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Infection & ResponseDeep Dive

Complement System

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

This deep dive covers Complement System within Human Defense Systems - Non-specific for GCSE Biology. Physical and chemical barriers, white blood cell responses, inflammatory response It is section 8 of 18 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 8 of 18

Practice

19 questions

Recall

22 flashcards

Complement System

The complement system is a complex cascade of proteins that enhance the body's ability to fight infection:

Complement Activation

  • Pattern recognition: Complement proteins recognize common pathogen structures
  • Cascade activation: One protein activates the next in a chain reaction
  • Amplification: Small initial signal produces large response
  • Three pathways: Classical, alternative, and lectin pathways

Complement Functions

Direct Pathogen Killing
  • Membrane Attack Complex (MAC): Proteins form pores in pathogen membranes
  • Cell lysis: Pores cause pathogens to burst due to osmotic pressure
  • Effective against: Bacteria, some viruses, and parasites
Opsonization
  • Coating pathogens: Complement proteins coat pathogen surfaces
  • Enhanced recognition: Makes pathogens easier for phagocytes to recognize
  • Increased phagocytosis: Dramatically improves efficiency of pathogen engulfment
Chemotaxis
  • Chemical signals: Complement fragments act as chemoattractants
  • White cell recruitment: Draws neutrophils and macrophages to infection site
  • Inflammatory response: Enhances local inflammation

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.

Fever ResponseExam Tips: Non-Specific ImmunityYour Body's Security SystemKey Facts: Non-Specific Immunity

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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Exam Tips: Non-Specific Immunity