* Kidneys maintain the purity and constancy of our in internal fluids. Every day, the kidneys filter gallons of fluid from the bloodstream. They then process this filtrate, allowing wastes and excess ions to leave the body in urine while returning needed substances to the blood in just the right proportions. Kidneys also regulate the blood’s volume and chemical makeup so that the proper balance between water and salts and between acids and bases is maintained. * The Kidneys alone perform the functions and manufacture urine in the process. The other organs of the urinary system- the paired ureters and the single urinary bladder and uretha provide temporary storage reservoirs for urine or serve as transportation channels to carry it from one body region to another. Location and Structure
* Small, dark red organs with a kidney-bean shaped lie against the dorsal body wall in a retroperitoneal position in the superior lumbar region. The kidneys extend from the T12 to the L3 vertebra: thus they receive some protection from the lower part of the rib cage. Because it is crowded by the liver, the right kidney is positioned slightly lower than the left. The kidney is convex laterally and has a medial indentation called the renal bilus. Atop each kidney is an adrenal gland, which is part of the endocrine system and is a distinctly separate organ functionally. * A fibrous, transparent renal capsule encloses each kidney and gives a fresh kidney a glistening appearance. A fatty mass, the adipose capsule, surrounds each kidney and helps hold it in place against the muscles of the trunk wall.