Download Search for Better Health

THE SEARCH FOR BETTER HEALTH
Contextual Outline
When physiological processes malfunction, the body tries to repair the damage. The
process is similar in all living things and it is only when the process fails to contain the
damage that disease can be recognised.
Humans have long recognised the symptoms of disease both in themselves and the
animals and plants around them. Since the beginnings of recorded history, they have
noted the signs that reveal that the body is malfunctioning. Increasing understanding of
the causes of disease together with accompanying advances in technology have changed
approaches to treatment and management of disease.
The search for measures to treat and manage diseases of humans and other organisms
continues and this search is paralleled by continued refinements in technology.
This module increases students’ understanding of the history, nature and practice of
biology, the applications and uses of biology, and the implications of biology for society
and the environment.
Discuss the difficulties of defining the terms ‘health’ and ‘disease.’
Things to consider:
- What does discuss mean?
- Underline key words
- Be succinct
Defining the term health is not easy as there are many components which fall under
health and some of these components are very subjective. According to the World Health
Organisation, (WHO) “health is a state of complete physical, mental, and social well –
being and not merely the absence of disease or infirmity.” This basically means that good
health revolves around a biological, psychological and social well – being.
Biological health: being active and free from pain.
Psychological health: feeling happy, not depressed.
Social well – being: interrelating within the community.
Each of the above factors would all have slight different meanings to different people
making the term health harder to define.
Disease is also another word which is hard to define. Disease as a definition is a state of
impaired functioning by interfering with the structure of organs, tissues or cells or by
altering normal metabolism. This definition is subjective to the functioning of each
individual. Meaning that one person may feel that they are sick while another person with
the same symptoms does not feel sick.
Outline how the function of genes, mitosis, cell differentiation and specialisation assist in
the maintenance of health.
Things to consider:
- What does outline mean?
- Underline key words
- Ensure you write about each of the key components that assist in the maintenance
of health.
The function of genes, mitosis, cell differentiation and specialisation all assist in the
maintenance of health. They are outlined as follows:
Genes:
Genes assist in the maintenance of health by ensuring that the correct proteins are
produced in a cell. This enables all other cellular processes to continue and to maintain
health within the organism.
Mitosis:
Mitosis assists in the maintenance of health by ensuring that genetic material is copied
accurately when new cells are formed. These new genetically correct cells enable the
organism to grow as well as repair any damaged cells or tissue. This therefore maintains
health for the organism.
Cell differentiation/specialisation:
During the development of a cell the cell differentiates and becomes a specialised cell for
a specific function. Genes release certain proteins which enable the cell to have a
specialised function. Cell differentiation and specialisation is important in the
maintenance of health as these cells enable the organism to grow as well as repair
damaged cells or tissues. Cells may become specialised to fight of infection such as
macrophages.
Use available evidence to analyse the links between gene expression and maintenance
and repair of body tissues.
Things to consider:
- What does analyse mean?
- What is gene expression?
- Underline key words and understand what the question is asking before you
answer.
- Draw a link between gene expression and repair of body tissue.
Gene expression: is the entire process that takes the information contained in genes on
DNA and turns that information into proteins. (The process of transcription and
translation.)
To maintain a healthy lifestyle the appropriate genes during mitosis must be expressed. If
there is damage or no damage to cells or tissue it is still necessary for the appropriate
genes to be expressed efficiently in order for necessary compounds to be produced and
therefore a healthy existence.
Example:
During mitosis cells differentiate to have a specialised function. For example in order for
muscles to contract they need the proteins called actin and myosin. The gene responsible
for these proteins is “switched on.” The cell differentiates and becomes a specialised
muscle cell. This relates to gene expression and the repair of body tissue in the sense that
the gene responsible for the expression of actin and myosin was triggered. This resulted
in the development of a specialised muscle cell, which in turn repaired the muscle tissue.
Distinguish between infectious and non – infectious disease.
Things to consider:
- What does distinguish mean?
- What are infectious and non – infectious diseases?
- Be succinct



INFECTIOUS
Infectious diseases are caused by an
infecting organism which usually
invades the body.
Infecting organisms can
microscopic or macroscopic.
A pathogen is an example of an
infectious organism. They include;
prions, viruses, bacteria, protozoans
and fungi.


NON - INFECTIOUS
Non – infectious diseases are not
caused by a pathogen and can not
be passed on from person to person.
Non – infectious disease are usually
the cause of genetic inheritance,
nutritional deficiency and
environmental factors. Examples
include Down syndrome (genetic),
anorexia (nutritional) and skin
cancer (environmental).
