eddiethe search for better health.docx
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The Search For Better Health
What is a healthy organism?
Discuss the difficulties of defining the terms health and disease
Difficulty to define health:
World health organisation:
Astate of complete physical, mental and social well-being and not merely the absence of disease or infirmity
Too broad and if taken literally, it is very difficult to achieve a healthy status Concept of health is constantly changing and is relative to others and ourselves
e.g. person who has diabetes may be doing the best she can and feeling healthy
Term is used in many different ways. For e.g. in every day conversationDifficulty to define disease:
Any condition that adversely affects the normal functioning of any part of a living thing
Quite broad and impreciseconditions that would not normally be classed as disease could bebroken arm normal functioning may be at different levels for different individuals. e.g. absent mindedness in elderly may
be a normal facet of aging
Terms used by general public in everyday conversationOutline how the function of genes, mitosis, cell differentiation and specialisation assist in
the maintenance of health
GenesContains coded information for protein.
Genes are responsible for controlling the rate of cell division; thus faulty control genes can lead to cancer. DNA repair
genes code for proteins responsible for stopping cell cycle while other proteins remove damaged regions of DNA and
replace them with new correct sequence. Proto oncogenescode for proteins that stimulate cell growth and mitosis.
Tumour suppressor genescode for proteins that slow down or stop cell growth and mitosis
MitosisProcess of cell division by which identical body cells are produced. This is often a response to disease because
damaged cells and tissue need to be replaced. It also normally occurs to replace old or damaged cells
Cell differentiationProcess by which a cell changes its structures and function as it develops
Cell specialisationfunctioning of a cell to perform a particular role
Cells are differentiated and specialised to perform roles that maintain and repair tissue and also allow the whole body to
survive.
Use available evidence to analyse the links between gene expression and maintenance and
repair of body tissues
Gene expression occurs when a gene is switched on and the DNA code is converted into polypeptides that control the
structures and functions of a cell
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Mutations occur when a gene is altered and it can no longer code for the correct polypeptide. This puts the health of the
individual at risk, as a particular chemical reaction may be unable to occur, resulting in a particular disease. Therefore
correct gene expression is therefore necessary for ongoing maintenance and repair or tissues.
For e.g. PTEN gene is a tumour suppressor gene that limits amount of cell division and encourages cell death. BRCA1 is a
tumour suppressor gene responsible for coding for proteins involved in repair of PTEN gene. Mutations in the BRCA1
gene mean PTEN gene would not be repaired, resulting in lack of control of cell cycle and runaway cell division leading to
formation of tumours.
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Over 3000 years ago the Chinese and Hebrews were advocating cleanliness in food,
water and personal hygiene
Distinguish between infectious and non infectious disease
An infectious disease is a disease that is caused by an organism called pathogens, which are transmitted from one
organism to another or from an environment to an organism.
A non infectious disease is a disease that is not caused by a pathogenincludes inherited, environmental and nutritionadiseases
Explain why cleanliness in food, water and personal hygiene practices assist in control of
disease
Intake of food and water provide an easy way for micro- organisms to enter our bodies. Therefore minimising the
number of such organisms in our food and water reduces the risk of infection
Food:
Store food in dry places or by freezing to avoid/inhibit growth of bacteria Clean utensils before using for different foods All chicken and mince based foods cooked thoroughlykill bacteria Foods covered before storageprotect from contamination Hairs and skin lesions covered in food shops
Water:
Government has established standards and water is tested daily to ensure standards are met If water quality is unsure of, boil the water and allow it to cool
Personal hygiene:
Hands always washed before preparing and eating food and after going to the toiletprevents spread ofpathogens
Body and hair should be regularly washed and teeth cleaned to prevent build up of pathogens Cough or sneeze into handkerchief
Community hygiene:
Sewage and garbage disposal- reduces risk of pathogen number increasing Sterilisation and disinfection of equipment in hospitals
City planningreduce overcrowding
Identify the conditions under which an organism is described as a pathogen
Pathogenorganism or infective agent that causes disease
Able to survive outside a host Transfer through direct or indirect means or by a vector (mosquito)
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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
Primary treatment:
FlocculationChemicals e.g. polyelectrolytes are added to the water to neutrialise electrical charges of fineparticles in water allowing particles to come closer, stick together to form large clumps (flocs). The clumps are
