Search for Better Health Booklet

7/28/2019 Search for Better Health Booklet

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9.4 SEARCH FOR BETTER HEALTH(booklet)

(Last updated 5th May 2011 by SR/IR)

1. What is a healthy organism?

What is meant by the term disease?

Background: Disease is any condition that adversely affects the function of any partof a living thing. Health is the wellbeing of the organism. All our body functions, whichare under the control of our genes, work together to maintain health.

Discuss the difficulties of defining the terms 'health' and 'disease'

The definition of disease above is very broad. Disease can cover a wide range ofconditions that fit the above definition including minor conditions, such as a cutfinger or an ant bite, as well as the more obvious diseases.

Health varies on a daily basis and is not just the absence of disease. Healthvaries with age and the susceptibility to disease. It is a state of physical, mentaland social wellbeing.

The difficulties of defining the terms health and disease include that:o it is possible for a person to be healthy and have a disease at the same

timeo the terms are used in general conversation and have different meaning to

the scientific definition.

Use available evidence to analyse the links between gene expression andmaintenance and repair of body tissue

Gene expression refers to the transfer of information from a gene to produce aprotein or RNA. If you cut yourself, the genetic code contained in all your cells isused to form the new tissue to repair the damage from the cut.

Analyse the information by identifying cause and effect relationships betweengene expression and the maintenance and repair of body tissue.

Consider, that if a certain gene expresses, what the effect will be on:

o regulation of the cell cycleo mitosiso protein synthesis.

Use the information you have gathered to synthesise an account of the

connection between gene expression and the maintenance of healthy tissue.

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Outline how the function of genes, mitosis, cell differentiation andspecialisation assist in the maintenance of health

Gene expression is essential for the maintenance of health.

Genes are the units of inheritance. They control the process of protein synthesis.They assist the maintenance of health by regulating the cell cycle and limitingthe growth and reproduction of cells. Genes provide the code for proteins thatare needed for growth and repair. Enzymes, which control all body processes,are proteins and thus have been produced from the codes of genes.

Mitosis is cell division that produces identical cells. These cells are important forgrowth and reproduction. Each day millions of cells die and are replaced by theprocess of mitosis.

Cell differentiation is the process undergone by the cells that are formed aftermitosis. Each cell has the genetic information necessary to produce all types ofcells. However, each cell normally differentiates to become a specialised cell,with a specialised structure and function. Undifferentiated cells form tumours.


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Many types of cells have specialised roles in maintaining the health of anorganism. For example, there are specialised blood cells that produce antibodiesto attack a disease causing micro-organism.


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2. Infectious and non-infectious diseases

2. Over 3000 years ago the Chinese and Hebrews were advocatingcleanliness in food, water and personal hygiene

Background: Even though they did not know about microscopic disease-causing

organisms, many social groups established rules and practices that protected peopleagainst infectious diseases. These practices resulted from observing cause and effectrelationships. For example, the Chinese could have deduced the connection betweenwater contaminated by faeces and gastro-intestinal diseases, and the Hebrews maywell have made a connection between the symptoms of infection by tapeworms andeating undercooked pork.

Distinguish between infectious and non-infectious disease

An infectious disease is one that is caused by an organism and that can betransferred from one person to another. The transfer may be direct, where thedisease-causing organisms, such as viruses or bacteria, pass directly fromperson to person, or it may be carried out by an intermediary (called a vector),such as a blood-sucking insect. Examples of infectious diseases are colds,influenza, chicken pox, herpes and measles.

Non-infectious diseases are diseases that are not due to disease-causingorganisms. They include genetic diseases, such as Down syndrome,haemophilia, and those that are related to lifestyle or environment, such ascardiovascular disease and skin cancer.

Identify data sources, plan and choose equipment or resources to perform a

first hand investigation to identify microbes in food or in water

Agar is a jelly-like substance obtained from seaweed. When it is dissolved inwater, nutrients suitable for microbes can be added to it before it sets to form agel. If a microbe makes contact with the agar and if conditions are suitable, themicrobe will grow and reproduce to form a visible colony.

To design a first-hand investigation to identify microbes in food and water, firstlyidentify data about microbiological techniques from practical manuals or theInternet. Gather information about the techniques used to grow micro-organisms on agar plates in Petri dishes. You will need to know what sort ofnutrients can be added to agar, the correct way of exposing the agar to the

source of micro-organisms and the safety precautions that must be followedonce a plate has been exposed. Also you will need to know the best temperaturefor microbial growth and how to distinguish between colonies of bacteria andfungi, growing on agar plates.

Use the information to plan a valid and reliable investigation. You will needto decide on which nutrients you will add to the agar, what food and watersamples you will test and how you will expose the agar to the microbes thatmay be present in your food and water samples. Decide on the temperature youwill provide for microbial growth.

Choose equipment and resources that will ensure your investigation is safe.

Carry out a risk assessment of your experimental procedures and addresspotential hazards. In this type of investigation, the most important safetyprocedures are:

o to seal and not open again the Petri dishes after exposureo to correctly autoclave exposed Petri dishes prior to final disposal.