Explain why cleanliness in food, water and personal hygiene practices assist in control of
disease.
Things to consider:
- What does explain mean?
- Underline key words.
- Understand the question before answering
It is important that food, water and personal hygiene practices are maintained in order to
assist in control of disease. Food is easily contaminated by visible applications such as
dirt or insects or microscopic by micro – organisms such as salmonella. Hygienic
handling of this food controls the spread of disease. Hygienic practices include; using
clean utensils, not sneezing/coughing over food, not using food that has fallen on the
floor, washing hands after being to the toilet, covering cuts and abrasions before
preparing food and always placing perishable foods in the fridge/freezer. If these general
hygienic practices were not followed populations could suffer from food poisoning and
disease. It is these simple practices that control disease. Water is easily contaminated by
pathogens such as Giardia and cryptosporidium. These pathogens are controlled by
Sydney Water by constant water testing as well as being filtered and chlorinated before
reaching the household. Sewage is also disposed of in a safe manner in order to control
the spread of disease. Personal hygiene refers to the nature of keeping oneself clean. This
includes washing hands after using the toilet, washing hands before preparing food,
showering regularly and washing hands after you have been in contact with something
dirty or a sick person. If this personal hygiene was not kept in order people would easily
contract disease from infectious pathogens. Therefore it is important to maintain
cleanliness in food, water and personal hygiene to assist in the control of disease.
Identify the conditions under which an organism is described as a pathogen.
Things to consider:
- What does identify mean?
- What is a pathogen?
An organism that causes disease is known as a pathogen. For the pathogen to cause
disease it must have the right conditions in order to multiply and transmit itself from
organism to organism.
Pathogens can come in the form of prions, viruses, bacteria, protozoans, fungi and
parasites. These pathogens can either be microscopic or macroscopic, meaning they can
be seen by the naked eye.
Pathogens can be transmitted in the following ways:
- Air
- Water
- Food
- Direct contact
- Vectors
Identify data sources, plan and choose equipment or resources to perform a first – hand
investigation to identify microbes in food or in water.
Things to consider:
- What does identify, plan and choose mean?
- What are microbes?
- Ensure you plan your own investigation as it is a HSC requirement
Background:
Microbe – an organism which is too small to be seen by the naked eye.
Streaking: Streaking is the technique whereby you use the inoculation loop to streak an
agar plate. Firstly the inoculation loop is placed in the blue flame of the Bunsen burner to
sterilise the inoculation loop. (Kill off any pathogens) The inoculation loop is then
swabbed across an area you are wishing to test, for example a piece of food or a water
sample. Then you open the agar plate at a 45 degree angle and swap in a zig zag pattern
in the middle of the agar.
AIM:
To identify a variety of microbes in food and water.
MATERIALS:
 Sterile agar plates
 Inoculation loops
 Various water samples
 Incubator
 Bunsen Burner
 Food samples
METHOD:
1. Collect a number of agar plates and place them under various conditions. For
example in the science lab, near a rubbish bin or outside on the school oval.
Expose each plate for the same amount of time. Keep one plate closed as a control
plate.
2. Collect your plates close them and seal them with sticky tape. Once closed ensure
you label your plates with your name, date and area of exposure.
3. Collect a number of agar plates to test the various water and food samples. Using
the streaking technique collect a sample from the food and water sample and
streak your various agar plates. Close your plate and label with your name, date
and food/water you exposed your plate to.
4. Invert your plates and incubate for 24 hours.
5. Once incubated observe your agar plates for bacterial colonies. Colonies can be
distinguished through their characteristics such as colour and texture. Count the
number of colonies and record your observations in the results table.
RESULTS:
NO. OF
COLONIES
LOCATION
COLOUR
TEXTURE
BRIEF
DRAWING
Gather, process and analyse information from secondary sources to describe ways in
which drinking water can be treated and use available evidence to explain how these
methods reduce the risk of infection from pathogens.
Things to consider:
- What does gather, process and analyse mean?
- What does explain mean?
- Underline key words
- Understand what the question is asking before answering.
Water is treated to remove impurities and microbes from causing disease to the general
public. To prevent the spread of disease water companies take the following steps to
prevent the spread of disease:
- Coagulation and sedimentation
- Filtration
- Disinfection
Coagulation involves adding certain chemicals to the treated water such as alum. The
coagulating material causes dirt, plant debris and other organic matter to clump together
and form what is known as a floc. As the water flows through the tanks the floc settles to
the bottom and is removed.
