Liver, pancreas and gallbladder

Your liver makes about a litre of bile a day, and your pancreas makes more than a litre of pancreatic juice.

Three organs, one destination

When chyme leaves the stomach it is very acidic and full of fat droplets that water-based enzymes cannot easily reach. The first part of the small intestine, the duodenum, has to fix both problems at once. It gets help from three accessory organs. The liver makes bile and sends it to the duodenum. The gallbladder stores and concentrates the bile and releases it when it is needed. The pancreas makes pancreatic juice, full of enzymes and bicarbonate. Bile and pancreatic juice meet in a small chamber in the wall of the duodenum, the hepatopancreatic ampulla, and a ring of muscle there controls how much flows in.

The liver and bile

The liver's main cells, the hepatocytes, make up about 80 percent of its volume. They secrete about one litre of bile each day. Bile is mostly water, with bile salts, phospholipids, cholesterol, bile pigments and salts, and it is slightly alkaline (pH 7.6 to 8.6). It contains no digestive enzymes. Its job is emulsification: bile salts have one end that mixes with water and another that mixes with fat, so they break large fat globules into many tiny droplets. That gives fat-digesting enzymes far more surface to work on. Once the bile salts reach the end of the small intestine, most are absorbed and carried back to the liver to be used again.

Bile also carries away waste. When old red blood cells are broken down, the pigment bilirubin goes into bile and gives it its colour. Bacteria in the intestine later turn it into stercobilin, the brown pigment that colours stool. The liver also sits in a special spot in the circulation. Veins from the small intestine do not go straight back to the heart. They form the hepatic portal system and carry nutrient-rich blood to the liver first, where nutrients are processed or stored. At rest about 1,500 mL of blood flows through the liver every minute.

The gallbladder

The gallbladder is a small sac, about 8 to 10 cm long, tucked under the right lobe of the liver. Between meals it stores bile and concentrates it by removing water. When you eat, it squeezes bile through the bile ducts into the small intestine, as the NIDDK describes.

The pancreas

The pancreas lies behind the stomach, with its head tucked into the C-shaped curve of the duodenum and its body stretching about 15 cm to the left. It makes more than a litre of pancreatic juice a day. The juice is clear, mostly water, with salts, sodium bicarbonate and several enzymes. The bicarbonate makes it slightly alkaline (pH 7.1 to 8.2). When acidic chyme enters the duodenum, the hormone secretin triggers a flow of bicarbonate-rich juice, which neutralises the acid and stops pepsin from working.

The enzymes cover all three main foods: amylase for starch, lipase for fats, and protein-splitting enzymes. The protein enzymes are made in an inactive form so they do not digest the pancreas itself. In the small intestine an enzyme on the intestinal wall, enteropeptidase, switches trypsinogen into trypsin, and trypsin then switches on the other protein enzymes. The pancreas also makes hormones that are important to digestion and to the use of nutrients.

This is educational material about how the body is built and works. It is not medical advice and is not for diagnosing or treating anyone.