Digestive glands: structure and functions. Stomach glands, their types and functions Why, along with digestive enzymes

Which animal has salivary glands? What type of muscle tissue are the walls of the stomach made of? What are its features?

Salivary glands appear for the first time in amphibians.

The walls of the stomach are formed by smooth muscle tissue, which contains thin threads that are capable of slow contraction.

1. Name the functions of saliva.

Saliva moistens food, which makes it easier for it to pass further, in addition, saliva contains digestive enzymes and substances that kill microbes.

2. Why does starch break down under the influence of saliva to form sugar?

It is affected by enzymes contained in saliva.

3. What functions do the tongue, epiglottis and uvula perform during swallowing?

The tongue performs the function of mixing food, determining taste; The epiglottis prevents food from entering the trachea when swallowing, blocking it; the tongue does the same, but blocks the access of food to the nasopharynx.

4. Try to make swallowing movements several times in a row. Why can this be done no more than two to four times?

The saliva that we swallow is gastric juice. When swallowing movements are made in a row, saliva is not deposited in the oral cavity, so there is nothing to swallow.

5. Explain the results of the experiment with a starched bandage on which letters were written with saliva. Why did a white letter appear on a blue background after treatment with iodine water?

Since starch, under the action of enzymes contained in saliva, has turned into glucose.

6. What layers does the stomach wall consist of and what function do they perform?

The cells of the inner layer of the stomach walls secrete gastric juice, which contains mucus, hydrochloric acid and enzymes that digest food. Hydrochloric acid kills harmful microorganisms and promotes the digestion process. Under the action of the gastric juice enzyme (pepsin), protein molecules break down into simpler compounds. The inner wall of the stomach has numerous folds that increase the surface of the mucosa that secretes gastric juice.

The middle layer of the stomach wall is formed by smooth muscle tissue. By contracting and relaxing, the muscles mix its contents with gastric juice. This promotes better digestion of food.

The outer layer consists of the peritoneum - outgrowths of the inner wall of the abdominal cavity that cover the stomach and fix its position.

The food is in the stomach from 3 to 6 hours. It turns into a semi-liquid mush, which gradually, in portions, enters the intestines.

7. Why, along with digestive enzymes, do the stomach glands secrete hydrochloric acid?

Since pepsin acts only in an acidic environment.

8. What experience can be used to prove that gastric juice digests proteins only in an acidic environment?

Gastric juice itself has an acidic pH. If you bring the pH to neutral or alkaline, that is, more than 6, protein digestion will stop.

