Paul Sarebresole

See also: Apparatus

The gastro-intestinal system or digestive system is the system of bodies of the pluricellular animals which takes food, digests it to extract some from energy and the nutrients, and evacuates the fecal matter surplus.

The digestive tract substantially varies from one animal specie to another. For example, certain animals have stomachs with several rooms.

On the level embryologic, the digestive tract consists of several embryonic layers: the mouth and the anus are of origin ectodermal, whereas the remainder of the tube is of origin endodermal.

This system is a tube making forward in various compartments food introduced by the living beings which are provided with it. This food carries successively the gastric name of contents, Chyle and food Chyme. In this tube various mechanical and chemical operations will transform food into Nutriment S.

The mechanical transformations are carried out by the system masticator and the layer of muscles bordering the digestive tract. The chemical conversions are carried out by the enzymatic complex (enzymatic Catalyze). These enzymatic transformations are coupled with a pH supporting these reactions. For example the pH of the stomach is of 3 on standby of a food catch.

The crucial role of the digestive system is to assimilate, absorb the nutrients in blood circulation and lymphatic and to eliminate the nonassimilable elements.

However, the digestive system also has two other roles:

  • a role of defense of the organization
  • a role endocrinien

Components of the digestive system

At an adult normal man of male sex, the digestive tract is approximately 7,5 m long. It has a variable diameter. Its movement is called peristalsis. It has four tunics which are on the basis of the light towards outside: the mucous membrane (secretary role and of absorption), the submucosa (one finds there all the elements of vascularization and of in), a musculeuse tunic (broken up itself into an internal layer known as circular and an external layer known as longitudinal) and finally a séreuse called external layer when one is in the peritoneum and adventitious that one is apart from the peritoneum. It is composed of the following elements.

Elements of the oral cavity

Elements of the digestive tract

  • Esophagus , finished by the Cardia
  • Stomach , which includes the Antre and the channel of the Pylore
  • Intestin S :
    • Small intestine, which has three parts:
    • Large intestine or colon, which has three parts:
      • Cæcum . The appendix is a rudimentary body, remainder of the evolution, attache to the Cæcum.
      • Colon which includes/understands:
        • ascending Colon
        • transverse Colon
        • sigmoid Colon descending and
      • Rectum , ending in the Anus

Additional glands

The liver has as a principal function to detoxify what the digestive system introduced. It is located in the cavity péritonéale and more precisely in the right hypochondriac, under the diaphragm. Its lower face rests on the other internal organs. Its vascularization is double (a vascularization to nourish it, known as feeder and a functional vascularization which enables him to fulfill its function of cleaning). The liver is by its role a vital body. One of its products is the Bile which it secretes in the small intestine via the bile ducts. The bile, when it arrives in the small intestine, joined the duodenum. Blood is purified by the hepatic lobules.

The Pancréas is a body rétropéritonéal. It is crossed by the termination of the bile duct. The extrahepatic bile duct (outside the liver) is consisted of the cholédoque one. The accumulation of bile ducts in the pancreas can generate a pancréatite. It secretes an Iso-osmotic liquid containing of the Bicarbonate and various enzymes, among which Trypsine, Chymotrypsine, Lipase, and pancreatic Amylase, as well as nucleolytic enzymes, in the small intestine.

All these bodies Sécréteur S assist the Digestion. The dariotype is the center of the digestive system.

The process of digestion and the excretion

See also: Digestion

After mastiquéebeing mastiquée, food is swallowed and directed towards the Estomac via the esophagus. Thanks to the action of mixing of the muscles of the stomach and gastric juices, it is transformed into liquid paste which passes then through the Intestin hail, where the nutritive particles are absorbed by the organization while passing in the Sang. The remainder walks on towards the Côlon and is rejected as deposit. Mouth, master keys through the Esophagus to the Stomach, where the continuous processes off breakdown. Internal It then master keys to the Small where further breakdown occurs, and the useful particles are absorbed into the Bloodstream. Internal The remaining particles not through the Broad and are ultimately expelled ace Deposit. -->

See also body, Anatomy, abdominal Cavity -->

The digestive system and its mode of action

The digestive system consists of a succession of hollow bodies, connected to each other to form a tube which goes from the mouth to the anus. Inside, this tube is papered of a Muqueuse. In the mouth, the stomach and the small intestine, this mucous membrane contains small glands which produce juices supporting digestion.

