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Physical vs Chemical Barriers

Part of Human Defense Systems - Non-specific — GCSE Biology

This comparison covers Physical vs Chemical Barriers within Human Defense Systems - Non-specific for GCSE Biology. Physical and chemical barriers, white blood cell responses, inflammatory response It is section 5 of 16 in this topic. Use this comparison to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 5 of 16

Practice

19 questions

Recall

22 flashcards

Physical vs Chemical Barriers

Physical Barriers Chemical Barriers
  • Skin — continuous barrier, hard for pathogens to penetrate
  • Mucus — traps pathogens in nose and airways
  • Cilia — tiny hairs that sweep mucus (with trapped pathogens) to the throat
  • Scabs — blood clots seal wounds to stop pathogens entering
  • Stomach acid — hydrochloric acid (pH 2) kills most pathogens
  • Lysozyme — enzyme in tears and saliva that destroys bacterial cell walls
  • Skin oils — create an environment hostile to microorganisms

Keep building this topic

Read this section alongside the surrounding pages in Human Defense Systems - Non-specific. That gives you the full topic sequence instead of a single isolated revision point.

First Line of Defence: Chemical BarriersFirst Line Defence MechanismsYour Body's Security SystemKey Facts: Non-Specific Defences

Practice Questions for Human Defense Systems - Non-specific

Which part of the body acts as the main physical barrier to prevent pathogens entering?

  • A. The skin
  • B. The lungs
  • C. The heart
  • D. The brain
1 markfoundation

Explain how mucus and cilia in the airways protect against pathogens.

3 marksstandard

Quick Recall Flashcards

What is sebum?
An oily substance produced by sebaceous glands in the skin that creates an acidic environment on the skin surface, inhibiting bacterial and fungal growth.
What is phagocytosis?
The process by which white blood cells (phagocytes) engulf and digest pathogens or foreign particles.

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First Line of Defence: Chemical Barriers

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First Line Defence Mechanisms