Filters are used to remove small particles such as viruses and protozoans, for example
Giardia. Filters are usually comprised of a specialised membrane, a sand pebble mixture
or activated carbon.
The final step is to disinfect the water. Chlorine is the common chemical used in the
disinfection stage. Ozone and U.V. radiation can also be used. Fluoride in some countries
may be used to prevent tooth decay. Once disinfected, water is piped to homes and
businesses.
These are the main methods to reduce the risk of infections from drinking water. Not only
are these steps followed but Sydney Water also incorporates strict controls on N.S.W
drinking water. These include; fences around major dams to prevent contamination from
animals, adequate distance from farming communities and distance from sewerage
systems. These steps all prevent infection from pathogens.
Describe the contribution of Pasteur and Koch to our understanding of infectious
diseases.
Things to consider:
- What does describe mean?
- Who are Pasteur and Koch?
- Ensure you understand their work as scientists are regularly referred to in the
HSC.
Louis Pasteur and Robert Koch played a pivotal role to our understanding of infectious
diseases. Louis Pasteur a French chemist discovered that most infectious diseases are
caused by micro – organisms, or germs. This became known as Germ Theory. Through
Pasteur’s research on fermentation he was able to identify and describe the micro –
organisms that cause fermentation. During this research Pasteur also disproved the theory
of spontaneous generation.
Due to Pasteur’s knowledge of microbes and fermentation he was involved in many
industries including the wine industry. Pasteur showed that microbes, which caused wine
to spoil, could be killed by heating the wine to 55oC. This process was also applied to
milk and beer and is now known as pasteurisation.
Pasteur also demonstrated that anthrax a disease that affected cattle, sheep and horses was
caused by a bacterium known as Bacillus anthracis. He developed a technique by
weakening a strain of this bacterium and injecting it into certain animals. On one
occasion he took 50 sheep and injected 25 of them with the weakened disease. Several
days later he injected all 50 of the sheep with a strong dose of the disease. Pasteur
predicted that 25 of the sheep would die. Subsequently 25 sheep did die and 25 survived.
Today this process is commonly known as vaccination. Pasteur developed many
vaccines including vaccines for anthrax, chicken cholera and swine erysipelas.
Robert Koch was also heavily involved in microbial work, in particular anthrax. Koch
was successful in isolating the bacterium from the blood of dying animals. He examined
the blood under the microscope and identified active rod – shaped cells and resting
spores. He concluded that all infected organisms contained these microbes, while healthy
organisms did not. Koch also found that if blood taken from an infected organism was
injected into another organism it would contract the disease. To prove that it was not
another component of the blood Koch extracted the bacteria only and injected it into a
healthy organism, subsequently causing the disease. From this research Koch provided
step by step guidelines to prove that a particular micro – organism causes a particular
disease. These are known as Koch’s postulates and are as follows:
1. The specific micro – organism must be present in all infected organisms.
2. The specific micro – organism must be isolated from the host and grown in a pure
culture.
3. A healthy organism is then injected with the micro – organism. This organism
must develop the same symptoms as previous infected organisms.
4. The specific micro – organism must be isolated from the second host and be the
same species of micro – organism as the one originally injected.
It was through the work of Pasteur and Koch, which laid the foundations for scientists to
study micro – organisms. This has led to a greater understanding of infection control and
hygienic practices.
Distinguish between:
- Prions
- Viruses
- Bacteria
- Protozoans
- Fungi
- Macro – parasites
And name one example of a disease caused by each type of pathogen.
TYPE OF PATHOGEN
Prions
Viruses
Bacteria
Protozoans
DESCRIPTION
EXAMPLE(S)
A prion is a special type of
Scrapie in sheep. Bovine
protein that causes the
spongiform encephalitis
degeneration of brain tissue. (mad cow disease) and
Creutzfeldt – Jakob disease.
Viruses are many times
AIDS, chicken pox, genital
smaller then the smallest
herpes, cold sores, measles,
bacterial cell. They are
rubella, glandular fever,
borderline between living
hepatitis and influenza.
and non – living. This is
due to a lack of metabolism
and life characteristics.
Viruses rely on the hosts
individual cells and nucleic
acids to produce more of
the same virus.
Bacteria are disease –
Pneumonia, Cholera,
causing to the host as they
legionnaire’s disease,
multiply rapidly in blood
diphtheria and tetanus.
and tissues. Bacteria also
produce toxins which are
harmful to the host’s body.
Bacteria reproduce by
binary fission which can
take as little as 10 minutes
to as long as 24 hours.
