That would be a capillary.
What Is The Very Small Tube That Carries Blood?
There is the arteries, veins and capillaries along with the blood cells etc
In your body or outside of your body(man made) I.v. Tube. In your lungs the bronchial veins /venules/tubes receive blood from aterioles or capillaries. This I think is where literally the trash from the blood(carbon dioxide is expelled and oxygen is taken into the blood).I think. biology.about.com