Do all arteries carry oxygenated blood?

No. Most arteries carry oxygenated blood, but the pulmonary artery carries deoxygenated blood from the heart to the lungs.

Why do veins have valves but arteries do not?

Veins carry blood at low pressure against gravity, so valves are needed to stop blood flowing backward. Arteries have high-pressure flow that does not need valves.

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Difference Between Artery and Vein

Arteries and veins are the two main types of blood vessels. They differ in the direction of blood flow, wall thickness, and pressure.

In short

Arteries carry blood away from the heart under high pressure and have thick muscular walls; veins carry blood towards the heart under low pressure, have thinner walls and valves to prevent backflow.

Artery vs Vein — Comparison Table

Basis	Artery	Vein
Direction of flow	Away from the heart	Towards the heart
Wall thickness	Thick, muscular, elastic	Thinner
Blood pressure	High	Low
Valves	Absent	Present (prevent backflow)
Lumen	Narrow	Wide
Blood carried	Oxygenated (except pulmonary artery)	Deoxygenated (except pulmonary vein)

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Frequently Asked Questions — Artery vs Vein

Do all arteries carry oxygenated blood?: No. Most arteries carry oxygenated blood, but the pulmonary artery carries deoxygenated blood from the heart to the lungs.
Why do veins have valves but arteries do not?: Veins carry blood at low pressure against gravity, so valves are needed to stop blood flowing backward. Arteries have high-pressure flow that does not need valves.

Difference Between Artery and Vein

Artery vs Vein — Comparison Table

Frequently Asked Questions — Artery vs Vein

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