then easier to filter or settle from water CoagulationAluminum sulfate is added to help sink flocs and make sedimentation faster Sedimentationwater flows into a tank called a sedimentation basin where gravity causes flocs/particles to
settle down the bottom to form sludge
Sludge processingsolids and liquids are collected from the settling tanksSecondary treatment:
Filtrationwater is filtered e.g. by through sand beds so that particulate matter that may harbor pathogens areremoved
Backwashingoccurs when clean water is pumped backwards through the filters to flush them clean of sludgeTertiary treatment:
Chlorinationfew part per million of chlorine is injected into water to kill most remaining microbes Fluoridationsodium fluorosilicate is added to water (reduce tooth decay) Other ways to disinfect waterheat, UV light, Ozone gas injected into water
This treatment of water kills most pathogens, reducing the risk of infection from these pathogens
Identify data sources, plan and choose equipment or resources to perform a first hand
investigation to identify microbes in food or in waterMicroorganisms in air:
Workbench area was sterilised by swabbing with methylated spirits Four sterilised petri dishes that contained nutrient agar was collected One plate was unexposed, sealed with sticky tape and labeled as the control Three locations were selected where each plate was exposed to the air of the location for 15 minutes, then
sealed with sticky tape and labeled with the location/date
Plates were incubated for 37 days at 40Microorganisms in water:
Workbench area was sterilised by swabbing with methylated spirits Four sterilised petri dishes that contained nutrient agar was collected One plate was unexposed, sealed with sticky tape and labeled as the control 0.5ml of each water sample was placed onto the agar plate using a sterile pipette, lid was closed and dish gently
rocked so that the water sample spread evenly over the entire plate
All dishes were sealed with sticky tape and labeled and then incubated for 3 7 days at 40Microorganisms in food:
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Pathogen Description Example of disease
Prions Protein that has been altered
from its normal structure and
can then alter other proteins to
develop more prions, so that the
change spreads like a chain
reaction.
Kuru
Viruses Consist of DNA or RNA enclosed
in protein, live inside living cells.They are so small that they
cannot be seen with a light
microscope.
Influenza
Bacteria Single celled prokaryotic
organismhave cell wall but no
membrane bound organelles
Cholera
Protozoans Single celled eukaryotic
organismshave cell membrane
but no cell wall and possess
membrane bound nuclease and
membrane bound organelles
Malaria
Fungi Eucaryotic organisms that
possess cell walldo not contain
chlorophyll and not capable of
producing own food. Can be
unicellular or multicellular
Thrush
Macro parasites Parasites/ organisms that are
visible to the naked eye Flatworms Fleas
Identify the role of antibiotics in the management of infectious disease
Antibiotics are chemicals with the role of destroying or inhibiting the growth of the bacteria that cause disease.
In 1928, Alexander Flemming discovered the first antibiotic when he observed the effect of Penicillium mould on the
growth of bacterial colonies on an agar plate. Penicillin became available for medical use in 1941.
Some antibiotics accumulate in the cells of the bacteria and prevent them from forming a new cell wall whendividing e.g. penicillin
Some antibiotics destroy the cell membrane, thus effectively destroying the bacteria, for e.g. amphotericin Some antibiotics interfere with protein synthesis so that bacteria are unable to make essential compounds,
resulting in death of the celle.g. erythromycin
Broad spectrum antibiotics such as sulfonamides act on a wide range of bacteria and are used when the identity of the
bacteria causing the infection is unknown while narrowspectrum antibiotics such as penicillin act on only one or two
types of bacteria.
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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
Influenza:
Cause:
Caused by infection with influenza virusesinfluenza A and B (virus) being the two main types They are viruses that infect humans, containing RNA surrounded by a protein coat
Transmission:
Direct contactthe viral particles inhaled through nose and mouth in droplets that have been exhaled by aninfected person when they sneeze or cough
Indirect contactinfected person touches respiratory tract and then something else such as a handrail andwhen a healthy person touches it soon afterwards and then places hand on their nose or mouth
Host response:
Immune system is initiatedproduces antibodies and other immune response cells specific for the particularstrain of influenza virus that has infected the body.
Immune system is responsible for destroying the viral particles that have invaded the bodyMajor symptoms:
Fever Headache Inflammation of the upper respiratory tract Sore throat Muscle pain (myalgia) Nasal catarrh (inflammation of the mucous membrane) Sneezing and coughing
Treatment:
No treatment that will cure it
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Main method of treatment is to relieve symptoms by getting plenty of bed rest and drinking extra fluids. Bedrest allows body to fight disease and then recover.
