# Compare the walls of arteries and veins in terms of their muscle layer, elastic fibre layer and lumen size, and explain how one of these differences is related to the function of arteries.

> Cambridge International IGCSE Biology (0610) — 9.3 Blood vessels · Compare · 4 marks

## Mark scheme (4 marks)

1. Arteries have a thicker muscle layer than veins (or veins have only a thin/small muscle layer compared to arteries).
2. Arteries have a thicker elastic fibre layer than veins (or veins have little elastic fibre compared to arteries).
3. Arteries have a smaller/narrower lumen than veins (or veins have a wider/larger lumen than arteries).
4. Correct functional explanation linking one structural difference to the function of arteries carrying blood at high pressure — e.g. thick elastic walls stretch and recoil to maintain high pressure / thick muscle layer allows the artery to dilate and constrict to control blood flow / narrow lumen helps maintain high blood pressure.

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Compare" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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