What is glucose? Obtaining glucose and its properties. Why is glucose needed in the human body?

13.10.2019

The main source of energy for a person is glucose, which enters the body along with carbohydrates and performs many vital functions for the full functioning of the human body. Many believe that glucose has a negative effect, leads to obesity, but from a medical point of view, it is an indispensable substance that covers the energy needs of the body.

In medicine, glucose can be found under the term "dextose" or "grape sugar", it must be present in the blood (erythrocytes), provide the brain cells with the necessary energy. However, for the human body, glucose can be dangerous both in excess and in deficiency. Let's try to get acquainted with glucose in more detail, its properties, characteristics, indications, contraindications and other important aspects.

What is glucose. General information?

Glucose refers to simple carbohydrates that are well absorbed by the body, easily soluble in water, but practically insoluble in alcohol solutions. In medicine, glucose is produced in the form of a hypertonic or isotonic solution, which is widely used for the complex treatment of many diseases. Glucose itself is a white powder with colorless crystals, having a slightly sweet taste and odorless.

About 60% of glucose enters the human body with food in the form of complex chemical compounds, including polysaccharide starch, sucrose, cellulose, dextrin and a small amount of animal polysaccharides, which are actively involved in many metabolic processes.

After carbohydrates enter the gastrointestinal tract, they are broken down into glucose, fructose, galactose. Part of the glucose is absorbed into the blood stream and used for energy needs. The other part is deposited in fat reserves. After the process of digestion of food, the reverse process begins, in which fats and glycogen begin to turn into glucose. Thus, there is a constant concentration of glucose in the blood. The content of glucose in the blood during normal functioning of the body is considered to be from 3.3 to 5.5 mmol / l.

If the level of glucose in the blood decreases, then a person feels a feeling of hunger, energy forces decrease, and weakness is felt. A systematic decrease in blood glucose can lead to internal disorders and diseases of different localization.

In addition to providing the body with energy, glucose is involved in the synthesis of lipids, nucleic acids, amino acids, enzymes and other useful substances.

In order for glucose to be well absorbed by the body, some cells require a pancreatic hormone (insulin), without which glucose cannot enter the cells. If insulin deficiency is noted, then most of the glucose is not broken down, but remains in the blood, which leads to their gradual death and the development of diabetes mellitus.

The role of glucose in the human body

Glucose takes an active part in many processes of the human body:

participates in important metabolic processes;
considered the main source of energy;
stimulates the work of the cardiovascular system;
used for medicinal purposes for the treatment of many diseases: liver pathology, diseases of the central nervous system, various infections, intoxication of the body and other diseases. Glucose is contained in many cough medicines, blood substitutes;
provides nutrition to brain cells;
eliminates the feeling of hunger;
relieves stress, normalizes the functioning of the nervous system.

In addition to the above benefits of glucose in the human body, it improves mental and physical performance, normalizes work internal organs and improves overall health.

Glucose - indications and contraindications for use

Glucose is often prescribed by doctors in various fields of medicine, it is available in several pharmaceutical forms: tablets, intravenous solution for 40; 200 or 400 mil. The main indications for the appointment of glucose:

liver pathology: hepatitis, hypoglycemia, liver dystrophy, liver atrophy;
pulmonary edema;
treatment of chronic alcoholism, drug addiction or other intoxications of the body;
collapse and anaphylactic shock;
decompensation of cardiac functionality;
infectious diseases;

Glucose for the treatment of the above diseases is often used in combination with other drugs.

Contraindications - to whom glucose is dangerous

In addition to the positive qualities of glucose, it, like any drug, has several contraindications:

diabetes;
hyperglycemia;
anuria;
severe stages of dehydration;
hypersensitivity to glucose.

If glucose is contraindicated for the patient, then the doctor prescribes an isotonic sodium chloride solution.

What foods contain glucose?

The main source of glucose is food, which must be fully supplied to the human body, providing it with the necessary substances. A large amount of glucose is found in natural juices of fruits and berries. A large amount of glucose contains:

grapes of different varieties;
cherry, sweet cherry;
raspberry;
Strawberry wild-strawberry;
plum;
watermelon;
carrots, white cabbage.

Given that glucose is a complex carbohydrate, it is not found in animal products. A small amount of it is found in eggs, dairy products, bee honey, and some seafood.

When is glucose prescribed?

Glucose preparations are often prescribed by doctors in the form of intravenous infections for various disorders and ailments of the body:

physical exhaustion of the body;
restoration of energy balance - typical for athletes;
medical indicators during pregnancy - oxygen starvation of the fetus, chronic fatigue;
hypoglycemia - a decrease in blood sugar levels;
infectious diseases of different etiology and localization;
liver disease;
hemorrhagic diathesis - increased bleeding;
shock, collapse - a sharp decrease in blood pressure.

