Veins vs. Arteries: Key Structural Differences

Steps:

• Identify comparison categories: lumen width, wall thickness, elastic fibers, smooth muscle.
• Recall veins carry low-pressure blood, needing wider lumen for volume and thinner walls with less support tissue.
• Note arteries handle high pressure with narrow lumen and thick walls rich in elastic fibers and smooth muscle.
• Match to choice D: veins have wider lumen, thinner walls, fewer elastic fibers, fewer smooth muscle cells than arteries.

Why D is correct:

• Veins adapt to low pressure with wider lumens for blood volume and thinner walls with fewer elastic fibers and smooth muscle, per vascular anatomy definitions.

Why the others are wrong:

• A: Veins are not narrower or thicker; arteries have those traits for pressure resistance.
• B: Veins are not narrower; their wider lumens facilitate return flow.
• C: Veins are not thicker; their thinner walls suit low-pressure function.

Final answer: D