Download Health and Disease - 10Science2-2010

Health
and
Disease
What your syllabus says…
► Prescribed
► 5.1explains
Focus Areas
how social factors influence the
development and acceptance of scientific
ideas
► 5.3evaluates the impact of applications of
science on society and the environment
► 5.5analyses how current research might
affect people’s lives
► Knowledge
► 5.12technology
► b) Discuss the benefits
and problems associated
with medical and industrial uses of nuclear energy
describe some medical applications of
electromagnetic radiation
► 5.85.8.4 relates the structure and function of
living things to models, theories and laws
► Humans
► a) Describe the role of, and interaction between,
coordination systems in maintaining humans as
functioning organisms
► b) Describe some responses of body systems to
infectious and non-infectious diseases
Skills
5.13.3 Choosing equipment or resources
 Describe ways to reduce the risk to themselves and others when
working in the laboratory or field.
5.14 Performing first-hand investigations
 follow the planned procedure when performing an investigation
safely and efficiently construct, assemble and manipulate identified
equipment
 g) record data using the appropriate units
5.16accesses information from a wide variety of secondary sources
5.17explains trends, patterns and relationships in data and/or
information from a variety of sources
5.18selects and uses appropriate forms of communication to present
information to an audience
5.19uses critical thinking skills in evaluating information and drawing
conclusions
Focus Verbs
► Identify
► Describe
► Explain
► Discuss
► outline
Spelling
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Vaccine
Infectious
Health
Antibody
Disease
Virus
Traditional
Immune
Pathogen
Bacteria
Medicine
System
Let’s Make a Glossary
► Construct
a table that will show the terms and
their meanings used in the spelling list. You will
add to this glossary throughout the topic.
► Glossaries are a very useful tool for studying for
exams because they let you define terms in your
own words clearly in questions and know what key
words you can use instead of being conversational
in your answers. This will help you to get better
marks in your School Certificate.
► The
Disease
study of disease is called
pathology and people working in this
field are called pathologists.
► A disease is defined in biology as
anything that stops the body
functioning properly. This does not
only include the flu, but also other
conditions such as colour blindness.
► NOW add these to your glossary
Other definitions you will need to
remember are :
• An organism is any living thing.
• A micro-organism (often called a
microbe) is a very small organism that
cannot be seen with the naked eye but
can be seen using a microscope. Some
micro-organisms consist of only one cell.
An pathogen is an organism that
causes disease.
• A host is the organism being affected
by the pathogen.
•
• A parasite is a pathogen
that uses the host for food
and/or shelter and has a
negative effect on the
host.
• An infection is where a
pathogen enters the body
and is able to cause
disease. The pathogen will
multiply and have numbers
that are so large that
symptoms will show.
► SYMPTOMS
are the physical effects on the body
by a disease. These can include fever, increased
sweating, a rash, coughing etc.
► INCUBATION PERIOD is the time between entry of
the pathogen and the development of symptoms.
Some diseases have short times, such as influenza
and ebola. Others have longer times, such as up
to 3 weeks with Chickenpox. This can be a
problem because the hosts can be spreading the
disease before they know they have it.
► TRANSMISSION is the passing of disease from one
person to another.
• Virulence is a measure of
how much damage a
disease does to the host.
Highly virulent diseases
cause very serious
symptoms, perhaps death.
Can you think of some
examples?
Endemic means that a disease regularly affects
a small number of people in the population.
What examples do you know of ?
• An epidemic is when there are higher
than normal numbers of people being
affected by a particular disease in a
certain place.
►A
pandemic is when an epidemic spreads across
countries. This was recently an issue with the SWINE
FLU, and then the Avian Influenza (Bird Flu) before
that.
► PFA:5.1
The history of science
Describe historical cases where
developments in science have led to the
development of new technologies
Universal Flu Vaccine digital article including videoclip.
http://www.abc.net.au/catalyst/stories/2613604.htm
Causes of Disease
Disease can be caused by many
factors, some infectious, some
avoidable and others you are
born with.
