Question

Blood pressure in the veins is lower than that of arteries. The best hypothesis to explain this is that

• A. Capillaries offer resistance to the blood flow
• B. Veins are farther from the heart
• C. Most veins carry blood up-hill
• D. Veins have thinner walls than arteries

Answer 1

Answer: (B)

Veins are farther from the heart

The arteries carry blood away from the heart, while veins return blood to the heart. With both, their structure is related to their function. Blood in the arteries is under high pressure generated by the heart. The arteries have thick outer walls and thick layers of muscle and elastic fibers. The blood in veins is under lower pressure than the blood in arteries. The veins have thin walls and thin layers of muscle and elastic fibers. Unlike arteries, veins have one-way valves in them to keep the blood moving in the correct direction.

So, the correct answer is option B.