The main difference between artery and vein lies in their relationship to the heart. Arteries carry blood away from the heart into the periphery and that is why the pressure of blood in arteries is high. While on the other side, veins carry blood towards the heart.
An artery carries blood away from the heart. All arteries are said to carry oxygenated blood because this blood is going to be distributed in the periphery, but pulmonary artery carries deoxygenated blood because it is going into the lungs for purification. The wall of an artery is made up of three layers and that makes it thicker in diameter than veins. The elasticity in the muscle layers is capable of handling great pressure of blood inside arteries. The thickest layer is tunica media and the rest of two layers are, tunica externa, tunica interna.
A vein carries blood towards the heart after collecting it from the periphery. All veins carry deoxygenated blood and carry it to the heart for purification. Pulmonary vein carries oxygenated blood. There are semilunar valves inside veins which do not allow retrograde flow of blood. So, they basically prevent the blood from flowing in the opposite direction. Veins are thinner as compared to arteries. They have got thin elastic muscle layers and the thickest layer of a vein is tunica adventitia.
- Artery carries blood away from heart and vein carries blood towards the heart.
- An artery is thicker than a vein, in terms of their structures.
- Artery is a resistance vessel while vein is a capacitance vessel.
- Arteries carry oxygenated blood and veins carry deoxygenated blood.
- Pulmonary artery carries deoxygenated blood while pulmonary vein carries oxygenated blood.
- There are no valves in arteries but in veins, there are semilunar valves.
- Arteries have got more rigid walls as compared to veins.
- The thickest muscular layer in the walls of artery is tunica media and that in veins is, tunica adventitia.
- Blood flow in artery is under a very high pressure.
- Artery have elastic walls and vein have non-elastic walls.