INFECTIOUS DISEASES
• The body could be infected by
micro-organisms such as
bacteria, viruses, protozoa and
fungi. These diseases are
classified as “infectious”.
Parasites such as
worms , ticks and lice
can be transmitted
from other infected
people. These would
then infect the new
host..
A Summary of Infectious
Diseases
► Caused
by organisms called PATHOGENS.
► Infect a “host”
► Can be TRANSMITTED (passed on) from
one host to another via faeces, breath
droplets, water supplies, utensils etc.
► Pathogens include viruses (eg Influenza),
bacteria (eg Tetanus), fungi (eg Tinea),
protozoans (eg Giardia) and parasites such
as worms, ticks and lice.
Lets Look at Some Pathogens.
► Using
the Microscope COMPARE the
structures of different pathogens.
► You will need to draw and label what you
observe for each pathogen and include
some description as well.
► What is the best way to present these
results?
DRAWING SCIENTIFIC
DIAGRAMS
►
►
►
►
►
Always include a title/heading for each one
stating what the specimen is and the
magnification used to view it.
Use lead pencil!!!!
Make the diagrams large enough to be
seen clearly.
Drawings need to be 2D and not be “furry”
or “sketchy” but have clear lines.
Labels must be included in all diagrams
but do NOT use arrows to connect the
label to the structure.
Scenario of a Fictitious Infectious
Disease
► http://tlf.dlr.det.nsw.edu.au/learningobjects
/Content/L2019/object/sc_004_clt_750/
NON INFECTIOUS
DISEASES
Some part of the body
could malfunction due
to some imperfection or
fault.
For example, diabetes
can develop if the
pancreas isn’t working
properly. This is called
physiological
malfunction.
• Environmental factors might cause your
body not to function properly.
Heavy Metals in soil and
water pollution, can cause
disorders such as lead
poisoning and Minamata
Disease ,with Mercury ,in
Japan.
Cataracts are caused by
normal but still damaging
exposure to UV radiation) and
not wearing proper
sunglasses.
Lifestyle factors can also cause disease.
These factors are
‘self-inflicted’ and
include drug abuse,
overuse of alcohol,
smoking, sunbaking
and high-fat, highsugar diets.
Diseases such as
lung cancer,
melanaoma and
heart disease can
be classified as
lifestyle diseases.
Genetic disorders
or diseases are
“passed on” from
parents to their
offspring. The
parents either
had or ‘carried’
the genes for the
disease.
► Sometimes
these diseases are due to
mutations or changes in the structure of the
parts that make up chromosomes. These
small parts are called genes and can be
changed through radiation, Xrays and
chemicals or can be due to other factors
that scientists have yet to work out.
► Diseases such as Cystic Fibrosis, colour
blindness and Down’s Syndrome are genetic
diseases.
Infectious Disease
► There
are many ways that pathogens can
be shared. An infectious communicable
disease is a disease
that is transmitted easily from
person to person. The disease
is said to be endemic if small
numbers of cases are present
in the population and an
epidemic if large numbers of
people are affected. An
outbreak happens when the
disease is suddenly out of
control.
Diseases Caused by MicroOrganisms
Not all micro-organisms are harmful to humans. In fact, some are
very helpful. Some micro-organisms serve as food sources, others
help decompose wastes, some help protect us from disease and
others aid digestion. Only a few micro-organisms cause disease. The
micro- organisms that cause disease are known as pathogens and
include varieties of bacteria, viruses, protozoa and fungi.
Bacteria
► One
characteristic that is used to identify
bacteria is their shape. They may be
rod-shaped (bacilli), spiral (spirilla) or
spherical (cocci). All bacteria consist of
only one cell, but they can join together in
pairs, chains or clusters. Bacteria can
multiply very quickly under the right
conditions.
Bacteria Cont.
► If
conditions are not favourable for growth,
some types of bacteria can form thickwalled spores that allow them to withstand
cold, heat and prolonged drying. They can
remain inactive for days or even years.
Antibiotics can kill many types of bacteria.
