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Edexcel ·Biology·Cambridge AS & A Level Biology

Gas Exchange & Smoking

13 min read

The mammalian gas-exchange system, the role of surfactant, and the effects of tobacco smoke.

The gas-exchange system

Air passes: trachea → bronchi → bronchioles → alveoli. The trachea and bronchi have cartilage (support, keeps airways open), smooth muscle (controls diameter), elastic fibres (recoil), goblet cells and a ciliated epithelium (mucus traps particles; cilia sweep it up).

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