Aspirin and paracetamol can be given to help alleviate headaches, sore throat and muscle pain and to reducefever
Prevention:
Use of influenza vaccines that are produced each year and are derived from the influenza A and influenza Bviruses that circulated during previous influenza season
Due to mutations of the influenza virus, vaccines have to be constantly updated Other strategies include wearing protective masks, avoiding crowded areas and ensuring adequate nutrition and
sleep
Control:
Implementing immunisation programs along with education programs to encourage at risk individuals to bevaccinated
Isolating infected individuals to reduce spread of influenza throughout population Following quarantine procedures to prevent spread of disease from one country to another
Gather and process information to trace the historical development of our understanding
of the cause and prevention of malaria
Malaria is a disease caused by a protozoan of the genus Plasmodium.It has a complicated life cycle requiring a mosquito
of theAnophelesgenus (female) to carry the Plasmodiumto its host.
Malaria is one of the most prevalent infectious diseases, with more than 300 million cases reported and 1.53 million
deaths, mostly of African children under 5 years old each year.
Causes:
Symptoms of malaria recorded since in Ancient China Ancient Greeks noted symptoms of malaria were common in people who lived in low, moist and hot districts
near swamp
Charles Laveran in 1880 discovered pathogen that causes malaria by looking at the blood of malaria patients.Organism was classified as a protozoan and called Plasmodium
In 1897, Ronald Ross, British army doctor demonstrated that malaria was transmitted from infected patients bymosquitoes and identified anopheles mosquito was the transmitter
Prevention:
Chinese used anti fever properties of the Chinese qinghao plant Greeks and Romans built drains to remove stagnant water to reduce malarial symptoms First drug in Europe in mid 1600s was quinine Choloroquinine in late 1940s World Health Organisationintroduction of DDT 1971- active ingredient of qinghao plant, artemisisin was isolated by Chinese scientists 2000present:
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Combination of drug therapy that includes highly effective artemisinin is the only consistently successfultreatment.
Use of netting treated with long lasting insecticides Preventing being bitten by mosquitostill most effective way to prevent infection with malaria
Process information from secondary sources to discuss problems relating to antibiotic
resistance
Source of antibiotic resistance
When antibiotics are administered to treat a bacterial infection, some bacteria may possess a natural resistanceto the particular antibiotic, and so they survive and reproduce building up a population resistant to the antibiotic
It is being accelerated by:o Overuse of antibiotics for treatment of diseaseso Only taking antibiotics provided until symptoms disappearo Food producing animals are fed antibiotics to prevent infectiono Use of cleaning products that contain anti bacterial ingredients
Problems of antibiotic resistance
Micro organisms that cause diseases once easily cured, have developed resistant strains with more severeeffects and taking much longer to cure
o Second line and third line antibiotics sometimes have to be used which are more expensive and toxic Now faced with a number of infectious bacteria resistant to almost all known antibiotics
o super bugs are becoming extremely difficult to treat and eradicate Current trend indicates that in near future, some diseases will have no treatment unless a significant
breakthrough in producing more effective drugs
Strategies to slow development of antibiotic resistance
Antibiotics should only be prescribed for bacterial infections Antibiotic prescribed should target the pathogen and not be broad spectrum Taking the whole course of antibiotics Not taking antibiotics that are prescribed for someone else Not using cleaning products that contain anti microbial ingredients
Perform an investigation to model Pasteurs experiment to identify the role of microbes in
decay
1. 600ml of water was measured by a measuring cylinder and poured into a 1000ml beaker2.
Two beef stock cubes were placed into the beaker to make a clear broth. This broth was poured evenly into3 flasks (200ml each)
3. Steps 1 and 2 were repeated for 3 other flasks4. 3 flasks were fitted with S shaped stoppers while the other three were fitted with straight tubing stoppers5. These flasks were allowed to stand for 3 weeks. The appearance of each flask were observed every three
days and results recorded
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Often we recognise an infection by the symptoms it causes. The immune response is
not so obvious, until we recover.
