Microorganisms as Pathogens
- Gain ENTRY to the host.
- COLONISE the tissues of the host.
- Resist DEFENCES of the host.
- Cause DAMAGE to the host tissues.
INFECTION = Pathogen has COLONISED its tissue.
DISEASE = INFECTION leads to recognisable symptoms.
TRANSMISSION = When a pathogen is TRANSFERRED from one individual to another.
Microorganisms entering the body:
Pathogens enter by penetrating one of the organism's interfaces with the environment.
INTERFACE = a surface or boundary linking two systems.
In the body - this is the external environment and the internal environment.
An example of an interface is the skin - invasion happens when the skin is broken.
Some interfaces of the body have evolved to allow the exchange of material between internal and external environments. This has resulted in body linings at these points to be THIN, MOIST, HAVE LARGE SURFACE AREAS and well supplied with BLOOD VESSELS.
REMEMBER: That these features also mean that pathogenic microorganisms have an easy…