Incisors and canines have simple single roots; they bite food.

Posted by on Juil 7, 2020 in Blog | Commentaires fermés sur Incisors and canines have simple single roots; they bite food.

Incisors and canines have simple single roots; they bite food.

The main nutrients that come with food are: proteins, fats and carbohydrates. In addition, vitamins, organic acids, including nucleic acids, minerals and others that are not a source of energy play an important role in human nutrition. But without which the assimilation of substances in the body is not possible.

Foods in the human diet are diverse and are divided into animal and plant.

Animal products are a source of plastic (due to proteins) and energy (due to fats) substances. These include: meat and meat products, fish and fish products. Milk and dairy products, eggs. The most important component of these products are proteins (3-20% 0, which contain essential amino acids. Digestibility of animal proteins – 96%.

Animal fats enter the body mainly in the form of cream, butter. Lard, fatty poultry, fish.

Plant foods are a source of energy from carbohydrates. These products are represented by cereals, legumes: cereals, flour, bread; vegetables, fruits and berries.

Vegetables, fruits personal narrative topics for middle school, berries and their juices are a source of biologically active substances – vitamins, enzymes, trace elements (iron, copper, iodine, cobalt).

These products contain fiber, pectin and others, carbohydrates, organic acids.

A refrigerator is needed to store perishable food. Storage areas for meat, fish and dairy products must be separated.

According to the accepted sanitary rules, perishable products should be stored in refrigerators at t – 0 -8˚С.

Product shelf life:

boiled sausages – 48 hours, milk – 20, kefir – 24, cheese – 36, sour cream – 72, butter 10 days, eggs – 20, frozen fish – 3, frozen meat – 5. half-smoked sausages – 10 days.

Saliva has bactericidal properties and prevents tooth decay, quickly heals damaged mucous membranes, thanks to the enzyme lysozyme contained in it. For a day of saliva a person secretes 1-1.5 liters.

Saliva is released reflexively. Food irritates the receptors of the tongue and mucous membranes. Nerve impulses from receptors on sensitive nerve fibers come to the medulla oblongata, where the center of salivation is located. From it on motor nerve fibers nerve impulses arrive to salivary glands and stimulate salivation. This is definitely a reflex salivation.

Saliva can also be secreted when a person sees food, smells it or even thinks about it. This is a conditioned reflex salivation.

Structure and functions of teeth

Teeth (dentes) are located in the oral cavity and are designed to bite, hold and chew food, as well as participate in the formation of certain sounds of speech.

The baby is born without teeth (bookmark in the womb), the first baby appear from 6 months, and by 10-12 years they are replaced by permanent ones. The last pair of teeth (wisdom teeth) appear before the age of 25. An adult has 32 teeth, in shape and function there are incisors, canines, small and large canines. In front of each jaw there are 4 flat incisors, next to them there is one canine. Incisors and canines have simple single roots; they bite food.

Then on each side there are two small and three large canines that grind food. The canines have roots with several processes.

In each tooth there is a crown, neck and root. The roots of the teeth are fixed in the pits of the alveolar processes of the jaws. The necks of the teeth cover the gums, and only the crowns protrude into the oral cavity.

Externally, the crown is covered with enamel – the hardest substance in the human body (97% – mineral salts: Ca, P, F), which protects the tooth from destruction and penetration of infection. It contains the main substance of the tooth – dentin (72% mineral salts, 28% organic matter and water), which also fills the neck and root of the tooth and is similar in strength to bone tissue. At the root, dentin is covered with a substance similar to enamel – cement. In the center of the tooth is a cavity that contains soft tissue – pulp, which houses blood vessels (arteries, veins) and sensitive nerves.

The role of language in mixing food and perception of its taste

The tongue (lingua) is a muscular organ covered with a mucous membrane with receptors located in it, which control the processes of filling the mouth with food, swallowing, perception of food taste. The tongue is involved in the processes of chewing food, swallowing, as well as in the articulation of various sounds, ie in the articulatory language.

Swallowing food, the mechanism of its implementation. Structure and functions of the esophagus

Chewed food, soaked in saliva, with the help of coordinated movements of the cheeks and tongue moves to the root of the tongue, where it irritates the receptors of the mucous membrane of the throat and soft palate. Nerve impulses are transmitted to the swallowing center, which is located in the medulla oblongata. Centrifugal impulses enter the muscles of the pharynx, tongue, and respiratory system.

