PATHOLOGY

Detailed explanation-1: -One cell thick vessels are the blood vessels that join arteries and veins are the tiniest and most abundant blood vessels, called capillaries. They primarily serve the purpose of exchanging materials between the blood and tissue cells.

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: -Endothelial cells form a single cell layer that lines all blood vessels and regulates exchanges between the bloodstream and the surrounding tissues. Signals from endothelial cells organize the growth and development of connective tissue cells that form the surrounding layers of the blood-vessel wall.

Detailed explanation-4: -Capillaries have a very thin walls. The main function of capillaries is to transport digested food, oxygen, and other materials to all the cells of the body. Hence, their walls are thin, so that the substances can get in and out of them easily by diffusion.