Bio Hsc Notes (Except Parcs)

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Health is defined as the complete physical, physiological, mental and social wellbeing of an organism. It is not merely the absence of disease. Disease can be defined as a state which prevents correct functioning or impairs bodily function. It is difficult to define these terms as they are very subjective and dynamic, i.e. they differ from person to person. Old age is an example of how definitions can be misleading because they suffer impaired body function yet they may not be diseased or sick.

• Outline how the function of genes, mitosis, cell differentiation and specialization can assist in the maintenance of health.

Genes – growth and healing is controlled by protein metabolism which is controlled by genes. Mitosis – keeps cells at a healthy ratio and allows new cells to replace ones that can no longer function Cell Differentiation and specialisation– without this there would be no specialized cells to maintain health e.g. lymphocyte production is increased during infection.

• Use available evidence to analyse the links between gene expression and maintenance and repair of body tissues.

Genes account for the maintenece and repair of body tissue. As DNA controls cell function and DNA is made up of genes, it can be said that genes control cell activity. In regards to repair, gene expression therefore controls this repair process. For example when a person is cut, genetic material controls the renewal process. Without this, organisms would not be able to repair themselves and maintain cell size etc. and an organism would thus be unhealthy.

• Distinguish between infectious and non-infectious diseases

Infectious diseases are caused by pathogens that can be transmitted from one
organism to another. Non infectious diseases can not be transmitted. They can be either environmental, genetic or dietary factors as well as physiological malfunction such as diseases associated with aging.

• Explain why cleanliness in food, water and personal hygiene practices assist in control of disease

Cleanliness prevents:
– contamination via spreading of pathogens
– decomposition
– transmission of diseases and infection
This is because cleanliness ensures that microorganisms that cause disease are killed or kept at bay, thus preventing the above.

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

A pathogen is any organism living in or on another organism with the capacity to cause disease. To cause disease it must have enough virulence, survive barriers, escape from one host to another.

• Gather and process and analyse info to describe ways in which drinking water can be treated and use available evidence to explain how these methods reduce risk of infection from pathogens

Ways water can be treated:
Screening – removes large parts that may be in the water – e.g. sticks and leaves small beetle etc. Filtration – water passes through a membrane to remove any solid matter in the water Flocculants – these make small particles stick together so they can be removed. Sterilisation – chlorine is added to kill and microorganism which have survived above stages. Testing – water is extensively tested to prevent an outbreak of disease if the above measures don’t work.

• Describe the contributions of Pasteur and Koch to our understanding of infectious diseases

Pasteur –
Identified that microorganisms develop from pre-existing microorganisms rather than spontaneous generation. He developed steralisation as a method of destroying pathogenic microorganisms. This enabled further links between microorganisms and disease to be made, including destruction of microorganisms and understanding for need of basic hygiene, sanitation and water treatment.

Koch – Developed a series of postulates that could be used to identify microorganisms and determine whether it was responsible for a particular disease. This lead to the identification of a range of specific disease causing microorganisms and subsequently their treatment.

• Distinguish between, and name an example of disease for the following:

Prions – Diseases caused by a protein produced in the brain called prion protein. A disease occurs if abnormal prion protein occurs, causing death of brain cells. E.g. Mad cow Disease

Virus – nucleic acid surrounded by a protein coat. They invade host cells and insert their DNA into host cell’s genetic code e.g. Influenza

Bacteria – Tiny Procaryotic cells that secrete toxins and invade and disrupt other cells. E.g. Cholera

Protozoan – like bacteria except their DNA is in a nucleus. They are eukaryotic e.g. Thrush

Fungi – Heterotrophic organisms – they are distinguished from others due to the mass of threads that make up multicellular individuals

Macro-parasites – large; seen with naked eye; either internal or external – e.g. fleas, lice

• Identify the role of antibiotics in the management of infectious diseases

Antibiotics prevent bacterial growth. They do so by breaking down the bacterial membrane and interfering with the interaction of bacterial metabolism.