The dose of the drug, the course of treatment is prescribed by the doctor individually for each patient, depending on the diagnosis, the characteristics of the body.

Glucose fermentation

Fermentation or fermentation provides a complex biochemical process, during which the decomposition of complex organic substances into simpler ones occurs.

Fermentation involving glucose occurs under the influence of certain microorganisms, bacteria or yeast, this allows you to get a different product. During the fermentation process, sucrose is converted into glucose and fructose, and other ingredients are also added.

For example, for the preparation of beer, malt and hops are added, vodka - cane sugar, followed by distillation, and wine - grape juice and natural yeast. If the fermentation process goes through all stages, then dry wine or light beer is obtained, but if fermentation is prematurely stopped, then sweet wine and dark beer will be obtained.

The fermentation process consists of 12 stages in which you must adhere to all the rules and regulations for the preparation of a particular drink. Therefore, such procedures should be carried out by specialists with certain skills and knowledge.

The blood glucose level has big influence on human health, so doctors recommend periodically taking laboratory blood tests for blood sugar levels, this will help monitor the internal environment of the body.

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Glucose: about the harm it brings to the body. What is dangerous in excess quantities

Glucose has been around for a long time. However, there is nothing strange here, because it is an excellent natural sugar substitute, and today everything natural is highly valued. Most glucose in the juice of grapes (hence the name grape sugar). It is not only found in food, but also produced by the body itself.

Yes, undoubtedly this monosaccharide is very useful, but still, in excessive amounts, it can cause great harm to the human body, become a catalyst for serious diseases. Elevated blood glucose levels are called hyperglycemia.

This disorder is characterized by the following symptoms:

Hyperhidrosis (the so-called excessive sweating);

Tachycardia (rapid heartbeat);

Chronic fatigue syndrome;

The appearance of diabetic signs (type 2 diabetes);

At first glance, causeless weight loss;

Numbness in fingers

Strong "malicious" diarrhea;

Various fungal infections;

The development of shortness of breath;

appearance pain in the chest;

Problems with the immune system, long-healing wounds.

Hyperglycemia also causes kidney failure, impairs work in the peripheral nervous system. In especially severe cases, you can generally fall into a coma.

To protect yourself from hyperglycemia, you need to eat less sweet and fatty foods, because they contain a large amount of glucose and other carbohydrates.

What is dangerous lack of glucose

Hypoglycemia is what is called a lack of glucose. The harm to the body from this disorder is very great. The brain suffers the most, for which glucose is the main source of energy. Problems with memory begin, it becomes difficult to concentrate, study, and solve elementary tasks. Generally, Negative influence The disorder extends to all cognitive functions.

There can be several reasons for hypoglycemia: or carbohydrate enters the bloodstream in insufficient quantities, or moves too quickly out of it into the cells. In the first case, the culprits of the disorder may be irregular meals, curative fasting, specific diets. Too fast “leaving” glucose from the blood, oddly enough, is often found in diabetics. As soon as they forget to "seize" insulin with something and write wasted - the glucose level will drop catastrophically. The fact is that if the hormone is administered artificially, then it comes too quickly from the blood into the cells. This is why hypoglycemia occurs in a diabetic. True, not for long.

Tumor of the pancreas (insulinoma)- another reason for the lack of glucose. Such a neoplasm produces insulin uncontrollably, as a result of which the level of grape sugar in the blood falls below normal.

The main symptoms of hypoglycemia include:

Strong causeless irritability;

Tachycardia;

Cold sweat (especially at night);

Migraine;

blanching of the skin;

clouding of consciousness;

Severe dizziness, fainting.

Also, the person's coordination of movements is disturbed.

To "raise" the level of sugar in the blood, you just need to eat something rich in glucose. Chocolate or cake is great.

Glucose: about contraindications. Who should not use it and why?

Glucose is especially dangerous for diabetics, whose body does not produce enough insulin. As soon as they eat something sweet (candy, even a regular banana), the carbohydrate concentration rises to critical levels. Therefore, they have to follow a strict diet with a low glucose content. This is the only way diabetics can save their heart, blood vessels and nerve cells from serious diseases.

In addition to diabetics, there are many other different groups of people who are better off not consuming too much glucose. Contraindications, for example, apply to the elderly and old people, since this substance greatly disrupts their metabolism in them.

It should also not be abused by people prone to obesity. It is better for them not to do this, because the excess monosaccharide turns into triglyceride - a dangerous substance similar in its properties to cholesterol. Because of it, the cardiovascular system suffers, coronary disease occurs, and blood pressure rises.

However, no one should abuse glucose, otherwise:

Insulin will be produced in excess, which means that the risk of developing diabetes will increase dramatically;

In the blood, the content of cholesterol, a substance that causes atherosclerosis, will increase;

Thrombophlebitis may develop.

