respiratory passage from foreign
particles such
as dust and bacteria.
4) Other irritating substances
To show the presence of tar in cigarette smoke
to suction
pump
cigarette
U-tube
OR
white cotton wool
squeeze the wash bottle a dozen of times to simulate the smoking action
What is the function of the cotton wool ?
Ans: The cotton wool in the U-tube serves to collect tar.
to suction
pump
cigarette
U-tube
OR
white cotton wool
What has happened to the colour of the cotton
wool at the end of the experiment ?
Ans: It changes from white to dark brown.
to suction
pump
cigarette
U-tube
OR
white cotton wool
Which substance in cigarette smoke causes
the colour change ?
Ans: Tar.
The experiment illustrates how cigarette smoke may affect the lung surface
by coating it with tar
Health risks associated with tobacco smoking
1) Cardiovascular diseases
a) Coronary diseases
Men who smoke are nearly 65% more likely to
suffer from coronary disease and 2 to 3 times more
likely to die unexpectedly from it than are men who
do not smoke. Women smokers also have a higher
incidence of heart disease than their non-smoking
counterparts, and those who also take oral
contraceptives increase their risks tenfold. In
addition, these women risk developing blood clots
that may cause strokes or impede movement.
Comparative death rates from coronary
heart disease (men aged 50-70)
Relationship between smoking and coronary heart disease
Non-smokers
Stopped
smoking more
than 10 years
Stopped
smoking 1 - 10
years
206
160
100
Still smoking
220
175
154
109
Smokers of less than 20 cigarettes a day
Smokers of more than 20 cigarettes a day
Smokers show a greater incidence of coronary heart disease
b) Clogging of blood vessels
Smoking accelerates the build-up of fatty materials
within the arteries, including the arteries that supply the
heart and brain. Moreover, chemicals in tobacco smoke
affect blood platelets making them 'sticky'. They clump
together and, together with red blood cells, form a
blockage, or blood clot, which can slow or stop blood
flow.
i) clogged arteries in the heart can cause a heart
attack
ii) clogged arteries in the brain can cause a stroke
iii) clogged arteries in the legs can make movement of
any
kind, but especially exercise, painful.
c) Reduced ability to carry oxygen due to carbon monoxide
in
tobacco smoke combining with haemoglobin in red blood
cells
d ) Increase in heart pressure due to the acceleration
of
heart beat by nicotine, which also constricts
blood
vessels
Number of deaths
2) Lung cancer
Over 80% of lung cancer can be attributed to smoking. The risk
of
lung cancer is clearly related to the amount of exposure to
cigarette
smoke - the length of time the person has smoked and the
number of
cigarettes smoked. The rate of death from lung cancers
has
increased greatly since 1915 while the death rate from other
cancers
has been dropping, suggesting a relationship between lung
cancer and smoking.
cancers other than lung
lung cancer
Year
Number of deaths from lung cancer and other causes
2 or more packs a day
30 times the risk
1 12 - 2 packs a day
20 times the risk
1 pack a day
O pack a day
10 times the risk
never smoked
Relationship between number of cigarettes smoked and lung cancer
People who smoke are more likely to develop lung cancer than those who don’t smoke
The more a person smokes the greater is his chance of getting lung cancer
Annual death rate/ 1,000 men
Death rate from lung cancer among men who
gave up smoking cigarettes
Years after giving up smoking
The longer people have stopped smoking the smaller is the death rate from lung cancer
3) Other respiratory diseases
a) Chronic bronchitis - repeated inflammation of the
air
passages between the trachea and the lungs. This
is
because chemicals in tobacco smoke kill cilia lining
the
air passage so that dirt and germs trapped by
the
mucus cannot be swept away from the bronchial
tubes.
b) Emphysema - a disease in which the lungs lose
their
normal elasticity and the walls of the tiny air
sacs
that absorb oxygen into the body are destroyed
by
chemicals in tobacco smoke so that they become
thin
& weak and are even broken down completely to
leave
large empty spaces in the lungs. As a result, the
lung's
surface area for the uptake of oxygen is
reduced. The
emphysema sufferer is short of breath
after exercise.
