Causes of disease

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  • Created by: r98
  • Created on: 10-04-16 20:45
What's the definition of a pathogen?
Any microorganism that causes disease.
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What is disease?
A description of certain symptoms, either physical or mental, or both.
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What does disease suggest?
A malfunction of body or mind which has an adverse effect on good health.
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What aspects does disease have?
It has mental, physical and social aspects.
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What four things must a microoganism do to be considered a pathogen?
Gain entry to the host, colonise the tissues of the host, resist the defences of the host, and cause damage to the host tissues.
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What are 3 examples of pathogens?
Bacteria, viruses and fungi.
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What results, if a pathogen gets into the host and colonises its tissue?
An infection.
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How does disease occur from an infection?
Disease occurs when an infection leads to recognisable symptoms in the host.
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What is transmission?
When a pathogen is transferred from one individual to another.
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What is an interface? What is an example of an interface?
A surface or boundary linking two systems. Example: linking the external environment with the internal environment of the body.
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How do pathogens normally get into the body?
By penetrating one of the organism's interfaces with the environment.
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On the body, what is an example of an interface? What does this interface form? When does invasion from a pathogen therefore usually occur?
The skin, it forms an effective barrier to infection. Invasion usually occurs when the skin is broken, as a result of cuts and abrasions or through insect bites.
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What is the body lining like at interfaces of the body that allow the exchange of material, between the internal and external environments?
Thin, moist (therefore sticky), have a large surface area and are well supplied with blood vessels.
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What 2 interfaces of the body are common points of entry for pathogens?
The gas-exchange system & the digestive system (food and water carry pathogens into the stomach and intestines via the mouth).
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What are 3 natural defences that the body has, to prevent the entry of pathogens?
A mucous layer that covers the exchange surfaces, forms a thick sticky barrier = difficult to penetrate. The production of enzymes that break down the pathogen. The production of stomach acid, kills microorganisms.
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What are the 2 main ways that pathogens affect the body?
By damaging host tissues or by producing toxins.
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How do pathogens damage host tissues?
A large number of pathogens prevents the tissues from functioning properly. Viruses inhibit the synthesis of DNA, RNA and proteins by the host cells. Pathogens can break down the membranes of host cells.
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What type of pathogen are likely to produce toxins?
Most bacterial pathogens produce toxins.
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What 3 things can cause disease?
Pathogens, lifestyle and genetic factors.
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What is the rate at which a pathogen divides, related to?
How quickly a pathogen causes damage, and hence the onset of symptoms.
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When does a correlation occur?
When a change in one of the two variables is reflected by a change in the other variable.
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What must there be between two variables (e.g. drinking alcohol and breast cancer) before we can state that one variable cause the other variable?
There needs to be a clear causal connection.
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What is needed to prove that one variable (e.g. drinking alcohol) causes another variable (e.g. breast cancer) ?
Experimental evidence to show that a component of the alcoholic drink led directly to women getting breast cancer.
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Does a correlation mean that there is a causal link?
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What's the definition of risk?
A measure of the probability that damage to health will occur as a result of a given hazard.
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What 2 elements does the concept of risk have?
The probability that a hazardous event will occur, & the consequences of that hazardous event.
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When should we become concerned about a risk?
When the probability is high and the consequences are severe.
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What is risk measured as?
Risk is measured as a value that ranges from 0% (no harm will occur) to 100% (harm will certainly occur).
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What do health risks need?
A timescale.
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Why is risk often relative?
Risk is often measured by comparing the likelihood of harm occuring in those exposed to the hazard with those who are not exposed to it.
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What are 2 causal factors of cancer that are beyond our individual control?
Age & genetic factors.
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What are the lifestyle factors that contribute to cancer?
Smoking, diet, obesity, physical activity, and sunlight.
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Apart from smokers, who else is at risk of getting cancer, due to smoking?
Those who passively breathe tobacco smoke also have an increased risk of getting cancer.
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What are the lifestyle factors that contribute to coronary heart disease (CHD)?
Smoking, high blood pressure, blood cholesterol levels, obesity, diet, physical activity.
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What factors can increase blood pressure?
Excessive prolonged stress, certain diets and lack of exercise.
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What measures can be taken to reduce the risk of getting both cancer and CHD?
Giving up or not taking up smoking, avoiding becoming overweight, reducing salt intake, reducing intake of cholesterol and saturated fats, regular aerobic exercise, keeping alcohol consumption within safe limits, increasing fibre & antioxidant intake
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Card 2


What is disease?


A description of certain symptoms, either physical or mental, or both.

Card 3


What does disease suggest?


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Card 4


What aspects does disease have?


Preview of the front of card 4

Card 5


What four things must a microoganism do to be considered a pathogen?


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