Artery vs Vein vs Capillary: what's the difference?
GCSE Biology
The three blood vessel types, each adapted to its job.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Artery vs Vein vs Capillary — side by side
| Artery | Vein | Capillary | |
|---|---|---|---|
| Direction of blood | Away from the heart | Towards the heart | Through tissues (links arteries to veins) |
| Pressure | High | Low | Falling |
| Wall | Thick, muscular, elastic | Thinner wall, large lumen | One cell thick |
| Valves | No | Yes (prevent backflow) | No |
| Adaptation | Withstands high pressure | Returns blood at low pressure | Short diffusion distance for exchange |
Exam tip — how to tell them apart: Arteries carry blood Away. Capillaries are one cell thick for fast diffusion of gases and nutrients.
Common trap: Pressure, not oxygen, defines an artery/vein — the pulmonary artery carries deoxygenated blood but is still an artery (away from heart).
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