Percentage of men aged 55-64 who
develop coughs or bronchial illnesses
Effect of smoking on the chance of developing bronchitis
Non-smokers Smokers: No. of cigarettes a day
1 - 14
15 or more
Ex-smokers
50
40
30
20
10
men with persistent cough and phlegm
men who have also had a recent bronchial illness
Smokers show a greater incidence of bronchitis
4 )
Other cancers, e.g. cancers of the mouth,
larynx,
oesophagus, bladder, kidney, pancreas and
organs
connecting the mouth and pancreas.
5 )
Gastrointestinal disorders, e.g. gastric ulcer
and
duodenal ulcer.
Passive smoking - breathing in of other people’s smoke
The non-smoker suffers many of the harmful effects of smoking
by breathing in contaminated air. These include nose and eye
irritation, coughing, headache and an increased rate of heart and
respiratory illnesses.
Hence government implements many anti-smoking actions:
1) prohibit smoking in public areas such as concert halls, MTR/KCR
trains and platforms, government offices, etc.
2) Requiring that cigarette packets and advertisements carry
warning that smoking is hazardous to health
3) Heavy taxation on tobacco to discourage smoking
Risks of smoking to the foetus
1) Women who smoke have more abortions (foetus
dies),
stillbirths (baby born dead) and premature births
(baby
born early) than non-smoking mothers. Stillbirths
and
deaths in the first week of life occur 30% more often
to
mothers who smoke regularly after four months
of
pregnancy.
2) The babies born to mothers who smoke are smaller in size
and
are about 200 g lighter than those born to
nonsmoking
women. Although the placenta is enlarged to
increase the
oxygen supply to the foetus, nevertheless the
foetus
receives less oxygen if the mother smokes.
3) Nicotine may cross the placental barriers to harm the
foetus.
Fits and convulsions may be caused in young infants
by
nicotine. Nursing mothers also pass on nicotine in their
milk
to the young infants.
Situations leading to the development of a smoking habit
1) Some smoke in times of emotional stress or tension
2 )
Many smokers' social activities revolve around
other
smokers.
3) Users of all kinds of tobacco are often psychologically
or
physically dependent on it. They may be victims
of
psychological and social forces that combine to
portray
this habit as sophisticated, fashionable, and sexy.
For
decades, films portrayed beautiful but smoky
nightclubs
and glamorous stars smoking side by side. Once
the habit
is started, your mind may develop a dependency
on the
nicotine tobacco contains. Psychological
dependency
develops because nicotine can provide a sense
of pleasure.
This pleasure reinforces a smoker's desire to
keep on
smoking.
Mental health - definition
Mental health is a state characterized by psychological wellbeing and self-acceptance. The term mental health usually implies
the capacity to love and relate to others, the ability to work
productively, and the willingness to behave in a way that brings
personal satisfaction without encroaching upon the rights of others.
In a clinical sense, mental health is the absence of mental illness.
A mentally healthy person is someone
1) who is comfortable with himself
Self-confident; able to stand failures; and is not enslaved
by
emotions of anxiety, anger, depression or fear.
2) who relates well to other people:
Responsible, loving and trusting
3) who is able to adapt to society:
Capable of working, solving problems in life,
accepting
changes and coping with stressful situations
Possible causes of mental disorders
The exact cause of mental illness is still unknown, but rarely
is it sparked off by any one single factor. The interplay of
biological, physical and environmental factors is believed to be
the main cause. In other words, a person may be born with a
tendency to mental illness but the illness may not develop if
other biological and environmental conditions are favourable.
a) Biological factors, e.g. genetic make-up, physical constitution
and
temperament.
b) Physical factors, e.g. head injury, infection of the brain,
drugs
and alcohol.
c) Environmental factors, e.g. defective early
development,
maladjustment and stress or crisis.
With the high stresses in the modern way of living, they are
becoming more and more common.