In addition, due to the abuse of this carbohydrate, allergies to various foods and drugs appear.

Glucose: about the beneficial properties of a monosaccharide

This monosaccharide is very important for all of us, since a person receives the bulk of his energy from food rich in it. In addition, glucose is a "strategic" energy reserve of the body, which is located in the liver and muscles. It plays a huge role in the process of thermoregulation and the work of the respiratory apparatus. It allows our muscles to contract and our hearts to beat. And this monosaccharide is very important for the normal functioning of the central nervous system, since it is the main source of energy for nerve cells.

Due to the low calorie content, glucose is very well absorbed and quickly oxidized.

about glucose and useful properties which she possesses can be said endlessly. For example, thanks to her:

Mood improves, it becomes easier to endure stress;

Muscle tissue is regenerated. That is why it is advisable to have a snack shortly after physical exertion in order to replenish the reserves of healthy carbohydrates.

The overall performance increases, since it is the excess of grape sugar in the muscles that helps us to work physically for a long time;

The transmission of nerve impulses is accelerated, mental abilities improve: it becomes easier to memorize information, concentrate, and solve various problems. Glucose even helps the mentally retarded, as well as those with dementia (senile dementia), partially restore the lost cognitive functions of their brain.

And glucose is also a component of various medicines that save in case of poisoning and liver diseases. Often carbohydrate is used in blood substitutes.

What foods are high in glucose

Carbohydrates are especially abundant in:

grapes;

Various juices;

carrots;

Milk (especially in milk, curdled milk, kefir).

It is also rich in honey, corn and legumes.

You literally cannot live a day without glucose, but you still need to be careful with foods that contain a lot of it - otherwise you will be in trouble. Eat such food wisely and then diseases will bypass you.

zhenskoe-opinion.ru

What is glucose?

Glucose is a type of simple sugar (monosaccharide). The name comes from the ancient Greek word for "sweet". It is also called grape sugar or dextrose. In nature, this substance is found in the juice of many berries and fruits. Glucose is also one of the main products of photosynthesis.

The glucose molecule is part of more complex sugars: polysaccharides (cellulose, starch, glycogen) and some disaccharides (maltose, lactose and sucrose). And it is also the end product of the hydrolysis (decomposition) of most complex sugars. For example, disaccharides, getting into our stomach, quickly break down into glucose and fructose.

Properties of glucose

In its pure form, this substance is in the form of crystals, without a pronounced color and odor, sweet in taste and highly soluble in water. There are substances sweeter than glucose, for example, sucrose is as much as 2 times sweeter than it!

What are the benefits of glucose?

Glucose is the main and most versatile energy source for metabolic processes in humans and animals. Even our brain is in dire need of glucose and begins to actively send signals in the form of a feeling of hunger, with its deficiency. The body of humans and animals stores it in the form of glycogen, while plants store it in the form of starch. More than half of all biological energy we receive from the processes of glucose conversion! To do this, our body hydrolyzes it, as a result of which one molecule of glucose is converted into two molecules of pyruvic acid (the name is terrible, but the substance is very important). And this is where the fun begins!

Various conversions of glucose into energy

The further conversion of glucose occurs in different ways, depending on the conditions in which it occurs:

aerobic route. When there is enough oxygen, pyruvic acid turns into a special enzyme that participates in the Krebs cycle (the process of catabolism and the formation of various substances).
anaerobic pathway. If there is not enough oxygen, then the breakdown of pyruvic acid is accompanied by the release of lactate (lactic acid). According to popular belief, it is precisely because of lactate that we have P±PѕP»СЏС‚ РјС‹С€С†С‹ РїРѕСЃР»Рµ С‚СЂРµРЅРёСЂРѕРІРєРё. (Actually this is not true).

The level of glucose in the blood is regulated by a special hormone - insulin.

The use of pure glucose

In medicine, glucose is used to relieve intoxication of the body, because it has a universal antitoxic effect. And with its help, endocrinologists can determine the presence and type of diabetes in a patient, for this a stress test is performed with the introduction of a high amount of glucose into the body. Determination of glucose in the blood is a mandatory step in the diagnosis of diabetes mellitus.

The norm of glucose in the blood

The approximate level of glucose in the blood is the norm for different ages:

in children under 14 years old - 3.3-5.5 mmol / l
in adults from 14 to 60 years old - 3.5–5.8 mmol / l

Blood glucose levels can rise with age and during pregnancy. If you, according to the results of the analysis, have greatly exceeded sugar levels, then immediately consult a doctor!

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Chemical composition

Glucose is monosaccharides with hexose. The composition includes starch, glycogen, cellulose, lactose, sucrose and maltose. Once in the stomach, grape sugar is broken down into fructose.