• Gather and process information to trace the historical development of the cause and prevention of malaria Early – believed it was transmitted through the air
1870 – Thought it was caused by bacteria
1880 – Protozoan ‘plasmodium’ is identified as the cause – transmission mode unclear. Ross – 1890s researched the transmission which found mosquitoes in some areas had malaria – malaria was not transmitted by ingestion

– Mosquito bites an infected bird which leads to mosquito developing malaria. This causes cysts to develop on mosquito stomach wall and when this bursts, the plasmodium migrates to the salivary gland which enables the mosquito to pass on the disease when they bite a victim. It was then found that it was only the female Anopheles mosquito transmits the disease. PREVENTION: mosquito breeding areas have been drained and netted; drug DDT was spayed in WWI to kill mosquitoes, subsequent resistance evolved and now they use the drug quinine.

• Describe one named infectious disease in terms of:
Cause: Bacteria – Vibrio Cholerae
Life Cycle and Transmission: Direct life cycle – ingest food/water which is infected by the excreta of an infected person. Bacteria then remain in the intestine but do not invade other material. Host Response: Antibodies are produced to the toxin the bacteria produce Symptoms: The toxin disrupts sodium and potassium transport system.

The bacteria break down the enzyme which is responsible for the control of this. The bowel therefore becomes inflamed diarrhea occurs. Muscle cramps and dehydration. Treatment: rapid fluid and salt replacement or death can occur in as little as 12 hours. Antibiotics are only helpful early on. Control: chlorination of H20, better sanitary conditions in food preparation.

• Discuss problems relating to antibiotic resistance
High use of antibiotics means that resistant strains develop in numbers and the antibiotics are not longer useful. Golden Staph is an example of this – the ‘super strain’ of it is now resistant to nearly all antibiotics.

• Identify defense barriers to prevent entry of pathogens in humans: Skin: keratin protein prevents penetration; Dryness prevents growth; glands secrete antibacterial chemicals Mucus membranes: trap pathogens. They contain the antibody IgA which prevents bacteria and viruses attaching to the epithelial surfaces. Cilia: used to sweep mucous with trapped pathogens out.

Chemical barriers: antimicrobial secretions that inhibit entry of pathogens. E.g. the acid mantle in the vagina inhibits fungi growth. Other secretions: urine cleans and flushes out lower urinary tract. Tears and bile are also helpful.

• Identify antigens as molecules which trigger an immune response. Antigens are substances that cause the production of particular antibodies.

• Explain why transplanted organs trigger the immune response The body recognizes what is ‘self’ and what is ‘not self’. Proteins on the transplanted organ are not recognized as ‘self’ and are therefore identified as foreign antigens which triggers the immune response. The body thus tries to reject the tissue.

• Identify defence adaptations (2nd line defence) including:

Inflammation response – Tissue swells and becomes red as more blood is directed to the injured area. This carries more white blood cells which aid in fighting pathogens. The response allows the body to optimize fighting in areas where injury has occurred to body tissue.

Phagocytosis – phagocytes are cells that engulf and destroy foreign cells. It is carried out by some WBCs, scavenger cells and macrophages. Macrophages are large mobile phagocytic cells filled with lysosomes ready to ingest foreign particles. Lymph System – filters out particles; responsible for production of WBCs; thus responsible for immune response. Cell Death to seal off pathogens: phagocytes die after they engulf foreign particles and pus is formed and removed from the body. • Show how a named disease results from an imbalance in microflora in humans.

Named disease – Thrush (Candidiasis)
Caused By – Imbalance in number of naturally occurring candida albicans. This is a result of antibiotics killing off the microflora which cause an imbalance and allow the fungus to invade.

• Identify the components of the immune response (3rd line defence): ANTIBODIES- produced in the lymph nodes by B cells in response to an antigen. The antibodies directly inactivate or destroy antigens, neutralize their toxins or make them more susceptible to phagocytosis. B-CELLS- form plasma cells that form antibodies.