Protozoan’s are classified
African sleeping sickness,
by the way they move. For
Malaria, Amoebic dysentery
example flagellates move
and giardiasis.
by using a whip like
structure called flagellum.
Ciliates move by using tiny
hairs called cilia,
Fungi
Macro - parasites
pseudopods use feet like
structures which are
extensions of the cytoplasm
and sporozoa have no
structures for motion.
Protozoa are mainly found
in water.
Fungi can either be caused
by saprophytes, the fungi
you find on dead plant or
animal tissue or parasitic
fungi such as athlete’s foot.
(Causes flaky, itchy dry
skin.)
Macro - parasites can either
be external parasites
(ectoparasites) or internal
parasites (endoparasites).
Candidiasis (thrush),
athlete’s foot.
Fascioliasis,
Schistosomiasis, hydatid
disease, taeniasis,
enterobiasis, scabies, house
dust (mites).
Identify the role of antibiotics in the management of infectious disease.
Things to consider:
- What does identify mean?
- What are antibiotics and what are their uses?
The chief role of antibiotics is to destroy or inhibit the growth of bacteria. They are
special types of chemicals which act selectively on invading pathogens without affecting
the host. They only work on bacterial infections, not viruses.
Different types of antibiotics target different types of bacteria. ‘Broad - Spectrum,’
antibiotics act on a large range of bacteria while ‘narrow – spectrum,’ antibiotics act on a
small range of bacteria.
Antibiotics work at a cellular level. They interfere with the development of the bacteria
by either damaging or destroying the bacterial cell. For example penicillin has a special
ring shaped molecule which gives it bacteriocidal properties. This affects the formation
of the bacteria’s cell wall.
Gather and process information to trace the historical development of our understanding
of the cause and prevention of malaria.
HISTORY SHOWING THE DEVELOPMENT OF OUR UNDERSTANDING OF
MALARIA
Early 19th Century: Cause of malaria unknown. Antimalarial properties found on
cinchona tree. (Quinine)
1880: First malaria parasite seen in blood by Charles Laveran.
End of the 19th Century: Connection between mosquito and malaria parasite made by
Ronald Ross. Found that mosquitoes carrying the disease infected volunteers who were
bitten by the mosquitoes.
1898: Ross describes the life cycle of the malaria parasite.
The Beginning of the 20th Century: Chemical nature of quinine determined which led
to the synthesis of drugs. Most effective was chloroquin. Continued use of drugs led to
resistance in the malarial parasite.
1940’s: Evidence to suggest that people with one gene for sickle – cell anaemia are more
resistant to malaria due to shape of their red – blood cells.
1990’s – 2000: Continued research to produce a vaccine.
LIFECYCLE OF MALARIAL PARASITE
Firstly a female anopheles mosquito bites a human using their feeding tube or stylet. On
the stylet are many sporozoites. These sporozoites make there way into the bloodstream.
The sporozoites need to develop. This is achieved if the sporozoites make it to the liver.
Once the sporozoites make it to the liver they are supplied with nutrients to grow and
divide. This is known as asexual reproduction and each sporozoite produces 16 smaller
spherical merozoites. They are released into the blood plasma where the merozoites
invade red blood cells. The red blood cells become so full of merozoites that they burst
causing waste product to enter the bloodstream. This causes symptoms such as a fever.
Some merozoites develop into female and male gametocytes. If a mosquito feeds on a
human suffering from malaria these gametocytes maybe transferred into the mosquito.
These gametocytes become gametes in gametes in the mosquito, they replicate and
eventually produce sporozoites, and so the cycle continues.
PREVENTION OF MALARIA
 Anti – Malarial drugs administered before visiting endemic areas.
 Prevention aims to keep the disease at a minimum.
 Breeding grounds of the vector maybe destroyed.
 Draining of swamps and using insecticides.
 Development of vaccines.
 Genetic engineering of mosquitoes to develop individuals who will resist the
parasite.
These are some of the measures to prevent the spread of malaria.
Process information from secondary sources to discuss problems relating to antibiotic
resistance.
Things to consider:
- What does process mean?
- Always refer to antibiotic resistance.
Identify defence barriers to prevent entry of pathogens in humans.
- Skin
- Mucous membranes
- Cilia
- Chemical Barriers
- Other Body Secretions
Things to consider:
- What does identify mean?
- Be succinct; write briefly about each defence barrier.