The crystallized substance is colorless, but with a pronounced sweet taste. Glucose is able to dissolve in water, especially in zinc chloride and sulfuric acid.

This allows you to create medicines based on grape sugar to make up for its deficiency. Compared to fructose and sucrose, this monosaccharide is less sweet.

Significance in the life of animals and humans

Why is glucose so important in the body and why is it needed? In nature, this chemical is involved in the process of photosynthesis.

This is because glucose is able to bind and transport energy to cells. In the body of living beings, glucose, due to the energy produced, plays an important role in metabolic processes. Main benefits of glucose:

Grape sugar is an energy fuel, thanks to which cells are able to function smoothly.
In 70%, glucose enters the human body through complex carbohydrates, which, when they enter the digestive tract, break down fructose, galactose and dextrose. The rest of the body produces this chemical, using its own stored reserves.
Glucose penetrates into the cell, saturates it with energy, due to which intracellular reactions develop. Metabolic oxidation and biochemical reactions take place.

Many cells in the body are capable of producing grape sugar on their own, but not the brain. An important organ cannot synthesize glucose, therefore it receives nutrition directly through the blood.

The norm of glucose in the blood, for the normal functioning of the brain, should not be lower than 3.0 mmol / l.

Surplus and deficiency

Glucose is not absorbed without insulin, a hormone produced in the pancreas.

If there is a deficiency of insulin in the body, then glucose is not able to penetrate into the cells. It remains unprocessed in human blood and is enclosed in an eternal cycle.

As a rule, with a lack of grape sugar, the cells weaken, starve and die. This relationship is studied in detail in medicine. Now this condition is classified as a serious disease and is called diabetes mellitus.

In the absence of insulin and glucose, not all cells die, but only those that are not able to independently absorb the monosaccharide. There are also insulin-independent cells. Glucose in them is absorbed without insulin.

These include brain tissue, muscles, red blood cells. The nutrition of these cells is carried out at the expense of incoming carbohydrates. It can be seen that during starvation or poor nutrition, mental abilities change significantly in a person, weakness, anemia (anemia) appear.

According to statistics, glucose deficiency occurs in only 20%, the remaining percentage is accounted for by an excess of the hormone and monosaccharide. This phenomenon is directly related to overeating. The body is not able to break down carbohydrates that come in large quantities, which is why it simply begins to store glucose and other monosaccharides.

If glucose is stored in the body for a long time, it will be converted into glycogen, which is stored in the liver and muscles. In this situation, the body falls into a stressful state, when glucose becomes excessive.

Since the body cannot independently remove a large amount of grape sugar, it simply deposits it in adipose tissue, due to which a person is rapidly gaining excess weight. This whole process requires a lot of energy (breakdown, conversion of glucose, deposition), so there is constant feeling hunger and a person consumes carbohydrates 3 times more.

For this reason, it is important to use glucose correctly. Not only in diets, but also in proper nutrition, it is recommended to include complex carbohydrates in the diet, which slowly break down and evenly saturate the cells. Using simple carbohydrates, the release of grape sugar in large quantities begins, which immediately fills the adipose tissue. Simple and complex carbohydrates:

Simple: milk, confectionery, honey, sugar, preserves and jams, carbonated drinks, White bread, sweet vegetables and fruits, syrups.
Complex: found in beans (peas, beans, lentils), cereals, beets, potatoes, carrots, nuts, seeds, pasta, cereals and cereals, in black and rye bread, pumpkin.

Use of glucose

For several decades, mankind has learned how to get glucose in large quantities. For this, cellulose and starch hydrolysis are used. In medicine, glucose-based drugs are classified as metabolic and detoxifying.

They are able to restore and improve metabolism, and also have a beneficial effect on redox processes. The main form of release is a sublimated combination and a liquid solution.

Who benefits from glucose

The monosaccharide does not always enter the body with food, especially if the food is poor and not combined. Indications for the use of glucose:

During pregnancy and suspected low fetal weight. Regular consumption of glucose affects the weight of the baby in the womb.
With intoxication of the body. For example, chemicals such as arsenic, acids, phosgene, carbon monoxide. Glucose is also prescribed for overdose and drug poisoning.
With collapse and hypertensive crisis.
After poisoning as a restorative agent. Especially with dehydration on the background of diarrhea, vomiting or in the postoperative period.
Hypoglycemia, or low blood sugar. Suitable for diabetes, checked regularly with glucometers and analyzers.
Diseases of the liver, intestinal pathologies against the background of infections, with hemorrhagic diathesis.
It is used as a restorative agent after prolonged infectious diseases.

