Glycogen. What it is? Let's find out!

Glycogen is a complex, complex carbohydrate, which in the process of glycogenesis is formed from glucose entering the human body together with food. From a chemical point of view, it is defined by the formula C6H10O5 and is a colloidal polysaccharide having a highly branched chain of glucose residues. In this article, we will tell you all about glycogen: what is it, what are their functions, where they are stored. We will also describe what are the deviations in the process of their synthesis.

Glycogen: what is it and how are they synthesized?

Glycogen is a necessary body of glucose reserve. In the human body, it is synthesized as follows. During the meal, carbohydrates (including starch and disaccharides - lactose, maltose and sucrose) under the action of the enzyme (amylase) break down into small molecules. Then in the small intestine such enzymes as sugarase, pancreatic amylase and maltase carry out the hydrolysis of carbohydrate residues to monosaccharides, including glucose. One part of the released glucose, entering the bloodstream, is sent to the liver, and the other is transported to the cells of other organs. Directly in the cells, including in the muscle, there is a subsequent disintegration of glucose monosaccharide, which is called glycolysis. In the process of glycolysis occurring with or without participation (aerobic and anaerobic) oxygen, ATP molecules are synthesized, which are the source of energy in all living organisms. But not all glucose, ingested with food in the human body, is spent on the synthesis of ATP. Part of it is stored in the form of glycogen. The process of glycogenesis involves polymerization, that is, sequential addition of glucose monomers to each other and the formation of a polysaccharide branched chain under the influence of special enzymes.

Where is glycogen?

The resulting glycogen is stored as special granules in the cytoplasm (cytosol) of many cells in the body. The content of glycogen in the liver and muscle tissue is especially high. Moreover, muscle glycogen is a source of glucose for the muscle cell itself (in case of a heavy load), and the hepatic glycogen maintains a normal concentration of glucose in the blood. Also, a stock of these complex carbohydrates is found in nerve cells, heart cells, aorta, epithelial cover, connective tissue, uterine mucosa and embryonic tissues. So, we considered what is meant by the term "glycogen". What is it is now clear. Next, let's talk about their functions.

What are the glycogen essential for the body?

In the body, glycogen serves as an energy reserve. In case of acute need, the body can get from it the missing glucose. How does this happen? The decomposition of glycogen occurs during periods between meals, and is also significantly accelerated during serious physical work. This process occurs by cleavage of glucose residues under the influence of specific enzymes. As a result, glycogen decomposes to free glucose and glucose-6-phosphate without the cost of ATP.

What is the use of glycogen in the liver?

The liver is one of the most important internal organs of the human body. It performs many different vital functions. Including provides a normal level of sugar in the blood, necessary for the functioning of the brain. The main mechanisms by which to maintain glucose in the normal range - from 80 to 120 mg / dL, are lipogenesis followed by the breakdown of glycogen, gluconeogenesis and the transformation of other sugars into glucose. When the blood sugar level drops, activation of phosphorylase occurs, and then the liver glycogen cleaves. From the cytoplasm of cells, its clusters disappear, and glucose enters the blood, giving the body the necessary energy. With an increase in the level of sugar, for example after eating, liver cells begin to actively synthesize glycogen and deposit it. Gluconeogenesis is a process of glucose synthesis by the liver from other substances, including amino acids. Regulatory function of the liver makes it critically necessary for the normal functioning of the body. Deviations - significant increases / decreases in blood glucose - pose a serious threat to human health.

Impaired synthesis of glycogen

Disorders of glycogen exchange are a group of hereditary glycogen diseases. Their causes are various defects of enzymes directly involved in the regulation of the processes of formation or cleavage of glycogen. Among the glycogen diseases are glycogenoses and aglycogenoses. The first are rare hereditary pathologies due to excessive accumulation of the polysaccharide C6H10O5 in cells. Synthesis of glycogen and its subsequent excess in the liver, lungs, kidneys, skeletal and cardiac muscles are caused by defects in enzymes (for example, glucose-6-phosphatase) involved in the breakdown of glycogen. Most often, with glycogenosis, there are violations of organ development, delay in psychomotor development, severe hypoglycemic conditions, up to coma. To confirm the diagnosis and determine the type of glycogenosis, a liver and muscle biopsy is performed , after which the material is sent for histochemical examination. In the course of it, the content of glycogen in tissues is established, as well as the activity of enzymes that promote its synthesis and disintegration.

If the body lacks glycogen, what does it mean?

Aglykogenozy represent a serious hereditary disease, caused by the lack of an enzyme that is able to carry out the synthesis of glycogen (glycogen synthetase). In the presence of this pathology, the liver completely lacks glycogen. Clinical manifestations of the disease are as follows: an extremely low level of glucose in the blood, resulting in permanent hypoglycemic convulsions. The condition of patients is defined as extremely difficult. The presence of aglycogenosis is examined by performing a liver biopsy.