The gallbladder is located right underneath the liver. This thin-walled, pear-shaped sack is about 7 to 10 centimeters (2.7 to 3.9 inches) long and up to 5 centimeters (2 inches) across at its widest point.

The gallbladder stores and concentrates bile from the liver. The bile is then released into the first section of the small intestine (the duodenum), where it helps your body to break down and absorb fats from food.

The cells of the liver produce about 800 to 1,000 milliliters (about 27 to 34 fluid ounces) of bile every day. Bile is a yellow, brownish or olive-green liquid that helps our body digest fats. The liver cells secrete the bile into small canals that lead to the common bile duct. From there, a smaller duct branches off and leads to the gallbladder. The common bile duct ends at the small intestine.

The bile produced by the liver flows directly into the small intestine during a meal. Between meals, when there's no fat that needs to be digested, most of the bile flows into the gallbladder instead, where it is concentrated and stored. The gallbladder usually holds about 30 to 80 milliliters (about 1 to 2.7 fluid ounces) of fluid. When we eat fatty foods, the gallbladder contracts and squeezes bile through the bile duct. The bile is mixed into the semi-digested food in the small intestine.

Bile is mainly made up of water, but also has bile salts, cholesterol, certain fats (lecithin) and bile pigments in it. The most important bile pigment, bilirubin, is made when red blood cells are broken down in the liver. Bilirubin is what makes urine yellow and stool brown.

Bile salts break down larger fat globules in food into small droplets of fat. Smaller fat droplets are easier for the digestive enzymes from the pancreas to process and break down. The bile salts also help the cells in the bowel to absorb these fat droplets.