Identify defence barriers to prevent entry of pathogens in humans:
- Skin-
Mucous membranes
- Cilia- Chemical barriers- Other body secretions
Skin:
Intact, tough outer barrier with keratin protein that covers the body and prevents penetration by microbes Fairly dry, which helps to prevent growth of pathogens Contains its own population of harmless bacteria that help to stop the invaiding microbes from multiplying Oil and sweat glands in skin produce antibacterial and antifungal substances that further inhibit the growth of
invading pathogens
Mucous membranes:
Respiratory, digestive, reproductive and urinary tracts are covered with membranes that produce a thick layer ofmucus which traps entering pathogens until removed by cilia or processes such as coughing and sneezing
Can contain the antibody IgA which prevents attachment of viruses and bacteria to epithelial surfaces Provides moist, nutritious layer in which harmless microbes live and produce substances that inhibit growth and
entry of pathogens
Pathogens overcome this barrier as many spores are resistant to heat and chemicals such as bacterial sporesChemical barriers:
Different types of chemicals secreted in different parts of body act as a barrier to invading pathogens Stomach wall secretes gastric juices that contain hydrochloric acid and protein digesting enzymes which
destroy pathogens in stomach
Alkaline conditions of intestines destroy pathogens Urinary and vaginal openings and surface of skin are also acidic which inhibits growth of bacteria
Other body secretions:
Urine is sterile and slightly acidic and flushes and cleans the ureters, bladder and urethra and helps to preventgrowth of microorganisms
Tears contain lysozymes that destroy cell walls of some bacteriasurface of the eye is cleaned and pathogensare washed away
Saliva contain lysozymes and washes microorganisms from teeth and lining of the mouth
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Identify antigens as molecules that trigger the immune response
An antigen is any molecule the body recognises as foreign and that triggers the immune response. E.g. virus, bacteria,
foreign cell, protein debris or toxin
On surface of cells in the body, there are marker molecules that identify the cell as belonging to the body. When
pathogens enter, they have chemical markers called antigens on their surface and the immune system recognises these
as not belonging to the body and is activated to destroy the foreign substance
Explain why organ transplants should trigger an immune response
When a person has an organ transplant, the new organ has different marker molecules (antigens) than that of their
own cells which activates the immune response to reject the organ in order to defend its body. To prevent this:
Tissue type of donor is matched to recipient as closely as possible so there is a high number of matchingmarker molecules les violent immune response
Treated with immunosuppressant drugs to lesson immune response so that transplanted organ is not attacked vulnerability to other pathogens is increased
o hence recipient is isolatedIdentify defence adaptations, including:
- Inflammation response- Phagocytosis- Lymph system- Cell death to seal off pathogen
Inflammation response:
Non specific defence mechanism that occurs at site of infection Release of chemicals such as histamines and prostaglandins
o cause blood vessels to dilate, increasing blood flow to site of infection or injury, causing area to becomered hot and swollen
o causes increase in permeability of blood vessels; allows movement of phagocytes from blood intotissues so they can attack invading pathogens
Plasma moves into tissues, bringing more phagocytes and producing swelling in area of infection, forcing tissuefluid into lymph and taking debris and pathogens with it
Chemicals that increase temperature are releasedinhibits growth rate of pathogens, inactivates someenzymes and toxins made by pathogens and increases rate of biochemical reactions occurring in body
Phagocytosis:
Phagocytes are specialized white blood cells or leucocytes Neutrophils:
o First to be called upon and move to site of infection, inactivating pathogenso Short acting and then self destruct after a few dayso Used by body to fight acute (short, severe) infections
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Macrophages:o Long lasting phagocytes that can either stay in tissues or travel from blood vessels into infected tissueso Used by the body t o fight chronic infectionso After foreign particle is destroyed, parts of the antigen are displayed on surface of the macrophage
Phagocytosis is not always successfulo Pathogens can sometimes repel phagocyteso Pathogens may escape before being completely destroyed
Lymph system:
As blood circulates around the body, some of the plasma moves out of the capillaries into the tissues andbecomes part of the tissue fluid
o Tissue fluid then moves into a system of vessels known as the lymphatic system The lymph system returns intercellular fluid to the blood system (point near heart), filters cell debris and
produces white blood cells (lymphocytes) responsible for the immune response
o When tissue fluid get to the lymph node, waste particles are filtered off and any foreign particles aredestroyed by macrophages
Cell death to seal off pathogens:
Cells die to seal off an area of tissue that is infected and is not being successfully being defended by the body Infected cells surrounded by a wall of dead cells
o Prevents infection from spreading to other areas and infecting themo Wall of dead cells form a capsule (granuloma or cyst)cells within will die, causing destruction of
pathogens that are infecting them
o Debris inside granuloma or cyst destroyed by macrophages that had also surrounded the walled off area
