The kidneys filter wastes and excrete fluid when the pressure of blood in the bloodstream forces blood through the internal structures of the kidney.
Review Date: 11/2/2010 Reviewed By: Jennifer K. Mannheim, ARNP, Medical Staff, Department of Psychiatry and Behavioral Health, Seattle Children’s Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.