Choose one correct answer A1. Ribosomes are cell organelles responsible for: 1) breakdown of organic substances 2) protein synthesis 3) ATP synthesis 4) photosynthesis A2. The Golgi apparatus is responsible for: 1) transport of substances throughout the cell 2) rearrangement of molecules 3) formation of lysosomes 4) all answers are correct A3. Tissue lining internal organs 1 connective 2 epithelial 3 nervous 4 muscular A4. Which blood group can be transfused to all people: 1) 0 (I) 2) A(II) 3) B(III) 4) AB(IV)A5. Disinfection of substances occurs in: 1) lungs 2) in all cells of the body 3) blood 4) liver A6. The pancreas secretes 1) adrenaline 2) thyroxine; 3) growth hormone 4) insulin.A7. In the temporal lobe of the cerebral cortex there is 1) the motor zone; 2) auditory zone; 3) zone of olfactory sensitivity 4) visual zone A8. What is lymph formed from? 1) from arterial blood 2) from tissue fluid absorbed into the lymphatic capillary. 3) from blood plasma released from a blood vessel; 4) from venous blood; A9. What substance contained in the blood can carry oxygen? 1) glucose; 2) adrenaline; 3) hemoglobin; 4) insulin.A10. The medulla oblongata is located between 1. the spinal cord and the diencephalon 2. The spinal cord and the pons 3. The diencephalon and midbrain 4. the diencephalon and hemisphere A11. Gas exchange in the lungs occurs 1) in arterioles; 2) in the arteries; 3) in capillaries; 4) in the veins. A12. When you inhale, air from the larynx enters 1) the lungs; 2) nasopharynx; 3) bronchi; 4) trachea.A13. In which part of the digestive tract is hydrochloric acid released? 1) in the small intestine; 2) in the esophagus; 3) in the large intestine; 4) in the stomach. A14. The thoracic cavity contains 1) the spinal cord; 2) lungs; 3) stomach; 4) kidneys.A15. The blood clotting factor is protein 1) pepsin, 2) hemoglobin 3) fibrinogen 4) trypsin A16. Scurvy develops with a lack of vitamin1) D; 2) B12 3) C; 4) AA17. The conditional beginning of the pulmonary circulation is considered to be 1) right ventricle 2) left ventricle 3) right atrium 4) left atrium A18. Auditory receptors are located 1) in the semicircular canals 2) in the cochlea 3) in the auditory ossicles 4) auditory nerve A19. Sympathetic nervous system1 ) increases blood pressure 2) activates the digestive tract 3) increases breathing 4) increases heart rate A20. Immunity caused after an illness is called 1) natural innate 2) Artificial active 3) Artificial passive 4) Natural acquiredII B1. Choose three correct answers. Signs of nervous tissue include A. tissue is formed by cells that have a body and processesB. cells are capable of contracting. There are contacts between cells called synapses. cells are characterized by excitability D. There is a lot of intercellular substance between cells B2. Indicate the sequence of location of the brain sections (starting with the spinal cord):
A. diencephalon D. pons
B. midbrain D. cerebral cortex
B. Medulla oblongata

The endocrine glands secrete:

A) vitamins B) hormones

C) digestive juices D) sweat and sebum
The endocrine system includes:

A) sweat glands B) salivary glands

C) sebaceous glands D) adrenal glands
Thyroid dysfunction may be due to dietary deficiencies

A) iodine B) chlorine C) vitamin A D) carbohydrates

Increased body temperature, thinness, “bulging” eyes and increased excitability may be signs of a disorder
A) liver B) thyroid gland

C) pancreas D) sweat glands

The pancreas is considered a mixed secretion gland, because.

A) secretes digestive juice and the hormone insulin

B) produces digestive enzymes

C) contains different tissues

D) its work is regulated by the nervous and humoral pathways

A person suffering from diabetes needs to regularly
A) take vitamins B) inject insulin

B) take a walk in the fresh air

D) do physical exercise

The main adrenal hormone is

A) vitamin D B) insulin C) growth hormone D) adrenaline.

In a person who is late for an important event, secretion increases

A) digestive juices B) insulin

C) adrenaline D) growth hormone

Growth hormone is released

A) pancreas B) thyroid gland

C) liver D) pituitary gland

The hypothalamus is an area

A) medulla oblongata B) cerebellum

B) thyroid gland D) cerebral cortex

The stomach is the most important human organ. It is necessary to prepare incoming food for further absorption in the intestines. This work is impossible without a large number of digestive enzymes that are produced by the stomach glands.

The inner shell of the organ has a rough appearance in appearance, because on its surface there is a huge number of glands designed to produce various chemical compounds that make up the digestive juice. Outwardly, they resemble long narrow cylinders with an extension at the end. Inside them there are secretory cells, and through the enlarged excretory duct, the substances they produce necessary for the digestive process are delivered to the stomach cavity.

Features of digestion in the stomach

The stomach is a cavity organ, an expanded part of the digestive canal, into which food products are periodically delivered at irregular intervals, each time with a different composition, consistency and volume.

The process of processing incoming food begins with the oral cavity, here it undergoes mechanical grinding, then moves further along the esophagus, enters the stomach, where it undergoes further preparation for absorption by the body under the influence of acid and enzymes of gastric juice. The food mass acquires a liquid or porridge-like state and, mixed with the components of gastric juice, smoothly enters the small and then large intestine to complete the digestion process.