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Perform your investigation. Dispose carefully and safely of the waste materialsproduced during the investigation. Safe working practices such as wearing latexgloves, washing benches and hands with chemical treatments for sterilisationare important when working with micro-organisms.Use data from the investigation to explain why cleanliness in food, water andpersonal hygiene practices are important.

Explain why cleanliness in food, water and personal hygiene practices assistin the control of disease

There are huge numbers of disease causing organisms. Most of them aremicroscopic and can enter the body through any body opening. The intake offood and water provide an easy way for micro-organisms to enter our bodies.Therefore, minimising the number of such organisms in our food and waterreduces the risk of infection. Good personal hygiene ensures that bodyopenings, including broken skin, are clean, so that the number of micro-organisms that might gain entry to our bodies is kept low. Since we cannot seeindividual micro-organisms we take precautions that we know will help toprotect us. Examples of precautions include, washing hands after going to thetoilet, cleaning wounds, boiling water and water treatment of water that doesn'tcome from a known safe source to make sure untreated sewage does not getinto food or water supplies.

Identify the conditions under which an organism is described as a pathogen

A pathogen is any organism that can produce a disease. Pathogens range fromviruses so small that thousands will fit side by side in one millimetre to

tapeworms that can be several metres long. They are all infectious. Pathogens may live outside the body, such as the fungus that causes ringworm,

inside particular organs, such as parasitic worms in the intestine, in tissues orinside cells. Some information on water pathogens is found below.

Gather, process and analyse information from secondary sources to describeways in which drinking water can be treated and use available evidence toexplain how these methods reduce the risk of infection from pathogens

Contamination of drinking water is a common way for pathogens to enter the body.

Gather information from your local water supply authority or the Internet to findout the ways in which water can be treated and the range of pathogens that aretargeted.

Process your information by recording a description of each water treatmentmethod and by looking for trends and patterns in why they are used.

Information to get you started

Examples of water treatments are filtration, chlorination and ozone filtration. InNSW water is filtered, chlorine is added to kill bacteria and samples are tested

for the presence ofcoliform bacteria, giardia and cryptosporidium.

Use questions as an effective processing technique to focus your attention whenlooking for trends in information sources. Some examples in this case might beWhich microbes are controlled by the treatment?, Which microbes are not


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controlled by the treatment? and What combination of treatments can be usedto make a water supply safe for drinking?

Use the evidence you have gathered to propose logical explanations of howeach form of water treatment protects people from the target pathogens.


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3. Identifying microbes that cause disease

3. During the second half of the nineteenth century, the work of Pasteur andKoch and other scientists stimulated the search for microbes as causes ofdisease

Background: Microbes as the cause of infectious disease:

Until mid 19th century, spontaneous generation believed origin of living things.

Derived from non-living matter.

680, Francesco Redi disproved spontaneous generation.

Scientists refused to accept his results.

Belief of spontaneous generation remained.

Prevented people understanding causes of disease & transmission.

Describe the contribution of Pasteur and Koch to our understanding ofinfectious diseases

Louis Pasteur

The role of Pasteur in identifying the causes of disease was:o that he disproved the theory ofspontaneous generation, which was widely

held at the time. Before Pasteur's work, people believed that maggots andfungi grew naturally from non-living material

o that he showed that micro-organisms came from pre-existing micro-organisms.

o Discovered germ theory of disease:o Most infectious diseases caused by micro-organisms or germs.o Examined fermented wines under microscope.o Described micro-organisms growing.o Demonstrations of living organisms existing in air destroy theory of

spontaneous generation.o Showed French wine industry that heating wine to 55oC destroyed

microorganisms.o Pasteurisation - Now applied to:

Beer; Milk.

o Founded vaccination.

Inoculated 25 sheep with weakened Bacillus anthracis (anthraxbacteria);

Injected 50 sheep with strong dose of anthrax;

Predicted 25 would die;

25 inoculated sheep survived.

Developed vaccination for Anthrax, Chicken cholera, Swine

erysipelas. Developed rabies vaccination in 1885, saved life of infected boy.

Robert Koch


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About 150 years ago, Pasteur's work in identifying, under the microscope, theorganism that caused fermentation, led some people to suggest the infectiousdiseases were caused by microscopic pathogens. Others argued that bacteriafound in sick animals followed the infection, rather than causing it.

The work of Robert Koch (1843 - 1910) provided the proof that was needed toconvince people that microscopic pathogens cause disease. His first

experiments were with the disease anthrax in sheep. Later, he obtained similarresults for tuberculosis and cholera.

First Koch found bacteria in sheep infected with anthrax. Then, he placed thebacteria on agar plates in Petri dishes so that many colonies of the bacteriawere produced. He used bacteria from these colonies to infect healthy sheepand found that they became infected.