Gather, process and present information from secondary sources to show how a named
disease results from an imbalance of microflora in humans
Microflora:
Variety of microbes that live mainly on skin, intestines, colon, mouth and vagina in women Body supplies microflora with nutrients they require and conditions they need to survive Presence of microflora inhibits growth and multiplication of many pathogens that come into contact with body,
thus protecting body from contracting disease
If conditions of body change and balance of microflora is upseto Growth and multiplication of harmful pathogens resulting in disease
Candidiasis (thrush) Crohns disease
Candidiasis:
Disease caused by the fungus Candida albicans. This fungus (yeast) is part of the natural microflora of the humanbodynormally present on mucous membranes of female genital tract, mouth and respiratory tract and the
alimentary canal
No. Of C.albicans is usually kept low by competition from other microorganisms present in bodys microflora andhence imbalance of microflora results in increase of C.albicans and disease candidiasis develops
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One of the ways the natural balance of microflora can be upset is by taking antibiotics to treat a bacterial infection in
addition to reducing number of pathogenic bacteria in body, it also reduces no. of bacteria in natural population of
microfloralowers competition for C.albicansmultiplies in uncontrolled waydisease candidiasis becomes
established
MacFarlane Barnets work inthe middle of the twentieth century contributed to a
better understanding of the immune response and the effectiveness of
immunisation programs
Sir MacFarlane Burnet (18991985) was an Australian scientist and is recognized as one of the founders ofimmunology
In 1946, he developed an experimental technique that enabled him to isolate and cultivate human influenzavirus in chicken eggs
o This method produced a high concentration of the virus, enabling it to be used to develop a vaccine 1960 Developed the clonal selection theoryall the B cells and T cells for all the possible antigens are already
present in very small amounts in the immune system. When antigen is present in body, B cell or T cell specific
for the antigen is activated, cloned and the antigen destroyed
o Helped gain better understanding of the immune systemo Led to establishment of more effective immunization programs
Identify the components of the immune response:
- Antibodies- T cells- B cells
Antibodies:
Proteins, called immunoglobulins which are produced in response to the presence of an antigen in the bodyo When appropriate B cells activated, they form plasma cells that produce antibiodies
Antibodies are antigen binding siteso match the shape of the antigen they are specific foro seek out the antigen and bind to a part of it, forming the antigenantibody complex, which causes the
deactivation of the antigen
Antibodies can react with the antigen in various ways:o Neutralises toxins produced by the antigeno Immobilising, blocking or neutralising the active binding site of the antigen so it has no effect on the
body
o Cause antigenantibody complex to clump together, making them easier to eliminate by phagocytosis
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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 differences in their rolesInteraction between B and T lymphocytes
When macrophage encounters foreign particle with antigen attached to its surface, it engulfs ito Antigen present on surface is also moved to surface of macrophage
Antigen is then transported to lymph nodes
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Antigenpresenting macrophage is presented to helper T cell that has T cell receptor corresponding to theantigen
o Effect of activating the helper T cell Helper T cell can also be activated by B cells
o B cell encounters antigen that corresponds to its surface antibodies, it binds antigens to the antibodiesand process antigen, attaches it to its surface molecules and presents this to the helper T cell with
matching T cell receptors
Chemical signals in the form of cytokines are secreted by the T cell to activate more of the same helper T cellsand macrophages
o Interleukin2 activates production of clones of B cells specific to that antigen and activates cytotoxic Tcells
The mechanisms that allow interaction between B and T lymphocytes
Two types of MHC molecules allow interaction between B and T cells to be successfulo MHCI molecules present on all cells that have a nucleus and are involved in recognition of antigens by T
cells
Infected cells hold antigen on its MHCI so that cytotoxic T cell can identify it and destroy ito MHCII molecules are present only on B cells and macrophages and are involved in recognition of
antigens on macrophages by helper T cells and recognition of antigens by B cells
macrophage holds antigen on its MHCII molecule on surface and is recognised by helper T cellwith same antigen receptor and activates appropriate B and T cells
o Interaction is also helped by their close proximity to each otherThe range of T lymphocyte types and the differences in their roles
Helper T cells (Th)o Each cell has a receptor protein that recognises only one type of antigen o When Th cell is activated by presence of a particular antigen, it releases a cytokine chemical (interleukin
2) that activates the cytotoxic T cells and B cells specific for the antigen. Other cytokine chemicals that
stimulate activity of macrophages are released
Cytotoxic T cells (Tc)o Cells stimulated to produce many copies (clones) of themselves when activated by Th cells or when they
detect cells with antigen that match their own surface receptor protein