Mental disorders
Arise when a person cannot cope with stress and develops
abnormal behaviour, i.e. becomes mentally ill. It ranges from
mild reactions to stress to serious psychotic conditions.
Some examples
1) Neurosis - mild form of mental disorder, usually showing exaggerated
and
excessive emotional reactions of anxiety and depression. They repeatedly
check
the same thing or wash hands. They may develop phobia towards
particular
things or situations.
2) Psychosis (精神分列症)- more serious form of mental illness which can lead
to
complete mental breakdown or insanity. A psychotic person may believe
that
everyone dislikes him and may even try to kill him.
3) Personality disorders - some distorted personalities developed during
childhood,
probably caused by lack of love, care or guidance.
4) Depression - feeling depressed in moments of frustration or disappointment.
The
feeling disappears quite rapidly normally but there is risk of suicide in
severe
cases.
Ways to prevent mental disorders
Public health authorities customarily distinguish among three
forms of prevention.
1) Primary prevention - attempts to prevent the occurrence
of
mental disorder, as well as to promote positive mental
health.
2) Secondary prevention - the early detection and treatment of
a
disorder
3) Tertiary prevention - rehabilitative efforts that are
directed
at preventing complications.
Two avenues of approach to the prevention of mental illness in
adults are:
1) Reduce the stressful effects of such crises as
unemployment,
retirement, bereavement, and marital disruption;
2) Create environments in which people can achieve their
full
potential.
However, more emphasis should be placed on
helping children through the following steps:
1) good care during pregnancy and childbirth, so
that
early treatment can be instituted as needed;
2) early detection and correction of problems
of
physical, emotional, and intellectual
development;
3) developmental day-care programs focusing
on
emotional and intellectual development; and
4) support services for families, directed
at
preventing unnecessary and inappropriate
foster
care or other out-of-home placements
for
children.
Treatment for mental disorders
1) Drug treatment, e.g. using tranquillisers,
sleeping
tablets and anti-depressants. However
the effect
is only temporary.
2) Psychotherapy, which aims to help the patient
and
his family understand the cause of his
problem,
correct his abnormal behaviour and
promote
normal relationship with other
people.During
therapy, the patient is helped, e.g.
to discover his
hidden emotional conflicts, such as
hatred, fear or
frustrations developed in childhood
or other
stages.
Importance of social relationship in healthy living
1) Family - a good relation helps us to develop love and
care,
understanding, acceptance, tolerance and compromise
with
other people.
2) Work - a good relationship with colleagues, maintained
by
courtesy, sincerity and mutual understanding, is
essential
for a happy working environment, which can be a
source of
joy and achievement.
3) Leisure - Pastimes and creative hobbies can help to
relieve
tension and enables one to relax. Sports is good to
the
physical body and participation in community services
can
give us a sense of achievement and develop selfconfidence.
4) Friends - We need friends for sharing joy and sorrow,
and
for support and help during difficult hours.
Diseases - Cause & Effect
Diseases (failure of body to work properly)
Organisms causing them - pathogens, e.g.
Bacteria, viruses, fungi, protozoa and
some
parasitic
worms,
e.g.
liver
tapeworm and Ascaris.
tapeworm
fluke,
Ascaris
They are said to be infectious if the pathogens
are spread from person to person by various means,
e.g. air, water, animals
How pathogens cause disease
1) Som e p a tho ge n s re le as e poi s on o u s che m i ca ls
called toxins. Most toxins are proteins and are byproducts
of the parasites‘ metabolism. They
produce disease
symptoms in the host like high
temperature, headache, and vomiting.
2) Others invade and damage cells. For instance,
many
bacteria attack mucous membranes, as in
the respiratory and intestinal tracts.
Both processes may also occur at the same time.
Infectious diseases
Causative agents:
1) bacteria
spherical
- Three common shapes:
spherical, rod-shaped and spiral
e.g. Escherichia coli. found in
human large intestine
Disease caused, eg.
cholera (霍亂),
pneumonia (肺炎),
tetanus (破傷風) or
tuberculosis (肺結核)
rod-shaped
spiral
2) viruses
They are even smaller than
bacteria and can be seen only
under the electron microscope.
