#**causes of disease**


1)what they are,2) how they get into the body & 3) how they cause disease

1) pathogen: any micro-organism that causes disease. (pathogens include bacteria, viruses & fungi)
2) gas exchange system: many pathogens enter the body through the gas exchange surfaces. pathogens that cause influenza, tuberculosis & bronchitis infect in this way.
2) digestive system: food & water may carry pathogens into the stomach & intestines via the mouth. cholera, typhoid & dysentery pathogens enter by this means.
3) By damaging host tissue: numbers can cause damage, some break down the membranes, viruses can take over the DNA and RNA of hosts.
3) by producing toxins: pathogens can produce toxins. cholera can produce toxins that lead to excessive water loss from the lining of the intestines.

lifestyle & health

1) risk, 2) lifestyle choice and cancer, 3) lifestyle choice and coronary heart disease, 4) reducing risk of cancer and CHD