Briefly about the structure of the stomach

Average stomach size for an adult:

• length 16-18 cm;
• width 12-15 cm;
• wall thickness approximately 3 cm;
• capacity about 3 liters.

The structure of the organ is conventionally divided into 4 sections:

1. Cardiac - located in the upper sections, closer to the esophagus.
2. The body is the main part of the organ, the most voluminous.
3. The bottom is the lower part.
4. Pyloric - located at the outlet, closer to the duodenum.

The mucous membrane is covered over the entire surface by glands; they synthesize important components for the digestion and assimilation of consumed food:

• hydrochloric acid;
• pepsin;
• mucus;
• gastrin and other enzymes.

Most of them enter the lumen of the organ through the excretory ducts and are components of the digestive juice; others are absorbed into the blood and participate in the general metabolic processes of the body.

Types of gastric glands

The glands of the stomach differ in location, the nature of the secretion produced and the method of its secretion.

Exocrine

Digestive secretions are released directly into the lumen of the organ cavity. Named according to their location:

• cardiac,
• own
• pyloric.

Own

This type of gland is very numerous - up to 35 million; they are also called fundic bodies. They are located mainly in the body and fundus of the stomach and produce all the components of gastric juice, including pepsin, the main enzyme of the digestive process.

The gastric glands are divided into 3 types:

• the main ones are large in size, combined into large groups; needed for the synthesis of digestive enzymes;
• mucous membranes are small in size and produce protective mucus;
• Parietal cells of the stomach are large, single, and produce hydrochloric acid.

Parietal (parietal) cells occupy the outer part of the main or fundal bodies located on the bottom and body of the organ. Outwardly they look like pyramids with bases. Their function is the production of hydrochloric acid and internal Castle factor. The total number of parietal cells in the body of one person approaches a billion. The synthesis of hydrochloric acid is a very complex biochemical process, without which food digestion is impossible.

Parietal cells also synthesize the most important component - a glycoprotein that promotes the absorption of vitamin B12 in the ileum, without which erythroblasts cannot reach mature forms, and the normal process of hematopoiesis suffers.

Pyloric

They are concentrated closer to the transition of the stomach into the duodenum, have a smaller number - up to 3.5 million, and have a branched appearance with several wide end exits.

The pyloric glands of the stomach are divided into 2 types:

• Endogenous. This type of gland is not involved in the process of producing digestive juices. They produce substances that are absorbed directly into the blood to participate in the reactions of numerous metabolic processes in the stomach itself and other organs.
• The mucous glands are called mucocytes. They are responsible for the production of mucus, to protect the mucous membrane from the destructive effects of digestive juices, rich in aggressive components - hydrochloric acid and pepsin, and to soften the food mass, in order to facilitate its sliding into the intestines.

Cardiac

Located in the initial part of the stomach, close to the junction with the esophagus. Their number is relatively small - about 1.5 million. In appearance and secreted secretions, the glands are similar to the pyloric glands. There are only 2 types:

• Endogenous.
• Mucous membranes, the main task of which is to soften the food bolus as much as possible and prepare it for the digestion process.

The cardiac glands, like the pyloric glands, do not participate in the digestion process.

Scheme of the glands

The startup of the glands can be schematically represented as follows.

1. The smell, appearance and irritation of food receptors in the oral cavity give a signal to the beginning of the production of gastric secretions and preparation of the organ for food processing.
2. In the cardiac section, the production of mucus begins, which protects the mucous membrane from self-digestion and softens the food mass, which makes it more accessible for further stages of processing.
3. Own (fundic) bodies begin to produce digestive enzymes and hydrochloric acid. The acid, in turn, transforms foods into a semi-liquid state and disinfects them, and enzymes begin to chemically break down proteins, fats and carbohydrates to the molecular level, preparing them for further absorption in the intestines.