A virus basically consists of a
protein coat enclosing a strand
of genetic material, which is
made up of either DNA or RNA.
Electron micrograph of a
Disease caused, eg.
bacterial virus (bacteriophage)
colds (傷風),
influenza (流行性感冒),
prote
in coat
rubella (German measles) (德國麻疹)
DN
hepatitis B (乙型肝炎) or
A
AIDS(愛滋病)
bacteriophage
3) fungi
They lack chlorophyll and
cannot make their own food by
photosynthesis. They are
saprophytes or parasites. The
body is made up of numerous
filaments called hyphae which
form a network called mycelium.
They reproduce by spores.
Disease caused, eg.
Athlete’s foot (香港腳),
ringworm (癬)
4) protozoa
They are single-celled animals. Those which cause
diseases are parasitic.
Disease caused, eg.
malaria (虐疾),
vaginitis - inflammation and irritation of the vagina.
amoebic dysentery ( 亞 米 巴 痢 疾 ), in which ulcer develops
in intestinal epithelium and bleeds
red blood cells
attacked by protozoa
causing malaria
5) Parasitic worms
They invade a host, attach themselves externally and
internally (to tissues and organs), and rob the host of
nutrients, weakening the host and even causing diseases in
them.
Tissues which they infect include skin, muscle, lungs,
intestine, lymphatic system or even the brain.
a) Those which infect the digestive tract can cause
abdominal
pain, weakness, diarrhea, loss of appetite,
weight loss,
vomiting, anemia and malnutrition with
deficiencies of
vitamins, minerals (iron), fats, and protein.
b) Those infecting the skin cause eruptions, fluid-filled
sacs
or even intense facial swelling.
c) Those infecting the lungs can cause coughing (even
of
blood) and difficulty in breathing.
Life cycle of Chinese liver fluke
fertilized eggs are passed
down the bile duct into the
intestine
the larvae hatch into the adult form at
the liver and produce a large number of
eggs
larvae move into the
bile duct and the liver
eggs pass out of the
human body in faeces into
water
eggs are eaten by snails in ponds
or streams. Eggs then hatch into
larvae
fish eaten raw
or undercooked
larvae leave snails and swim in water and burrow
through skin of fresh water fish (usu. a carp) and
develop
Means to prevent & control the spread of Chinese liver fluke
1) Cook freshwater fish thoroughly before eating
This kills all larval flukes in the fish.
2) Sanitary disposal of human faeces to
avoid contamination of fish ponds with human faeces
3) Keeping ponds free of snails (e.g. by letting ducks feed
on them) so that the life cycle of liver flukes cannot be
completed.
Experiment to show the presence of
microorganisms in air, water and food
1) Label 4 sterilized petri dishes containing nutrient agar A to D.
2) Open the lid of each agar plate slightly and carry out one of
the following treatments. Close the lid immediately after each
treatment.
A
Leave lid off for about
30 minutes and then
replace the lid
B
Add about 1cm3 of water
collected from an aquarium to the
nutrient agar. Swirl the dish
gently to spread the water
C
D
Add 1 cm3 of fresh milk (or bread,
meat or fruit) to the nutrient agar
Untreated (control)
3) Seal the plates with adhesive tape and incubate them at 25°C
for at least 48 hours. Stack the plates upside down.
4) Examine each agar plate carefully without opening it. Record
the number of bacterial colonies formed in each agar plate.
Q. Why should the agar plates be stacked upside-down
during
incubation?
This is to avoid condensed water falling onto the agar.
Result
Yellow or white spots appear on the agar surface, indicating
the presence of bacteria. Each spot is a colony made up of
millions of bacteria which are formed by repeated division of a
single bacterium.
Spots appear in dish A to C but not in D, indicating that
bacteria are present in air, water and food.