After his experiments with anthrax, Koch was able to state a series of steps thatare needed to identify the micro-organism responsible for a particular disease.These steps are called Koch's postulates.

o Step 1: All infected hosts must contain the suspect organism.o Step 2: A pure culture of the suspect organism must be obtained.o Step 3: A healthy organism infected with the pure culture must have the

same symptoms as the original host.o Step 4: The suspect organism must be isolated from the second host,

grown in pure culture and prove to be identical to the first culture. Koch's postulates can be used to identify the causative organism of an

infectious disease. The symptoms of the disease are carefully identified andthen the blood of sufferers is examined to determine possible causativeorganisms. A particular micro-organism will be suspected if other sufferers havethe same micro-organism present in their blood and a mechanism can beidentified to allow transfer of the micro-organism. Identification of the organism

in more sufferers will confirm the causative organism. Sometimes, a suspectedcausative organism can be confirmed by infecting a test organism.

Perform an investigation to model Pasteur's experiment to identify the roleof microbes in decay

Perform Pasteur's experiment that showed that something from the air causesmeat broth to go bad. As you conduct your experiment consider which variablesneed to be kept constant and be able to explain which are the dependent andwhich are independent variables.

Procedure:

1. Use a meat extract cube to make a clear broth.2. Use two conical flasks instead of Pasteur's balloon flasks. Fit the flasks

with one-holed stoppers. Use glass tubing bent into an S-shape to replacePasteur's swan-necked flask. Place a straight piece of glass tubing in theother flask.

3. Put some broth into both flasks and boil gently for fifteen minutes.4. Leave both flasks, not in direct sunlight for several weeks. Every two or

three days compare the contents of the two flasks. Look for cloudiness,

scum, bubbles and mould colonies. Record your results. Assess the accuracy of your observation and the relative importance of the data

gathered. You could do this by comparing your experiment with the descriptionof Pasteur's experiment, which follows.


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Pasteur's experiment When Pasteur did his experiment, the broth in the swan-necked flask remained

clear for several weeks, while that in the open flask quickly became cloudy andsmelly.

Both flasks were open to the air. In the swan-necked flask, air could move freelythrough the neck of the flask just as it did in the straight-necked flask, but the

much heavier micro-organisms, in the air, were trapped in the bottom part ofthe S-curve.

This experiment showed that for the broth to grow micro-organisms and start todecay, there had to be access to air containing the spores of micro-organisms.


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Gather and process information to trace the historical development of ourunderstanding of the cause and prevention of malaria

Background on malaria

Malaria is a disease caused by a protozoan of the genus Plasmodium. It has acomplicated life cycle requiring a mosquito of theAnopheles genus to carry thePlasmodium to its host. The disease is common in tropical areas where theAnophelesmosquito lives. The female mosquito requires a blood meal to complete thereproduction cycle of the mosquito. During the blood meal the Plasmodium(sporozoites) are transferred from the mosquito salivary glands into the blood systemof the host. The sporozoites travel to the liver via the blood system and enter cells inthe liver. After 12 days a new form of the protozoan called merozoites are releasedand these enter blood cells. At the same time toxins are released. This causes thesweats and fever that are associated with the disease. Some of the merozoitesdevelop into gametocytes and may be sucked up by another mosquito in anotherblood meal. In the gut of the female mosquito the gametocytes become gametes andare fertilised. This forms sporozoites which will travel to the salivary glands of thefemale mosquito and await the next blood meal to enter another host.

The disease was known from the start of recorded history but it took manyresearchers to uncover the complicated life cycle above. Sir Ronald Ross (1857 -1932) was a British medical officer working in India. For thousands of years, peoplehad been puzzled about the way in which malaria spread but they knew that malariawas common in areas close to swampy land. In the late 1800s, people were beginningto wonder if mosquitoes could spread malaria. Ross collected mosquitoes and

painstakingly dissected them under a microscope. He discovered the micro-organismthat was known to cause malaria, inside the bodies ofAnopheles mosquitoes. This ledto the realisation that insects could carry pathogens, that is, they can be vectors ofdisease.

Use reference books or the Internet to gather information to trace howscientists identified the cause and prevention of malaria.

Process this information to show how their work contributed to ourunderstanding of the cause and prevention of malaria. Trends and patternscould be well illustrated through the use of an annotated timeline. The tablebelow is a guideline.

Date Development

18 BCThe disease malaria was described by the Romans. Malaria was thought tocome from swamps so the name means 'bad air'

1820 Quinine used to prevent the disease

1880 Charles Laveran a French army doctor observed the malarial parasite

1886Golgi observed asexual reproduction in the protozoan Plasmodium andidentified two species

1898Giovanni Grassi named theAnopheles mosquito as the carrier of themalarial parasite

1897Ronald Ross discovered that Plasmodium was the protozoan that causedthe disease malaria.

1940 Chloroquinine the first synthetic anti-malarial drug was used


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Distinguish between:

o prionso viruseso bacteria

o protozoanso fungio macro-parasites

and name one example of a disease caused by each type of pathogen

Pathogen Description Examples of diseases it causes

Prions Protein that has been altered fromits normal structure and can thenalter other proteins to develop moreprions, so that the change spreads

like a chain reaction.

scrapie in sheep spongiform encephelopathy in cattle

(mad cow disease)

Creutzfeldt-Jakob (CJD) disease inhumans

Viruses Consist of DNA or RNA enclosed inprotein, live inside living cells. Theyare so small that they cannot beseen with a light microscope.

influenza measles a common cold herpes AIDS Warts Hepatitis Foot-and-mouth disease

Plum pox virus

Bacteria Very simple cells with no internalmembranes.

