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First Line of Defence: Chemical Barriers

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

This deep dive covers First Line of Defence: Chemical Barriers within Human Defense Systems - Non-specific for GCSE Biology. Physical and chemical barriers, white blood cell responses, inflammatory response It is section 4 of 16 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 4 of 16

Practice

19 questions

Recall

22 flashcards

First Line of Defence: Chemical Barriers

Stomach Acid

Your stomach produces hydrochloric acid that creates an extremely hostile environment for pathogens that are swallowed:

  • Low pH: Stomach acid has a pH of around 2, killing most bacteria and viruses
  • Denatures proteins: The acid destroys the proteins and enzymes that pathogens need to survive

Lysozyme

Lysozyme is an antimicrobial enzyme found in several body secretions:

  • Where it is found: In tears, saliva, and mucus
  • How it works: It destroys the cell walls of bacteria, killing them

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: Physical BarriersPhysical vs Chemical BarriersYour 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 phagocytosis?
The process by which white blood cells (phagocytes) engulf and digest pathogens or foreign particles.
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.

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First Line of Defence: Physical Barriers

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Physical vs Chemical Barriers