Know Your Body
Immune System
Your body's defence team
Official source located — human medical review required.
How it works
Your immune system defends your body against germs and other harmful substances. White blood cells are a key part of this system — they patrol your body and attack invaders. Vaccines work by imitating an infection, without causing the actual disease, so your immune system learns how to fight it. This teaches your body to build antibodies. Washing your hands with soap and water is one of the best ways to help stop germs from spreading.
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Explore three questions
Select a card to open its answer. Select it again to close.
Three key learning points
- Your immune system defends your body against things it identifies as harmful or foreign.
- Vaccines imitate an infection so your immune system can learn to fight a disease without you getting seriously sick from it.
- Washing your hands with soap and water is one of the best ways to remove germs.
Official source located — human medical review required.
Five-question quiz
One question at a time, with feedback after each answer. There is no pass or fail here.
Question 1 of 5
All official sources for this lesson
Source pages
Official source located — human medical review required.
Medical-review checklist for this system
- Q4 needs extra care before publishing — the adolescent-specific source wording must be re-confirmed (flagged as the weakest-sourced item in the pack)
- Confirm vaccine-related wording stays general and educational — no claims about any specific vaccine, disease, or side effect
- Confirm handwashing guidance matches current CDC wording exactly