Release form

There are three forms of glucose release:

intravenous solution. It is prescribed to increase osmotic blood pressure, as a diuretic, to dilate blood vessels, to relieve swelling of tissues and remove excess fluid, to restore the metabolic process in the liver, and also as nutrition for the myocardium and heart valves. Produced in the form of dried grape sugar, which dissolves in concentrates with different percentages.
Pills. Assign to improve the general condition, physical and intellectual activity. Acts as a sedative and vasodilator. One tablet contains at least 0.5 grams of dry glucose.
Solutions for infusions (droppers, systems). Assign to restore water-electrolyte and acid-base balance. Also used in dry form with a concentrated solution.

How to check your blood sugar level, learn from the video:

Contraindications and side effects

Glucose is not prescribed for people suffering from diabetes and pathologies that increase blood sugar levels. With the wrong appointment or self-medication, acute heart failure, loss of appetite and violation of the insular apparatus may occur.

It is also impossible to inject glucose intramuscularly, as this can cause necrosis of the subcutaneous fat. With the rapid introduction of a liquid solution, hyperglucosuria, hypervolemia, osmotic diuresis and hyperglycemia may occur.

Unusual uses of glucose

In the form of syrup, grape sugar is added to the dough when baking bread. Because of this, the bread is able to be stored at home for a long time, not stale or dry out.

At home, you can also make such bread, but using glucose in ampoules. Grape sugar in a liquid candied form is added to baked goods, such as muffins or cakes.

Glucose provides softness and long-lasting freshness to confectionery products. Dextrose is also an excellent preservative.

Eye baths, or rinsing, with a dextrose-based solution. This method helps to get rid of vascularized corneal opacity, especially after keratitis. Baths are used according to strict instructions to prevent delamination of the cornea layer. Also, glucose is dripped into the eye, using in the form of homemade drops or diluted.

Used for decoration textile products. A weak glucose solution is used as a top dressing for withering plants. For this, grape sugar is purchased in an ampoule or dry form, added to water (1 ampoule: 1 liter). Such water is regularly watered with flowers as it dries. Thanks to this, the plants will again become green, strong and healthy.

Dry glucose syrup is added to baby food. Also used during diets. It is important to monitor your health at any age, so it is recommended to pay attention to the amount of monosaccharides that are eaten along with easily digestible carbohydrates.

With a deficiency or excess of glucose, failures occur in the cardiovascular, endocrine, and nervous systems, while brain activity is significantly reduced, metabolic processes are disturbed, and immunity deteriorates. Help your body using only healthy foods such as fruits, honey, dried fruits, vegetables and cereals. Limit yourself from unnecessary calories that enter the body along with waffles, cookies, pastries and cakes.

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Glucose is a white or colorless, odorless, sweet-tasting substance that is soluble in water. Cane sugar is approximately 25% sweeter than glucose. Glucose is the most important carbohydrate for humans. Scientists are still wondering why exactly glucose, and not some other monosaccharide, for example, fructoseFructose - the benefits and harms of a natural product , is widely distributed in living organisms.

One reason for this may be that it is less likely than other sugars to react nonspecifically with the amino groups of proteins. Such reactions reduce or destroy the function of many enzymes. However, some complications of diabetes (associated with increased level blood glucose levels) are probably caused by the reactions that glucose has with proteins and lipids. These complications include blindness, kidney failure, and peripheral neuropathy.

What is glucose for?

Glucose is a key source of energy for humans, as well as for plants and animals. It is, moreover, the main food for the brain, and in many ways it is this sugar that affects many mental processes. When glucose levels are low, processes that require mental effort (for example, self-control, acceptance difficult decisions, and so on) can be violated.

In addition, glucose is used in the production of certain foods. A five or ten percent glucose solution is used for intravenous feeding of patients who, for whatever reason, cannot take food by mouth.

How is glucose used?

If the body receives more glucose than necessary, the excess in the form of glycogen is deposited in the liver and in the form of fat in adipose tissues. In the blood of an adult there is, on average, 5-6 g of glucose (or a teaspoon). This volume is enough to provide the body with energy for approximately 15 minutes. Therefore, the level of glucose in the blood is constantly maintained by glycogen stored in the liver.

Sources of glucose are fruits, flower nectar, various plants, their juice, and blood.

Insulin is a hormone that regulates blood glucose levels. High glucose levels may indicate diabetes or prediabetes. Glucose is present in the urine only when its level in the blood is significantly higher than normal - this can be the case with diabetes.

In healthy people, even when eating large amounts of carbohydrate-rich foods, glucose is oxidized and converted to glycogen quickly and its blood levels never become high enough for glucose to enter the urine.