o Army of identical cytotoxic T cells move to site of infection, bind with infected cells and releasechemicals that destroy the infected cell
Memory T cellso Cells are produced at the same time as the Tc cells are multiplying and remain in the body so body can
respond more quickly to future invasions by same antigen Suppressor T cells
o Responsible for stopping immune response when infection has been defeated
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Outline the way in which vaccinations
prevent infection
Active acquired immunity:
Naturally induced Primary response
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o Sufficient antibodies are made to destroy all infecting pathogens and person recovers completelyo Memory T cells and memory B cells specific to antigen are produced and remain in body
Secondary response:o Activated if same antigen were to re enter the bodyo Memory cells activate the production of the cytotoxic T cells and the B cells o More rapid and requires less antigen to initiate ito Produces a much greater quantity of antibodieso Lasts for a longer period of time
Vaccinations:
Preparations from weakened or dead infective microorganisms (vaccines) injected into body with intention ofprovoking immunity to a disease without producing the symptoms
Vaccines:
Living but attenuated (weakened) and therefore harmless (rabies and measles) Dead (typhoid, whooping cough)
Modified toxins called toxoids (tetanus, diphtheria) Contains antigens that cause body to undergo an immune response and produce memory cells for that
particular antigen
o If body exposed to that antigen again, secondary response is activated and antigen will be destroyedbefore any symptoms of disease are experienced
Active immunisation:
Process in which the body reacts to the vaccine by going through the immune response that produces memorycells for the antigen and confers immunity to the body
Passive acquired immunity:
Involves injection of antibodies that another organism has produced in response to infection by a particularantigen to prevent a disease from developing
Does not provide long term protection Carries risk of stimulating reactions against other foreign blood proteins that might be in the vaccine
Outline the reasons for the suppression of the immune response in organ transplant
patients
Patients of transplanted organs:
Donor organ, on its surface, have marker molecules that are different from the marker molecules on thecells in the recipients body
marker molecules on donor organ act as antigens that identify the organ as foreign materialo Immune response initiatedo Cytotoxic T cells are activated and move to transplanted organ to attack and destroy the cells
Causes rejection of transplanted organTo reduce severity of immune response:
Tissue of the donor and recipient are matched as closely as possible
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Drugs such as cyclosporine are given in order to suppress the immune system to lower risk of rejectiono Acts to reduce activity of T cellsprincipal cells that attack transplanted organo Advantageous as whole immune system is not suppressed and can still act to defend body against other
disease causing organisms
o Transplant recipient is still at much greater risk of suffering from many more infections as normalinteractions between B and T cells will not occur
Process, analyse and present information from secondary sources to evaluate theeffectiveness of vaccination programs in preventing the spread and occurrence of one
common disease, including small pox, diphtheria and polio
Vaccination programs:
Vaccination gives artificially acquired immunity from a diseaseo Once common diseases such as small pox, diphtheria and polio are now uncommon because of
successful vaccination programs
Mass immunisation programs not only prevent occurrence of disease in individuals, but also help to decreasethe spread of disease throughout the population
o Chance of infected individual coming into contact with unprotected person is lowered and transmissionof disease is effectively stoppedherd immunityEvaluation of effectiveness of vaccination programs in preventing spread and occurrence of:
Small pox:
Epidemiological studies involve the collection and careful statistical analysis of
large quantities of data. Such studies assist the casual identification of non infectious diseases
Identify and describe the main features of epidemiology using lung cancer as an example
Epidemiology is the study of diseases that affect many people. It describes the patterns and cause of diseases in
population
There are three major types of epidemiological studies:
Descriptive studies:
Provides information about:o Patterns of the diseaseo Frequency of the diseaseo Which section of population is affected (age, gender, occupation etc.)o Geographical locationo Particular time period in which individuals were affected
Early epidemiological studies on cause of lung cancer collected data including information about sex, age,smoking habits, diet, occupation and drinking habits of both smokers and non smokers
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Analytical studies:
More data is collected, statistically analysed to develop hypotheses as to the likely cause(s) of the diseaseo Casecontrol studies: compare people with disease (case) to people without the disease (control) and
look for differences in exposure to possible causes of the disease
Casecontrol study in London 1947 by Richard Doll compared patients with lung cancer topatients with other conditions. Results showed most individuals with lung cancer were smokers
and suggested link between smoking and lung cancer
o Cohort studies: studying two or more similar groups of people who are free of the disease while one isexposed to potential cause of disease
