Full Capillaries Description
[Continued from above] . . . muscular branches of arteries, called arterioles, with tiny veins called venules. The capillaries allow nutrients, oxygen, and fluids to pass into tissue, and they also collect carbon dioxide waste materials and fluids for return through the veins to the lungs and the lymph system. The capillaries are where the important functions of the circulation take place: the exchange of material between the circulatory system and cells.