Staphylococcus epidermidis bacteria
Common Bacteria Shapes
Viruses
► Viruses
are so small that they can be
seen only with an electron microscope.
Viruses are not considered to be living
things because they do not self-reproduce,
feed, grow, produce waste or move. They
do move from place to place, but only if
they hitch a ride on something else, like
other organisms, wind or water. Viruses
are parasitic invaders made of DNA (or a
similar material called RNA) in a protein
coat.
Viruses cont.
► If
viruses come into contact with a suitable
cell (called a host cell) they can attach to
the cell and enter it. They hijack the cell
and force it to make more virus particles.
The cells make so many virus particles that
they burst open, releasing the virus
particles, which then invade other cells.
► Some
viruses invade cells and remain dormant
or inactive for long periods of time. An
example is the herpes simplex virus, which is
responsible for cold sores. Cold sores come
and go, but the virus is always there, awaiting
the right conditions for rapid reproduction and
‘re-appearance’. Others do not kill the cell
they infect, but re-program it in a way that
causes it to become
cancerous. Viruses are
hard to treat as they are
not stopped by antibiotics.
With most viral infections
you have to wait until your
body itself stops the
invading virus.
Foot and Mouth Virus
The Problem with Viruses
► Because
they are so
small, viruses are
difficult to isolate in
the laboratory. They
also multiply so
rapidly that new
strains are
appearing all the
time. As yet no
chemicals can
eradicate a viral
infection.
► Diseases
Protozoa
caused by protozoa
(sometimes called protists) are most
often seen in tropical and subtropical
areas. Like bacteria, protozoa are singlecelled. Most protozoa are harmless to
humans, but some parasitic types can
cause serious illness. Protozoa
sometimes form protective cysts around
themselves if conditions are
unfavourable, allowing them to survive
between outbreaks. Giardia and
Cryptosporidium are both examples of
protozoa that contaminate water
supplies.
► Another
example is the
common tropical disease,
malaria. Malaria is caused by
Plasmodium, which live in the
red blood cells and cells of
the liver. Falciparum malaria,
the most dangerous type, is
fatal in about 20% of
untreated cases.
•Initial infection occurs
through a female
Anopheles mosquito bite.
► Very
Fungi
few fungi cause
disease in humans and
those that do commonly
invade the hair, skin and
nails.
► Fungi are opportunistic
pathogens. They are not
usually associated with
infection, but they can
cause infection if the
conditions are ideal or if
the person’s immune
system is not working
properly.
Fungi Cont
People can have
lowered immunity
due to a number of
causes and all are
more susceptible to
these fungal
infections. Tinea
(athlete’s foot),
ringworm and thrush
are all opportunistic
fungal infections.
Diseases Caused by
Macroscopic Parasites
► Parasites
that can be seen without a
microscope are called microscopic
parasites.
► The
Flukes
most common type
of disease-causing
macroscopic parasite is
the flatworm. Parasitic
flukes are flatworms,
best
known for causing disease in many animals, including
humans. Intestinal flukes, blood flukes, lung flukes and
liver flukes all affect humans, causing damage to the
organs they inhabit, resulting in serious illness for the
host. For example, blood flukes can damage blood
vessels near major organs like the bladder and kidneys.
Tapeworm
► Another
type of flatworm is the tapeworm,
which can sometimes live in human intestines.
One type of tapeworm causes hydatid disease.
If the tapeworms’ eggs are swallowed by
humans, the tiny embryos will hatch
from the eggs and move from the intestines
into the bloodstream. Cysts develop
wherever the embryos end up, most often
in the liver. Here they are capable of killing
the host human.
Life
Cycle of
a Blood
Fluke
Bird ‘Flu
► Bird
flu, or more correctly avian influenza A virus,
usually only infects birds. But sometimes these
flu strains mutate into more dangerous forms.
This happened in Hong Kong in 1997 when avian
influenza (H5N1) infected both poultry and
humans. This was the first time a bird flu had
ever transmitted directly to
humans. During this outbreak, 18 people were
hospitalised and six of them died. To control
the outbreak, authorities killed about 1.5
million chickens to remove the source of the
disease. Further outbreaks occurred in 2003
and 2004.
