Human Defence Systems - Immune Systems
Biology: AQA GCSE Higher, topic 3.1.10
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.
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 Human Defence Systems - Immune Systems
Why does a white blood cell change shape during phagocytosis?
Why are antitoxins important in fighting a bacterial infection?
What must the immune system produce to fight a new type of pathogen it has not encountered before?
What makes antibody production different from phagocytosis in fighting a pathogen?