The immune system uses several kinds of defence. Barriers help keep microbes out, broad responses can react after entry, and specific responses recognize particular features. Some responses leave memory for a later matching encounter. That memory is not a defence against every different microbe. Innate defences include physical barriers and rapid, broad cellular responses. Adaptive responses involve specific recognition and can create immune memory. These systems communicate and overlap. Recognising one invader’s features does not guarantee recognition of an unrelated invader. The model uses invented symbols to compare specificity, not to predict whether someone will become ill.
The human body · Discover & try
How do different defences work together?
Reading level 3 of 5 · IndependentChange
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Innate
Broad defence mechanisms present without a new specific memory.
Immune memory
Cells retained after some responses that can recognise particular features.
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See how it works
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Conceptual defences shown in separate panels; real responses overlap. Invented symbols and timing do not predict illness or protection.
What to look for
- Barriers, broad responses and specific recognition contribute different defences.
- The memory route refers to a matching feature; it does not mean protection from everything.
Explain what you noticed
A memory cell recognises symbol M, but a new invader has a different symbol N. What can you conclude?
Keep this idea: Broad defences and specific recognition cooperate; immune memory is not a universal match.
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