Human physiology of digestion. Anatomy short and clear. Presentations, spreadsheets, organs and their functions

Physiology of the process of digestion of the ingested food is complex and consists of a variety of physical and chemical processes. They constitute the essence of digestion. When complex substances break down into simpler components. In other words, this is one of the first stages of catabolism in humans. In a series of mechanical and chemical reactions involving enzymes and play a very important role.

Divisions and subdivisions of the digestive system of humans

Food enters initially into the oral cavity. This is the beginning of the digestive tract, which is not always the case referred to in common parlance gastrointestinal, identifying concepts. metabolic products will eventually enter into the rectum. This terminal part of the digestive tube.

GI	functions
Oral cavity	Machining, grinding meal, participate in the elementary decomposition of complex carbohydrate foods
Pharynx	Bolus propulsion and swallowing
Esophagus	food transit, esophageal phase of swallowing.
Stomach	Mechanical action, hydrolysis of proteins
Small intestine	Participation in all types of metabolism, absorption of oligosaccharides, fatty acids and oligopeptides, water
Colon	Absorption of water, vitamins, bacterial digestion
Rectum	Formation of feces
Pancreas	Participation in the hydrolysis, lipolysis
Liver	"Factory" enzymes

At all stages of the food bolus transit was happening to him mechanical or chemical transformation. Each of the departments of the gastro-intestinal tract has its own function and task in a complex, multi-step process.

Oral cavity

It has two major divisions: the buccal cavity and oropharynx. Here begins to form the bolus. Received products cause stimulation of the receptor language. According to the olfactory and gustatory ways information is delivered to the brain.

Reflexively increase or decrease depending on the quality of the amount of saliva production. Under the influence of these pulses is preparing the ground for the further process of food digestion in the human body: increased secretion of various digestive juices.

Tongue and teeth are involved in crushing food components. This is an important step, because the machining precedes the chemical starting in the mouth.

Here, the complex carbohydrate components split by the action of saliva. As a part of saliva two important enzyme: maltase and alpha-amylase. Formed more simple di- and oligosaccharides, which then makes it easier to digest.

Pharynx

The oral cavity is responsible not only for the formation of a lump, but it further propulsion, movement through the tube.

The oropharynx he does not stay long. At a time when food enters the area of ​​the tongue ends oral phase of swallowing. The following pharyngeal or oropharyngeal. Within approximately 1 second occurs a cascade of muscle contractions as a result of which the muscles contract pharynx, esophagus and sphincter apparatus - next GI - relaxes.

Esophagus

In the cavity of the long curved tube extends third step swallowing - esophageal. Due to secretion of glandular cells of the mucous body and muscle contraction moves the food toward the stomach.

That's where it gets after the reduction of the lower sphincter pischegodnogo. Begin more complex chemical processes of digestion.

Stomach

Human physiology of digestion involves the process of food processing after passing through the esophagus continues in the stomach. This is a very important organ. It consists of several anatomical and functional departments. From the contents of the esophagus enters the cardiac department. There are virtually no digestive enzymes. Hydrogen index does not reach the optimum for their normal operation.

From the cardia of the stomach the food enters the body. Here, a large number of so-called parietal or parietal cells. They are responsible for the production of chlorine anions and hydrogen cations. Hydrochloric acid is responsible for the high acidity of gastric juice. Optimal for the normal operation of enzymes is pH 1.5 to 2.5.

Gastric juice also has the following functions:

• participation in the obturator mechanism pyloric stomach as acidic food in the duodenum will not be able to do;
• decontamination: the presence of a sufficient amount of acid leads to protection against bacteria causing putrefaction and fermentation;
• It creates conditions for autocatalysis pepsin - a cascade of reactions.

Zymogen (an inactive form) formed in the principal cells of the gastric mucosa. Their maximum is also in the area of ​​the body. In acidic medium pepsinogen converted into an active protein which activates and accelerates protein breakdown. He is transformed into simpler oligosaccharides and polypeptide chains.

