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10 Cards in this Set
- Front
- Back
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What are pathogens?
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Pathogens are microorganisms that cause disease. for a microorganism to be considered a pathogen it must:
- gain entry to the host - colonise the tissue of the host - resist the defences of the host - cause damage to the host tissue |
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How do pathogens enter the body?
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By penetrating one of the organism's interfaces with the environment:
- the gas exchange system (e.g. influenza, tuberculosis). - the digestive system (e.g. cholera, typhoid). To prevent the entry body has a number of natural defences: - a mucus layer forms a thick, sticky barrier - enzymes, which break down the pathogens - stomach acid, which kills microorganisms |
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How do pathogens cause disease?
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Pathogens affect the body in two ways:
- by damaging the host tissues. Viruses inhibit the synthesis of DNA, RNA and proteins by the host cells and many pathogens break down the membranes of the host cells. - by producing toxins. most bacterial pathogens produce toxins e.g. cholera bacterium produces a toxin that leads to excessive water loss from the lining of the intestines. |
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How are data on disease interpreted and analysed?
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Epidemiologists collect data on diseases and the look for a pattern or a relationship between these diseases and various factors in the lives of people who have them.
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What is a correlation and what does it mean?
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A correlation occurs when a change in one of two variables is reflected by a change in the other variable.
A correlation does not mean that there is a causal link! |
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How is a causal link established?
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A causal link is established when we can provide experimental evidence of which specific factor and how affects the formation of disease.
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What is a risk?
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A risk is a measure of the probability that damage to health will occur as a result of a given hazard.
Risk has two elements: - the probability that hazardous event will occur - the consequences of that hazardous event |
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How is a risk measured?
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It can be measured as a value that ranges from 0 per cent (no harm will occur) to 100 per cent (harm will certainly occur).
Health risks need a timescale and it is often relative- comparing the likelihood of harm occurring in those exposed to hazard with those who are not exposed to it. |
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What factors affects a risk of contracting cancer?
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- Smoking; also those who passively breathe tobacco smoke also have an increased risk of getting cancer.
- Diet; strong evidence that a low-fat, high-fibre diet, rich in fruit and vegetables reduces the risk. - Obesity - Physical Activity; people who take regular exercise are at lower risk from some cancers. - Sunlight; the more explosion to sunlight or light from sunbeds the greater the risk of skin cancer. |
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What factors affect a risk of contracting a coronary heart disease?
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- Smoking
- High Blood Pressure - Blood Cholesterol Levels - Obesity - Diet; high levels of salt in diet raise the blood pressure while high levels of saturated fatty acids increase blood cholesterol concentration. - Physical Activity |
