# Explain how air moves from the atmosphere into the lungs during inhalation.

> WJEC GCSE Biology (Wales) — 1.2.2 The respiratory system · Explain · 4 marks

## Mark scheme (4 marks)

1. The intercostal muscles contract / the diaphragm contracts
2. The ribcage moves upwards and outwards / the diaphragm flattens, increasing the volume of the thorax (chest cavity)
3. The pressure inside the lungs decreases (below atmospheric pressure)
4. Air moves into the lungs down the pressure gradient / from high pressure outside to low pressure inside

## Key terms

- [inhalation](https://www.gradenine.co.uk/glossary/inhalation)

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-air-moves-from-the-70b648ef) · Published by Druglandscape Ltd.