Two other bodies, the Liver and the Pancreas, secrete gastric juices which are poured in the small intestine. Many other factors (e.g.: nerves and blood) also play a big role in the process of digestion of food.

Mouth to the Anus (see figure). Inside this tube has lining called the Mucosa. In the mouth, Stomach, and Small internal, the mucosa contains tiny nipples that produce juices to help digest food.

Two solid organs, the Liver and the Pancreas, produce digestive juices that reach the internal through small tubes. In addition, shares off other organ systems (for authority, nerves and blood) play has major role in the digestive system. -->

Importance of digestion

See also: Digestion

To be absorptive by the organization, food must be treated, i.e. broken into small Molécule S able to pass in blood circulation for then being distributed to all the cells of the body. Digestion is this process of fractionation and absorption of the food which will be used thereafter of nutrients and energy source at the organization.

How food is digested

Digestion implies the mixing of food, their progression through the digestive system and the fractionation of the large molecules in smaller. It begins in the mouth, with the chewing and swallowing and finishes in the intestine. The chemical process in question is somewhat different according to the type of introduced food. The bacteria normally present in the digestive system are responsible for several chemical conversions useful for digestion.

Bacteria which naturally live in the gastrointestinal leaflet C has batch off the actual chemical work off digesting for custom. -->

Movements of food through the digestive system

The hollow bodies of the digestive system are equipped with muscles which make it possible the walls to make movements which push food or brew it. The typical movement of the esophagus, the stomach and the intestine is the Péristaltisme. The action of the peristalsis resembles vague crossing the muscle, resulting in decreasing the diameter of the digestive tract. These contractings slowly move from one end to another of the body, always in the same direction, with for effect to push the contents of it through all the food channel.

The first movements of these muscles occur when food or a liquid is ingurgity. Although the fact of swallowing is at the beginning a voluntary gesture, once started, it becomes involuntary and continues under the control of the nerves

The esophagus is the body in which food (Bolus) thorough is once swallowed. It connects the throat with the stomach. With its junction with the stomach, a Sphincter is which closes the passage between the two bodies. However, with the approach of the bolus, the sphincter is slackened and made it possible food to pass.

Food penetrates in the stomach which has then three mechanical tasks to carry out. Firstly, it must contain all swallowed food and liquids, which requires that the sphincter higher remainder slackened and accepts a great quantity of matter. Secondly, it must mix food with the gastric juices which it produces. This is done by the action of the muscles of the base of the stomach. Finally, it must empty its contents in direction of the small intestine.

Various factors affect the evacuation of the contents of the stomach, including the nature of the food (in particular their content of fat and proteins), as well as the degree of muscular action necessary to empty the stomach and on the level of the intestine, to receive the contents from it. As food is digested in the intestine and dissolved by pancreatic juices, hepatic and intestinal, it is brewed and always thorough further along the intestine.

Finally, all the digested nutrients are absorbed by the intestinal walls. Waste of this process consists of fibers or dead cells. They are propelled towards the colon, where they are kept one day or two, until deposit are expelled.

Peristalsis. The action off peristalsis looks like year ocean wave moving through the muscle. The muscle off the organ produces has narrowing and then propels the narrowed portion slowly down the length off the organ. Thesis waves off narrowing push the food and fluid in face off them through each hollow organ.

The first major muscle movement occurs when food gold liquid is swallowed. Although we are whitebait to start swallowing by choice, ounce the swallow begins, it becomes involuntary and proceeds under the control off the nerves.

