What are the differences in the structures of arteries and veins?
- Arteries have a much narrower lumen (the middle bit of space) and a much thicker wall. This is due to the fact that arterial walls contain more muscle and elastic fibres, than those of veins. Reason: Arteries always carry blood away from the heart, so the blood passing through them is at a very high pressure. A thick muscular wall allows the arteries to withstand this high pressure, whilst the elastic fibres allow the vessels to recoil to their original size after each surge of blood (in association with each heart beat).
- Arteries DO NOT contain one-way valves, whilst veins do. Reason: The blood in veins is at a much lower pressure, and so these valves are necessary to stop the blood from flowing in the wrong direction. In arteries, the blood pressure is constantly high enough that there is no chance of blood flow in the reverse direction, and so valves are not necessary
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