Human Defence Systems - Immune Systems
Biology: Cambridge International GCSE Supplement, topic 10.1.5
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 (absorbs) and digests the pathogen, destroying it.
Antibodies
- White blood cells recognise foreign antigens (proteins) on the surface of pathogens and produce protein molecules called antibodies.
- Antibodies are specific to particular pathogens.
Autoimmune diseases
- Sometimes the immune system doesn't function properly and attacks healthy body cells instead of pathogens.
- Type 1 diabetes is caused by the immune system destroying cells in the pancreas that produce insulin.
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