The esophagus is the organ into which the swallowed food, in the form off has Bolus, is pushed. It connects the throat above with the stomach below. At the junction off the esophagus and stomach, there has ringlike valve closing the passage between the two organs. However, ace the food approaches the closed boxing ring, the surrounding relaxed muscles and allow the food to not.

The food then enters the stomach, which has three mechanical task to C. First, the stomach must blind the swallowed food and liquid. This requires the muscle off the upper share off the stomach to relaxed and accept broad volumes off swallowed material. The second job is to mix up the food, liquid, and digestive juice produced by the stomach. The lower share off the stomach mix thesis materials by its muscle action. The third task off the stomach is to empty its content slowly into the small internal.

Several factors affect emptying off the stomach, including the natural off the food (mainly its conceited and protein content) and the dismantles off muscle receive action off the emptying stomach and the next organ to the content (the small internal). Ace the food is digested in the small internal and dissolved into the juices from content the pancreas, liver, and internal, the off the internal are mixed and pushed forward to allow further digestion.

Finally, all off the digested nutrients intestinal are absorbed through the walls. The waste products off this process include undigested shares off the food, known ace fiber, and older concealments that cuts been saw-tooth from the mucosa. Thesis materials are propelled into the colonist, where they remain, usually for has day gold two, until the deposit are expelled by has bowel movement. -->

Production of gastric juices

The first glands which enter in action are the salivary Glandes. Saliva that they produce contains a Enzyme which starts the digestion of the Amidon.

Then, the cells papering the internal wall of the stomach secrete the gastric juices made up of Hydrochloric acid and enzymes which digest proteins. Curiously, the acid produced by the stomach does not destroy it itself. The Mucus which it produces succeeded in protecting it and the action of the acid concentrate only on food.

After the stomach was emptied of its contents in the intestine, the gastric juices of the Pancréas and the Foie are added to food in order to continue digestion. The produced pancreas of many enzymes able to degrade the Carbohydrates, the Lipid S and the Protéine S. Of other enzymes is also secreted by the walls of the intestine.

The liver, for its part, produces the Bile. This one is put in reserve in the Gall bladder. At the time of the food catch, the blister contracts to release the bile in the intestine via the Cholédoque. The bile dissolves the lipids, a little as the Détergent S act on the grease of a frying pan. The molecules thus obtained are digested by the enzymes of the pancreas and the intestine.

The next set off digestive nipples is in the stomach lining. They produce stomach acid and year enzyme that digests protein. Digestive One off the unsolved puzzles off the system is why the acid juice off the stomach does not dissolves the tissue off the stomach itself. In most people, the stomach mucosa is whitebait to resist the juice, although food and other tissues off the body boat.

After the stomach empties the food and juice mixture into the small internal, the juices off two other digestive organs mix with the food to continues the process off digestion. One off thesis organs is the pancreas. It produces has juice that contains has wide array off enzymes to station-wagon down the carbohydrate, conceited person, and protein in food. Internal Other enzymes that are active in the process as from nipples in the wall off the gold even has share off that wall.

The liver produces yet another digestive juice-- Bile. The bile is stored between meals in the gallbladder. At mealtime, it is squeezed out off the gallbladder into the internal bile ducts to reach and mix with the conceited in food. The bile acids dissolves the off conceited into the watery content the internal, much like detergent that dissolves grease from has frying side. Conceited After the is dissolved, it is digested by enzymes from the pancreas and the lining off the internal.

Examples are bread, potatoes, vegetables, rice, corn, noodles, -->

Proteins

Food (like the meat, nuts and eggs) contains giant molecules called proteins. These molecules must, first of all, being digested by the enzymes for then being absorptive by blood. These molecules are used to repair cellular fabrics. The largest share of digestion is located in the small intestine.

Greases

The molecules of fat constitute an important energy source for the body. The first stage of the digestion of a greasy substance as butter for example, is to dissolve it in the aqueous medium of the intestinal cavity. The acids of the bile reduce these large molecules in smaller like the Fatty-acids and the Cholestérol. These molecules can then be absorptive by the cells of the intestinal wall where they are transformed into larger molecules which are poured in the lymphatic vessels. From there they pass then in the blood which directs them towards the reserves of grease of the organization.