The body has numerous defence barriers which prevent the entry of pathogens into the
body. They are as follows:
Skin
- Has a tough coating
- Contains chemicals that destroy invading organisms
- Certain bacteria on skin destroy incoming pathogens
- Dry, pathogens rely on damp areas to grow
Mucous membranes
- Production of mucus carries pathogens out of the body
- Nasal passage traps and secretes pathogens
- Respiratory system produces mucus. Reflex actions such as coughing eject the
pathogen from the body
- Urogenital surfaces can produce mucus to excrete any invading pathogens
Cilia
- Found in the nasal, throat, ear and respiratory system.
- Consists of tiny hairs
- With the help of mucus trap pathogens and secrete them out of the body
Chemical Barriers
- Stomach acid provides a lethal environment for pathogens
- Saliva and tears contain lysosomes which destroy invading pathogens
Other Body Secretions
- Other body secretions include; bacteria in intestines, wax in ears, urine and sweat.
These all prevent invading pathogens.
Identify antigens as molecules that trigger the immune response.
Things to consider:
- What does identify mean?
- What is an antigen?
- What is an immune response?
An antigen is a molecule that causes an immune response within the body. Antigens are
carried on pathogens. When the pathogen enters the body, the body recognises the
antigen and begins to produce an immune response.
Explain why organ transplants should trigger an immune response.
Things to consider:
- What does explain mean?
- Relate answer to antigens
- What is an immune response?
The body immune response is due to the invasion of foreign material. In organ
transplants diseased tissue is replaced by healthy tissue such as kidney’s, liver, heart,
lungs and bone marrow. These healthy tissues are foreign to the body and contain certain
proteins (antigens) that are recognised as foreign. The patient’s body then stimulates the
production of antibodies that attack and possibly destroy the new tissue. To prevent the
rejection of the organ transplant the patient’s immune system is suppressed. This is due to
the fact that blood drains into the recipient’s circulation; the body recognises the foreign
tissue cells and produces antibodies in response.
Rejection is reduced by matching the transplanted tissues proteins as closely as possible
with the recipient’s proteins. Anti – rejection drugs are also administered. These suppress
the immune response and prevent rejection of the organs. E.G. Antilymphocyte Globulin
(ALG)
Identify defence adaptation including:
- Inflammation response
- Phagocytosis
- Lymph System
- Cell death to seal of pathogens
Things to consider:
- What does identify mean?
- Consider a suitable method of answering this question such as a table.
DEFENCE
ADAPTATION
Inflammation
response
Phagocytosis
Lymph system
Cell death to seal
of pathogens
DESCRIPTION
When body tissue has been invaded by a pathogen, the area of
infection may become hot, red, swollen and painful. The blood
circulation to that area is increased and the blood vessels dilate
leaking more blood in the infected area. This response helps confine
the pathogen, while the increase in blood volume leads to an
increase of white blood cells which help destroy the invading
pathogen. This process also allows for the quick removal of dead
cells as well as the removal of toxins so that normal body function
can occur. (Histamines and prostaglandins are chemicals which
mediate the inflammation response.)
Phagocytes are a special type of white blood cell which actively
moves from the blood where they ingest and destroy any foreign
materials such as pathogens. This is known as phagocytosis. In acute
inflammation which only lasts for a few hours or days, the main
phagocytes used are called neutrophils. In chronic inflammation
which lasts for weeks or months the main phagocyte used are called
macrophages. This defence adaptation allows for the efficient
decomposition and destruction of invading pathogens.
The lymph system is a network similar to that of our own circulatory
system. This system transports a special fluid known as lymph
similar to that of extracellular fluid. Lymph is transported away from
the cells towards the heart. At various points around the body are
smaller vessels called lymph nodes. Lymph nodes are responsible
for the production of lymphocytes. These lymphocytes are added to
the lymph as it flows through the body. Lymph nodes are also
responsible for engulfing and destroying bacteria and other foreign
material. Lymph nodes become swollen or inflamed when fighting
off infection due to the toxins released by the bacteria. Lymphocytes
are white blood cells the main two types being T cells and B cells.
Sometimes the body will seal of a group of pathogens to form a cyst.
Part of this cyst will involve a group of cells. These cells are
sacrificed so that the pathogen can be destroyed.
Perform an investigation to model Pasteur’s experiment to identify the role of microbes
in decay.
Things to consider:
- What does perform mean?
- What does identify mean?
Refer to page 395. “INVESTIGATION 2: A MODEL OF PASTEUR’S CLASSIC
EXPERIMENT.” Part A ONLY
Gather, process and present information from secondary sources to show how a named
disease results from an imbalance of microflora in humans.
Things to consider:
- What do gather, process and present information mean?
- Ensure you used a named disease
- What is microflora?
