# Describe how air moves from the atmosphere into the alveoli during inhalation.

> Eduqas GCSE Biology — 1.2.2 The respiratory system · Describe · 4 marks

## Mark scheme (4 marks)

1. The intercostal muscles (and diaphragm) contract
2. The ribcage moves upwards and outwards / the diaphragm flattens
3. The volume of the thorax / chest cavity increases, causing air pressure inside to decrease / fall below atmospheric pressure
4. Air moves in along a pressure gradient / air flows in from high to low pressure / air enters through the trachea, bronchi, bronchioles to the alveoli

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Biology](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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/describe-how-air-moves-from-the-582a7f99) · Published by Druglandscape Ltd.