<Tr> <Th> FMA </Th> <Td> 7206 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> The duodenum 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 . In mammals the duodenum may be the principal site for iron absorption . </P> <P> The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine . </P>

The organ located within the duodenal loop in the mammal is