In the hydrolysis of carbohydrates gastric juice and its components are not involved. The acidic environment for them ruinous.

The fat component is also not chemically cleaved. But here the acidic environment of the stomach creates the conditions for their emulsification. As such, the lipids in the downstream sections of the gastro-intestinal tract break easier and with less energy.

Small intestine

It consists of duodenum, jejunum and ileum. They differ in their structure and the functions performed.

Of the pyloric part of the stomach the food goes directly into the duodenum. This is a relatively small portion of the bowel, but extremely important. It was here carried catabolic reactions of all types of metabolism and absorption of nutrients.

Slurry, ranked here from the stomach undergoes further propulsion movements, resulting in the continued mechanical processing of the bolus. The pH of the alkaline have here - from 7.5 to 8.4. If acidification enzymatic processes become slower and less effective.

The most important enzymes involved in the breakdown of protein structures, it trispin and chymotrypsin. They are produced in the brush border of intestinal cells. They also are synthesized in an inactive form and are activated by enterokinase.

Trypsinogen transformed into trypsin cleaves remaining polypeptides to shorter amino acid chains and oligopeptides. More careful hydrolysis of the resulting mixture was subjected to using chymotrypsin.

In this breakdown of protein is not completed. Terminal carboxyl groups are cleaved from the peptide chain using elastase and carboxypeptidase. As a result, the distal intestine come oligopeptides, amino acids.

Fat metabolism in the duodenum occurs under the action of lipase. This enzyme cleaves the different groups of lipids. The result is glycerol and fatty acids.

From the carbohydrate components under maltase, amylase digested sugars and monosaccharides are produced. They are used in the future in anabolic reactions.

Human Physiology digestion continues in the jejunum and ileum. Here are absorbed oligosaccharides and monosaccharides, fatty acids, amino acids. It is responsible for this membrane digestion. Together with them, absorbed water. These metabolites fall through the microvilli in the lymphoid apparatus. Next way is through the blood system and liver filter.

Colon

This continues digestive tract absorption of water. Parallel formation begins feces.

The colon has the following departments:

• cecum;
• ascending and descending colon;
• Front transverse colon;
• sigmoid colon.

Within the proximal tract occurs absorption of water, vitamins, and the remaining chlorine ions, potassium, magnesium. In addition, blind and colon bacteria colonize different. They are involved in the processing of the remaining masses. This process is known as bacterial digestion. There may appear fermentation and putrefaction.

The large intestine - a reservoir, a kind of depot for future feces. They are deprived of the excess water. And come below.

Rectum

Human physiology of digestion does not end with the suction elements. Rectum - the final parts of the digestive tube. Here are finally formed stool.

Excess water is sucked mucous body shell. She richly supplied with blood. There is a feature - here originates hemorrhoid bloodstream, where the blood goes directly into the portal vein of portocaval anastomosis. Therefore, even here can be absorbed into the bloodstream a substance dissolved in water.

anus

In the process of digestion is not involved. The role of the anus is in the process of defecation.

Muscle sphincters are subject to the cerebral cortex, which allows a person to control the process. Through the anus of the final digestion product exits the body.

Other bodies - members of digestion

Physiology is arranged so adequately and unique that in the process of digestion in the human body organs are involved, are not part of the digestive tract.

Pancreas (also called Joaquín Albarrán gland). It synthesizes hormones involved in carbohydrate metabolism and the enzymes that are directly involved in the digestion of food.

Pancreatic lipase - an important enzyme needed to break down fats. That is why the secretion of pancreatic juice is maximal during the reception of fatty foods.

In addition, in pancreas secret contains deoxyribonuclease, chymotrypsin and trypsin.

The role of the liver in the digestion is difficult to overestimate. After all, this body - a storehouse of enzymes. It is responsible for the synthesis of proteins involved in the cleavage products from complex to simple, ready to enter the bloodstream.

