Duodenum

The primary function of the duodenum is to continue the digestion process that begins in the stomach. It serves as a mixing chamber where bile, produced by the liver, emulsifies fats into smaller droplets, enhancing their digestion by enzymes. Additionally, pancreatic juices contain enzymes that further break down carbohydrates, proteins, and nucleic acids. The duodenum also regulates the pH of the chyme received from the stomach, neutralizing the acidic contents to create an optimal environment for enzyme function. Furthermore, the duodenum is involved in nutrient absorption, particularly in the absorption of amino acids, simple sugars, and fatty acids, which are necessary for the body’s energy and biosynthesis processes.

The duodenum is situated in the upper central part of the abdominal cavity, just below the stomach and above the jejunum, the next part of the small intestine. It begins at the pyloric sphincter, where it receives chyme from the stomach, and bends around the head of the pancreas, forming a C-shape. Its anatomical positioning allows it to effectively interact with bile and pancreatic secretions, as the common bile duct and pancreatic duct empty into the duodenum at a region called the ampulla of Vater.

• The duodenum plays a significant role in enterohepatic circulation, where bile salts are absorbed and recycled back to the liver.
• It is named 'duodenum' from the Latin term meaning 'twelve', as it is approximately twelve finger widths long.
• The lining of the duodenum contains specialized cells that secrete hormones such as secretin and cholecystokinin, which regulate digestive processes.
• Malfunctions in the duodenum can lead to conditions such as duodenal ulcers, often caused by Helicobacter pylori infection or the use of nonsteroidal anti-inflammatory drugs (NSAIDs).