Question

Which blood vessels have the thinnest walls?

Answer 1

The capillaries.

Explanation:

The walls of the capillaries are so thin that molecules can diffuse through the walls of the capillaries to the membranes of the cells that surround the capillaries.

The pulmonary capillaries allow oxygen to diffuse into the blood while carbon dioxide is able to diffuse outward in the lungs.

Arteries and Veins have thick walls that do not allow blood cells or molecules to diffuse into the body cavities,