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Unit 1…read more

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Chapter 1 ­ Causes of disease
- microorganisms that cause disease
- bacteria, viruses and fungi
- for a microorganism to be considered a pathogen it must;
gain entry to the host,
colonise the tissues of the host,
resist the defences of the host,
cause damage to the host tissues.
- e.g. Mycobacterium leprae - the bacterium that causes leprosy
- pathogens cause disease by damaging host tissues and producing
- Key words to note for this chapter:
Transmission - when a pathogen is transferred from one individual
to another.
- Infection - when a pathogen gets into the host and colonises its
- Disease - when an infection leads to recognisable symptons.…read more

Slide 3

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Chapter 1 ­ Causes of disease
Points of entry for pathogens:
· skin
· reproductive and urinatry system
· gas-exchange system (respirtatory)
· digestive system
Diseases are not only caused by pathogens. They
can also be caused by lifestyle and genetic
factors - such as Coronary Heart Disease…read more

Slide 4

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Chapter 1 ­ Causes of disease
· - the study of diseases that affect large
numbers of people
· - provides very important information (we can
use it to work out where certain diseases can
be contracted, how to deal with it, what it's
symptons are, prevelency etc.)
· - can ultimately help to prevent contracting
diseases…read more

Slide 5

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Chapter 1 ­ Causes of disease
A correlation occurs when a change in 1 of 2 variables is
reflected by a change in the other variable. (positive or
negative.)There is research to suggest that there is a
correlation between drinking alcohol and breast
cancer. However, we cannot conclude that drinking is
the cause of breast cancer. The data may seem to
suggest this in the case of a correlation, but it could be
due other factors.
For example; it could be that women who are stressed
drink more alcohol and that it is the stress, not the
alcohol, that is infact causing breast cancer.…read more

Slide 6

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Chapter 1 ­ Causes of disease
· RISK - 'a measure of the probability that damage
to health will occur as a result of a given hazard'
· Risk factors and cancer:
- uncontrollable causal factors -> age/genetic
- lifestyle choices -> smoking, diet, obesity,
physical activity, sunlight
· Risk factors and CHD:
- uncontrollable causal factors -> genes, age, sex
- lifestyle choices -> smoking, high blood pressure,
high blood cholesterol, obesity, diet and amount
of physical activity…read more

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