Everything about Jejunum totally explained
In
anatomy of the
digestive system, the
jejunum is the central of the three divisions of the
small intestine and lies between the
duodenum and the
ileum. The change from the duodenum to the jejunum is usually defined as the
ligament of Treitz.
In adult
humans, the small intestine is usually between 5.5-6m long, 2.5m of which is the jejunum.
The
pH in the jejunum is usually between 7 and 8 (neutral or slightly
alkaline).
The jejunum and the ileum are suspended by
mesentery which gives the bowel great mobility within the
abdomen. It also contains muscles to help move the food along.
Internal structure
The inner surface of the jejunum, its
mucous membrane, is covered in projections called
villi, which increase the surface area of tissue available to absorb nutrients from the gut contents. The epithelial cells which line these villi possess even larger numbers of microvilli. The transport of nutrients across epithelial cells through the jejunum and ileum includes the
passive transport of sugar fructose and the
active transport of amino acids, small peptides, vitamins, and most glucose. The villi in the jejunum are much longer than in the duodenum or ileum.
The jejunum contains very few
Brunner's glands (found in the duodenum) or
Peyer's patches (found in the ileum). Instead, it has many large
circular folds in its
submucosa called plicae circulares which increase the surface area for nutrient absorption.
Etymology
Jejunum is derived from the adjective
jejune, which means "
fasting" or "hungry" in
Early Modern English.
It was so called because this portion of the intestine was found "empty" following death [Latin:jejunus, fasting; barren]
Additional images
Image:Gray1042.png|Duodenojejunal fossa.
Image:Microvilli.jpg|Transmission electron microscope (TEM) of Human Jejunum
Image:Nudemousejejunum_EM.jpg|TEM of Mouse Jejunum x14000
Further Information
Get more info on 'Jejunum'.
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