Disease transmission
How infectious diseases are transmitted
1) By air and droplets
Coughing, sneezing, talking or even normal breathing may
discharge small water droplets into air. If these droplets
contain pathogenic microorganisms and they are breathed in
by another person, infection may occur.
Diseases spread in this way include common cold,
influenza, measles, chicken pox, pneumonia and tuberculosis.
Infection in this way can be reduced when a place is well
ventilated because then, water droplets evaporate more
easily and most microorganisms will die. However, in
crowded places such as buses and cinemas, air is humid and
droplets evaporate slowly and remain suspended in air for a
longer period.
Covering the nose and mouth with a handkerchief can
also give protection against infection.
2) Through contaminated water
Water is a very common medium for dispersing the
eggs of parasitic worms and pathogenic microorganisms
that cause infections of the digestive tract, e.g. amoebic
dysentery and cholera. When these organisms reproduce
in the gut, their eggs or spores are carried out with the
faeces. If the faeces is not disposed properly, the eggs
or spores in the faeces may be washed by rain into
streams or reservoirs and contaminate drinking water.
Prevention:
a) Dispose sewage in a sanitary way
b) Bury faeces as far away as possible from streams
and reservoirs.
3) Through contaminated food
Food can be contaminated by:
a) Washing food in contaminated water
b) Leaving food uncovered in air, leading to visits by flies
c) Handled by people with unwashed hands after going
to
the toilet
Examples of diseases so caused: cholera and
diseases caused by parasitic worms.
Prevention:
a) Cover food well and keep in refrigerator
b) Wash and cook food thoroughly
c) Wash our hands before meal or after using the toilet
4) Through vectors
Vectors are animals (esp. insects) serving as agents in
transmitting disease-causing organisms to man while they
do not suffer any harmful effects, e.g.
a) Mosquitoes - transmit malaria
When a mosquito sucks blood from a person suffering
from malaria, the parasites are taken into the
mosquito’s body at the same time. Inside the mosquito,
the parasites multiply rapidly and migrate to the
salivary gland. When the insect bites another person,
its saliva containing the malaria parasites is introduced
into the person and the person therefore becomes
infected.
compound eye
protective tube bent back
stylets piercing skin of host
host’s skin
Sucking tube withdrawing
blood from capillary
A mosquito biting through
the skin
b) Dogs - transmits through their saliva a virus that causes
rabies.
c) Houseflies - transmit many intestinal diseases
When the flies visit faeces, pathogens such as the
bacteria causing cholera or dysentery may be carried on
their mouth-parts, legs or body hairs. These flies will
contaminate human food, cups or utensils on which they
land on .
d) Cockroaches - transmit pathogens from dirty places to
human food in similar way.
e) Rats & mice - contaminate food with pathogens carried
on their fur and feet.
5) Through contact
Examples :
a) Sexually transmitted diseases, e.g. gonorrhoea (淋病), and
syphilis (梅毒)
The bacteria causing the diseases are spread during
intercourse or by contact with genital organs. They are very
susceptible to drying and die quickly outside the body.
b) Fungal diseases such as athlete’s foot
A person may be infected if his skin makes contact
with skin fragments bearing the fungus that have been
rubbed on to a towel or a floor surface from an
infected person.
Prevention:
1) Protect the skin with suitable clothing and shoes
2) Avoid direct contact with people having skin diseases
3) Clean skin regularly to prevent accumulation of dirt & bacteria
Personal hygiene
Common measures of personal hygiene
to keep the body clean and healthy to reduce the chance of
bacteria or other pathogens making contact with or getting
entry into our bodies.
Hygiene of the hands
Wash our hands after using the toilet or before eating, using
soap or other detergents that remove fat from our skin which
tends to stick microorganisms to the skin
This is necessary because our hands constantly handle things
such as furniture, door handles, books, coins and pets which
carry microorganisms that stick to the skin of our hands. When
our fingers touch food or wounds in the skin, these microorganisms are transmitted into our body and can cause disease.
Hygiene of the feet
Wash feet with soap and water and dry thoroughly after
washing.
