Human Defence Systems - Non-Specific Defences
Biology: Cambridge International GCSE Supplement, topic 10.1.4
Non-Specific Defences
The human body has non-specific mechanical and chemical defences. They are designed to prevent any pathogens from entering the body and causing harm.
Skin (mechanical)
- Skin is a waterproof barrier that pathogens cannot pass through.
- Good bacteria live permanently on our skin, covering the surface and preventing pathogens from growing on our skin.
Stomach acid (chemical)
- Glands in the stomach wall produce hydrochloric acid, which destroys any pathogens that enter the stomach.
Mucus (chemical)
- Mucus is produced in the respiratory system and traps the particles and bacteria entering our airways.
- There are cells in the airways that have tiny hairs called cilia. These waft this mucus to the back of the throat to be swallowed.
Nose hairs (mechanical)
- Prevent the entry of larger microorganisms and dust into the airways.