Infectious diseases
Microorganisms
- E.g bacteria, viruses, fungi
- Not all cause diseases
- Ones that cause diseases are called pathogens
Pathogens
Microorganisms that cause disease
Bacteria
Produce toxins (poisons)
Viruses
Much smaller
Infect body cells by getting inside and reproducing so many times that the cell explodes/breaks so is permanently damaged
DEFENCE - white blood cells
They ingest bacteria and release enzymes to digest pathogens
They produce antibodies to latch onto the antigens (small shapes on cell walls) of the pathogen and start destroying them. Different diseases have different antigens.
They produce antitoxins which neutralise bacteria toxins, making them harmless.
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