Physical barriers and chemical defencesSpec 5.12
The body has first lines of defence that try to stop pathogens getting in or kill them before they can cause harm.
| Defence | Type | How it protects |
|---|---|---|
| Skin | Physical barrier | Forms a barrier that pathogens cannot easily pass through |
| Mucus | Physical barrier | A sticky liquid in the nose and airways that traps pathogens |
| Cilia | Physical barrier | Tiny hairs on the cells lining the airways that move the trapped mucus up and away from the lungs |
| Lysozymes | Chemical defence | Enzymes in tears and other secretions that break down the cell walls of bacteria |
| Hydrochloric acid | Chemical defence | Acid in the stomach that kills pathogens swallowed with food and drink |