- Page 350 – 351
Microflora in humans are microbes which live in the human body without causing
disease. This is a symbiotic relationship whereby the digested food is processed by the
microbe in return for essential vitamins.
An example of a named disease which results in an imbalance of microflora in humans is
candidiasis. The following information outlines how the imbalance of Candida affects a
human:
- Candidiasis is the over population of the yeast/fungus Candida albicans.
- This yeast like organism is highly present in our mucous membranes.
- Candida albicans is controlled by lactobacilli and bifidobacteria largely found in
the intestinal tract.
- When lactobacilli and bifidobacteria numbers drop there is a sudden increase in
the numbers of Candida in the gastrointestinal tract.
- Candida then changes from a yeast like form to a fungal form. This fungal form
has root like structures which enter the lining of the gastrointestinal tract.
- This weakens the gastrointestinal tract and substances usually confined to the
gastrointestinal tract leak into the bloodstream.
- Partly digested proteins enter the bloodstream which results in the production of
antibodies from the immune system.
- This usually results in severe allergic reactions including cerebral (brain)
allergies.
- Rapidly growing populations of Candida can almost relocate anywhere in the
body causing numerous amounts of problems. In children an excess of Candida
usually results in the common disease known as thrush.
It is evident that through a slight imbalance in microflora in humans may result in the
emergence of disease.
(http://www.wadsworth.org/databank/hirez/wongp1.gif)
MICROGRAPH OF CANDIDA ALBICANS
Identify the components of the immune response:
- antibodies
- T cells
- B cells
Things to consider:
- What does identify mean?
- Write brief descriptions of the above components of the immune response.
- Page 367, 368
COMPONENTS OF
IMMUNE
RESPONSE
ANTIBODIES
T CELLS
B CELLS
DESCRIPTION
Antibodies also known as immunoglobulins are produced in the
lymph nodes by B cells in response to a specific antigen.
Antibodies are special proteins which circulate in the blood
plasma and combine with B cells to destroy antigens. This is
called antibody – mediated immunity.
T cells are a type of lymphocyte which form in the bone marrow
and mature in the thymus gland. They remain inactive while
travelling around the body until they come into contact with an
antigen. The T cell binds onto the antigen and makes copies of
itself. T cells control the cell – mediated response whereby
various types of T cells destroy the antigen or foreign cell.
B cells develop and mature in the bone marrow. B cells are
activated in the blood when there is a presence of an antigen.
Activated B cells clone themselves into either plasma cells
which send antibodies into the blood or into memory cells.
Describe and explain the immune response in the human body in terms of:
-
interaction between B and T lymphocytes
the mechanisms that allow interaction between B and T lymphocytes
the range of T lymphocyte types and the difference in their roles
Things to consider:
- What does describe and explain mean?
- Identify the best way to answer this question.
- Understand what you are writing before you write it down.
The immune system and the components within the immune system are constantly
interacting with one another to provide the best defence against invading organisms. One
such interaction is the interaction between B and T lymphocytes (cells). T cells and B
cells work together by attacking the same antigen. Helper T cells, a special type of T cell,
stimulate the cloning of T cells and B cells to help destroy invading pathogens. T cells
can also trigger an immune response in B cells by secreting a substance known as a
cytokine. This special protein signals other cells to trigger an immune response. Although
B cells and T cells are constantly interacting there are certain mechanisms in place which
prevent these cells from attacking one another. For example if a B cell is expressing an
antigen on its membrane it is not destroyed by another T cell. The body has adapted a
mechanism whereby cells are capable of recognising “self” molecules. This prevents the
unnecessary destruction of the bodies own cells.
There are a range of T cells that all have a specialised function in preventing the spread
of disease in the human body. Cytotoxic T cells destroy cells that contain foreign
antigens. These non – self molecules such as bacteria are destroyed by cytotoxic T cells
and are removed from the body. Helper T cells secrete a chemical known as interleukin
which regulates the function of T and B cells. Suppressor T cells regulate the activity of
B and T cells. For example cytotoxic T cells are suppressed once they have carried out
their role.
Outline the way in which vaccinations prevent infection.
Things to consider:
- What does outline mean?
- What are vaccinations?
- Be succinct
The process of vaccination also known as immunisation is the process of making people
resistant to an infection caused by a pathogen. Vaccines can be administered in two ways,
one via injection the other via an oral dose. Vaccines are a preparation of a weakened or
dead infective micro – organism. This dose is injected into the patient with the intention
of eliciting an immune response to the disease without causing any symptoms. Some
vaccines are only administered once as the patient will have immunity for life, for
example the measles vaccine. Other types of vaccines require a “booster,” vaccine which
is administered 5 – 10 years after the original vaccination. This increases the immunity
against the disease, a type of this vaccination is tetanus. Overall vaccinations prevent
disease as they enable our body to register an immune response and build up memory
cells which in turn will fight the disease if the person is ever exposed to that disease.