The most active production of all components of digestive juice (hydrochloric acid, enzymes and mucus) occurs at the initial stage of food intake, reaches a maximum in the second hour of the digestive process and persists until the food mass passes into the intestines. After the stomach is emptied of food mass, digestive juices stop being produced.

Endocrine glands

The gastric glands described above are exocrine, that is, the secretion they produce enters the stomach cavity. But among the digestive glands there is also a group of endocrine glands, which do not take part in the process of digesting food, and the substances produced by them enter, bypassing the gastrointestinal tract, directly into the blood or lymph and are needed to stimulate or inhibit the functions of various organs and systems.

Endocrine glands produce:

• Gastrin is needed to stimulate the activity of the stomach.
• Somatostatin slows it down.
• Melatonin – controls the daily cycle of the digestive tract.
• Histamine – starts the process of accumulation of hydrochloric acid and regulates the function of the vascular system of the gastrointestinal tract.
• Enkephalin – has an analgesic effect.
• Vasointerstitial peptide - has a dual effect: dilates blood vessels and also activates the activity of the pancreas.
• Bombesin - stimulates the production of hydrochloric acid, controls the function of the gallbladder.

Correct and efficient functioning of the gastric glands is very important for the functioning of the entire human body. For their coordinated work you need little - just follow the rules of a healthy diet.

The stomach is a muscular organ, a kind of temporary reservoir for storing and processing food.

The stomach is the widest part of the digestive canal. It is located under the diaphragm on the left side of the abdomen. The shape and size of the stomach changes depending on the volume of food taken. The stomach of an adult can hold up to 3 liters of food.

FUNCTIONS OF THE STOMACH

The stomach has powerful muscular walls that contract, crush and soften food, preparing it for processing in the intestines. In general, the stomach performs the functions of accumulation, mechanical and chemical processing, and evacuation of food into the intestines.

STRUCTURE OF THE STOMACH

Actually myself The stomach is a muscular organ.

Glands - some of which secrete mucus, which protects the walls of the stomach from gastric juice, others secrete hydrochloric acid, and still others secrete enzymes.

In addition to enzymes, mucus and hydrochloric acid, gastric juice contains a number of organic and inorganic substances.

In the middle layer of the stomach wall there is muscle membrane, consisting of smooth muscles, the contraction of which helps to mix food and soak it with gastric juice.

TO circular muscle - sphincter, located on the border between the stomach and duodenum, which periodically opens and allows semi-digested food into the duodenum.

DIGESTION PROCESS

From the pharynx, the food bolus formed in the oral cavity enters the esophagus. The mouth of the esophagus is equipped with circular muscles that prevent the reverse movement of food from the stomach into the esophagus. Food enters the stomach crushed and soaked in saliva.

From the outer surface of the food bolus is exposed to the action of gastric juice, and inside it the action of saliva continues. Gradually, the food bolus disintegrates and turns into mush, which is processed by gastric juice.

Glands. The gastric mucosa contains many glands. Some of them secrete mucus, which protects the walls of the stomach from the action of gastric juice and irritating food substances on them, others secrete hydrochloric acid.

The glands of the stomach secrete gastric juice, which processes food. There are glands that secrete the enzyme pepsin, which breaks down proteins. Hydrochloric acid not only creates the necessary environment for the enzyme to work, but also destroys many harmful microorganisms that have entered with food.

In the middle layer of the stomach wall there is a muscular layer consisting of smooth muscles, the contraction of which helps to better mix food and soak it with gastric juice. Gradually, the muscles push the food pulp towards the duodenum. At the border between the stomach and duodenum there is a circular muscle - the sphincter. Periodically, it opens and allows semi-digested food into the duodenum.

The secretory activity of the stomach is greatly influenced by a person’s emotional mood. If you get a little nervous, your stomach will immediately react with heartburn or, conversely, indigestion.

Gastric juice- an integral part of the stomach. Gastric juice is a digestive juice produced by the glands of the gastric mucosa; is a colorless transparent liquid with a sour taste.