Cohort study was set up in England in 1951 by A.B. Hill following more than 40 000 doctors overa 10 year period
Intervention studies:
Used to test the effectiveness of a treatment (e.g. clinical trial of a new drug) or effectiveness of a public healthcampaign to change behaviour of population as a whole in order to decrease the incidence of disease
o E.g. Effectiveness of campaigns such as the Quit campaign to decrease no. of people smoking isevaluated using this study
Identify causes of non- infectious disease using an example from each of the following
categories:
- inherited diseases- nutritional deficiencies- environmental diseases
Inherited diseases:
Diseases that are genetically transmitted and are caused by errors in genetic informationo Down Syndrome caused by an extra chromosome 21o Cystic fibrosis caused by mutation to cystic fibrosis transmembrane conductance regulator (CFTR) gene
that is found on chromosome 7
Nutritional deficiencies:
Caused by diets lacking proper balance amount of nutrientso Anaemia, causing lethargy results from lack of iron or folic acido beriberi resulting in retarded growth, weakened heart muscle, digestive disorders and muscle atrophy
caused by a lack of vitamin B1
Caused by psychological conditions that lead to inappropriate dietsEnvironmental diseases:
Diseases caused due to lifestyle, physical factors of environment or exposure to chemicals in the environment Lifestyle diseases such as cardiovascular disease caused by substance abusealcoholism and smoking related
diseases
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Skin cancer caused by excessive exposure to UV in sunlight Lead poisoning caused by exposure to high levels of lead in atmosphere from pollution or lead based paints
Gather, process and analyse information to identify the cause and effect relationship of
smoking and lung cancer
Lung cancer:
Disease caused by the abnormal growth of cells in the lung Main causes are smoking tobacco or exposure to carcinogens in the environment (e.g. eating carcinogenic food)
Cause and effect relationship of smoking and lung cancer:
Collection and analysis of epidemiological data about lung cancer since 1947 has increased our knowledge aboutlung cancer
o Findings have universally demonstrated clear link between smoking and increased incidence of lungcancer and clear link between smoking and reduced life expectancy
The Australian Cancer Council and the State Cancer Councils all collect and report on incidence, mortality,prevalence and survival of lung cancer
Detailed studies have shown variations in the disease for factors such as age, sex, regional area and occupation Trends in lung cancer incidence reflect changes in smoking habits and that the incidence of lung cancer in males
has fallen in the past 10 years but risen in females
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
Scurvy:
nutritional deficiency diseaseOccurrence:
Rarely seen in developed countries except in people with poor diets or unusual food habits More commonly found in developing nations where fresh fruit and vegetables (rich sources of vitamin C) may
not be available
Occur in people of any age with risk groups being infants, elderly and alcoholicsSymptoms:
Initial symptoms:o Pain and tenderness in legso Swelling of long boneso Swollen, purplish and spongy gums
Advanced symptoms: Gangrene (degeneration of tissue) Reopening of old wounds Spontaneous haemorrhaging (pure/black spots on skin) Separation of once healed broken bones If left untreated, death will result
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Cause:
Results from a lack of adequate amounts of vitamin C in the daily dietTreatment/management
Treatment is very easy and simply involves the inclusion of adequate amounts of vitamin C in the diet More serious casessupplements of vitamin C taken daily Prevention involves including adequate amounts of vitamin C in dietcitrus fruits (oranges, lemons andlimes), blackcurrants, cranberries, cauliflower, spinach and tomatoes- foods rich in vitamin C (ascorbic
acid)
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Increased understanding has led to the development of a wide range of strategies to
prevent and control disease
Discuss the role of quarantine in preventing the spread of disease and plants and animals
into Australia or across regions of Australia
Australia is one of very few countries in the world that remains free of worlds most serious pests and diseasesdue to its geographical isolation
o Isolation decreased as international travel and trade increased Australia has very large agricultural industryexport more than $30 billion worth of food a yearhigh in
demand due to absence of diseases such as mad cow disease and footandmouth
o If pests and diseases were to gain entrycause huge financial loss to Australian agricultural industry Role of quarantineminimise risk of exotic pests and diseases entering Australia in order to protect our native
flora and fauna, agricultural industries, environment and health
AQIS (Australian Quarantine and Inspection Service) have strategies: Plant control:
o Involves examining all plants, parts of plants or plant products (fruits, seeds, cuttings, blubs and wood)many will be refused entry
o Only allowed if treated by quarantine officers to ensure any likely pests or pathogens are destroyed orkept at quarantine stations until any diseases present have had time to develop
Animal quarantine: Involves all animals coming into Australia spending time at quarantine stations to make sure they are
free of disease before release
Examined on regular basis for any signs of disease (several weeks) Human quarantine:
Captains of aircrafts and ships are required to notify AQIS if any passengers or crew are displaying anysymptoms of prohibited diseases such as rabies, yellow fever, malaria etc.
