Human gastrointestinal tract
The terms digestive tract or digestive tract (Latin: Apparatus digestorius ) the organs which serve to reduce the recording, the crushing and the further transport of food to digest this and ultimately to make the contained nutrients used by the body. Other synonyms for the digestive tract are Canalis Alimentarius and Systema digestive. The digestive tract consists of the oral cavity, the pharynx (throat ), esophagus, the gastrointestinal tract (Synonyms: gastrointestinal tract, from Greek gaster stomach and Latin intestinum intestine), liver, biliary tract and pancreas.
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Function
In the digestive tract of the actual enzymatic digestion of food, absorption of nutrients and water and the excretion of indigestible or non-recyclable food components takes place. Enzymes, in addition to various microorganisms are involved in the digestion, which can be summed up under the term intestinal flora.
The large digestive glands, the liver - with gall bladder - and the pancreas, produce digestive juices that break down food into its components. The lower part of the digestive system serves mainly to absorption of water, and the precipitation of the non-digestible food ingredients.
Construction
The digestive tract can be divided into a head and a body portion ( synonymously upper and lower digestive tract ). Apart from the actual gastrointestinal tract ( GI tract ) are still part of the digestive system, the oral cavity, mainly where the mechanical grinding of food occurs, salivary glands, pharynx and the esophagus, which serves to further transport into the stomach. The assignment of the esophagus to the stomach -intestinal tract is controversial.
Headboard
The mouthparts and oral cavity (lips, teeth, tongue ) are used for food intake and crushing. The salivary glands produce saliva, which makes the food slippery and in some mammals contains enzymes for breaking down starch ( amylase). The pharynx (throat, pharynx ) is the transition to the esophagus. In it intersect Food and airway.
Body part
- Esophagus: is used to transport the food from the mouth to the stomach.
- Stomach: converts the food into chyme and enriches it with gastric juice.
- Small intestine with Duodenum ( duodenum): The bile duct opens here with him are the chyme pancreatic juice, which is used for protein and fat digestion, and bile, which helps in the digestion of fat, added.
- Jejunum ( jejunum ): Place the absorption of the now split into peptides proteins, fats, carbohydrates, vitamins and water
- Ileum (ileum )
Differentiation of the digestive systems
Through the evolution of the digestive tract is optimally adapted to the respective food of the species. On the one hand relates to the anatomy of the digestive tract, and on the other hand, the medium of the nutritional gap microorganisms. Here is an overview of common digestive systems:
- System such as human, pig and dog stomach
- Small intestine
- Appendix
- Colon
- System with a functional cecum such as the horse, rabbit and rat stomach
- Small intestine
- Cecum ( with microbial digestion)
- Colon
- Multiple system (ruminants ), such as cattle, sheep and goat rumen
- Omasum
- Reticulum
- Abomasum (glandular stomach)
- Small intestine
- Appendicitis ( pronounced but not functional )
- Colon
- Avian system ( poultry) such as chicken, turkey, duck Glandular stomach ( proventriculus or ventriculus glandularis )
- Gizzard ( ventriculus muscularis ) (microbial digestion)
- Small intestine ( Hauptabsorbtionsort )
- Colon (microbial digestion)
- Cloaca ( common excretion of urine and feces )
Wall layers
The wall of the digestive tract is in all portions fundamentally four tissues, which are in layers above one another. In the various sections of the gastrointestinal tract, the structure differs depending on function something.
The layers from inside to outside:
- Mucosa (mucous membrane ): It forms the inner layer of the wall of the gastrointestinal tract.
- Submucosa: It forms a fairly narrow layer of connective tissue between the mucosa and muscularis.
- Muscularis: This consists of the esophagus from striated muscle, which are subject to the arbitrary and, for example, can be hooked on swallowing mouth, pharynx and the upper part. In the remaining part of the digestive tract outweighs the smooth muscle, which is controlled by the parasympathetic nervous system. She is also responsible for the peristalsis of the intestines and is also arranged longitudinally, so that the digestive tract can also contract either longitudinally or transversely, both as a ring.
- Tunica serosa ( visceral peritoneum also ). Forms the outermost layer of tissue of the gastrointestinal tract. It secretes fluids and allows the slipping over each other organs. However, the serosa only occurs in organs that lie in the peritoneum. In the other areas of the body, the connection of individual organs by loose connective tissue ( adventitia ) is realized.