What’s the difference between arteries, veins and capillaries?

Blood vessels allow blood to be circulated around the whole body for delivery of oxygen/nutrients and removal of waste products. Structure relates to function.• Arteries - take blood away from the heart. Arteries have thick, muscular, elastic walls with small lumens, which allows them to withstand and maintain the high pressure of blood being pumped from the heart. • Veins - carry blood back to the heart. They have thin walls, with large lumens. They also contain valves, to prevent backflow of blood. Arteries transport oxygenated blood, except for the pulmonary artery, while veins transport deoxygenated blood, except for the pulmonary vein.• Capillaries are very small blood vessels that connect arteries to veins. Capillaries are the site of exchange between the blood and body tissues. The capillaries allow food and oxygen to diffuse from the blood to cells, and at the same time, allow waste to diffuse from cells into the blood. Capillaries are only one cell thick. This makes diffusion easier. The blood in capillaries is under low pressure. This means that the blood travels slower than in arteries, giving more time for exchange.