what is the role of the small intestine in digestion
Small intestine The small intestine or small bowel is the part of the gastrointestinal tract between the stomach and the large intestine, and is where most of the end absorption of food takes place. The small intestine has three distinct regions â€“ the duodenum, jejunum, and ileum. The duodenum is the shortest part of the small intestine and is where preparation for absorption begins. It also receives bile and pancreatic juice through the pancreatic duct, controlled by the sphincter of Oddi. The primary function of the small intestine is the absorption of nutrients and minerals from food, using small finger-like protrusions called villi.[2]
Duodenum The duodenum [help 1] is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. 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.[5] In mammals the duodenum may be the principal site for iron absorption.[6]
Duodenum The duodenum[help 1] is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. 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.[5] In mammals the duodenum may be the principal site for iron absorption.[6]
Nutrient Non-essential nutrients are substances within foods that can have a significant impact on health; these substances can be beneficial or toxic.[medical citation needed] For example, dietary fiber is not absorbed in the human digestive tract, but is important in maintaining the bulk of a bowel movement to avoid constipation.[medical citation needed] A subset of dietary fiber, soluble fiber, can be metabolized by bacteria residing in the large intestine.[19][20][21] Soluble fiber is marketed as serving a prebiotic function – promoting "healthy" intestinal bacteria.[citation needed] Bacterial metabolism of soluble fiber also produces short-chain fatty acids like butyric acid, which may be absorbed into intestinal cells as a source of calories.[19][20][21]