What are the structural and functional differences between arteries and veins?

Structural Differences

1. Arteries have a much thicker wall to withstand the high pressure of blood flowing in them, whereas veins have a thinner wall so that they can be pressed flat against adjacent muscles, helping to move the blood.

2. Veins have valves, contrary to arteries, to prevent back-flow of blood flowing in them.

3. Arteries have a narrow lumen to maintain the high blood pressures, while veins have a wide lumen to accommodate the slow-flowing blood.

4. Arteries have a thick outer layer of longitudinal collagen and elastic fibres to avoid leaks, while veins have a thin outer layer of longitudinal collagen and elastic fibres, because there is little danger of bursting.

5. Arteries have a thick inner layer of circular elastic and muscle fibres, to help pump the blood on after every heartbeat, whereas veins have thin layers with relatively few circular elastic and muscle fibres, as blood does not flow in pulses so the wall of the veins cannot help to pump it.

Functional differences

1. Arteries carry blood away from the heart and towards the different areas of the body, while veins carry blood from the rest of the body towards the heart.

2. Arteries, with the exception of the pulmonary artery and the umbilical artery, carry oxygenated blood towards the different parts of the body, whereas veins, with the exception of the pulmonary veins and the umbilical vein, carry deoxygenated blood back to the heart.