•Pathologists are concerned about the possibility that
genes might swap between bird flu and human flu. This
could happen if a person got infected with both diseases
at the same time. The new bug would then have the
potential to be as deadly as bird flu, and as easy to catch
as human flu. It could then bring us the next pandemic.
Similar pandemics have occurred in the
past:
• 1957–58, Asian flu caused about 70
000 deaths.
• 1968–69, Hong Kong flu caused
approximately 34 000 deaths. This virus
still circulates today.
Transmission and Control of
Infectious Diseases
► You
can get infectious diseases by direct
or indirect transmission.
► Direct transmission comes about by direct
contact with the infected person or by
contact with droplets of body fluid.
Diseases transmitted by direct contact are
called contagious diseases.
► Indirect
transmission occurs
through an intermediary agent like
an insect, air or contaminated
water. Carriers of disease are called
vectors. An example of a vector is
the mosquito that carries malaria
from person to person.
Natural control
► The
first line of defence
► The human body has several mechanisms
for coping with disease. The first defence
on theconsisting
skin can be
is the outer layer of the skin,
shed with the dead
of dead cells. Harmful pathogens
cells. There are also
a lot of good bacteria
on your skin, which
help fight the
invaders.
► The
second line of defence
•The second line of
defence is in your
blood, as white blood
cells or leucocytes.
They travel in the
blood to the site of
infection, converge on
the pathogens, digest
them and engulf their
remains. Dead microorganisms and dead
white cells are left
behind and form the
discharge call pus.
► The
third line of
defence
► When invaded by a
pathogen your body
responds by making
antibodies. These
antibodies are produced in
a process called acquired
immunity.
► The antibodies float
around in the blood and
attach to a specific part of
the pathogen, which is
called an antigen. The
antibody disables the
pathogen, which is then
The
process of
acquired
immunity
Vaccinations
The threat of many of the killer diseases of
the past has been greatly reduced, and
sometimes eliminated, by the
development of vaccines. A person can
be immunised against a certain disease
by being injected (inoculated or
vaccinated) with a vaccine. Most
children in Australia are routinely
vaccinated against diseases like polio,
tetanus and measles, chicken pox and
tuberculosis
►
Active immunity: the body is
stimulated to make its own antibodies.
This usually involves injecting a live but
disabled version of the virus or bacteria.
An example is the Sabin polio vaccine,
which uses a live but non-contagious
strain of the disease.
► Passive
immunity: the body is injected with
antibodies previously produced by another
organism. This is good in emergency situations,
where immunity is needed quickly. Unfortunately
it does not last as long as active immunity.
active immunity does not last forever.
Production of antibodies can reduce with time
and a booster shot (re-injection with the
vaccine) may be needed.
Antibiotics
► Antibiotics
are drugs that are able to
selectively kill off certain pathogens while
leaving the patient’s own body cells intact.
Although antibiotics can fight many
bacterial
infections,
they are ineffective
antibiotics are
used,
against
viruses. Overuse and misuse of
the more quickly
resistant strains
antibiotics
have led to the development of
emerge. It takes up
antibiotic-resistant
strains of bacteria. The
to 20 years to
more
develop new drugs
and soon doctors
might be left without
any drugs to fight the
new strains.
Non Infectious Diseases
► Genetic
disorders are
caused by abnormalities
in one or more genes—
this means that the code
contained on the
chromosomes for
building new cells is
faulty. These genetic
abnormalities may be
caused by mutations
mutagens such as
radiation, drugs,
Diseases Caused by Diet
► Malnutrition
People in developing
countries generally do
not have the quantity
or range of foods that
you have, making
them susceptible to
malnutrition. Vitamin
and mineral
deficiencies can easily
cause death.
► Eating
disorders Anorexia nervosa
results in severe weight loss, often
enough to cause massive organ failure
and death. Bulimia nervosa is a related
disorder characterised by a bingeing
and purging cycle. The imbalance of
electrolytes (mineral salts) that
results from this cycle may cause heart
failure.
