Pathogens Flashcards
What is disease?
Disease is a description of certain symptoms which have an adverse effect on good health. These can be mental, physical or social.
What is a Pathogen?
A pathogen is a micro-organism which causes disease
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
If a pathogen gets into the host and colonises its tissues, what occurs?
An infection
What is it called when a pathogen is transferred from one individual to another?
Transmission
What is an interface? An example?
An interface is a surface or boundary linking two systems, in this case linking the external environment with the internal environment of the body. The skin is an example.
How is skin a good barrier to infections?
It is a thick, continuous layer
Give two examples of interfaces which pathogens can enter through:
The Gas exchange system eg influenza and The Digestive system eg cholera (contaminated food taken into the small intestine)
Give 3 examples of natural bodily defences against pathogens:
- a mucous layer covers exchange surfaces, forming a thick, sticky layer which is hard to penetrate
- production of enzymes that break down pathogens
- production of stomach acid which kills microorganisms
How do pathogens cause disease?
By damaging hosts (eg viruses inhibit the synthesis of DNA, RNA and proteins by the host cells. Many pathogens break down the membranes of host cells)
By producing toxins
Why are the digestive and respiratory systems good entry sites for pathogens?
The body linings at these point are thin, moist, sticky, have a large surface area and are well supplied with blood vessels
What changes how quickly a pathogen can cause damage?
How rapidly the pathogen divides
