Infection & ResponseTopic Summary
Knowledge Organiser
Part of Human Defense Systems - Non-specific — GCSE Biology
This topic summary covers Knowledge Organiser within Human Defense Systems - Non-specific for GCSE Biology. Physical and chemical barriers, white blood cell responses, inflammatory response It is section 17 of 18 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 17 of 18
Practice
19 questions
Recall
22 flashcards
Knowledge Organiser
First Line of Defence
- Skin: physical barrier; sebum (acidic, antimicrobial)
- Mucus: traps pathogens in airways
- Cilia: sweep mucus upward (ciliary escalator)
- Stomach acid (pH 1-2): kills ingested pathogens
- Lysozyme: breaks down bacterial cell walls (in tears, saliva)
Second Line of Defence
- Neutrophils: arrive first, short-lived, engulf bacteria
- Macrophages: larger, longer-lived, present antigens
- Phagocytosis: recognise, attach, engulf, lysosome fusion, digest
- Inflammation: vasodilation, increased permeability, swelling
- Fever: high temp inhibits pathogen growth, boosts immunity
Common Marks Lost
- Saying mucus kills bacteria (it traps; lysozyme kills)
- Missing lysosome fusion step in phagocytosis
- Saying all white blood cells engulf pathogens (only phagocytes)
- Not linking inflammation signs to causes (redness = vasodilation)
- Forgetting macrophages present antigens to activate adaptive immunity