Functions of the stomach and structure

Nutrition is the process necessary to ensure the vital activity of the human body. Stomach in this process plays a major role. Functions of the stomach consist in the accumulation of the food mass, its partial processing and further progression to the intestine, where nutrient absorption takes place. All these processes occur in the gastrointestinal tract.

Stomach: structure and function

It is a muscular hollow organ of the digestive system, which is located between the esophagus and the duodenum.

Next, we will find out what function the stomach does and analyze its structure.

It consists of the following conditional departments:

1. The cardiac (entrance) part. Its projection is at level 7 of the rib on the left.
2. A vault or a bottom, the projection of which is located on the left at the level of the 5th rib, more precisely, its cartilage.
3. Bodies of the stomach.
4. Doorkeeper or pyloric department. At the exit from the stomach is located the sphincter of the gatekeeper, which separates the stomach from the duodenum. The projection of the gatekeeper is in front of the 8th rib to the right of the middle line and behind the 12th thoracic and 1st lumbar vertebra.

The shape of this organ looks like a hook. This is especially noticeable on X-ray images. The stomach has a small curvature, which is turned towards the liver, and large, facing the spleen.

The body wall consists of four layers, one of which is external, it is a serous membrane. The other three layers are internal:

1. Muscular.
2. Submucous.
3. Slimy.

Due to the rigid muscular layer and the submucosal lying on it, the mucosa has numerous folds. In the region of the body and bottom of the stomach these folds have oblique, longitudinal and transverse direction, and in the region of low curvature - only longitudinal. Due to this structure, the surface of the gastric mucosa is significantly increased. This makes it easier to digest the food lump.

Functions

What is the function of the stomach? A lot of them. We list the main ones.

• Motor.
• Secretory.
• Suction.
• Excretory.
• Protective.
• Endocrine.

Each of these functions plays an important role in the process of digestion. Next, the functions of the stomach will be discussed in more detail. It is known that the process of digestion begins even in the mouth, from there food through the esophagus enters the stomach.

Motor function

In the stomach there is further digestion of food. Motor function of the stomach consists in the accumulation of the food mass, its mechanical processing and further progression to the intestine.

During food intake and in the first minutes after that the stomach is relaxed, which contributes to the accumulation of food in it and secures secretion. Then the contractile movements that the muscle layer provides begin. In this case, mixing of the food mass with gastric juice occurs.

The musculature of the organ is characterized by the following types of movements:

• Peristaltic (wavy).
• Systolic - occur in the pyloric department.
• Tonic - contribute to a decrease in the size of the stomach cavity (its bottom and body).

After eating, the peristaltic waves are initially weak. By the end of the first hour after the meal, they are intensified, which helps to move the food lump to the exit from the stomach. Pressure in the gatekeeper's stomach increases. The sphincter of the gatekeeper opens and part of the food mass enters the 12-colon. The remaining bulk of this mass is returned to the pyloric department. Evacuation function of the stomach is inseparable from the motor. They provide grinding and homogenization of the food mass and thus contribute to a better absorption of nutrients in the intestine.

Secretory function. Gastric gland

The secretory function of the stomach is the chemical processing of the food lump with the help of secreted secret. For a day an adult can produce from one to one and a half liters of gastric juice. It includes hydrochloric acid and a number of enzymes: pepsin, lipase and chymosin.

On the entire surface of the mucosa are the glands. They are glands of external secretion, which produce gastric juice. The functions of the stomach are directly related to this secret. The glands are divided into several varieties:

• Cardiac. Are in the field of the cardia near the entrance to this organ. These glands produce a mucoid mucus secret. It performs a protective function and serves to protect the stomach it self-digestion.
• Major or fundal glands. Are in the bottom and body of the stomach. They produce gastric juice containing pepsin. Due to the produced juice, the digestion of the food mass occurs.
• Intermediary glands. Located in a narrow intermediate zone of the stomach between the body and the gatekeeper. These glands produce a viscous mucoid secret that has an alkaline reaction and protects the stomach from the corrosive effects of gastric juice. In its composition, including, includes hydrochloric acid.
• The pilor glands. Are located in the gatekeeper. The secret, produced by them, also plays a protective role from the acidic environment of gastric juice.

The secretory function of the stomach is provided by three types of cells: cardiac, fundus, or major, and pyloric.

Suction function

This activity of the organ, rather, has a secondary role, since the main absorption of the processed nutrients takes place in the intestine, where the food mass is brought to a state in which the body can easily use all substances necessary for life activities that come with food from the outside.

Excretory function

It consists in the fact that some substances come from the lymph and blood into the stomach cavity through its wall, namely:

• Amino acids.
• Proteins.
• Uric acid.
• Urea.
• Electrolytes.

If the concentration in the blood of these substances increases, then their intake into the stomach increases.

Excretory function of the stomach is especially important in fasting. The protein found in the blood can not be used by the cells of the body. They are only able to assimilate the final product of the breakdown of the protein - the amino acid. Getting from the blood into the stomach, the protein is subjected to further processing under the action of enzymes and breaks down into amino acids, which are later utilized by the tissues of the body and its vital organs.

Protective function

This function is provided by the secret that the organ produces. The infected pathogens die from the action of gastric juice on them, more precisely, from the hydrochloric acid in its composition.

In addition, the stomach is designed in such a way that if it gets into poor quality food, it is able to ensure its return and prevent the entry of dangerous substances into the intestines. Thus, this process will prevent poisoning.

Endocrine function

This function is carried out by the endocrine cells of the stomach, which are located in its mucous layer. These cells produce more than 10 hormones, which are able to regulate the work of the stomach and digestive system, as well as the whole body as a whole. These hormones include:

• Gastrin - produced by the G-cells of the stomach. It regulates the acidity of gastric juice, responsible for the synthesis of hydrochloric acid, and also affects the motor function.
• Gastron - inhibits the production of hydrochloric acid.
• Somatostatin - inhibits the synthesis of insulin and glucagon.
• Bombesin - this hormone is synthesized both by the stomach itself and by the proximal part of the small intestine. Under its influence, the release of gastrin is activated. It also affects the contraction of the gallbladder and the enzymatic function of the pancreas.
• Bulbogastron - inhibits the secretory and motor function of the stomach.
• Duocrinin - stimulates the secretion of the duodenum.
• Vasoactive intestinal peptide (VIP). This hormone is synthesized in all parts of the digestive tract. It inhibits the synthesis of pepsin and hydrochloric acid and relaxes the smooth muscles of the gallbladder.

We found out that in the process of digestion and maintenance of vital functions of the body, the stomach plays an important role. The structure and its functions are also indicated.

Functional disorders

Diseases of the gastrointestinal tract, as a rule, involve the violation of any of its structure. Violation of the function of the stomach is observed quite often. About such pathologies can be said only if the patient does not show any organic lesions of this organ during the examination.

Violations of the secretory or motor function of the stomach can occur with pain syndrome and dyspepsia. But with proper treatment, these changes often have a reversible character.