Its relationships to the major structures of the upper abdomen lend it to exposure during a large number of gastrointestinal surgical interventions. The duodenum is the first section of the small intestine and is the shortest part of the small intestine. The duodenum is largely retroperitoneal and has an intimate anatomic relationship with the pancreas. It has four parts: Superior part: Horizontal to and in front of the 1st lumbar vertebra. Fatty acids are insoluble in water, which makes them very difficult to absorb through the intestinal wall. Th… Ingestion. Although it is the shortest segment of small bowel, the duodenum is the initial site of contact for gastric secretions, bile, and digestive enzymes from the common bile duct and the pancreas. The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine. As such, it is important to understand both the structure and function of the duodenum as it relates to alimentary surgery. Nearly all absorption of dietary iron occurs within the duodenum (1 to 2 mg/day). Located inferior to the stomach, the duodenum is a 10-12 inch (25-30 cm) long C-shaped, hollow tube. Iron absorption from... Nutrient Absorption and Digestion. The functions of the digestive system are: 1. Physiology Calcium Absorption. The duodenum is a part of the gastrointestinal (GI) tract, attached to the pyloric sphincter of the stomach on its superior end and to the jejunum of the small intestine on its inferior end. The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. Copyright © 2020 Elsevier B.V. or its licensors or contributors. It has a lining which is designed to absorb carbohydrates and proteins. Jejunum means empty in Latin and supposedly was so named by the ancient Greeks who noticed it was always empty at death. Descending part: Runs inferiorly along the right borders of the 2nd and 3rd lumbar vertebrae. Food must be placed into the mouth before it can be acted on; this is an active, voluntary process called ingestion. By continuing you agree to the use of cookies. In mammals the duodenum may be the principal site for iron absorption. Copyright © 2019 Elsevier Inc. All rights reserved. No clear demarcation exists between the jejunum and the final segment of the small intestine, the ileum. The ileum is the longest part of the small intestine, measuring about 1.8 meters (6 feet) in length. The jejunum is the middle section of the small intestine. It is where most chemical digestion using enzymes takes place. The breakdown of fat globules in the duodenum into tiny droplets, which provides a larger surface area on which the enzyme pancreatic lipase can act to digest the fats into fatty acids and glycerol is called bile emulsification. The name is derived from the Latin phrase intestinum duodenum digitorum, or “intestine of twelve digits.” This Latin phrase may have derived from the writings of the Greek physician Herophilus (334–280 bc). 2. It is roughly horseshoe-shaped, with the open end up and to the left, and it lies behind the liver. The duodenum is the shortest segment of the intestine and is about 23 to 28 cm (9 to 11 inches) long. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine may be used instead of duodenum. Calcium balance depends on the net absorption of calcium across the intestine and the regulated loss... Iron Absorption. Shackelford's Surgery of the Alimentary Tract, 2 Volume Set (Eighth Edition), https://doi.org/10.1016/B978-0-323-40232-3.00068-6. It is thicker, more vascular, and has more developed mucosal folds than the jejunum. We use cookies to help provide and enhance our service and tailor content and ads. The duodenum is the first section of the small intestine. Although spanning only 20 to 30 cm, from the pylorus to the ligament of Treitz, the duodenum is the “gate” that controls the passage of food from the stomach to the jejunum. The jejunum is about 0.9 meters (3 feet) long (in life) and runs from the duodenum to the ileum. Duodenum, the first part of the small intestine, which receives partially digested food from the stomach and begins the absorption of nutrients. It begins at the pylorus and ends at the ligament of Treitz and is approximately 25 cm in length. Propulsion. Thus it plays an important role in the regulation of digestion, absorption of essential micronutrients and macronutrients, and bowel motility. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V.

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