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All pathogens can be categorized by the following:
Entering the host
Colonizing within the host
Damaging the tissues in the host
Resisting the defence mechanism
Transmission of Pathogens
In order for pathogens to cause harm, it must first enter the host.
There are 3 main ways of entering the host:
1. Air- Pathogens can be found in the air. Once breathed in, the
body is able to remove the majority of them by trapping
them with mucus secreted by the goblet cells in the body.
The ciliated cells then beat the mucus up the trachea and is
coughed up or collected in the nasal passages.
2. Ingested- Pathogens can be ingested but most are destroyed
in the stomach due to the acidic conditions. However, some
are able to survive and damage the cells of the intestinal
3. Skin- When skin becomes injured and damaged, the
bloodstream is exposed to the air containing pathogens. The
pathogens can then enter the bloodstream of the host easier.
However, the blood is able to clot and form a barrier against
the air and the bloodstream of the host. Although some
pathogens can enter before the blood is able to clot.
How Pathogens Cause Disease
There are 2 main ways in which pathogens can affect the body:
Damage to the host cells
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The pathogen can damage the host cells by the following
a) Breaking down the cell membrane and releasing the
nutrients inside them
b) Taking up the nutrients instead of the cell leading to the cell
to become starved
c) Replicating inside the cell to the point where the cell bursts
due to large capacity/pressure within.
The rate of the time a pathogen can cause a disease= the rate of
how fast a pathogen can REPLICATE.…read more