Single-celled organism including bacteria and viruses
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What are the microorganisms called that cause disease?
Pathogens
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What must a microorganism do to be considered a pathogen?
Gain entry to host, Colonise the tissue of the host, Resist the defences of the host and causee damage to the host tissue
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What happens if a pathogen gets into the host and colonises its tissue?
An infection results
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When does disease occur?
When an infection leads to recognisable symptoms in the host
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What is transmission?
When a pathogen is transferred from individual to another
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How do pathogens get into the body?
Normally by penetrating one of the organisms interfaces with the enviroment
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How does the interface skin sometimes lead to pathogens entering the body?
The skin forms a thick layer however pathogens can occur if the skin is broken due to cuts or bites
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What kind of pathogens enter the gas-exchange system?
Pathogens that cause influenza, tuberculosis and bronchitis enter here easily as the gas-exchange system easily allows the entry and exit of substances
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How do pathogens enter the digestive system?
Food and water may carry pathogens into the stomach and intestines via the mouth, examples are cholera
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Name the body's 3 natural defences against pathogens
A mucous layer that covers the exchange surfaces and forms a thick sticky barrier that is difficult to penetrate, the production of enzymes that break down pathogens and the production of stomach acid which kills microorganisms
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How do pathogens affect the host body?
By damaging host tissue and by producing toxins
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Explain how a pathogen can damage host tissue
If there's a large number then pathogens can prevent tissue function, break down the membrane of the host cells, viruses can inhibit the synthesis of DNA and RNA
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What determines how quickly a pathogen causes damage?
How quickly it divides
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What is the definition of 'a risk' when relating to risk factors?
A measure of the probability that damage to health will occur as a result of a given hazard
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What is risk measured in?
% - 0% - no harm will occur, 100% - harm will certainly occur
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Name the lifestyle choices that are risk factors for cancer
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