Do not walk barefooted.
Rationale
The areas between the toes are often warm and moist. Such
conditions favour the growth of fungi. Drying discourage their
growth.
Wearing shoes gives protection against infection by pathogens
which may penetrate through the skin of the feet.
Hygiene of the skin
Wash skin frequently with soap or disinfectant (which inhibit
growth of microorganisms) because sweat, oil and dirt may
accumulate on the skin and promote the growth of pathogens
that can result in pimples, for instance.
Hygiene of the eyes
Avoid rubbing our eyes or using towels of another person for
cleaning our eyes
Rationale
Scratching the eyes may cause damage to the conjunctiva and
cornea which may lead to infection. Pathogens may also be
transmitted through towels used by a person with infected eyes.
Hygiene of the ears
Take extreme care when trying to remove the wax accumulating
in the tube of the outer ear, using sterile cotton wool or by washing,
seeking help of qualified medical personnel if necessary.
Rationale
Hard object can damage the delicate eardrum, leading to
infection or even deafness.
Disease treatment
Disease treatment
The different methods:
1) Chemotherapy - the treatment of disease using
chemical
substances, natural or synthetic, to kill
microorganisms or
prevent their reproduction.
Commonest chemical used: antibiotic - chemical
substances produced by a variety of fungi and bacteria
that suppress the growth of bacteria, e.g. penicillin and
tetracycline.
The effects of such antibiotics can be shown by:
a) Inoculating a sterile nutrient agar plate with bacteria
by
spreading 2 cm3 of a bacteria culture on the
agar
surfaces.
b) Placing paper discs soaked with different antibiotics
and
water onto the agar surface.
c) Then seal the agar plate with adhesive tape.
d) Incubate the agar plate at 25°C for at least 48 hours
e) Observe the growth of bacteria on the agar surface.
Paper disc
soaked with
antibiotic
A
B
C
D
nutrient
agar
A
B
C
D
Paper disc soaked with
penicillin
streptomycin
tetracycline
water
A milky surface on the agar shows growth of bacteria
while a clear region indicates absence of bacteria. The
inhibitory effects of different antibiotics on the growth of
the bacteria used can be compared by measuring the size of
clear region around each antibiotic disc after incubation.
Paper disc
soaked with
antibiotic
Clear region (no
bacterial growth)
milky surface (with
bacterial growth)
You can develop resistance to antibiotics if you fail to take the full
prescribed dosage (e.g. every 4 hours or every 6 hours around the clock
for a certain number of days). Such a failure (e.g. stop taking the
antibiotic after symptoms have disappeared) gives bacteria time to
produce enzymes to destroy the antibiotic or to develop mutant forms
of the organism to replace the vulnerable organisms. In any case, the
result is that, in the future, the antibiotic in question will not be able to
control a similar infection in your system.
2) Surgery - surgical operation on a patient to correct
some
disease conditions. It may involve removing an infected
part of
the body, a cancerous tissue, repairing a
defective heart,
setting a broken bone or attempting to correct
a damaged brain.
It takes place in an operation theatre under
sterilized conditions
to prevent infection of the patient.
3) Radiotherapy - the treatment of disease with ionizing
radiation
such as X-ray. The radiation can be used to kill certain
cells
such as cancer cells.
4) Physiotherapy - the use of physical methods to relieve pain or
to
improve the physical state of the patient. It may involve
the
application of low electric current, heat or massage. etc. to
the
affected body part or performing adequate exercise. It
is
normally used to treat diseases that affect the nervous
&
muscular systems and the joints.
5) Psychology - for the treatment of mental illnesses.
