The Immune System
Biology: AQA GCSE Higher, topic 3.1.13
The Immune System
If a pathogen passes the non-specific defences, the immune system is activated. The immune system is made up of different white blood cells, which have different functions.
Phagocytosis
- A white blood cell finds the pathogen and engulfs it by changing shape.
- The white blood cell ingests and digests the pathogen, destroying it.
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Antibodies
- White blood cells recognise foreign antigens on the surface of pathogens and produce protein molecules called antibodies.
- Antibodies are specific to particular pathogens.
Antitoxins
- Some bacteria produce toxins that can damage cells and tissues.
- The immune system responds to this by producing antitoxins, which neutralise the toxins released by the bacteria and prevent them from causing harm.
Test yourself on The Immune System
What happens when a pathogen manages to get past the body's non-specific defences?
How do white blood cells work together to fight pathogens?
What can toxins produced by some bacteria do to the body?