► Diabetes
Diabetes mellitus is a
disorder in which glucose, the
energy source for your bodies, is not
used correctly due to lack of a
substance called insulin. Diabetes
seems to have some sort of genetic
component but there is no defined
pattern of inheritance. There are
two types of diabetes:
• juvenile onset (Type I)
• mature onset (Type II).
•Being overweight is a common factor in
Type II cases. If the insulin deficiency is
serious, regular monitoring and
injections are needed throughout the
patient’s life.
Diseases of the Circulatory
System
► In
Australia, heart
disease is the leading
cause of death in
males over 35 and
females over 60. Many
of these diseases are
caused by poor diet,
smoking and a lack of
regular exercise.
Thrombosis and Embolism
► Thrombosis
is a
disease that causes
a large, solid mass
(a thrombus) to
form on the inside
wall of a blood
vessel. Sometimes
these large masses
can detach and end
up blocking major
arteries, causing
death.
The blockage of a blood vessel is called an
embolism. The embolism can result from a
thrombus, gas, fat, tumour cells or some type of
foreign body.
High Blood Pressure
► Hypertension
is the name given to
persistent high blood pressure. It can
cause arteriosclerosis, or hardening of
the arteries, and coronary heart disease.
The worst type of arteriosclerosis is called
atherosclerosis. It is characterised by fatty
deposits within arteries. These deposits
can eventually cause arteries to become
blocked. Atherosclerosis can occur in any
part of the body, not just the heart. It can
be inherited, but is also strongly linked to
environmental factors like smoking and
diet.
► In
WA, a four year study of 50 children
aged from 10 to 16 and found that all
the children had early signs of
arteriosclerosis.
Varicose Veins
► Irregularities
in vein walls
and weaknesses in the
valves can stop blood
flowing back to the heart
normally. Varicose veins
are the result and are
usually seen in the legs,
where blood must fight
gravity to get back to the
heart. Unsightly, bulging
veins develop wherever
blood is trapped.
Heart Disease
► Coronary
heart
disease refers to
anything that reduces
blood flow to the heart
and is usually caused
by arteriosclerosis. It
can cause milder
attacks of chest pain,
called angina, or a
serious heart failure,
called a heart attack.
Cancer
► Cancer
is one disease that is on the
increase in Australia. Cancer occurs
when the cell division that produces new
cells occurs uncontrollably. Cell division
is a carefully controlled process and
even tiny changes within cells can be
enough to disturb the process and
produce cancer. A tumour is abnormal
growth in the body.
► There
are two types:
► • A benign growth is one in which the
cells are not rapidly dividing. A wart is
an example of a benign tumour.
►A
biopsy is
carried out to
determine
whether a
tumour is
malignant or
benign. A small
sample of tissue
is taken, and is
then analysed
under a
microscope.
Cancer can occur
► Factors
that
can lead to
cancer are:
►•
environmental
—cigarette
smoking (lung
cancer),
exposure to
the sun (skin
cancer), poor
►•
genetic predisposition—a family history
of breast or prostate cancer suggests that
you have a higher risk of developing those
cancers. If a malignant growth is found, it
needs to be treated before metastasis
occurs. Metastasis is when cancerous cells
find their way into the circulatory or lymph
systems and travel to other parts of the
► Leukaemia
is a type of cancer of the bone
marrow and the tissues that produce blood
cells. The first symptoms are usually
fatigue, unexplained bruising and
anaemia, caused by the lack of red blood
cells. An abnormal number of white blood
cells appear. Like most cancers, there is no
known cure, but many treatment options
are available. Common treatments for
cancer are surgery, radiotherapy (using
radiation to kill localised growths) and
chemotherapy (using chemicals to poison
cells). These treatments can have serious
Abuse of Psychoactive Drugs
►A
drug is any substance that has the ability to
alter a person’s body chemistry. Psychoactive
drugs are those that alter mood. Drug use is
the controlled, beneficial use of a substance.
