Flashcards in Causes of Disease (UNIT 1) Deck (14):
A single celled organism that is too small to be seen without a microscope.
Includes viruses and bacteria and fungi
Disease causing micro-organism
What must a micro-organism do to be considered a pathogen?
-gain entry to host
-colonise the tissue of the host
-resist defences of the host
-cause damage to hosts tissues.
An infection occurs when...
a pathogen gets into the host and colonises its tissue
Disease occurs when...
an infection leads to recognisable symptoms in the host.
When a pathogen is transferred from one individual to another
What are the two common points of entry for a pathogen?
The gas exchange system- Many enter body through gas exchange surfaces. e.g. pathogens that cause influenza, tuberculosis and bronchitis
The digestive system- Food and water may carry pathogens into the stomach and intestines via mouth.
e.g. cholera, typhoid and dysentery pathogens
What are some of the bodies defences against pathogens?
-A mucus layer that covers exchange surfaces and forms thick stick barrier that is difficult to penetrate.
-Production of enzymes that break down the pathogens
-Production of stomach acid, which kills micro-organisms
What are the two main ways pathogens affect the body?
-By damaging hosts tissue- sometimes sheer number of pathogens causes damage e.g. by preventing tissue from functioning properly.
Viruses inhibit the synthesis of DNA, RNA and proteins by the host cells.
Many pathogens break down the membranes of the host cells.
-By producing toxins- Most bacterial pathogens produce toxins
What determines how quick a pathogen can cause damage?
Related to how quickly pathogen divides.
When does a correlation occur?
When a change in one of two variables is reflected by a change in the other variable.
Define risk in term of health,
A measure of the probability that damage to health will occur as a result of a given hazard.
What lifestyle factors contribute to cancer?