What generalization can be made about all veins?

What generalization can be made about all veins?

• A. Veins typically carry deoxygenated blood back to the heart, except for the pulmonary veins, which carry oxygenated blood.
• B. Veins carry blood away from the heart to the lungs.
• C. Veins have thicker tunica media than arteries.
• D. Veins always carry blood at high pressure.

Answer: (A)

Veins are vessels that return blood to the heart. The general idea is that most veins carry deoxygenated blood back to the heart, with the important exception of the pulmonary veins, which transport oxygenated blood from the lungs to the heart. This fits the two circulatory routes: systemic circulation sends blood to tissues and returns it deoxygenated, while the pulmonary circuit oxygenates blood and then returns it through the veins to the left atrium. Veins operate under low pressure and often have valves to prevent backflow, and their walls are thinner with a thinner tunica media compared to arteries. That’s why they don’t carry blood away from the heart or at high pressure.

Veins are vessels that return blood to the heart. The general idea is that most veins carry deoxygenated blood back to the heart, with the important exception of the pulmonary veins, which transport oxygenated blood from the lungs to the heart. This fits the two circulatory routes: systemic circulation sends blood to tissues and returns it deoxygenated, while the pulmonary circuit oxygenates blood and then returns it through the veins to the left atrium. Veins operate under low pressure and often have valves to prevent backflow, and their walls are thinner with a thinner tunica media compared to arteries. That’s why they don’t carry blood away from the heart or at high pressure.