Digestion begins in the mouth.

Here it is crushed, wetted with saliva, taste properties are analyzed, the initial hydrolysis of some nutrients and the formation of a food lump, as reported by the Internet publication for girls and women from 14 to 35 years old Pannochka. net Ingested food irritates taste, tactile and temperature receptors.

Signals from these receptors through the corresponding nerve centers reflexively excite the secretion of the salivary and gastric glands, the release of bile into the duodenum, and change the motor activity of the stomach..

Chemical processing of food (enzymatic hydrolysis) in the oral cavity is provided by saliva enzymes. It is produced by three pairs of large salivary glands: parotid, submandibular and sublingual, as well as many small glands located on the surface of the tongue, in the mucous membrane of the palate and cheeks..

From 0.5 to 2 liters of saliva is secreted per day. Mixed saliva contains 99.4-99.5% water and 0.5-0.6% solid residue, which consists of inorganic and organic components. Inorganic components are represented by ions of potassium, calcium, sodium, magnesium, iron, chlorine, fluorine, phosphate, chloride, sulfate, bicarbonate, etc.. , constituting approximately 30% of the dense residue.

Organic substances include various proteins (albumins, globulins), free amino acids, some carbohydrates, nitrogen-containing substances of non-protein nature (urea, ammonia, creatine), as well as mucin, which gives saliva viscosity and due to which the food bolus soaked in saliva is easily swallowed..

The most important component of saliva is enzymes, although the content of some of them is small.. Human saliva actively hydrolyzes carbohydrates. This is carried out by a-amylase, which breaks down polysaccharides (starch, glycogen) with the formation of dextrins, a small amount of maltose and an extremely small amount of glucose, as well as maltase (whose activity is very low), hydrolyzing maltose and sucrose.

Salivary amylase begins its action in the oral cavity, but it is insignificant due to the short stay of food here (15-18 s). Hydrolysis of carbohydrates by saliva enzymes continues in the stomach until acidic gastric juice penetrates into the deep layers of the food bolus, which stops the action of enzymes due to their inactivation..

Saliva also contains proteinases (cathepsins, salivanes, grandulans), peptidases, lipases, alkaline and acid phosphatases, RNases. Saliva has a bactericidal property due to the enzyme lysozyme (muromidase) contained in it.. Saliva contains kallikrein, which is involved in the formation of kinins, which dilate blood vessels, which plays a role in increasing the blood supply to the salivary glands when eating..

Saliva is produced in the acini and ducts of the salivary glands.. In the acini, the so-called primary secret is formed, containing mucin, ?-amylase and ions, the level of which in saliva practically does not differ from the level in extracellular fluids.. In the salivary ducts, the composition of the secret changes: the concentration of potassium ions increases, and sodium decreases..

Chewing.

Chewing is a reflex act that consists of mechanical and chemical processing of food, wetting it with saliva and the formation of a food bolus.. The duration of stay of food in the oral cavity is 15-18 s. It is important that chewing has a reflex effect on the secretory and motor activity of the digestive apparatus..

In the period of chewing, phases of rest, introduction of food into the mouth, approximate, basic, formation of a food bolus, swallowing can be distinguished.. The duration of these phases is different and depends on the quality of food, its quantity, the state of the dental apparatus, the age of the person, etc..

swallowing.

The act of swallowing is a complex process consisting of three reflex interrelated phases - voluntary (oral phase) and two involuntary (pharyngeal fast and esophageal slow).

The end of one phase is the beginning of the next. The first phase is the promotion of the food bolus behind the anterior arches of the pharyngeal ring, to the root of the tongue. The second phase - the entry of the food bolus into the esophagus and the third - through the esophagus to the stomach.

A huge number of receptor formations located in the mucous membrane along the digestive tract controls the chain of reflex acts until the food leaves the esophageal cavity..

Promotion of food through the esophagus.

A number of factors influence the movement of the food bolus through the esophagus.. The first factor is the pressure gradient between the pharyngeal cavity and the beginning of the esophagus.. When the pharyngoesophageal sphincter is closed, the pressure difference between them is 45 mm Hg.. st. when open - no more than 30 mm Hg. st. The second factor is the peristaltic movements of the esophagus and the third is the tone of its muscles (in the cervical region 3 times higher than in the chest). The fourth factor is the gravity of the food bolus.

The contractions of the esophagus have the character of a wave that occurs in its upper part and spreads towards the stomach. At the same time, the annularly located muscles of the esophagus are sequentially reduced, moving the food bolus located in a slightly expanded part of the esophagus towards the stomach in front of the wave of contraction..