Boils Cholera Legionnaire's disease Tuberculosis

Crown gall blight

Protozoans Microscopic single-celled organismswith internal membranes.

Amoebic dysentery Giardia,

Malaria,

Fungi Heterotrophic organisms. Some (e.g.yeasts) are unicellular, others consistof long branching threads.

Ringworm Tinea Thrush

Many plant diseases such as dampingoffin seedlings

Macro-organisms

Organisms that are visible to thenaked eye, also called parasites.

fleas ticks tapeworms bilharzia worms hydatid worms liver fluke

many plant parasites, e.g. aphids


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Identify the role of antibiotics in the management of infectious disease

Antibiotics play an important role in the management of infectious diseases.Antibiotics were discovered by Alexander Fleming in 1928. They are naturallyoccurring compounds produced by one organism to prevent the growth of

bacteria. Before the discovery of antibiotics, many people died of what we nowwould think of as simple infections.

Processinformation from secondary sources to discuss problems relating toantibiotic resistance

Background

Unfortunately, the overuse of antibiotics has led to the selection of more virulentbacteria that are resistant to antibiotics.

When antibiotics were first introduced, they had a dramatic effect on the pathogensthat cause disease. Over time, it became apparent that the effects of the antibioticswere beginning to become less potent. This was because of the development of drugresistance in the pathogen. Each time an antibiotic is used, there may be someindividual pathogens that have a natural resistance to the drug. These naturallyresistant individuals are left to breed the next generation and pass on the geneticinformation that made them resistant. The next time the drug is used, it will have noeffect. Overuse of antibiotics has resulted in "superbugs". These strains are resistantto antibiotics and include vancomycin resistant golden staph (Staphylococcus aureus).These organisms are not destroyed by our strongest antibiotics. Scientists are

developing new antibiotics such as Zyvox to deal with multi-resistant bacteria. In thefuture, unless new antibiotics are produced, common infections will once again beresponsible for many deaths.

Many household products and cleaning agents now contain antibiotics. These do notkill all bacteria so act as a selecting agent for antibiotic resistant bacteria. These canincrease in number without competing with other bacteria.

The use of antibiotics in farm animals also has the same effect of selecting forantibiotic resistant bacteria. Some farm industries put human antibiotics into the feedof their animals, thus increasing the build up of antibiotic resistant bacteria. During

the production of meat, animals are given antibiotics to prevent infections. When themeat reaches the table, it may still contain these animal antibiotics. This could lead tomore antibiotic resistant bacteria.

It is important to complete a course of antibiotics even when the symptoms are gone.This will ensure that the bacteria have been completely destroyed. Not finishingantibiotics can lead to the selection of antibiotic resistant strains.

Process this information to discuss the problems of antibiotic resistance. Trendsand patterns could be illustrated by the unending cycle between theintroduction of new antibiotics and the development of resistance in bacteria.


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Identify data sources, gather, process and analyse information fromsecondary sources todescribeone named infectious disease in terms of its:

o causeo transmission

o host responseo major symptomso treatmento preventiono control

To address this dot point, it is a good idea to select an infectious disease thatinterests you or that represents a significant problem in your community.

Use the list presented in the dot point to determine the type of informationthat you need to collect. Gather the information from a range of sourcesincluding digital technologies, locally available health brochures or pamphletsand the Internet. Process the accuracy of the information by looking forinformation that is consistently represented across a range of reputablepublications. Analyse your information by developing accurate generalisationsinto short notes.

A good example of a named infectious disease is malaria. The following is adescription of the disease.

Factors Description

Cause The parasitic protozoan, Plasmodium

Transmission Anopheles mosquito is the insect vector. Blood from a malaria victimcontains Plasmodium sex cells. These form zygotes in cysts in the stomachwall of the mosquito and mature into sporozoites. When a cyst bursts, thesporozoites travel to the mosquito salivary glands, from where they aretransferred to the victim of the mosquito bite. The sporozoites travel to theliver, multiply and then enter the red blood cells, where they also multiply.When the infected cells burst, they cause the malarial fever. Male andfemale gametes are produced from these sporozoites, which are then takenin the blood the next time a mosquito bites.

Host response When in the blood cells the host produces antibodies against Plasmodium

Major symptoms Chills, fever, sweating, delirium and headache

Treatment Anti-malarial drugs such as quinine and chloroquinine

Prevention Cover up after dark and use personal insecticide, mosquito nets

Control Draining swamps, spraying with insecticides.


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4. Defence against disease

4. Often we recognise an infection by the symptoms it causes. The immuneresponse is not so obvious, until we recover

Background: Our bodies have three types of defence against pathogens. The firstconsists of several barriers that prevent the entry of micro-organisms. The second isthe action of white blood cells in destroying foreign particles, in a process calledphagocytosis. The third is carried out by the immune system, which plays a complexrole in targeting and destroying pathogens as well as helping to make our bodiesresistant to them.

