# Explain how the structure of arteries and veins is related to their functions in the circulatory system.

> Pearson Edexcel A-Level Biology A (9BI0) — 1.2 Heart, blood and blood vessels · Explain · 5 marks

> Arteries carry blood away from the heart at high pressure. Veins return blood to the heart at low pressure.

## Mark scheme (5 marks)

1. Arteries have thick muscular/elastic walls
2. Thick walls withstand / cope with high blood pressure (from the heart)
3. Veins have thinner walls than arteries / large lumen
4. Veins have valves
5. Valves prevent backflow of blood / ensure blood flows in one direction towards the heart

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](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-the-structure-of-arteries-881905e9) · Published by Druglandscape Ltd.