The process of glucose metabolism in the human body, the process of sugar metabolism in the body

Specific breakdown pathways include anaerobic digestion, aerobic oxidation, and pentose phosphate pathways.

The so-called anaerobic digestion, for example, during strenuous exercise, although the heartbeat and breathing are accelerated and the blood circulation is accelerated, it still cannot meet the demand for oxygen from the muscles, so it can only rely on anaerobic digestion to provide energy urgently; People often experience muscle soreness after a long journey or labor, and it is glucose.

The result of anaerobic digestion of the accumulation of long-lived lactic acid.

Aerobic oxidation refers to the complete oxidation of glucose to carbon dioxide under aerobic conditions through a series of chemical changes.

and water, the process of generating energy at the same time. This is the main way in which intracellular sugar catabolism provides energy.

Another intracellular way of using sugar is called the pentose phosphate pathway. This pathway is mainly found in the liver, bone marrow, adipose tissue, lactation.

The breast, gonads, red blood cells and other tissue cells are carried out to produce pentose and participate in the body's metabolism.

When there is an abundant supply of glucose, the cells can take up the glucose and convert it into glycogen.

This process is called glycogen synthesis.

Glycogen synthesis is mainly carried out in liver and muscle cells, and glycogen granules are found in the cytoplasm, and when cells need to consume energy, it is easy to release glycogen into glucose phosphate under the action of related enzymes.

Glucose is the main substance that supplies energy to the body. Just as a car needs gasoline to drive, human activities require energy to sustain. For the cells in the human body, they are taking in nutrients to provide energy almost all the time, never interrupted.

Therefore, it is important to maintain a stable and consistent glucose concentration in the blood.

Extended Information; Glucose and ordinary sugar contain similar compositions, the only difference is that the former is a broken down monosaccharide.

But the effects of both on the human body are the same. Cao Xue, Secretary General of Shanxi Nutrition Association.

said that eating glucose is not as good as eating a variety of starch staple foods directly, because starch is a large molecule formed by a large amount of glucose, and the human body is very good at dismantling this molecule and turning it into a single glucose, "Glucose powder does not contain other nutrients, so eating glucose will not have any 'nourishing' benefits." In fact, glucose is a medicine, which is mostly made into a solution dosage form and used for injection, mainly to help those patients who cannot eat normally to replenish sugar. ”

The starch and sugar contained in various foods can be converted into glucose in the body, and as long as the appetite of infants and young children is normal, there will be no lack of glucose.

Cao Xue said that if glucose is commonly used to replace other sugars, the disaccharidase and digestive enzymes in the intestine will lose their effect, making the gastrointestinal tract lazy, and it will cause low digestive enzyme secretion and digestive function for a long time, affecting the growth and development of infants and young children, only the lack of amylase in the body.

The most abundant sugar in food is starch. The digestion of starch begins in the mouth. Under the action of salivary amylase, the starch in food is converted into starchdextrin, glucose and maltose and other products into the stomach.

This digestion stops quickly after the food enters the stomach, because the salivary amylase is quickly inactive due to the action of stomach acid. The small intestine is the most important part of starch digestion, and under the further digestion of pancreatic amylase, dextrinase and maltase in the intestinal lumen, monosaccharides that can be absorbed by the intestine are finally formed. The monosaccharides absorbed through digestion are mainly glucose.

Blood glucose refers to the glucose in blood sugar.

After blood glucose enters the liver through the hepatic portal vein, a portion of it is converted into liver glycogen, which is stored in the liver as a reservoir of sugar. Most of them enter the body through the hepatic vein for blood circulation, and are transported to various tissues and cells throughout the body, where they are used to decompose and burn to produce heat for the needs of the human body. There is also a small amount of sugar that is stored in the form of glycogen in other organs, especially muscle tissue.

The glycogen in the muscle group is called muscle glycogen. Although muscle glycogen only accounts for 1% and 2% of muscle weight, muscle has the largest weight in the body, so muscle is the organ that stores the most glycogen in the body, and it is another store of sugar.

If sugar is consumed in excess of it, it can also be converted into fat. When blood sugar is insufficient, the stock reserves of sugar - liver glycogen and muscle glycogen can be mobilized; The liver can also synthesize glucose from other raw materials, such as amino acids, lactic acid, and glycerol produced by the breakdown of fats—this is called gluconeogenesis. Therefore, the physiological significance of glycogenolysis and gluconeogenesis mainly lies in maintaining a relatively stable blood sugar level in a state of starvation.