Our bodies contain very large numbers of bacteria (15% of your body weight) andmany of those in the intestine are essential for our wellbeing. The collective term forall the micro-organisms in our bodies, both the beneficial and harmless ones, ismicroflora. An imbalance of microflora in the gut can lead to disease symptoms suchas diarrhoea and malabsorption of nutrients.

Gather, process and present information from secondary sources to showhow a named disease results from an imbalance of microflora in humans.

Background: Pathogenic microflora usually attack specific parts of the body. Forexample, the protozoan that causes malaria lives in red blood cells, the bacterium thatcauses cholera lives in the intestine, the bacterium that causes trachoma lives in theeyes, one type of the Herpes virus is active in cells around the lips and nose (causing

cold sores) and another type is active in cells in the genital area (genital herpes).

Choose a disease that results from an imbalance of microflora in humans, suchas Crohn's disease or candida (thrush). Use biology textbooks, library referencesand, if possible, the Internet to gather information about the cause, symptomsand effects of the disease.

To process the sources you find, assess their reliability by comparing theinformation provided. Look for consistency of information.

It is appropriate for this syllabus point that you present your findings as areport. A scaffold and some language features of a report follow:

Scaffold for a report Features

Classification

Classify the disease. Briefly preview the features to bedescribed. Use generalised terms. Use linking verbs like is,has, becomes. Use present tense.

Description

(Feature 1: e.g. cause)

(Feature 2: e.g. symptoms)

(Feature 3: e.g. effects)

Focus on a specific feature for each paragraph.Begin each paragraph with a topic sentence.

Use present tense.

Use action verbs, such as occurs, called, makes.


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Identify defence barriers to prevent entry of pathogens in humans:

o skino mucous membraneo cilia

o chemical barrierso other body secretions

Line of defence Description What it does

skin Skin continuously grows by newcells being produced from below.Cells fit tightly together to form aprotective layer covered by deadcells.

When unbroken, skin prevents theentry of pathogens. Pores in theskin secrete substances that killbacteria.

mucous membrane cells lining the respiratory tractand openings of the urinary andreproductive systems that secretea protective layer of mucus

Mucus is sticky and trapspathogens and other particles.When there are many pathogensmore mucus is produced to flushthem out.

cilia Hair-like projections from cellslining the air passages

Move with a wavelike motion topush pathogens from the lungs upto the throat.

chemical barriers acid in the stomach; alkali in thesmall intestine; the enzyme,lysozyme, in tears

Stomach acid destroys pathogens,including those that are carried tothe throat by cilia and thenswallowed. Alkali destroys acidresistant pathogens. Lysozymedissolves the cell membranes ofbacteria.

Other bodysecretions

secretions from sweat glands andoily secretions from glands in hairfollicles

Contain chemicals that destroybacteria and fungi.


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Identify defence adaptations, including:

o inflammation responseo phagocytosiso lymph system

o cell death to seal off pathogen

inflammation response

Inflammation occurs when blood vessels around an infected area are suppliedwith extra blood. This makes the area swollen and red. The release ofhistamines by the damaged tissue increases the permeability of the bloodvessels, which allows white blood cells to leave the blood vessels and move intothe damaged tissue.

phagocytosis

Some white blood cells, called macrophages and neutrophils, can very easilychange their shape so that they flow around particles and completely enclosethem within their cell, where they are broken up by cell enzymes. This is calledphagocytosis.

lymph system

The lymph system returns intercellular fluid to the blood system, filters celldebris and produces white blood cells responsible for the immune response.

cell death to seal off pathogen

For some pathogens, macrophages and lymphocytes completely surround apathogen so that it is enclosed in a cyst. The white cells involved die, so that thepathogen is isolated from its food supply and also dies.

Identify antigens as molecules that trigger the immune response.

Background: If the previous two systems fail to destroy a pathogen then the immunesystem comes into operation. It depends on distinguishing between parts of the bodyand particles from outside. It is important that phagocytes are able to make thisdistinction, otherwise they would destroy body cells.

Any molecule that the body recognises as being foreign is called an antigen.Antigens activate the immune response.

Explain why organ transplants should trigger an immune response.

Organs from another organism are recognised as foreign by the human immune

system. The surfaces of the new organ contain antigens. These trigger animmune response and body attacks the new organ as if it were a pathogen.


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5. The immune response

5. MacFarlane Burnet's work in the middle of the twentieth centurycontributed to a better understanding of the immune response and theeffectiveness of immunisation programs

Background: Sir Frank Macfarlane Burnet was an Australian scientist who won theNobel Prize for his research into physiology. He studied immunology and worked onthe development of the influenza vaccine.

Identify components of the immune response

o antibodieso T cellso B cells

Name What it is What it does

antibodies proteins that the body produces whenit detects antigens. Each differentantigen stimulates the production ofits own particular antibody.

join with antigens so that they areclumped together and can be moreeasily recognised and destroyed bymacrophages

B cell a special kind of lymphocyte producedin the bone marrow (thus B cell)

When a B cell recognises an antigen, itdivides repeatedly to produce a massof identical cells (clones) that work asantibody producers (plasma cells).

