What is your small blood vessles called?

The small blood vessels in your body are called capillaries. They are the smallest type of blood vessel and form a network that connects the arterioles (the smallest arteries) to the venules (the smallest veins). Capillaries are very thin and have a single layer of endothelial cells that allow oxygen and nutrients from the blood to pass into the tissues and waste products from the tissues to pass into the blood. Capillaries are also found in the lungs where they help to exchange oxygen and carbon dioxide between the air and the blood and in the kidneys where they help to filter waste products from the blood.