The kidney balances the liquids in the body and filters the blood.
The kidneys are located just below your ribcage and on both sides of the spine. They are bean-shaped organs, almost the size of your fist. The kidneys filter about 120 to 150 quarts of blood a day, which process produces about 1 to 2 quarts of urine filled with wastes and extra fluids. Urine moves from the kidney to the bladder through ureters. The bladder stores urine until it is full enough to empty, and when the bladder drains, the urine and fluids flow through the urethra located at the bottom of the bladder.
The kidney balances your liquids, but thirst controls your rate of liquid intake. Fortunately, when you urinate most of the fluids leave your body, but you also lose fluids through sweating, diarrhea, or even breathing.
Vasopressin, a hormone in the hypothalamus controls fluid removal. Pituitary glands store the vasopressin and release it into the bloodstream when you have low fluid levels. Vasopressin then signals the kidneys to remove less fluid from the bloodstream, and you produce less urine. On the reverse side, when your body has more fluid than it needs, the pituitary gland releases vasopressin in smaller amounts causing the kidneys to remove more fluid from the bloodstream.