Presence of an antigen stimulates the production of plasma by B-cells (lymphocytes) that in turn make antibodies (which are proteins). T-CELLS- they either destroy the antigens (killer T-cells) or activate phagocytes (helper T-cells). There are different types of T-cells, some mentioned, others enhance B-cells or help retain a memory of antigens for long term immunity.

• Describe and explain the immune response in terms of: – Interaction between B and T lymphocytes: Helper T cells release chemicals to stimulate B – Cells. These chemicals also aid in the coordination of the immune response. – The mechanisms that allow interaction between B and T cells: a) Cell contact – close contact allows T cells to signal B cells that they have come into contact with an antigen. b) Cytokines – T cells produce cytokines which is a soluble factor that is produced after contact with an antigen.

The B cell reacts and becomes a functional antibody producing cell. – Range of T Lymphocyte types and the difference in their roles: Killer T cells – secrete substances that directly destroy antigens, enhance activity of macrophages and inhibit replication of viruses. Helper T cells – enhance antibody production in B cells

Suppressor T cells – help turn off the immune response
Memory T cells – retain ability to recognize particular antigens Cytotoxic T cells – destroy cells which carry foreign antigens

• Outline ways in which vaccination prevents infection Vaccination is artificial immunity. By ingesting/injecting antigens from living, dead, weakened or non-virulent strains of microorganisms, immunity can be obtained without symptoms. It works by stimulating the immune response (i.e. T cells and B cells and antibodies) so that memory to the pathogen can be obtained, thus the immune response will be quicker and more effective if the antigen becomes present again.

• Outline the reasons for the suppression of the immune response in organ transplant patients – to prevent rejection – because organ blood drains into the recipients circulation, the body recognizes the proteins from the transplant as other than ‘self’, thus antibodies are produced in response – rejection is reduced by matching the recipients proteins to the transported tissue – Drugs are given to suppress this action and to ease the transplanted organ into the new recipients system.

• Evaluate the effectiveness of vaccination programs in preventing the spread and occurrence of once common diseases, including smallpox, diphtheria and polio.

Small Pox – 1700s – one in three who caught it died.
1776. – vaccine developed
1960s – WHO worldwide immunization
1980 – World is smallpox free.
Diphtheria – pre 1923 – common in kids in temperate climates
1923 – Vaccine developed
40s and 50s – shift from cyclical epidemics to occasional outbreaks, with less intensity 1974 – World health ‘Expanded Program on Immunisation’
1990 – 80% of world vaccinated
In Australia between 1926 and 35 there were over 4000 deaths with an epidemic in 1921
Virtually no cases since 1992 in Aust.
Polio – pre 1955 thousands of children became crippled with polio each year
1955 vaccine introduced
1960s an oral form of the vaccine was introduced and polio was controlled in industrialized countries 1988 – 350 000 cases
2001 – 600 cases

• Identify and describe the main features of epidemiology using lung cancer as an example. Epidemiology is the study of disease data. There are four main areas – Incidence – incidence in Lung Cancer is declining for men but increasing for women Mortality – death rates from Lung Cancer are increasing

Infant Mortality- not associated with Lung Cancer
Life Expectancy- as a result of high death rates from lung cancer, the impact on life expectancy is negative. Epidemiology has allowed for the establishment of links between smoking and lung cancer.

• Identify causes of non-infectious disease using an example from each of the following: Inherited diseases – caused by genetic factors. E.g. Down Syndrome, where part of or a whole extra chromosome is present in their DNA Nutritional Diseases – Kwashiorkor, a protein deficiency caused by an imbalanced diet. Body cannot repair itself, or grow in children Environmental Diseases – for example skin cancer. Caused by exposure to ultraviolet radiation which is a mutagenic factor, which interferes with genetic material in cells.

• Identify the CAUSE and EFFECT relationship of smoking and lung cancer – In 1880, cigarettes were introduced and were given to world war one soldiers. In the 1930s a sudden epidemic of lung cancer indicated a link between smoking and lung cancer. – In the 1950s the first large epidemiological study showed a link between smokers and lung cancer but not a causal relationship. – By 1964, the surgeon Generals Advisal committee concluded smoking was responsible for lung cancer.