The cells of the stomach glands are divided into main, facing And additional; each group produces certain components of the juice. The main cells form enzymes with the help of which food substances are broken down: pepsin, which breaks down proteins; lipase, which breaks down fat, etc. Parietal cells produce hydrochloric acid, which has a special and extremely important role in digestion: it softens the food bolus and activates enzymes.

Gastric juice kills microorganisms, enhances the production of enzymes by the pancreas, and promotes the formation of digestive hormones. Its concentration in human gastric juice is 0.4-0.5%.

The acidity of gastric juice depends on the content of hydrochloric acid, on the rate of juice secretion, on the neutralizing effect of gastric mucus, and changes with diseases of the digestive system.

The mucus secreted by accessory cells gives gastric juice viscosity; mucus has an alkaline reaction, neutralizes hydrochloric acid, reduces the acidity of juice, protects the mucous membrane from irritation and is involved in the digestion of food.

In addition to enzymes, mucus and hydrochloric acid, gastric juice contains a number of organic and inorganic substances. It also contains a special substance (the so-called Castle factor), which ensures the absorption of vitamin B 12, necessary for the normal maturation of erythrocytes (red blood cells) in the bone marrow.

The digestive ability of gastric juice secreted during different periods of secretion, as well as in different parts of the stomach, is not the same. Research by I.P. Pavlov has established that secretion is not continuous: under normal conditions outside of digestion, gastric juice is not released into the stomach cavity.

This occurs only under the influence of a food irritant - not only when food enters the mouth or stomach, but often from its smell, sight, and even when talking about food. An unpleasant smell or sight of food can, on the contrary, reduce or completely stop the secretion of gastric juice.

In case of diseases of the stomach, intestines, liver, gallbladder, etc., the amount of gastric juice and its composition can change until the secretion and enzymes completely stop (achilya). The amount and composition of gastric juice can change when a person is under emotional stress.

DISEASES OF THE STOMACH

The most common stomach diseases are gastritis (inflammation of the gastric mucosa), and when the inflammation spreads to the duodenum, another organ of the gastrointestinal tract, this is called gastroduodenitis.

The main and one of the main signs of problems in the stomach is a white or yellow coating on the tongue. Normally, the tongue should be bright pink with no signs of plaque. And if you are often accompanied by symptoms such as: heartburn, unpleasant taste in the mouth, bad breath (not due to diseased tonsils, caries, etc.), constant fatigue, poor appetite, a feeling of heaviness in the stomach after eating, This means it’s time to take your health seriously.

If a person has eaten poor quality food, a gag reflex may occur and the contents of the stomach are thrown out.

OUR STOMACH LOVES:

1) Frequent small meals 5-6 times a day, in small portions, otherwise, you can stretch the stomach to large sizes, resulting in a constant feeling of hunger. This is one of the main principles of healthy eating.

2) Warm food(the food eaten should not be too hot or cold).

3) Thoroughly chewed food will not irritate the stomach, and it will also contribute to the sufficient secretion of digestive juices.

OUR STOMACH DOESN'T LIKE:

1) Irregular diet(1-2 times a day).

2) Dry food(burgers, hot dogs, chips, crackers, etc.).

3) Very hot food or very cold food.

4) Very spicy or fatty foods(mustard, pepper, vinegar, onion - in large quantities irritate the esophagus and stomach).

5) Stress, It can cause not only heartburn but also indigestion.

6) Alcohol

7) Smoking

8) Antibiotics(taking antibiotics disrupts the microflora of the stomach)

9) Bacteria “Helicobacter pylori”, which damage the gastric mucosa and cause gastritis (found in 90% of patients).

10) Infections(Intestinal infections and chronic ones - oral cavity and pharynx (caries and inflammation of the tonsils).

11) Diseases gallbladder, liver, pancreas, since all these organs are interconnected and have a direct impact on each other.