In addition to diabetes, blood glucose levels can be elevated due to the following conditions:

In addition, some drugs affect glucose levels. Taking the following medicines can cause high blood glucose levels:

Atypical antipsychotics, especially olanzapine, quetiapine, and risperidone
Beta blockers (eg propranolol)
Corticosteroids
Dextrose
Adrenalin
Estrogens
Glucagon
Isoniazid
Lithium
Oral contraceptives (birth control pills)
Phenothiazines
Phenytoin
Salicylates
Thiazide diuretics
Triamterene
Tricyclic antidepressants

Glucose lowering drugs include:

Acetaminophen
Alcohol
Anabolic steroid
Clofibrate
Disopyramide
Gemfibrozil
Monoamine oxidase inhibitors (MAOIs)
pentamidine
Sulfonylureas (eg, glipizide, glibenclamide, and glimepiride).

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Glucose acts as fuel in the body. It is the main source of energy for cells, and the ability of cells to function normally is largely determined by their ability to absorb glucose. It enters the body with food. Food is broken down in the gastrointestinal tract into molecules, after which glucose and some other cleavage products are absorbed, and undigested residues (slags) are excreted through the excretory system.

In order for glucose to be absorbed in the body, some cells need the pancreatic hormone insulin. Insulin is usually compared to the key that opens the door to the cell for glucose, and without which it will not be able to penetrate there. If there is no insulin, most of the glucose remains in the blood in an unassimilated form, while the cells starve and weaken, and then die of hunger. This condition is called diabetes mellitus.

Some body cells are non-insulin dependent. This means that glucose is absorbed directly in them, without insulin. Brain tissues, red blood cells and muscles are made up of insulin-independent cells - that is why, with insufficient intake of glucose into the body (that is, during hunger), a person quite soon begins to experience difficulties with mental activity, becomes anemic and weak.

However, much more often modern people face not a lack, but an excess intake of glucose into the body as a result of overeating. Excess glucose is converted into glycogen, a kind of "can storehouse" of cellular nutrition. Most of the glycogen is stored in the liver, the smaller part - in the skeletal muscles. If a person does not take food for a long time, the process of splitting glycogen in the liver and muscles starts, and the tissues receive the necessary glucose.

If there is so much glucose in the body that it can no longer be used either for the needs of tissues or utilized in glycogen depots, fat is formed. Adipose tissue is also a "warehouse", but it is much more difficult for the body to extract glucose from fat than from glycogen, this process itself requires energy, which is why losing weight is so difficult. If you need to break down fat, then the presence of ... right, glucose to provide energy.

This explains the fact that diets for weight loss should include carbohydrates, but not any, but hard to digest. They break down slowly, and glucose enters the body in small amounts, which are immediately used to meet the needs of the cells. Easily digestible carbohydrates immediately throw an excessive amount of glucose into the blood, there is so much of it that it must immediately be disposed of in fat depots. Thus, glucose in the body is essential, but it is necessary to provide the body with glucose wisely.

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All parts of the body (muscles, brain, heart, liver) need energy to work. This energy comes from the food we eat. Our bodies digest the food we eat by mixing it with the fluids (acids and enzymes) in the stomach. When the stomach digests food, the carbohydrates (sugars and starches) contained in the food converted to other types of sugar called glucose and fructose. Fructose is not involved in supplying the body with energy, but glucose, on the contrary, is a source of energy.

stomach and small intestine absorbs glucose and then releases it into the bloodstream. Once glucose is in the blood, it can be used immediately for energy or stored in our bodies to be used later. But our bodies need insulin to metabolize glucose. Without insulin, glucose remains in the bloodstream, keeping blood sugar high (and sometimes dangerously high).

How does the body metabolize glucose?

Insulin is a hormone secreted by the pancreas. The cells that secrete it are very sensitive to the level of glucose in the blood. They are like check insulin concentration every few seconds to speed up or slow down the release of insulin. When you eat something high in carbohydrates, such as a piece of bread, insulin levels in the blood rise and cells begin to secrete more insulin.

Insulin, getting into the blood, instructs the cells to let glucose in. Once inside, the cells either use it for energy or store it for future use. At the same time, the amount of glucose in the blood begins to decrease and the cells of the pancreas reduce the secretion of insulin.

Such ups and downs in insulin secretion occur many times during the day, a person does not notice it. In a normal person, blood sugar levels are between 70 and 120 milligrams per deciliter. However, even in non-diabetic people, blood sugar levels can rise to 180 during or immediately after a meal. Within two hours of eating, your blood sugar should drop below 140.

Diabetes.

In diabetes, the body does not stop producing insulin, he simply secretes too little of it or stops using his own insulin. This leads to a number of bad consequences. For example, glucose cannot enter the cells where it is needed, so the amount of glucose in the blood begins to rise. This is called hyperglycemia (high blood sugar) . When blood sugar reaches 180 or higher, the kidneys try to get rid of excess sugar through urine. This causes the person to urinate more often than usual. It also makes the person feel thirsty due to the water he loses by urinating so much.

When a person loses sugar in the urine it is the same as losing energy because the sugar is no longer available for the cells to use or store. When this happens, the person may feel tired, lose weight, and may feel hungry all the time.