– By 1970s, lung cancer was the number one cause of death among cancers – In 1970s lung cancer was rare in women but campaigning increased cigarette use and by the 1990s it was the leading cause of cancer death for women – Since 1984 there has been a 2% decrease of incidence of men with lung cancer but an increase with women – People who smoke have a 10x higher risk of lung cancer

– Consistency among studies
– Graded response – death rate increases linearly with amount of cigarettes smoked per day – Smoking must precede lung cancer to be the cause of it.
– It is most likely the chemicals in cigarettes are carcinogenic

• Identify data sources, or gather information from secondary sources and present information about the occurrence, symptoms, cause, treatment management of a named non infectious disease. Cardiovascular Disease –

Occurrence – CVD accounts for 40% of deaths in Australia
Cause – arteries become clogged with cholesterol and fatty tissue causing blockage (atherosclerosis) or hardening of the arteries (arteriosclerosis). High Blood pressure, obesity and smoking contribute to the disease. The blockage means that blood cannot get to organs in the body and a heart attack can occur. Symptoms – breathlessness, chest pain, abnormal heart rhythm, swelling of legs and ankles. Treatment/management – rest, drugs to reduce BP, valve replacement surgery, pacemaker, exercise, quit smoking, low salt diet, stress management and weight control.

• Discuss the role of quarantine in preventing the spread of disease and plants and animals into or across regions of Australia. Quarantine refers to the isolation of plants, animals and items of risk in order to prevent spread of contagious disease. Laws in Australia are present to protect the local species and keep out agricultural pests and diseases.

There are border restrictions within states as well as laws preventing overseas products entering the country. Inspections take place at point of entry, both air and sea. All items require inspection and declaration by passengers, and sniffer dogs are used to ensure stray items don’t enter.

The Australian Quarantine and inspection service (AQIS) confiscate items of risk, and put items into quarantine for various periods of time. Agricultural products are subject to the strictest quarantine. There are great penalties for breaching the international quarantine laws.

There are regulations from state to state to prevent pests such as the Queensland fruit fly from getting into crops from NSW. Penalties are harsh but not as harsh as international. There is usually an honesty system present for crossing the borders, such as waste bins as you disembark from a plane. Overall it is extremely important to protect crops, animals etc. from the spread of disease and quarantine is successful in achieving this.

• Explain how one of the following strategies has controlled and or prevented disease: Public Health Programs: Public Health authorities build public policy which aids in preventing disease. For example, people in South America had a high incidence of Cholera in their drinking water – which is spread by drinking or consuming faecally contaminated product.

The public health authorities put foreword an educational campaign to raise awareness of how the disease is spread, and provided clean drinking water. The incidence in these areas has been reduced. Quit Smoking Campaigns by the state government provide supportive environments to quit smoking whilst also educating. The result is a reduction in the incidence of lung cancer and smoking over the past 10 years. Laws to inform partner about HIV AIDS.

• Evaluate the effectiveness of quarantine in preventing the spread of plant and animal diseases into Australia or across regions in Australia Quarantine ensures that infectious diseases are not spread across regions of Australia. They have been effective because the incidence of diseases such as foot and mouth disease have not become a problem in Australia.

Neither has the incidence of Malaria so far affected Australia. The fruit fly has been successfully isolated in Queensland – four freedom areas have been identified as fruit fly free. Quarantine is therefore effective; however, most of Australia’s problems lie in the lifestyle related disease sector.

• Discuss the changing methods of dealing with plant and animal disease, including the shift from treatment and control to management or prevention of disease. – prevention costs less, and it is better and easier to achieve than cure – Pro-active approach (e.g. BT tomatoes which are resistant to certain caterpillars – rather than having to kill the tomatoes when they are diseased. – Quarantine prevents disease spread rather than having to treat diseases which are spread later.

– Immunisation, active immunity prevents and eradicates diseases rather than treating them when they cause an outbreak. E.g. smallpox – world is smallpox free. – Natural resistance means there are many resistant strains of things so treating them becomes difficult

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