The Immune System
Biology: Edexcel IGCSE, topic 3.3.14
The Immune System
If a pathogen (disease-causing microorganism) enters the body, the immune system is activated. The immune system is made up of different white blood cells, which have different functions.
Phagocytosis
- White blood cells called phagocytes find the pathogen and engulf it by changing shape.
- The phagocyte ingests (absorbs) and digests the pathogen, destroying it.
Antibodies
- White blood cells called lymphocytes recognise foreign antigens (proteins) on the surface of pathogens and produce protein molecules called antibodies.
- Antibodies are specific to particular pathogens.