Which vessels return blood to the heart and have a one-way flow?

• A. Arteries
• B. Veins
• C. Capillaries
• D. Cardiovascular system

Answer: (B)

Veins are the vessels that bring blood back to the heart, and they achieve one-way flow primarily through venous valves that prevent backflow. These valves, along with the help of skeletal muscle contractions and gravity, keep blood moving toward the heart rather than pooling or reversing direction. Veins have thinner walls and larger lumens, acting as a capacitance network that stores a large portion of blood.

Arteries carry blood away from the heart under higher pressure, not back toward it. Capillaries are tiny vessels where exchange of oxygen, carbon dioxide, nutrients, and wastes occurs, rather than serving as return paths to the heart. The cardiovascular system refers to the entire circulatory network, not a single vessel.