Question

Which blood vessels have the thinnest walls?

Answer 1

Capillaries:

1. The arteries, which carry blood out from the heart, and veins are connected by small, extremely thin channels called capillaries (which carry blood back to the heart).
2. The capillaries' delicate walls allow nutrients and oxygen from the blood to reach the tissues, as well as waste materials from the tissues to enter the blood.
3. While carbon dioxide can diffuse outward in the lungs, oxygen can diffuse into the blood through the pulmonary capillaries.
4. Due to the thick walls of arteries and veins, blood molecules or cells cannot permeate into bodily cavities.
5. Thus, The walls of capillaries are the thinnest.