Very large part of the liver in carbohydrate metabolism. In case of violation of this body functions develop severe metabolic disorders, up to the formation of diabetes.

In the liver, bile formed. It contains bile acids - a necessary participant in digestion. This allows the fat molecules accessible for further biochemical transformations. In other words, the bile acids are responsible for fat emulsification. In addition, they provide the required level of acidity in the duodenum.

Bile ducts and gallbladder - tanks is synthesized in liver bile. There she deposited "on demand". When inflammation and systematic violation of the diet there is a tendency to the formation of gallstones.

Secrets of the pancreas, liver and gall bladder enter the duodenum and there exercise their action and participate in the digestion.

The total length of the gastrointestinal tract

In humans, the intestines has huge dimensions. After all, it increases the area of ​​contact with the food. This fact is important for intensive absorption of electrolytes, metabolites, vitamins and water.

The small intestine - the longest portion of the gastrointestinal tract. This is 6.5 - 7.0 m. It is in this section provides the maximum intensity of absorption and biochemical transformation of proteins, fats, carbohydrates.

On the large intestine is about 2 meters. digestion are less intense, since the main function is to deposit formed feces and final suction residual nutrients.

Digestion and ekskrektsiya

The process begins in the mouth and oropharynx. With the help of the tongue, lips, palate muscles formed a lump of food. Language carries taste reception. The pharynx is involved in the promotion of food to the esophagus, where food is largely unchanged into the stomach.

In this department continues machining begins emulsification of fats. Proteins are hydrolyzed with pepsin to simpler polypeptide chains. Fats are not affected in this segment of biochemical transformation.

In the small intestine, namely in the duodenal cavity under the action of pancreatic juice secretion of the liver and gall bladder carried breakdown of fats, proteins and carbohydrates. Especially fats rapidly disintegrate.

Simultaneously there occurs absorption pristenochnoe simple exchange and water. Further, only water and vitamins are absorbed in the colon. Something that does not suck previously exposed to the bacterial flora of the enzymes. As a result, there is bacterial digestion.

In the rectum formed stool, absorbed the last remaining water. Excretion via the anus.

Motility and innervation of the digestive tract

The walls of the hollow organs of the digestive system containing many plexus of autonomic nerve fibers. But each department has its own peculiarities innervation.

Sympathetic innervation of the pharynx at the expense laryngo-pharyngeal branches of the superior cervical sympathetic ganglion. And for parasimpatiku meets the vagus nerve.

The mucosa of the esophageal muscle fibers oriented longitudinally to better promote the food bolus in the craniocaudal direction. Near the body also formed plexus. They consist of fibers of the vagus nerve, which is responsible for parasympathetic innervation, and the branches of the thoracic and cervical sympathetic trunk node.

Stomach muscle mass consists of divergent and oriented muscle fibers. This is due to the fact that this body is actively mixed foods, and there is the most intensive mechanical effect on the bolus.

Innervation of the organ comes from fibers of the celiac plexus and the vagus nerve. Their form numerous branches plexus, among which strongly pronounced front and rear gastric plexus.

A similar principle of innervation in the small intestine. Only instead of the celiac plexus is involved mesenteric.

The large intestine is arranged differently. The muscle layer is substantially entirely composed of a circular layer. This causes the pendulum and the predominance of mixing movements in the transverse, ascending and descending colon, and sigmoid pendulum movement and rectum.

Human physiology of digestion is arranged is not easy. Sympathetic section is represented differently in the upper and lower floors of the colon. I care as parasympathetic nerves. Simpatico is formed from branches of existing pancreatic and mesenteric plexus. For parasympathetic innervation correspond nervus vagus branches (10 a pair of cranial nerves) and pelvic nerves.

The physiology of the digestive process in the human body allows to maintain consistency within the gastrointestinal tract. This is important in the ever-changing conditions of its operation.

Registration of the article: Mila Friedan

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