T cell another kind of lymphocyte, that ispassed through the thymus gland(thus T cell)

Some produce toxic substances thatdestroy cells that have been invadedby a virus. Others help the B cells todivide rapidly.

Describe and explain the immune response in the human body in terms of:

o interaction between B and T lymphocyteso the mechanisms that allow interaction between B and T lymphocyteso the range of T lymphocytes types and the difference in their roles

Interaction between B and T lymphocytes

B and T lymphocytes interact as they are both attacking the same antigen. Helper Tcells (see below) stimulate B cells and T cells to clone.

The mechanisms that allow interaction between B and T lymphocytes

The T lymphocytes that help B lymphocytes are called helper T cells (Th cells). If a Bcell has an antigen on its surface, there is a risk that a T cell will recognise the antigenand attack it together with the B cell. This does not happen because T cells are able torecognise self molecules that are on the surface of B cells. Every person has theirown particular "self" molecules, so there are millions of different B cells. They are like


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personal identity used to identify cells to T lymphocytes. This means that, in the caseof organ transplants, T cells can recognise cells that have come from a different bodyand so help B cells to destroy them. Only identical twins have the same selfmolecules on their B cells.

The range of T lymphocytes types and the difference in their roles

Type of T cell Roles

killer T cells (Tc cells) attack and destroy macrophages that have engulfed an antigen. Theyproduce cytotoxins.

helper T cells (Thcells)

secrete chemicals that stimulate cloning in B and T cells

memory T cells remain in the body and reactivate quickly with subsequent infectionsby the same antigen

suppressor T cells stop the reaction when the antigen is destroyed

Outline the reasons for the suppression of the immune response in organtransplant patients

When an organ is transplanted it is recognised by the immune system in thebody as non-self. The body attacks the new organ as if it is an invadingpathogen. To overcome this problem, transplant patients are given powerful

drugs to suppress their natural defences. This can lead to complications, as thepatient has reduced defences against any pathogen that they may encounter.

Process, analyse and present information from secondary sources toevaluate the effectiveness of vaccination programs in preventing the spreadand occurrence of once common diseases, including small pox, diphtheriaand polio

Background: Vaccination gives artificially acquired immunity from a disease. Oncecommon diseases, such as small pox, diphtheria and polio, are now uncommonbecause of successful vaccination programs. Smallpox was the first disease for which

a vaccine was developed. Edward Jenner did this in 1796. The vaccination programthat was started in the 1960s was so successful that the World Health Organisation(WHO) has declared it eradicated. Diphtheria vaccine is given as part of a tripleantigen injection that protects against diphtheria, tetanus and whooping cough. In1990, WHO stated that 80% of children had been vaccinated against this disease.There continues to be outbreaks of this disease and continued vaccination isrecommended. It is no longer thought of as a major child killer. Polio causedthousands of children to become paralysed every year. A vaccine was introduced in1955. It became available as an oral vaccine in the 1960s. Worldwide, the number ofcases is down by 80%.

Use the Internet, biology text books and encyclopedias to gather information onthe use of vaccines over the last 200 years and on the use of vaccines incontrolling common diseases. Make sure you gather information on small pox,


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diphtheria and polio. Numerical data or graphs are particularly useful for theevaluation purposes.

Assess the reliability of secondary information and data by consideringinformation from various sources. This is an ideal opportunity to process claimsabout the effectiveness of vaccination made in the mass media.

Analyse information by identifying trends or contradictions.

Present your findings as an evaluation report. Consider such aspects as howvaccination programs are implemented in Australia and different parts of theworld. Discuss the problems associated with producing and using vaccines,especially in less developed countries. Comment on the effectiveness ofvaccination. Consider using graphs to demonstrate the points you make.

Outline the way in which vaccinations prevent infection

Background: When a person has had an infection, some of the B cells produced inresponse to the pathogen are stored in the lymphatic tissue. They are called memoryB cells. They are ready to provide a very rapid response if the same pathogen laterattacks the body.

Vaccination is a way of giving a person the experience of having had aninfection without actually having it, so that the body responds to theexperience by producing the appropriate memory B cells.

The way in which the experience is given depends on the pathogen. In thecase of small pox a very similar, but very much less harmful pathogen (cowpox), was used. In other cases, the virus is made weaker, and thereforeharmless (attenuated), before being used in a vaccine. Examples of this type ofvaccine are those forpoliomyelitis, measles and whooping cough.

Many pathogenic bacteria are harmful to the body because of the toxins theyproduce. For diphtheria these toxins are modified to produce the vaccine. Whatever the source of the vaccine, the effect is the same. It introduces

antigens into the body so that B cells are activated to produce large amounts ofantibody and B cells that are stored in the lymph system are ready for a futureattack by the particular pathogen.


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6. Epidemiological Studies

6. Epidemiological studies involve the collection and careful statisticalanalysis of large quantities of data. Such studies assist the causalidentification of non-infectious diseases

Background: An epidemic is an outbreak of a disease that affects a large number ofpeople in a particular place at the same time. Epidemiology is the study of epidemics,especially by looking for common factors in populations affected by the disease. It isbased on careful collection and analysis of statistical information.

