MICROANATOMY

Detailed explanation-1: -Final answer: One-cell thick vessels are called capillaries.

Detailed explanation-2: -Capillaries measure 5-10 m in diameter and are only one cell thick. Capillaries connect arterioles and venules and enable the exchange of water, oxygen, carbon dioxide, and many other nutrients and waste substances between blood and surrounding tissues.

Detailed explanation-3: -The walls of capillaries are just one cell thick. Capillaries therefore allow molecules to diffuse across the capillary walls. This exchange of molecules is not possible across the walls of other types of blood vessel because the walls are too thick.

Detailed explanation-4: -Arteries have thicker wall as compared to arteriole and veins.

Detailed explanation-5: -Capillaries are the connection of the smallest branches of arteries and veins. The capillary walls are one cell thick. Capillaries allow molecules to pass through across the capillary walls. This exchange of materials is not possible across the walls of other types of blood vessels because the walls are too thick.