Vitamins

Other very important elements drawn from food are the Vitamine S. They are classified in two great groups according to their solubility: in water (all the vitamins B and the vitamin C) or in the lipids (vitamins has, D, K). Vitamin S. different The two types off vitamins are classified by the fluid in which they edge Be dissolved: toilet-soluble vitamins (all the B vitamins and vitamin C) and conceited person-soluble vitamins (vitamins has, D, and K). -->

Water and salts

The majority of the material absorptive by the walls of the intestine are composed of Eau in which Sel S are dissolved. This water and these salts come from absorptive food and liquids, but also from the gastric juices secreted by the organization. Toilets in which Salt is dissolved. Digestive The salt and toilets like from the food and liquid we swallow and the juices secreted by the many nipples. -->

Control digestive processes

Hormonal regulators

Hormone S that control the functions off the digestive system are produced and released by concealments in the mucosa off the stomach and small internal. Digestive thesis hormones are released into the blood off the leaflet, travel back to the heart and through the arteries, and return to the digestive system, where they stimulate digestive juices and causes organ movement. The hormones that control digestion are Gastrin, Secretin, and Cholecystokinin (CCK):

  • Gastrin causes the stomach to produce year acid for dissolving and digesting nap foods. Normal It is also necessary for the growth off the lining off the stomach, small internal, and colonist.

  • Secretin causes the pancreas to send out has digestive juice that is rich in bicarbonate. It stimulates the stomach to produce pepsin, year enzyme that digests protein, and it also stimulates the liver to produce bile.

  • CCK causes the pancreas to grow and to produce the enzymes off pancreatic juice, and it causes the gallbladder to empty. -->

Nervous regulators

Nerve S help to control the digestive action off the system. Extrinsic (outside) nerves like to the digestive organs from the unconscious share off the brain gold from the spinal cord. They release has chemical called Acetylcholine and another called Adrenaline. Digestive acetylcholine causes the muscle off the organs to squeeze with more force and increase the “push” off food and digestive juice through the leaflet. Acetylcholine also causes the stomach and pancreas to produce more digestive juice. Internal adrenalin releases the muscle off the stomach and decreases the flow off blood to thesis organs.

Important Even more, though, are the intrinsic (inside) nerves, which make up has off very dense network embedded in the walls the esophagus, stomach, small internal, and colonist. The intrinsic nerves are triggered to act when the walls off the hollow organs are stretched by food. Different They release many substances that speed up gold delay the movement off food and the digestive production off juices by the organs. -->

Specialization of the bodies

  • present The first organ is the tongue which is only in the phylum Chordata.

  • The second organ is the esophagus . It is instead called has crop . It is year enlargement off the esophagus used to blind food and exists in pigeons, bees and worms.
  • The third organ is the stomach . It is called Gizzard in birds. It has muscular stomach used to mechanically digest food instead off storing it.
  • The fourth organ is the broad internal . It is called the present Cecum and is in not-ruminant herbivores such ace rabbits. It aids in seedling digestion off Cellulose. -->

    • Other uses of the bowels

    Lamb gut. With the advent the modern off will era, musicians tightens to uses synthetic strings made off nylon, silk gold steel, however orchestral nap violinists still uses gut strings. Contrary to belief, Cat S were never used ace has source for gut strings

    • original Sheep gut was the source for natural gut string used in racquets, such ace for Tennis. Today, synthetic strings are much more common, goal the best strings are now made out off Cow gut
    • “Natural” sausage hulls are made off animal gut, especially pig and cow
    • Animal gut was used to make the cord lines in Grandfather clock S, goal may Be replaced by wire -->

    Reference

    External bonds

    • Diagram detailed on the anatomical digestive system
    • Atlas of the digestive system

    Simple: Gastrointestinal system Zh-min-nan: Siau-hoà hē-thóng

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