Drug abuse is when a drug is used in a way
that causes negative effects. People who use
so-called recreational drugs like Ecstasy or
marijuana are often unaware of the serious
side effects that can occur. Often, users
develop mental disorders that stay with them
for life.
Alcohol and
Smoking
► Two
of the most widely
used and abused drugs in
modern society are the
legalised drugs—alcohol
and nicotine. Because
they are legal, their use is
much more widespread,
open and accepted than
Alcohol
► In
Australia
approximately 7% of
all male deaths and
4% of all female
deaths can be directly
attributed to alcohol.
► Alcohol is technically a
depressant drug.
Although it doesn’t
necessarily make you
depressed, it does
Alcohol has different effects depending on
how much is consumed:
With a little more alcohol, muscle
coordination becomes difficult and speech
slurred. Reactions are slower and the
senses become dulled. Alcohol is a cause
of around one-third of all road deaths.
Hence the legal blood alcohol limit in New
South Wales for all learner and provisional
licence holders was reduced to zero in May
2004.
If more alcohol is ingested, intoxication
occurs. The person will be staggering,
nauseated, possibly vomiting, and will
have difficulty speaking. People are likely
to fall into a coma if their blood alcohol
content gets to 0.40%. Death through
heart and respiratory failure can occur at
► Alcohol
also
stimulates
urine
production,
dehydrating
body cells.
Part of the
liver is put out
poisonous
of actionchemicals
while that are then released back into
the
blood. Iton
is a combination of dehydration and these
it works
chemicals that give the symptoms of a hangover.
processing is particularly harmful since it gives no
Binge-drinking
time
for the A
body
alcohol.
by-to process the alcohol.
product of all
Chronic
Alcohol
Abuse
This causes many ill-effects including:
• digestive problems— alcohol destroys the
lining of the stomach.
• malnutrition and vitamin deficiencies—diet
is often neglected. Although alcohol is rich
in kilojoules, it has no nutrients.
• destruction of the liver—alcohol can cause
cirrhosis, a disease where cells are
replaced by fibrous tissue
• heart damage—alcohol can harden artery
► The
abuse of
alcohol can
result in the
disease called
alcoholism,
where drinking
is compulsive
and the person
dependent on
it. This
dependence is
► More
young
women than men
are currently
smokers, one
common reason
being that it is an
appetite
suppressant. The
nicotine in
tobacco is
addictive and
once the habit is
formed, it is not
Smoking
Smokers are likely to
have:
• more accidents than
non-smokers, due to the
slowing down of their
reflex actions following a
cigarette
middle-age death
twice that of non-smokers
•aconstriction
ofrate
blood
• an increased risk of developing many diseases, not just
vessels,
which
means
lung cancer
that
smokers’
brains
• an increased risk of having low birth weight babies with
don’tproblems
work as
as intelligence if the mother
health
andwell
reduced
non-smokers’
brains
smokes
during pregnancy
•• bad breath
• stained teeth and fingers.
Environmental Hazards
Exposure to radiation,
heavy metals such as
lead, and chemicals such
as asbestos are all
environmental hazards
that can cause diseases.
Although these hazards
are usually avoidable,
some people are exposed
thought
to be
safe andwarning.
many people innocently exposed
to
them
without
themselves to it in the past.
Many
environmental
Traditional Medicine
Traditional Aboriginal medicine is a
complex system linked to the belief
and culture of theTraditional
people,medicine
their and
knowledge of thehealth
landcare
andareofholistic,
its flora
taking a whole-being
and fauna.
approach. It recognises the
social, physical and
spiritual dimensions of both
health and life. Sorcery
remains a potent belief and
the casting and removing of
spells is still practised.
Good Nutrition
To survive, organisms
must take in
nutrients. A nutrient is
any substance that is
used by an organism
either as a source of
energy and so these are our
main nutrients.
A balanced
energy
or to build
living
diet should consist of a variety of foods including fresh
tissue. Fats, proteins
fruit and vegetables, breads and cereals, dairy products,
fish, lean meats and water.and carbohydrates can
all be used by the
human body to make