To sum up, there are three pathways for blood glucose: mainly absorption from the gastrointestinal tract; This is followed by the synthesis of glucose by the liver (i.e., gluconeogenesis) or the breakdown of glycogen by the liver to glucose; In addition, glycogen in the muscles is broken down into glucose into the bloodstream. There are four ways blood sugar goes:

First, the body's tissue cells take up, utilize and convert into energy; second, the synthesis of glycogen in the liver and muscles; third, it is transformed into fat; Fourth, it is transformed into other carbohydrates.

Blood sugar. Synthesis of muscle glycogen.

Gastrointestinal absorption. Synthesis of hepatic glycogen.

Hepatic glycogenolysis.

Synthetic fatty acids.

Hepatic neogenesis. Converted into energy.

Muscle glycogenolysis.

The main catabolic modes of sugar in the body are affected by the oxygen supply, including anaerobic oxidation (glycolysis), aerobic oxidation, pentose phosphate pathway, and glycogenolysis. Among them, the oxidative decomposition of sugar is the main way of energy.

Sugar in food is the main sugar in the body, which is ingested by the human body, digested into simple sugars and absorbed, and then transported to various tissues and cells through the blood for anabolism and catabolism. The main pathways of glucose metabolism in the body include anaerobic digestion of glucose, aerobic oxidation, pentose phosphate pathway, glycogen synthesis and glycogenolysis, gluconeogenesis and other hexose metabolism.

The way blood sugar goes out: It provides energy through oxidative decomposition in various tissues, which is the main way of blood sugar; Glycogen synthesis in liver, muscle and other tissues; transformation into other sugars and their derivatives, such as ribose, amino sugars and uronic acids; Conversion into non-sugar substances, such as fats, non-essential amino acids, etc.; When the blood sugar concentration is too high, it is excreted in the urine. Blood glucose concentrations greater than 8 9

Elevated FDG is a manifestation of a metabolic abnormality.

Generally speaking, compared with normal cells, tissues and benign lesions, the metabolic rate of glucose by malignant tumor cells is increased, so it is generally believed that the uptake of malignant tumors is increased compared with the uptake of 18F-FDG in normal tissue structure, which is reflected in the report of increased FDG metabolism.

Fluorodeoxyglucose is a fluorinated derivative of 2-deoxyglucose. Commonly referred to simply as 18F-FDG or most commonly used in positron emission tomography (PET) medical imaging devices: the fluorine in the FDG molecule is fluorine-18, which is a positron-emitting radioisotope, thus becoming 18F-FDG.

After FDG is injected into the body of the patient (patient, patient), the PET scanner can construct an image that reflects the distribution of FDG in the body. These images are then evaluated by a nuclear medicine physician or radiologist to make a diagnosis about various medical health conditions.

As a glucose analogue, F-18DG will be taken up by glucose-efficient cells such as the brain, kidneys, and cancer cells. In such cells, the phosphorylation process prevents the release of glucose from the cell in its original intact form. The 2-position oxygen in glucose is necessary for subsequent glycolysis.

Therefore, F-18DG is the same as 2-deoxy-D-glucose and cannot be metabolized in cells. In this way, the formed F-18DG-6-phosphate will not undergo glycolysis prior to radioactive decay. As a result, the distribution of F-18-F-18DG is a good reflection of the distribution of glucose uptake and phosphorylation by cells in vivo.

Glycolysis can be reacted into pyruvate, oxaloacetate is catalyzed by phosphoenolpyruvate carboxylkinase, which consumes 1 ATP to become phosphoenolpyruvate, which is then catalyzed by pyruvate kinase to produce pyruvate.

Pyruvate is catalyzed by pyruvate carboxylase to oxaloacetate, which is an important refill pathway of the tricarboxylic acid cycle, which requires biotin as a prosthetic group and consumes one molecule of ATP.

Malic acid is oxidatively dehydrogenated by NAD+ under the action of malate dehydrogenase to produce oxaloacetate, and the regenerated oxaloacetate can re-enter the tricarboxylic acid cycle for the synthesis of citric acid.