Violations of the synthesis and breakdown of glycogen

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In body tissues, glucose can enter cells both from food exogenous and endogenously formed from a deposited glycogen (glycogenolysis as a result), or other substrates such as lactate, glycerol, amino acids (resulting in gluconeogenesis). Sucked into glucose enters the small intestine via the portal vein to the liver and into the hepatocytes. For glucose transport in cells respond transport proteins - GluT, which are able to transfer glucose through the membrane against a concentration gradient and enhance passive transport. In cells, glucose is phosphorylated in the hexokinase reaction, turning into glucose 6-phosphate (G-6-P), G-6-P is a substrate for multiple pathways: this molecule begins glycogen synthesis, the pentose phosphate cycle, the glycolytic breakdown to lactate or aerobic total degradation to CO2 and H2O. In cells capable of gluconeogenesis (liver cells, kidney, intestinal), G-6-P and may be dephosphorylated as the free glucose in the blood flow and transported to other organs and tissues.

Especially important is the glucose to the brain cells.

Cells of the nervous system depends on glucose as the main energy of the substrate "At the same time, the brain glucose have stocks, there is not synthesized, neurons can not consume power other substrates besides glucose and ketone bodies.

Glycogen. From G-6-P as a result of the combined action of glycogen and "branching" enzyme synthesized glycogen - a polymer-like in appearance wood. In the molecule of glycogen can contain up to a million of monosaccharides. Thus there is a sort of crystallization of glycogen, and it does not have an osmotic effect. This form is suitable for storage in the cell. If this amount of glucose molecules have been dissolved, then due to osmotic forces would blow the cage. Glycogen is a form of glucose deposited. It is found in almost all tissues; cells of the nervous system in its minimum quantity, and in the liver and muscles it particularly much. Glycogen contains only two types of glycosidic bonds: and (1 → 4) -type and a (1 → 6) -type. Communication and (1 → 4) -type is formed every 8-10 residues of D-glucose.

Glycogenolysis. It is a way of splitting of glycogen. Glycogen in the body mainly retained by the liver and skeletal muscle. Muscle glycogen is used as an energy source during intense exertion. Hepatic glycogenolysis activated in response to a decrease in the concentration of glucose in the meal intervals or in response to stress factors. The main hormones activating glycogenolysis are glucagon, adrenaline (epinephrine) and cortisol.

Reduced glycogen synthesis. Reduced synthesis of hepatocytes occurs in lesions (hepatitis, phosphorous poisoning, carbon tetrachloride, etc.) Of hypoxia when oxygen deficit inevitably leads to a significant decrease in efficiency of ATP necessary for the synthetic processes; lowering the tone of the parasympathetic nervous system; hypovitaminosis B1 and C; endocrine diseases - diabetes, thyrotoxicosis, adrenal insufficiency (Addison's disease).

Increased glycogen breakdown. Hepatic glycogenolysis Amplification occurs during excitation of the central nervous system. Nerve impulses are conducted of the sympathetic nervous system to the depot of glycogen and activate the process of decay, providing a flow of glucose into the bloodstream. Increased glycogenolysis is also observed with an increase in hormone production - glycogenolysis stimulants (adrenaline, glucagon, growth hormone and thyroxine) and intense muscular work, which is due to an increase in muscle glucose uptake. In addition, the breakdown of glycogen increases in shock, fever, emotional stress.

When failure of glycogen (due to decreased synthesis or decreasing its degradation) Energy fabric proceeds for use as substrates for oxidation of fats and proteins. The result is excessive formation of ketone bodies and develops intoxication. Using cell proteins as an energy source causes enzymatic disorders and various plastic processes.