Karen Ann Pepper, age 13, of Fargo, N.D., for her question:

WHERE IS YOUR GALL BLADDER?

Your gall bladder is an oval shaped sac that is about three inches long. It is connected with the bile duct system and is attached to the undersurface of the liver. The gall bladder, however, does not open into the liver.

The liver cells make bile, which is used in digesting food. It flows through the ducts, or tubes, in the liver to the two large hepatic ducts that lead out of the liver.

Bile forms all of the time, but it is blocked from going into the intestine by a tight muscle, called a sphincter, when there is no need for the juice. During this time, bile is sidetracked up a duct into the gall bladder.

The gall bladder usually holds about one fifth of a cup of bile. When it remains there, nine tenths of the water is absorbed and the bile becomes thicker. When there is food in the intestines, the gall bladder becomes active. The muscular gall bladder squeezes down, the sphincter at the duodenum relaxes and bile flows into the intestine to aid in the digestion of food.