The human body requires glucose for the normal functioning of the brain and other tissues. If the system for obtaining, creating and using glucose is disrupted, diabetes occurs and many bad things can follow, such as heart attacks, blindness, and loss of limbs.

What is glucose? Everyone uses it, but few can give a definition. This is a substance that the human body needs. Human health depends on the timely intake of glucose.

Carbohydrates, proteins and fats can supply energy to the body. But glucose is the substance that occupies the main place among those used for energy needs.

Definition

Glucose, also called dextrose, is a white or colorless powder that is odorless and has a sweet taste. Glucose is a substance that can be called a universal fuel for the human body. After all, most of the energy needs are covered just at its expense. It must be present in the blood all the time. But it should be noted that its excess, as well as its deficiency, is dangerous. During hunger, the body feeds on what it is built from. In this case, muscle proteins are converted into glucose. This can be extremely dangerous.

Physical properties of glucose

What is glucose? As mentioned earlier, it is a colorless, sweet crystalline substance. It dissolves very well in water. Glucose is found in almost all plant organs: in flowers, roots, fruits and leaves. A very large amount of glucose is found in ripe berries and fruits, as well as grape juice. It is also present in animal organisms. The proportion of the substance in human blood is approximately one tenth of a percent.

Chemical properties of glucose

What is glucose? It is a substance belonging to its formula - C6H12O6. If glucose solution is added to a freshly precipitated solution, a bright blue color will be obtained. In order to have a complete picture of the structure of a substance, it is necessary to know how the glucose molecule is built. Since the six oxygen atoms are part of the functional groups, the carbon atoms that form the skeleton of the molecule are connected directly to each other.

Contains molecules with an open chain of atoms, as well as cyclic ones. What is glucose? This is a substance that has a dual chemical nature. It forms esters, oxidizes. A glucose cell can break down into two lactic acid cells and free energy. This process is called glycolysis. The glucose molecule exists in three isomeric forms. One of them is linear and the other two are cyclic.

glucose and food

Glucose enters the human body together with carbohydrates. After entering the intestines, they are broken down, turning into glucose, which then enters the bloodstream. Some part of the substance is spent on the energy needs of the body, the other is deposited in the form of fat reserves. Some of the glucose is stored as a substance called glycogen. After the digestion of food and the cessation of the influx of glucose into the blood from the intestine, the process of reverse conversion of glycogen and fats into glucose begins. In this way, the human body maintains a continuous level of glucose in the blood. In general, the process of converting fats and proteins into glucose and vice versa takes quite a long time. But the same process with glucose and glycogen occurs much faster. It is for this reason that glycogen is the main storage carbohydrate.

Hormones-regulators

The process of converting glucose to glycogen and vice versa is regulated by hormones. Insulin reduces the concentration of glucose in a person's blood. Increase its hormones such as adrenaline, glucagon, cortisol. In the event that any violations occur in the passage of such reactions between glycogen and glucose, a person may experience a serious illness. One of them is diabetes.

How to measure blood glucose?

Blood glucose measurement is the main test that is performed to detect diabetes. In venous and capillary blood glucose levels are different. It can fluctuate due to hunger or satiety of a person. When measured on an empty stomach (at least eight hours after a meal), venous blood glucose should be between 3.3 and 5.5 millimoles per liter, and slightly more in capillary blood - from 4 to 6.1 millimoles per liter. A couple of hours after eating, the level of the substance should not be higher than 7.8 millimoles per liter. This applies to both venous and capillary blood. If within a week, when measured on an empty stomach, the glucose level does not fall below 6.3 millimoles per liter, you should immediately contact an endocrinologist, as well as conduct an additional examination.

Excess blood glucose

This condition is called hyperglycemia. It develops most often in diabetes mellitus. What can cause glucose levels to rise? The reason may be:

diabetes;
stress, strong emotional stress;
myocardial infarction;
diseases of the kidneys, pancreas and endocrine system;
moderate physical activity.

When stressful situations occur, blood glucose may increase. This is due to the fact that the human body, responding to such a situation, begins to secrete stress hormones. And they just increase Hyperglycemia has different degrees of severity: from mild and moderate to coma, when the glucose level exceeds 55.5 millimoles per liter.

Low blood glucose

This phenomenon is called hypoglycemia. This is a condition when the concentration of a substance in the blood is less than 3.3 millimoles per liter. What are the clinical manifestations of hypoglycemia? These can be: muscle weakness, severe sweating, confusion, lack of coordination.

The level of glucose in the blood decreases due to factors such as:

malnutrition or starvation;
diseases of the liver and pancreas;
strong physical activity;
diseases of the endocrine system;
insulin overdose.

With very severe hypoglycemia, a person may have a hypoglycemic coma.