This type of contraction is called peristaltic.. The average speed of propagation of a peristaltic wave through the esophagus varies from 2 to 5 cm / s and largely depends on the properties of the food.. The speed of passage of the food bolus through the esophagus is determined by the consistency of food: dense passes in 3-9 s, liquid - in 1-2 s.

Pathophysiology.

Digestive disorders in the oral cavity, as well as disturbances in the activity of other parts of the gastrointestinal tract, can lead to disorders that are united in the concept of " This is understood as the state of the gastrointestinal tract, when it does not ensure the absorption of food entering the body.. The pathophysiology of the proximal gastrointestinal tract includes disorders of chewing, salivation, swallowing, and esophageal function..

Insufficient grinding of food in the oral cavity is often associated with disorders of the masticatory apparatus.. It includes teeth, chewing muscles, muscles of the tongue and bones of the skull, to which the chewing muscles are attached..

The most common cause of a decrease in chewing ability is dental damage - periodontal disease, etc.. , as well as dentures that reduce chewing pressure between teeth. Chewing is disturbed with inflammation of the chewing muscles, defects in its innervation, injuries of the jaw bones. Inflammatory processes in the oral cavity make chewing difficult, making it painful.

Reduced salivation (hyposalivation) is one of the most common types of digestive disorders in the oral cavity.. Lack of saliva causes dry mouth, making chewing and swallowing difficult.

With a lack of saliva in the oral cavity, microtraumas are easily formed, the epithelium of the mucous membrane and tongue is exfoliated, which is a nutrient medium for microflora. A decrease in the bactericidal ability of saliva during hyposalivation (lack of lysozyme) contributes to the activation of pathogenic microflora, the occurrence of inflammatory processes in tissues.

Hyposalivation often develops secondary to dehydration.. It may be a consequence of the destruction of the tissue of the salivary glands during pathological processes (mumps, tumors). A mechanical obstruction to the flow of saliva occurs when stones form in the salivary ducts..

Central inhibition of the secretion of the salivary glands occurs with strong emotions (fear, excitement), painful stimuli. Some drugs (anticholinergics, psychotropic drugs, Na + uretics, etc.) have an inhibitory effect on the secretory nervous apparatus of the salivary glands.. ), a number of toxic substances, including professional ones.

An increase in salivation (hypersalivation) occurs with direct or reflex stimulation of the salivation center in the medulla oblongata or the secretory nerves of the salivary glands..

Such stimulation is possible with lesions of the central nervous system, inflammatory processes in the mouth and stomach, diseases of the esophagus, nausea and vomiting, helminthic invasions, toxicosis of pregnancy, under the action of some vegetative poisons..

With hypersalivation, up to 5-14 liters of saliva can be secreted per day. If saliva is not completely swallowed, it causes maceration and inflammatory changes in the skin around the lips.. It is also possible for saliva to enter the respiratory tract and become infected with microorganisms contained in the oral cavity.. Prolonged loss of saliva leads to disruption of the functions of the stomach and intestines, metabolism and malnutrition..

The pathophysiology of the act of swallowing can consist of both disorders of the arbitrary phase of swallowing and disorders of the reflex phase.. The first of these components often occurs with language paresis, neuropsychiatric disorders (catatonia, hysterical neurosis, etc.)..

Violations of the reflex phase can be caused by damage to the receptors of the mucous membrane of the oral cavity and pharynx, the center of swallowing in the medulla oblongata, pathology of the motor nerves of the reflex arc of the act of swallowing, spasm of the swallowing muscles.

Difficulty swallowing can cause mechanical obstructions (tumors, scars). Swallowing is disturbed with CNS lesions, where the neurons of the swallowing center are localized, which is located at the bottom of the IV ventricle of the medulla oblongata.

A similar pathology can be observed in diseases such as cerebrovascular disorders, bulbar poliomyelitis, diphtheria, botulism, rabies, etc.. Swallowing is also disturbed with excessive swallowing of air (aerophagia), which leads to an increase in pressure in the stomach. As a result, belching, a feeling of discomfort.

In some cases, aerophagia occurs with a hasty meal, as well as with a number of diseases of the gastrointestinal tract.. Swallowing disorders can be dangerous as saliva and food particles can enter the respiratory tract and cause aspiration pneumonia or even lung gangrene.. Persistent violation of swallowing makes it difficult to eat, leads to starvation and exhaustion of the body.

If the motor function of the esophagus is impaired, the movement of the food bolus along it is difficult. The most common cause of this is a narrowing of the esophagus.. It can develop as a result of scarring of chemical or thermal burns of the esophagus, with its tumors, compression from the outside (aortic aneurysm, mediastinal abscesses, lymph nodes, etc.).. Narrowing of the esophagus leads to impaired swallowing of food and to exhaustion of the body..

Baranovsky.

medbe. en.