Outline the reasons for the suppression of the immune response in organ transplant
patients.
Things to consider:
- What does outline mean?
- Relate answer to the immune system.
- Understand what the question is asking before you answer.
Suppression of the immune response is a necessity after an organ transplant in order for
the new organ not to be rejected by the recipient. As some blood from the donated organ
enters the blood stream of the recipient, the body recognises the foreign tissue cells and
begins to produce antibodies in response. A number of cells such as cytotoxic T cells are
produced which could affect the implanted tissue.
The rejection of this organ is reduced by closely matching the donor organs proteins to
the recipient’s proteins. By doing this it allows the recipient a higher chance of accepting
the organ. The immune system is also suppressed after an organ transplant.
Antilymphocyte globulin (ALG) is a drug that suppresses the immune response. This
drug allows the recipient a greater chance of accepting the organ rather then destroying it.
A balance between suppressive drugs and monitoring increases the chances of the organ
transplant being a success.
Identify and describe the main features of epidemiology using lung cancer as an example.
Things to consider:
- What does identify and describe mean?
- What is epidemiology?
- Be succinct.
Epidemiology is the study of disease that affects many people. These types of studies
describe the patterns and causes of certain diseases within a population. The diseases
studied can be infectious diseases such as influenza and non – infectious diseases mainly
caused by lifestyle and environmental factors. Epidemiological studies have been able to
establish links between smoking and lung cancer. With this knowledge government
agencies can take preventative measures such as warnings on smoking packets or
advertisements which show the adverse effects smoking has on the human body. It is
through epidemiology scientists have been able to draw links between disease and certain
underlying factors which in turn gives rise to treatment, control and prevention.
Identify causes of non – infectious disease using an example from each of the following
categories:
- inherited disease
- nutritional deficiencies
- environmental diseases
Non – infectious disease is caused by many underlying factors. These factors include the
malfunction of the physiology, metabolism or structures of the body. These malfunctions
lead to the deprivation and disease for the human body. Non – infectious disease falls into
three main categories. Firstly inherited disease is a non – infectious disease passed on
from generation to generation through the genetic code of the family. An example of an
inherited disease is Down syndrome. Secondly nutritional deficiencies cause non –
infectious disease by either malnutrition (nutrients totally unbalanced) or under - nutrition
(not enough food). Some examples of nutritional deficiencies include anorexia nervosa,
kwashiorkor and Aboriginal nutritional diseases. Thirdly environmental factors cause non
– infectious disease by polluting the body with unnecessary and often poisonous
substances. Such substances include alcohol, tobacco, drugs and heavy metals. These
poisons can cause disease such as heavy metal poisoning, cirrhosis of the liver or lung
cancer.
Gather, process and analyse information to identify the cause and effect relationship of
smoking and lung cancer.
Ever since the introduction of tobacco and smoking, there has always been the conception
that smoking causes lung cancer. This was thought to be true as early as the 1920’s.
Subsequently epidemiological studies were performed between the 1930’s – 1960’s to
test whether or not smoking was the cause of lung caner. Two significant studies were
produced by Doll (1947) and Hill (1951).
Doll used a case study report by comparing two different groups of people. The first
group of people all had lung cancer while the other group had various diseases. Both of
these groups were asked about their smoking habits. What Doll found was that a large
percentage of the lung cancer patients were smokers while the control group a smaller
percentage were smokers and it was quite possible that their illness was caused by
smoking as well. Doll’s results were as follows:
CASES
TEST GROUP
CONTROL GROUP
Smokers
1350
1296
Non – Smokers
7
61
Total
1357
1357
Hill’s cohort study involved a number of doctors across Great Britain. The study involved
the doctors answering a number of questions on their smoking habits. Those doctors who
were smokers were part of the smoking group, while those doctors who did not smoke
were part of the control group. Both groups were followed over a 10 year period. During
this period 133 people died. Of those 130 of them were smokers. The results were as
follows:
DAILY NUMBER OF CIGARETTES
DEATHS FROM LUNG CANCER
SMOKED
0
3
1 – 14
22
15 – 24
54
25+
57
133
TOTAL
The above table indicates that the greater the number of cigarettes smoked a day the
greater chance of death by lung cancer.