Gather, process and analyse information to identify the cause and effectrelationship of smoking and lung cancer

Background: Cause and effect is difficult to establish. For example, it is one thing tosay that everyone with a certain disease also watches television, but to make the nextstep, and say that television caused the disease, is not possible. There could be anynumber of other possible causes for the disease. This difficulty arises withepidemiological studies. Smoking and lung cancer have been linked by research timeafter time but it is difficult to get the manufacturers of tobacco products to accept thatit is a direct cause and effect relationship, that is, smoking causes lung cancer.

Use the Internet to gather information on lung cancer. Make sure theinformation provides examples of or discusses the results of epidemiologicalstudies.Process the information to identify statistics that can be used to demonstrate a

possible link between cause and effect for the disease chosen. Analyse the information to decide how the cause and effect relationships

demonstrated in epidemiological studies can be used to identify the cause of thedisease.

Identify and describe the main features of epidemiology using lung canceras an example

Epidemiological studies need to investigate cause and effects of a disease. Tobe valid they must:

o focus on large groups of people rather than individuals and relate to a

target population that can be identified. This allows statistics to be used toidentify trends and possible causative factors.

o use populations where there is occurrence of the disease and where thereare unequal exposures to the suspected or possible causes. Noconclusions about the effect of smoking could be drawn from a group ofpeople who each smoke 20 cigarettes a day

o allow for analysis of factors that might contribute to the occurrence of thedisease among those afflicted, such as age, sex, ethnic group, andoccupation.


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Identify causes of non-infectious disease using an example from each of thefollowing categories:

o inherited diseaseso nutritional deficiencies

o environmental diseases

Inherited diseases

Inherited diseases result from mutations that lead to the production of differentor faulty enzymes, resulting in impaired body function.

Examples

Examples of inherited diseases are Down syndrome, colour blindness,haemophilia, phenylketonuria, thalassaemia and sickle cell anaemia.

Down syndrome is an inherited disease that is caused by the non-disjunction ofchromosome 21. This results in three chromosomes and not the usual two(trisomy 21). People with Down syndrome have a characteristic appearance andmay have a shortened life span. Mothers who have children later in life are moreprone to produce Down syndrome children.

Nutritional deficiencies

The effect of nutritional deficiencies depends on the kind of deficiency. In some

parts of the world diets may be deficient in certain elements, such as iodine,copper, iron or zinc.

Examples

Examples of nutritional diseases are scurvy, rickets, goitre, kwashiorkorand beriberi.

Scurvy is caused by a deficiency in vitamin C. Symptoms include bleeding gumsand tooth loss. It is treated by increasing the intake of food and drinkscontaining vitamin C, such as citrus fruit.

Rickets is a metabolic bone disease resulting from a deficiency of Vitamin D.This can be due to a lack of sufficient vitamin D in the diet or due to insufficientexposure to sunlight. The disease is called osteomalacia when it occurs inadults.

Environmental diseases

Environmentally caused diseases include those due to lifestyle, such assmoking-related diseases, as well as those caused by something in theenvironment, such as lead or substances that cause allergies.

Examples


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Examples of environmental diseases include smoking-related diseases,Minamata disease, lead or asbestos related diseases and melanoma.

Mesothelioma is caused by exposure to asbestos and patients don't get anysymptoms until 20 to 30 years after exposure. There is no cure and treatmentcan only slow down the progression of the disease.

Identify data sources, plan and perform a first hand investigation or gatherinformation from secondary sources to analyse and present informationabout the occurrence, symptoms, cause, treatment/management of a namednon-infectious disease

If you know someone with a non-infectious diseases, you could ask their permission tointerview them and then carry out a first-hand investigation of the disease.

If this is the case, begin by determining the type of data that needs to becollected through interview and what information you may need to collect fromsecondary sources. Consider how you might analyse the information to make ituseful in generalising about the occurrence, symptoms, cause and treatment ormanagement of the disease.

Plan your investigation so that valid and reliable information is collected. Youmay need to research some issues from secondary sources, particularly if yoursubject is uncertain about particular aspects required.

Perform your investigation by conducting the interviews and compiling areport. You could summarise your findings in a table format, like the one below.

If you complete this syllabus point using secondary sources, you could:

choose a non-infectious disease from one of the categories listed in theprevious section.

gather information from a range of resources, including popular scientificjournals, digital technologies like CD-ROMs and the Internet.

analyse the information to make a generalisation for each of the factors beingexamined.

present a summary using a table like the one below.

Name of disease

Occurrence

Symptoms


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Cause


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Treatment ormanagement


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7. Modern strategies

7. Increased understanding has led to the development of a wide range ofstrategies to prevent and control disease

Background: Modern knowledge of disease has led to the development of a widerange of strategies to prevent and control disease.

Discuss the role of quarantine in preventing the spread of disease andplants and animals into Australia and across regions of Australia.