Aircraft are also sprayed with insecticide to kill any pests that have entered Australia with aircraft
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
Pesticides: chemicals that are used to kill the pests of plants and animals, pathogens and vectors
If pests and vectors are killed, then occurrence of disease will be prevented Three types:
o Insecticideskill insectso Fungicideskill fungal pathogenso Herbicideskill weeds
DDT used widely during WW1 to kill lice that transmitted pathogen which caused typhus DDT also widely used to killAnophelesmosquito which carries the plasmodium that causes disease malaria
controlled spread of malaria
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Effectiveness of DDT was reduced as mosquitoes built up resistance to it through process of natural selectionand many countries have since banned use of DDT due to its harmful effects on the environment
Other insecticide, such as pyrethrum are now also used which are less harmful to environment and moreeffective in controlling mosquito numberscontrols to some extent, the spread of malaria
Pesticides prevent the spread of many diseases but are limited in that vectors and pathogens build up aresistance to pesticide through process of natural selection and effectiveness decreases. Pesticides are also
being discouraged more and more due to their damaging effects on the environment
Perform an investigation to examine plant shoots and leaves and gather first- hand
information of evidence of pathogens and insect pests
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
Effectiveness of Australian quarantine service, AQIS is very high when considering its success in preventing thespread of plant and animal diseases in Australia
o Australia is relatively free from many diseases that are common in other countries Strict controls and regulations are in place that reduce risk of entry of plant and animal diseases into Australia to
a very low level
Preventing spread of plant and animal disease into Australia:
Australia has been free from foot and mouth disease sin 1872 In 2001, outbreak of this disease occurred in Britain
o Australia enforced all its normal quarantine regulations, but also banned import of any clovenhoofedanimals or products from infected regions
o Passengers entering Australia from infected areas were subject to thorough processing, and treatmentto ensure infected soil from shoes was not carried
o Mail from these areas were also inspectedPrevention of spread of plant and animal disease across region of Australia:
If quarantine measures fail, response strategies are implementedo Contingency plans are already in place
In 2007, equine flu penetrated quarantine barrier and spread was rapid whereby horses in NSW and QLD wasinfected
o Response put in place to control and eradicate disease Response involved
o Infected areas were quarantinedo All facilities, equipment, clothes, shoes and other item were decontaminatedo Horses were tracked and observed to determine extent of infectiono Activities involving horses were bannedo Awareness campaign put in placeo Susceptible animals were vaccinated
Measures were successful and was no infected properties in 2008
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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
As little as 150 years ago, incidence of plant and animal diseases were met with an emphasis on treatment andcontrol
o Treatment involving strategies to cure disease or relive its symptomso Control involving reducing the spread of disease through the population of organisms once it is already
present
More recently, emphasis has shifted to management or prevention of diseaseo Prevention involves use of strategies that stop the occurrence of disease in organismso Management commonly involves programs improving outcomes of chronic conditions and improving
the quality of lives of sufferers
A number of decades ago, when drugs such as penicillin were discovered, emphasis when dealing with diseasewas on their treatment and control
o Antibodies were used to cure bacterial infections A number of plant disease was also controlled by the use of pesticides However as antibiotic resistance developed and as pathogens became resistant to pesticides, stronger
antibiotics and pesticides had to be used
o Resistant pathogens and pest caused further damaging effects on the environment Emphasis of dealing with diseases are now prevention so that the use of drugs and development of resistant
strain and their effect are reduced
Another example is AIDS where treatmentinvolves different types of drugs, many of which have side effectso Problems would not exist if disease had been prevented in the first place
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