The small intestine consists of three segments: duodenum, jejunum and ileum. Every segment of the small intestine performs different digesting functions. The duodenum is involved in breaking down the food and absorption of nutrients.
Duodenum OverviewThe duodenum is C- shaped organ located below the stomach and it curves around the pancreas. The duodenum is an upper portion of the small intestine and it is the first and shortest section of the small intestine. It is about 25-30 cm long. The duodenum is a hollow jointed tube that connects the stomach to the jejunum. The duodenum is divided into four sections: superior, descending, horizontal and ascending duodenum. Inner lining of the duodenum is made of crypts that increase the surface area of the intestinal membrane, making digestion more efficient. The duodenum also contains smooth muscle to push waste products to the large intestine. Apart from this, several ducts are open into the duodenum from the pancreas, gallbladder and liver.
The duodenum continues the process of digestion of food that begins in the stomach. Its main function is to receive the chyme which is a combination of partially digested food and stomach acids. The chyme is released into the duodenum through pylorus, which is a small valve located between the stomach and the duodenum. The duodenum accepts the chyme from the stomach and continues the digestion. This is done with the help of digestive enzymes and intestinal juices secreted by the crypts in the intestinal wall. Also, the duodenum receives bile drained from the liver and gallbladder and pancreatic juice secreted by the pancreas. These secretions aid in digestion of food.
Apart from digesting foods, the duodenum regulates the rate of gastric emptying. Gastric emptying represents stomach emptying which is the process of food going from stomach to the duodenum. The duodenum also triggers the hunger signals. Both of these functions are performed with the help of hormones that are produced and released by the duodenal epithelium. Duodenal epithelium includes the cells that secrete two hormones known as secretin and cholecystokinin. When excess acid is present in small intestine or duodenum, hormone secretin is released. On the other hand, cholecystokinin is released in the presence of fatty acids and amino acids. Both secretin and cholecystokinin encourage secretion of bile and pancreatic juice.
Finally, duodenum absorbs the nutrients and it does it even more than the stomach. Because of that, in obese people, the duodenum is frequently bypassed in gastric bypass surgery to decrease the absorption of nutrients.