Final answer:
Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart. Arteries have thick walls and smaller lumens, while veins have thinner walls and larger lumens with valves to prevent backward flow. Exceptions include the pulmonary artery carrying deoxygenated blood to the lungs and the pulmonary veins carrying oxygenated blood to the heart.
Step-by-step explanation:
The largest difference between arteries and veins is the direction of blood flow. Arteries carry oxygenated blood away from the heart to various parts of the body, while veins carry deoxygenated blood back to the heart. This difference in function is due to differences in their structures and the pressure within them.
For example, arteries have thick, elastic walls that help propel the blood forward. They also have a smaller lumen and contain more smooth muscle, allowing them to withstand the higher pressure of blood being pumped out of the heart. Veins, on the other hand, have thinner walls, larger lumens, and contain valves that prevent the backward flow of blood.
It is important to note that while arteries generally carry oxygenated blood and veins carry deoxygenated blood, there are exceptions. The pulmonary artery carries deoxygenated blood from the heart to the lungs, while the pulmonary veins carry oxygenated blood from the lungs back to the heart.
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