Physical vs Chemical Barriers

Part of Human Defense Systems - Non-specific · Section 5 of 16

ComparisonUnit: Infection & ResponseGCSE

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.

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

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.

First Line of Defence: Chemical Barriers

First Line Defence Mechanisms

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