The first part of the small intestine is called the duodenum. The duodenum is only 25 cm long, but...
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The first part of the small intestine is called the duodenum. The duodenum is only 25 cm long, but most of the digestion takes place in this region.
Small intestinesSmall amounts of chyme are ejected approximately every 20 seconds from the stomach into the duodenum. #digestion
Also opening into the duodenum are ducts from the pancreas and the gall bladder. These allow enzyme-rich pancreatic juice and bile to be released and mixed with the chyme.
Small intestinesChemical breakdown of carbohydrate, protein and fats into smaller absorbable molecules takes place.
Peristaltic waves of muscular contraction mix and move the chyme down the duodenum and into the jejunum, measuring about 2.5 m long.
Small intestinesPeristaltic waves of muscular contraction move the chyme through the jejunum until it reaches the ileum.
Small intestinesThe jejunum has a huge surface area created by finger-like structures called villi. These assist with the absorption of nutrients into the bloodstream.
VilliVilli play an important role in absorbing the breakdown products of digestion.The increase in surface area, allows for ready absorption of these products of digestion.
VilliWith villiFlat surface
Nutrients to bloodstream
VilliEach villus has a rich blood supply, allowing nutrients to be readily absorbed and transported to the liver. A lacteal is also present; absorbing fat nutrients and carrying them to the circulatory system.