Not all micro organisms are harmful to the body; these are called a
pathogen which are a microbe causing the body to react against the disease
Vaccination: Weakened, Inactive, Protein Coat > Lymphocytes > Antibodies in response
to an antigen > Pathogen destroyed > Memory Cells > Makes antibodies if re-encountered
Bacteria: Living, usually only one cell large (e.g ecoli,
salmonella, food poisoning, cholera, typhoid, MRSA)
Fungi: Live on dead/living
matter (e.g athletes foot)
Viruses: NOT living things,
need a host (e.g flu, cold,
rubella, chicken pox, HIV)
Antibodies: very specific, takes several days to produce
Every microbe has its own unique antigen pattern on the surface. From this the WBC can produce
antibodies that match the antigen exactly. This is called the lock and key theory. The antibodies made
will fight the microbe and the antibodies will remain in the body in the form of memory cells. If the same
antigen pattern is exposed again, the microbe is quickly destroyed- we say the person is immune.
Vaccines can contain one of the
following: A weakened strain of the virus.
Dead virus (deactivated). Antigen coat.
When a person is vaccinated, the body will respond in a similar way as if the
pathogen was naturally encountered. Memory cells would be produced and if the
pathogen was to be encountered again, a rapid response would occur.
White Blood Cells
Lymphocytes - can produce specific antibodies to kill a particular pathogen
Phagocytes - they coat pathogens, clumping them together
so that they are easily ingested by white blood cells
Example of microbes not simply appearing: Louis Passteur's investigation
with a swan necked flask and broth at the other end. Bacteria gathered but
because the curve in the flask, it wasn't able to reach the broth.