weirdfacts
Year 11 / Infectious disease and epidemiology

Stop the pathogen at the gate.

Pathogens include bacteria, viruses, fungi and protists. Their biology affects how they reproduce and how disease is treated. Transmission may occur through droplets, contact, food, water or vectors.

Skin and mucous membranes are first-line barriers. If a pathogen enters tissue, inflammation recruits immune cells and phagocytes engulf material. These innate responses act broadly, before a specific adaptive response develops.

INTERACTIVE MODEL

First-line defence

PathogenIntact skinStoppedBarrier blocks entry

Explore: Choose a transmission route and watch which barrier or response acts first.

exposurebarrier breachinnate response\text{exposure}\to\text{barrier breach}\to\text{innate response}
WORKED EXAMPLE

A virus crosses a damaged skin barrier.

  1. Inflammation increases blood flow and immune-cell recruitment.
  2. Phagocytes and later antigen-specific cells help control infection.
Assumed knowledge

Cell types and infection.

Learning checkpoints & sourceYOUR LEARNING CHECKPOINT
  • Compare pathogen types and transmission routes.
  • Link barriers and innate responses to infection control.
QCAA Biology · Unit 2 · Infectious disease and epidemiology
READY TO TRY IT?

Put the idea to work.

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