Duodenal Villi
Duodenum
- Region of Small Intestine -
Ducts (channels) from the liver and pancreas, called pancreatic ducts, come together to form one duct that enters the duodenum.
- Duodenum is an important place for chemical digestion of chyme, received from the stomach. This is where most of the digestion occurs.
- The ridges of the inner lining of the small intestine are covered in tiny projections called villi, which, in turn, are covered in microvilli. They are surface (epithelial) cells designed for absorption.
- Microvilli are microscopic extensions. They give the villi a brush-like appearance in electron photomicrographs; known as the “brush border.”
- Each villus contains tiny structures called capillary beds (also known as capillary networks) and lacteals (also know as lymph vessels) (Part of the circulatory system.)
- Here the digestive juices from the pancreas (digestive enzymes) and hormones and the bile (from the gull bladder) mix. The digestive enzymes break down proteins and bile and change fats into micelles (tiny balls of molecules).
- The duodenum contains Brunners glands, which produce bicarbonate. In combination with bicarbonate from pancreatic juice, this neutralizes hydrochloric acid of the stomach.
- The duodenum can sometimes inhibit stomach contractions due to hormones. These hormones include CCK. However, CCK also has a major role in digestion as it causes stimulations to increase in regards of enzymes. It allows discharges and contractions from the pancreas and gall bladder.
- Brunner's glands, which secrete mucus, are found in the duodenum. This mucus protects the duodenal wall from the digestive juices.
- Transport proteins on the epithelial cells move amino acids, glucose, water soluble vitamins, etc. by facilitated diffusion and active transport into the capillary system, then on to the liver immediately for processing.
- Fatty acids and glycerol are absorbed into the epithelial cells and are repackaged as triglyceride. They are found in most organs as well as the bile duct and salivary glands.
- Villi are packaged into protein packs, (to enable transport) because they are hydrophobic and are absorbed into the lacteals in the interior of the villi. They are transported through the body’s lymphatic system.
- Fat soluble vitamins will move with fats into lacteals for absorption in the body.