Australia has generally been fortunate in preventing the spread of plant andanimal disease from other parts of the world because of its geographicalisolation. Quarantine seeks to prevent the entry of harmful diseases intoAustralia and to stop the spread of diseases within Australia.

These diseases cause huge financial losses to farmers in other countries.Australia is able to sell its products to overseas markets because of the absenceof diseases, like mad cow disease and foot-and-mouth.

Australia also has declared fruit-fly free areas where the produce is sold with aguarantee of no fruit fly. This can be done by having inspections and bins to putfruit in when entering particular fruit growing areas.

Perform an investigation to examine plant shoots and leaves and gatheringfirst hand information of evidence of pathogens and insect pests

To perform this investigation, you may need some background information to

aid identification of the pathogens. Use gardening books or the Internet togather pictures of plant diseases.

When you know what several plant diseases look like, go to an area of

vegetation (such as a garden, park or area of bush) and examine plant shootsand leaves to gather evidence of plant diseases caused by pathogens or insectpest attack. You should aim to identify at least two examples of pathogens andinsect pests if possible. Look for black patches on the leaves, white powderyresidue or other spots that indicate a pathogen such as a fungus, or holes in theleaves caused by insect pests such as caterpillars. Use a hand lens to observethe symptoms.

For each example, record observations systematically and use the evidence tosuggest what kind of organism has caused the disease.

Explain how one of the following strategies has controlled and/or preventeddisease:

o public health programso pesticideso genetic engineering to produce disease resistant plants and animals

Public health programs

These provide quarantine, sanitation, safe drinking water and immunisation.They are also responsible for advertising campaigns that target cancer andAIDS. Examples of successful health campaigns are the Slip! Slop! Slap! skin


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cancer advertisements, the advertisements that show various diseases that canbe caused by smoking and the Grim Reaperseries for education about AIDS.

Pesticides

Pesticides, such as DDT, have been used to destroy mosquitoes, which are the

vectors of some diseases, such as malaria and dengue fever.

A good example of a strategy to control or prevent disease is the pesticidecontrol of the disease malaria. Adult mosquitoes can be destroyed by chemicalssuch as DDT, dieldrin, or by safer chemicals, such as pyrethrums. In 1956, theWorld Health Organisation was responsible for a major campaign using aresidual form of DDT. DDT has been banned in many countries of the worldbecause of its harmful ecological effects, but it is still used for mosquitoeradication in malarial areas. This has rid many areas of the world from malariabut has unfortunately not reduced it globally and malaria is still a major killer ofchildren today. Many areas have DDT-resistant mosquitos. Other pesticides,such as organophosphates and pyrethrums, have become popular. In someareas, bed nets have been sprayed with pyrethrums and have been found to beeffective in controlling mosquitoes.

Genetic engineering to produce disease resistant plants and animals

Genetically engineered plants can now kill their own pests because of theinsertion of a gene from a soil bacterium, Bacillus thuringiensis (Bt). Bt cottonwas the first genetically engineered crop grown in Australia. The bacteriacontain a gene that produces chemicals that kill certain insects. By taking that

gene from the bacteria and inserting into the genome of plants, the plants nowproduce the chemical that will kill insect pests.

Gather, process information and use available evidence, to discuss thechanging methods of dealing with plant and animal diseases, including theshift in emphasis from treatment and control to management or preventionof disease

Background:There has been a shift from waiting for a disease to occur, topreventing the occurrence of the disease. This can be seen in agriculture wheregenetically resistant crops are grown so that the plants do not have to be sprayed for

diseases later in life. Animal and plant diseases have been managed by quarantinerestrictions in Australia. Diseases, such as foot and mouth, rabies andplum pox, aremanaged by not allowing infected organisms to enter the country. World-wideimmunisation has caused diseases such as small pox to be eradicated.

Consider all the aspects of the disease you have studied. Make notes on thoseaspects that relate to the above syllabus statement.

Using these notes, plan a discussion of the changing methods of dealing withplant and animal diseases.

Decide whether you need further information, and if so, gather it from

textbooks or the Internet. Write a short concise response from the available evidence to show what youdeduce about the shift in emphasis from treatment and control to managementor prevention of disease. Make sure the response has:

o an introductory paragraph, written in general terms


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o a series of paragraphs that focus on specific issues. Each paragraph coulddiscuss any debatable issues, e.g. advantages and disadvantages of aparticular approach

o a concluding statement, providing your position or recommendationsbased on your evaluation.

Process and analyse information from secondary sources to evaluate theeffectiveness of quarantine in preventing the spread of plant and animaldisease into Australia or across regions of Australia

Use the Internet to obtain and process information from a range of sources,including the Australian Quarantine and Inspection Service (AQIS) about thecontrol of the movement of plants and animals and their products into Australiaand within Australia. Quarantine prevents entry of goods that may carrydiseases or pests at airports and seaports. Affected goods are destroyed.Fumigation is also part of the quarantine program.

Analyse this information to evaluate the effectiveness of quarantine regulationsin Australia, being sure to identify relationships as well as contradictions in theinformation.
http://www.daff.gov.au/aqishttp://www.daff.gov.au/aqis

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