The small intestine is the longest part of the entire digestive tract.This body is the longest intestinal department.It is situated next to the gatekeeper of the stomach and passes into the rectum.This part of the digestive tract allows you to perform many vital functions, the main of which is its absorption of nutrients from the walls of the fluid.


  • 1 How does
    • 1.1 structure walls
  • 2 How does digestion
    • 2.1 Part
    • endocrine
  • 3 Departments
    • 3.1 duodenum
    • 3.2 jejunum
    • 3.3 ileum

How does

small intestine

in the small intestine undergoing complex processes of digestion

small intestine is similar in structure to the fat, butis less thick and solid walls, diameter of the inner lumen is also different (from thin thinner).When considering the thickness distinguish large and small intestine walls is difficult because the small intestine has the ability to greatly expand.The diameter of the small intestine differs throughout its duration:

  • proximal he averages 5 cm
  • The distal - 3 cm

peritoneum covers the small intestine almost completely remains undisguised only at the connection to the peritoneum - in the mesentery.Location intestinal intraperitoneally.Motility of the small intestine quite active and varied:

  1. being reduced several muscles simultaneously
  2. tonic contraction (like gastric)
  3. wavy peristalsis: waves propagating from the proximal portion to the distal
  4. Pendulum reduction (alternately: the longitudinal, the circular musclefibers)

wall structure

walls of the colon are composed of layers:

  1. mucous
  2. submucosa
  3. Muscle
  4. serous

Muscle consists of:

  • internal circular layer
  • outer longitudinal layer

walls uniformly covered with a mucous layer over the entire area of ​​the small intestine in addition to the duodenum, where the gland and longer villus epithelial tissue.The villi are similar in shape to the leaves of the trees, from the inner surface of the intestine is much thicker.The network of capillaries supplying blood villi, between which there are grooves, opening the bowel ducts to carry digestive function.Slimy

layer consists of a plurality of circular and longitudinal folds.

Depending on the blood supply to the bowel mucosa changes color, in all departments, he rose, and in the iliac - gray-pink.Muscle shell consists of longitudinal and circular smooth muscle.Peritoneum is the serous portion that covers only the duodenum into ampoules area.Across the inside of the small intestine are lymph nodes and Peyer's patches (cluster nodes).

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How does digestion

small intestine

small intestine: a schematic

comes from the stomach the food has a high acidity.The intestine is its normalization and the creation of conditions for the normal enzyme activity and activation of pancreatic fluid.The intestines contain more than 98% liquid and less than 2% solids.

During the day, made more than two liters of juice digestive enzyme in the intestine.Upon receipt of food, its amount in the intestines is reduced.In the small intestine the food is digested in the blood capillaries and lymphatic vessels.Stages of the small intestine:

  1. digestion of protein by enzyme activity
  2. Splitting of carbohydrates
  3. synthesis of fats occurs in the least with limpazy

With villi absorbed carbohydrate and protein components, which are then fed through the veins in the liver, fat forwardedlymph vessels.

part of the endocrine system

Besides the digestive process, the small intestine performs endocrine function.It lies in the development of cell gastropankreaticheskoy system responsible for the enzymes.In the small intestine produced by a variety of hormones that promote digestion.

also produced by enzymes that contribute to the breakdown of food supplied to the components in the small intestine.After cleavage of synthesized proteins into amino acids, carbohydrates into simple sugars, fats components which do not prevent the absorption of nutritional components.


The following sections of the small intestine:

  1. duodenal
  2. jejunum
  3. iliac


Located duodenum in the immediate vicinity of the pylorus, the length of it reaches 20 cmalmost completely located in the retroperitoneal region except a portion, which is called an ampoule.Gut surrounds the pancreas, resembling a horseshoe.Adopted share duodenum in parts:

  • Rising
  • Downward
  • horizontal
  • Upper

small intestine

human intestine: a schematic representation of

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parallel to the first lumbar vertebra is the rising part of the small intestine duodenum.Also, determine its location can be on the level of the twelfth thoracic vertebra.

This department represents the loop length reaching up to 5 cm. It ends with a descending part of the colon.In the vicinity of this organ is the liver with a total gastric duct.

Downward part comes from the right side of the spine down to the third vertebra, and then bends to the left.The length of this section will vary in the region of 8-10 cm The duodenum is in close proximity to:.

  • right kidney
  • Liver
  • common bile duct

With this intestine is connected through a common pancreas pancreatic duct connected tobile duct groove.Horizontal intestine correlates with the third lumbar vertebra and inferior vena cava.Further, the horizontal part of the intestine goes up and goes into the ascending department.

ascending part of the duodenum and completes the loop is at the level of the second lumbar vertebra.Bend it passes into the jejunum.The rising portion of the duodenum of the intestine located near:

  • mesenteric vein
  • mesenteric artery
  • abdominal aortic


This part of the intestine is similar in structure to the previous one.Both these parts are called mesenteric part of the small intestine.Jejunum forms seven loops and is in the left upper abdomen.The back of the jejunum parientalnoy adjacent to the peritoneum.Jejunum is connected to the stomach, in the curved part, gland.


Skinny intestine passes into the ileum, which is located on the right side of the lower abdomen.The ileum is similar in structure to the thin intestine.It consists of a plurality of loop bends, the last of which come in a small basin.The ileum is near the bladder and uterus.

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small intestine has a simple structure, but it has many functions: digestion, absorption of nutrients, the breakdown of food into its component partsand the production of hormones.In this part of the intestine occurs absorption of many drugs that have come into the body orally, through its walls into the blood toxins.It is very important to preserve the health of the intestine to watch your diet and drink plenty of fluids to regulate its work.

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