Tiny, thin-walled blood vessels that allow the exchange of fluid, gases and nutrients between the blood [[cell]]s. The smallest capillaries are so small that red blood [[cell]]s must move through them in single file.<ref>Wile, Dr. Jay L. ''Exploring Creation With General Science''. Anderson: Apologia Educational Ministries, Inc. Capillaries are the smallest blood vessels. | Tiny, thin-walled blood vessels that allow the exchange of fluid, gases and nutrients between the blood [[cell]]s. The smallest capillaries are so small that red blood [[cell]]s must move through them in single file.<ref>Wile, Dr. Jay L. ''Exploring Creation With General Science''. Anderson: Apologia Educational Ministries, Inc. Capillaries are the smallest blood vessels. |