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 · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Arteries have a thicker muscle layer than veins.
Arteries have a thicker elastic fibre layer than veins.
Arteries have a smaller, narrower lumen than veins.
The thick elastic layer allows arteries to stretch when blood is ejected from the heart and then recoil, which helps maintain a high pressure pulse throughout the arterial system.

Examiner tips

Use the word ‘thicker’ or ‘larger’ for muscle and elastic layers, and ‘smaller’ or ‘narrower’ for lumen. Give a clear functional link – e.g. elastic recoil maintains pressure. Keep the answer concise, 4 points only.

Common mistakes

Confusing the direction of comparison (e.g. saying veins have a thicker muscle layer). Omitting the functional explanation or giving a vague one. Using non‑examiner terminology such as ‘big’ instead of ‘thicker’ or ‘larger’.

Mark scheme (4 marks)

Arteries have a thicker muscle layer than veins (or veins have only a thin/small muscle layer compared to arteries).
Arteries have a thicker elastic fibre layer than veins (or veins have little elastic fibre compared to arteries).
Arteries have a smaller/narrower lumen than veins (or veins have a wider/larger lumen than arteries).
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 in this question

vein · lumen