Subsequently many more epidemiological studies have taken place to illustrate the cause
and effect relationship between smoking and lung cancer. This has lead to a greater
awareness of the risk factors involved with smoking.
Identify data sources, plan and perform a first – hand investigation or gather information
from secondary sources to analyse and present information about the occurrence,
symptoms, cause, treatment/management of a named non – infectious disease. (Page 384
– 388)
Things to consider:
- This will be a secondary source task. What does gather, analyse and present
mean?
- How will you present your findings?
- Choose one disease and be succinct.
DOWN SYNDROME
OCCURRENCE
SYMPTOMS
CAUSE
The occurrence of down syndrome increases with
the age of the mother. The general rule of thumb is
that the chance of having a baby with down
syndrome increases with maternal age. However
the chance of having two babies with down
syndrome is less then 1%. According to Wikipedia
down syndrome occurs in 1 in 800 – 1000 births
however there are many underlying factors which
affect this result.
Symptoms of down syndrome include; mild to
sever mental retardation, small flat nose, skin folds
at the eye corners, appearance of slanted eyes,
protruding tongue, small ears, shorter neck, arms
and legs, increase chance of eye defects (often wear
glasses) and an increase chance of heart defects.
There are 3 types of down syndrome. Their causes
are outlined below:
Trisomy 21 – occurs in about 92% of down
syndrome cases. Trisomy 21 is caused by the
presence of an extra chromosome 21 in all cells.
Mosaic trisomy 21 – occurs in about 2 – 4% of
down syndrome cases. Mosaic trisomy 21 is caused
by the presence of an extra chromosome in some of
the babies cells.
Translocation trisomy 21 – occurs in about 3 – 4%
of down syndrome cases. Translocation trisomy 21
is caused by chromosome 21 getting stuck or
translocated during conception or growth of the
baby during pregnancy. This results in the baby
having 46 chromosomes but expressing down
syndrome symptoms.
TREATMENT/MANAGEMENT There is no cure as such for down syndrome.
However there are special education programs
which can assist children. Many children with
down syndrome can become independent and live
normal lives.
Explain how one of the following strategies has controlled and/or prevented disease:
- public health programs
- pesticides
- genetic engineering to produce disease – resistant plants and animals (Page 389 –
391)
Things to consider:
- What does explain mean?
- You only have to choose ONE. Some knowledge on all three could be beneficial
(if you have time).
- Be succinct.
Through genetic engineering scientists have been able to produce disease resistant plants
and animals. By increasing our knowledge of certain plants and livestock, and their
genetic make – up, humans have been able to increase food supplies. Genetic engineering
is a relatively new study and the full potential of this technique has not been realised.
For example Australian scientists have produced a genetically modified pea that is
resistant to the pea weevil. The pea weevil consumes large amounts of crops every year
in Australia. The gene that confers resistance to the pea weevil was extracted from the
common kidney bean. This gene was spliced into the pea crops. The result was that the
gene produces a certain protein that can not be broken down by the larvae and hence the
larvae die out.
A simple animal example is humans. In medicine scientists have genetically engineered
insulin using recombinant DNA to help control diabetes.
Perform an investigation to examine plant shoots and leaves and gather first – hand
information of evidence of pathogens and insect pests.
Things to consider:
- What are insect pests? (Rose bush cuttings will be acquired. Look for tiny insects
known as aphids. These insects suck the sap out of the rose bush.)
- What are pathogens? (Look for discolouration of leaves or bulges/growths on
leaves and stems
- Refer to page 397 for experimental procedure. Complete questions 1 – 4 and
conclude your experiment.
ASSESSMENT DOT POINTS
The following dot points were covered in your assessment. I have not written any
responses to these dot points, however if you need assistance with these please notify
myself as soon as possible.
1. Identify data sources, gather process and analyse information from
secondary sources to describe one named infectious disease in terms of
its:
 Cause
 Transmission
 Host Response
 Major Symptoms
 Treatment
 Prevention
 Control
2. Process, analyse and present information from secondary sources to
evaluate the effectiveness of vaccination programs in preventing the
spread and occurrence of once common diseases, including smallpox,
diphtheria and polio.
3. Discuss the role of quarantine in preventing the spread of disease and
plants and animals into Australia or across regions of Australia.
4. Process and analyse information from secondary sources to evaluate the
effectiveness of quarantine in preventing the spread of plant and animal
disease into Australia or across regions of Australia.
5. Gather and process information and use available evidence to discuss the
changing methods of dealing with plant and animal diseases, including the
shift in emphasis from treatment and control to management or prevention
of disease.