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

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 1.2 Heart, blood and blood vessels · Explain · 5 marks

> Arteries carry blood away from the heart at high pressure, while veins return blood to the heart at low pressure.

## Mark scheme (5 marks)

1. Arteries have thick muscular / elastic walls
2. Thick walls of arteries withstand / cope with high blood pressure (from the heart)
3. Veins have valves
4. Valves prevent the backflow of blood (so blood flows in one direction towards the heart)
5. Capillaries have walls that are one cell thick, allowing substances to diffuse between the blood and body cells / tissues

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-structure-of-arteries-e8439766) · Published by Druglandscape Ltd.