Occupational and industrial health hazards
A number of occupations in industry involve the handling
of substances that are toxic to the body. Special
precautions must be taken to prevent their intake. A few
examples include:
1) Lead and mercury - which have harmful effect on
the nervous system
2) Asbestos - which can cause lung cancer
First Aid
First aid
Objectives
1)
2)
3)
4)
To save the patient‘s life
To prevent the injury or illness from becoming worse
To reduce suffering and shock
To get qualified medical help as soon as possible
Some treatments
a) Artificial respiration
Used to maintain breathing in a person when he has stopped
his breathing movements (such as due to drowning, choking,
suffocation, head injuries, gas poisoning and electric shock). A
person will die if he stops breathing for 4-6 minutes, and the
brain will suffer permanent damage if it does not receive oxygen
supply for 2 minutes. It is therefore essential to carry out
artificial respiration on the victim with no delay.
Mouth to mouth resuscitation
The rescuer blows air into the victim’s lungs through the
mouth. The exhaled air of the rescuer contains oxygen (16-17%)
and carbon dioxide (4-5%). The oxygen helps to maintain aerobic
respiration in the victim’s body and the carbon dioxide stimulates
the respiratory centre of the victim to start working again.
When the rescuer blows air into the victim’s mouth, the
victim’s nose must be held closed. It is also important to tilt the
head well back so that the tongue does not block the air passage.
If the air passage is blocked by the
tongue, as shown in the diagram above,
or by other material, air will not be able
to reach the patient‘s lungs
Tilting the patient‘s head back as far
as it will go keeps the air passage open
as shown in the diagram above.
1. Ensure that the
air
passage is
clear.
Remove
anything that
may
block the mouth
or
throat . Loosen
the
clothing.
2 . T i l t t h e
head
backward
as far
as
possible.
4. Stop blowing. Watch
for
the victim‘s chest to
3. Take a deep breath.
Pinch
the victim‘s
nostrils. Put
your mouth
over the
victim’s mouth
and blow
slowly. The
victim‘s chest
should
rise.
5. Repeat the blowing at about
12
breaths/minute until
the
victim starts breathing
b) Prevention of minor wounds
Small cuts on the skin may lead to infection by microorganisms. A minor wound should be washed thoroughly in
clean, cold water. If the wound is dirty, a mild antiseptic
can be applied to the wound with sterile cotton wool.
Bleeding normally stops quite quickly. Dry the wound and
cover it with an adhesive plaster or bandage.
c) Treatment of bleeding
If the wound is deep, a lot of blood may be lost and this
can be dangerous. It is important to get medical help
quickly, e.g. by calling an ambulance. Before medial help is
obtained, bleeding may be reduced by washing the wound in
clean water and applying pressure to the wound with a piece
of clean cloth.
If the above treatment does not stop bleeding, apply
additional pressure to the major artery that supplies the
wounded area.
When an artery can be pressed against the bone to
prevent bleeding beyond it, the site is known as a pressure
point. If severe bleeding cannot be stopped by pressing on
the wound, it may be possible to stop bleeding by applying
pressure on a suitable pressure point. Press on the
pressure point only when dressing the wound. Never apply
pressure on the pressure point for more than 15 minutes,
otherwise the tissues may suffer permanent damage due to
lack of oxygen.
c) Treatment of shock (休克)
In a state of shock, a person looks pale and keeps sweating.
His breath is rapid and shallow, and his pulse rapid and weak.
He feels cold, weak and dizzy and may even lose consciousness. These symptoms are caused by a reduced blood supply
to vital organs of the body, esp. the brain.
Treatment
1) Treat any injury or condition which has caused
the shock, e.g. stop severe bleeding
2) Have the victim lie down in such a way that his head
is slightly lower than the rest of his body.
3) Loosen his clothing
4) Cover the victim with a coat or a light blanket
5) If the victim is conscious, give him warm drinks such
as tea but not alcoholic drinks. Do not give drinks to
an unconscious person.
d) Treatment of joint injuries
Sprains (扭傷) occur at joints when the ligaments connected
with a joint are torn. Sprained joints are usually associated
with swelling of the joint and severe pain. The victim may not
be able to move. He may be treated as follows:
1) Apply a cold compress, e.g. a wet cloth, to the joint
2) Wrap the affected region with a bandage so as
to immobilize the joint.
3) Consult a doctor for medical help and to check on
the state of damage.