Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The duodenum is the first section of the small intestine immediately beyond the stomach. It plays a crucial role in the digestion of chyme received from the stomach by mixing it with bile and pancreatic juices.
5 Must Know Facts For Your Next Test
The duodenum is about 25-30 cm long and forms a C-shaped curve around the head of the pancreas.
It receives acidic chyme from the stomach through the pyloric sphincter.
Bile from the liver and gallbladder, as well as digestive enzymes from the pancreas, enter the duodenum to aid in digestion.
The duodenal lining contains Brunner's glands, which secrete mucus to protect it from acidic contents.
Absorption of nutrients begins in the duodenum, where fats are emulsified by bile salts.
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Related terms
pyloricSphincter: A ring-like muscle at the junction between the stomach and duodenum that regulates passage of chyme.
bile: A digestive fluid produced by the liver and stored in the gallbladder that aids in fat emulsification.
pancreaticJuices: Enzymatic secretions from the pancreas that help break down carbohydrates, proteins, and fats in the small intestine.