The act of swallowing is performed in the following sequence: the soft palate rises and closes the nasal part of the pharynx, the epiglottis lowers and closes the entrance to the airways, breathing stops and food is pushed into the pharynx by the root of the tongue … (pharynx) and then into the esophagus

The esophagus is a narrow (2 cm in diameter) tube 25-30 cm long that connects the pharynx to the stomach. It consists of the cervical, thoracic and abdominal parts and has four membranes: mucous, submucosal, muscular and external connective tissue. The submucosa and muscles form folds to stretch when the food lump passes. The muscular membrane of the upper third of the esophagus is formed by striated muscle tissue. In the middle third of the body, smooth muscle cells attach to these muscle fibers. The muscular membrane of the lower third of the esophagus is formed by smooth muscle tissue.

Food moves through the esophagus through peristaltic movements.

The structure of the stomach, digestion in it and neuro-humoral regulation of its activity.

The composition of gastric juice, its role in the digestive process

The stomach (gaster) is an enlarged part of the digestive tract. The shape of the stomach has an individual feature and depends on the position of the body and the filling of the stomach with food (crescent-shaped). It is located in the upper part of the abdominal cavity under the diaphragm. In the stomach there are small and large curvature, as well as the inlet, bottom, body and portal (outlet or pyloric).

The pyloric part is the place where the stomach passes into the duodenum, where the ring-shaped muscles that form the clamp (pyloric sphincter) are located.

The walls of the stomach consist of four layers:

inner – mucous membrane – produces gastric juice. submucosa – allows the mucosa to gather in folds, and the stomach itself – to stretch and increase in volume; muscular membrane – consists of three layers of unstriated muscles that have a longitudinal, oblique and circular direction, due to which the stomach can perform complex movements; outer – connective tissue membrane, is part of the peritoneum.

The capacity of the stomach in an adult is 3 liters, but can increase to 5-10 liters. There are three types of glands in the mucous membrane: main, lining, additional. The main ones are digestive enzymes, the covering ones are hydrochloric acid, and the additional ones are mucus. A mixture of all these secretions forms gastric juice. In a day at the person it is formed 1,5-2 l.

I. Enzymes of gastric juice:

pepsinogens – inactive enzymes that under the action of hydrochloric acid are converted into pepsin, which breaks down complex proteins into simpler and amino acids. gastric lipase – not important in adults, slightly more active in children – affects naturally emulsified fats (milk). gelatinase breaks down the gelatin protein contained in the connective tissue of animal products. chymosin – together with pepsin acts on milk proteins (ruffles).

II. Hydrochloric acid – causes swelling and denaturation of proteins; what facilitates further disintegration; activates pepsinogens, forms the acidic environment of gastric juice necessary for action of pepsin; antibacterial effect; stimulates the movement of the stomach. In adults, hydrochloric acid causes milk to coagulate because they have almost no chymosin.

III. The mucus has an alkaline reaction and partially neutralizes hydrochloric acid. Helps the food lump to move to the small intestine, protects the stomach wall from self-digestion under the action of hydrochloric acid and gastric enzymes.

IV. Gastric juice also contains the hormone gastrin, which regulates the secretory and motor functions of the stomach, and vitamin B12, which prevents anemia.

Regulation of gastric juicing

Gastric juice is secreted during the day, but eating significantly increases its secretion. The secretion of gastric juice, in quantitative and qualitative terms, is subtly adapted to the nature of food.

Adaptation of gastric juice secretion to the nature of food is achieved through nervous and humoral regulation.

The phases of regulation have three types of gastric secretion:

cerebral, gastric, intestinal.

Methods of research of digestive processes

The foundations of modern physiology of digestion were laid by the research of the eminent Russian physiologist Pavlov. He developed fundamentally new methodological approaches that revealed the patterns of salivation, secretion of gastric juice and bile; to collect pure, not mixed with food digestive juices, to define their structure, to study regulation of digestion in natural conditions. For these works Pavlov in 1908 was awarded the Nobel Prize. He did his experiments on dogs. Pavlov developed the method of fistulas.

A fistula is a combination of the cavity of any organ with the external environment.

Currently using new modern research methods:

a well-known method of probing (introduction into the stomach or duodenum of a rubber probe to take juices, which are then examined in biochemical laboratories); endoscopy method – the introduction of a flexible plastic tube with lighting devices into the digestive tract, which allows a directly examined cavity of the digestive tract. Small pieces of mucous membrane are taken through the tube with a special manipulator for cytological examination; electrogastrography – registration of electric currents of the stomach – allows to determine its motor activity; X-ray examination makes it possible to detect tumors of the digestive tract, ulcers of the stomach and duodenum, intestinal obstruction, tumors of the colon.

To study the condition of the large intestine (worms, bleeding, microorganisms) used methods of fecal examination.