Small intestine

small bowelsmall intestinessmallabsorptionsmall intestinalintestineintestinesabsorbedabsorbed by the small intestineAbsorption (small intestine)
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place.wikipedia
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Gastrointestinal tract

intestinegastrointestinaldigestive tract
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place.
The GI tract includes all structures between the mouth and the anus, forming a continuous passageway that includes the main organs of digestion, namely, the stomach, small intestine, and large intestine.

Stomach

gastriccardiafundus
It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion.
In humans and many other animals, the stomach is located between the oesophagus and the small intestine.

Digestion

digestivedigestdigested
It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion.
In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream.

Duodenum

duodenaldodecadactylumduodenal cap
The small intestine has three distinct regions – the duodenum, jejunum, and ileum.
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds.

Jejunum

jejunaljejunal diseasesJejunal feedings
The small intestine has three distinct regions – the duodenum, jejunum, and ileum.
The jejunum is the second part of the small intestine in humans and most higher vertebrates, including mammals, reptiles, and birds.

Large intestine

coloncolorectallarge bowel
It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion.
In humans, the large intestine begins in the right iliac region of the pelvis, just at or below the waist, where it is joined to the end of the small intestine at the cecum, via the ileocecal valve.

Bile

biliarybiliousgall
It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion. Pancreatic enzymes and bile from the gallbladder enter the small intestine in response to the hormone cholecystokinin, which is produced in the small intestine in response to the presence of nutrients.
Bile or gall is a dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the digestion of lipids in the small intestine.

Intestinal villus

villiintestinal villivillus
The duodenum, the shortest, is where preparation for absorption through small finger-like protrusions called villi begins.
Intestinal villi (singular: villus) are small, finger-like projections that extend into the lumen of the small intestine.

Chyme

Chymuschyme digestivegastric chyme
Chyme or chymus (from Greek χυμός khymos, "juice" ) is the semi-fluid mass of partly digested food that is expelled by the stomach, through the pyloric valve, into the duodenum (the beginning of the small intestine).

Mesentery

mesentericmesenteriestransverse mesocolon
The jejunum and ileum are suspended in the abdominal cavity by mesentery.
The mesentery of the small intestine arises from the root of the mesentery (or mesenteric root) and is the part connected with the structures in front of the vertebral column.

Vitamin B12

vitamin B 12 cobalaminB12
The main function of the ileum is to absorb vitamin B 12, bile salts, and whatever products of digestion were not absorbed by the jejunum.
It is synthesized by some bacteria in the gut flora in humans and other animals, but humans cannot absorb this as it is made in the colon, downstream from the small intestine, where the absorption of most nutrients occurs.

Circular folds

plicae circularescircular foldKerckring's valves
Structurally, the mucosa is covered in wrinkles or folds called plicae circulares, which are considered permanent features in the wall of the organ.
The circular folds (valves of Kerckring) (also, plicae circulares, or valvulae conniventes) are large valvular flaps projecting into the lumen of the small intestine.

Pancreas

pancreaticexocrine pancreaspancreatic development
Many of the digestive enzymes that act in the small intestine are secreted by the pancreas and liver and enter the small intestine via the pancreatic duct.
Below the body of the pancreas sits some of the small intestine, specifically the last part of the duodenum and the jejunum to which it connects, as well as the suspensory ligament of the duodenum which falls between these two.

Intestinal epithelium

intestinal epithelial cellsepitheliumintestinal epithelial
The inner wall, or mucosa, of the small intestine is lined with simple columnar epithelial tissue.
The intestinal epithelium is the single cell layer that form the luminal surface (lining) of both the small and large intestine (colon) of the gastrointestinal tract.

Abdominal cavity

abdominalabdomenabdominal (peritoneal) cavity
The jejunum and ileum are suspended in the abdominal cavity by mesentery.
Organs of the abdominal cavity include the stomach, liver, gallbladder, spleen, pancreas, small intestine, kidneys, large intestine, and adrenal glands.

Suspensory muscle of duodenum

ligament of Treitzsuspensory muscle of the duodenumSuspensory ligament of duodenum
The suspensory muscle marks the formal division between the first and second parts of the small intestine, the duodenum and the jejunum.

Trypsin

trypticanti-tryptictrypsin serine proteases
Trypsin is formed in the small intestine when its proenzyme form, the trypsinogen produced by the pancreas, is activated.

Digestive enzyme

digestive enzymespancreatic enzymepancreatic enzymes
Many of the digestive enzymes that act in the small intestine are secreted by the pancreas and liver and enter the small intestine via the pancreatic duct.

Cholecystokinin

CCKpancreozymincholecystokinin (CCK)
Pancreatic enzymes and bile from the gallbladder enter the small intestine in response to the hormone cholecystokinin, which is produced in the small intestine in response to the presence of nutrients.
Cholecystokinin, officially called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum, the first segment of the small intestine.

Gallbladder

gall bladdergall-bladderHartmann's pouch
In vertebrates, the gallbladder is a small hollow organ where bile is stored and concentrated before it is released into the small intestine.

Goblet cell

goblet cellsglandular epithelial cellsgoblet
They are found inside the trachea, bronchi, and larger bronchioles in the respiratory tract, small intestines, the large intestine, and conjunctiva in the upper eyelid.

Cecum

caecumcaecaceca
In dissections by the Greek philosophers, the connection between the ileum of the small intestines and the cecum was not fully understood.

Simple columnar epithelium

simple columnarciliated columnar epitheliumciliated simple columnar epithelium
In humans, a simple columnar epithelium lines most organs of the digestive tract including the stomach, small intestine, and large intestine.

Ileum

terminal ileumilealsmall bowel
The small intestine has three distinct regions – the duodenum, jejunum, and ileum.
The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds.

Superior mesenteric artery

superiorSuperior mesentericcranial mesenteric artery
The small intestine receives a blood supply from the celiac trunk and the superior mesenteric artery.