Glucose and medicine

A solution of this substance is used in the treatment of a large number of diseases, with a lack of glucose. They are also diluted with some drugs before injecting them into a vein.

Glucose is a very necessary substance that plays an important role in the functioning of the human body.

Application

Glucose is very nutritious. Starch, which is contained in food, getting into the digestive tract, turns into glucose. From there it spreads throughout the body. Since this substance is very easily absorbed by the body, it also gives it energy, as a strengthening remedy.

Since it is sweet, it is also used in confectionery. Glucose is a sugar that is part of molasses, caramel, marmalade, gingerbread. In general, all that are called sugars are divided into two types: glucose, fructose. And most often one product contains a mixture of them. An example is table sugar, in which these two substances are in equal amounts.

It is worth remembering that too much consumption of sweets harms the human body. After all, there are such diseases as obesity, caries, diabetes. Life is shortened because of this. Therefore, you need to monitor your diet well and consume all the necessary substances within the normal range. Then health will be all right.

Properties of glucose

What are the benefits of glucose?

Various conversions of glucose into energy

The further conversion of glucose occurs in different ways, depending on the conditions in which it occurs:

aerobic route. When there is enough oxygen, pyruvic acid turns into a special enzyme that participates in the Krebs cycle (the process of catabolism and the formation of various substances).
anaerobic pathway. If there is not enough oxygen, then the breakdown of pyruvic acid is accompanied by the release of lactate (lactic acid). According to popular belief, it is because of lactate that our muscles hurt after a workout. (Actually this is not true).

The level of glucose in the blood is regulated by a special hormone - insulin.

The use of pure glucose

The norm of glucose in the blood

The approximate level of glucose in the blood is the norm for different ages:

in children under 14 years old - 3.3-5.5 mmol / l
in adults from 14 to 60 years old - 3.5–5.8 mmol / l

Blood glucose levels can rise with age and during pregnancy. If you, according to the results of the analysis, have greatly exceeded sugar levels, then immediately consult a doctor!

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Ministry of Education and Science of the Russian Federation

Federal State Budgetary Educational Institution of Higher Education

Tambov State University named after G.R. Derzhavin

on the topic: The biological role of glucose in the body

Completed:

Shamsidinov Shokhiyorjon Fazliddin ugli

Tambov 2016

1. Glucose

1.1 Features and functions

2.1 Glucose catabolism

2.4 Glucose synthesis in the liver

2.5 Synthesis of glucose from lactate

Used literature

1. Glucose

1.1 Features and functions

Glucomza (from other Greek glkhket sweet) (C 6 H 12 O 6), or grape sugar, or dextrose, is found in the juice of many fruits and berries, including grapes, from which the name of this type of sugar comes from. It is a monosaccharide and a six-atomic sugar (hexose). The glucose link is part of polysaccharides (cellulose, starch, glycogen) and a number of disaccharides (maltose, lactose and sucrose), which, for example, are quickly broken down into glucose and fructose in the digestive tract.

Glucose belongs to the group of hexoses, it can exist in the form of β-glucose or β-glucose. The difference between these spatial isomers lies in the fact that at the first carbon atom in β-glucose the hydroxyl group is located under the plane of the ring, and in β-glucose it is above the plane.

Glucose is a bifunctional compound, because. contains functional groups - one aldehyde and 5 hydroxyl. Thus, glucose is a polyhydric aldehyde alcohol.

The structural formula of glucose is:

Short formula

1.2 Chemical properties and structure of glucose

It has been experimentally established that aldehyde and hydroxyl groups are present in the glucose molecule. As a result of the interaction of the carbonyl group with one of the hydroxyl groups, glucose can exist in two forms: open chain and cyclic.

In glucose solution, these forms are in equilibrium with each other.

For example, in an aqueous solution of glucose, the following structures exist:

Cyclic b- and c-forms of glucose are spatial isomers that differ in the position of the hemiacetal hydroxyl relative to the plane of the ring. In β-glucose, this hydroxyl is in the trans position to the hydroxymethyl group -CH 2 OH, in β-glucose - in the cis position. Taking into account the spatial structure of the six-membered ring, the formulas of these isomers have the form:

In the solid state, glucose has a cyclic structure. Ordinary crystalline glucose is the b form. In solution, the s-form is more stable (at equilibrium, it accounts for more than 60% of the molecules). The proportion of the aldehyde form in equilibrium is insignificant. This explains the lack of interaction with fuchsine sulfuric acid (qualitative reaction of aldehydes).

For glucose, in addition to the phenomenon of tautomerism, structural isomerism with ketones is characteristic (glucose and fructose are structural interclass isomers)

Chemical properties of glucose:

Glucose has chemical properties characteristic of alcohols and aldehydes. In addition, it also has some specific properties.

1. Glucose is a polyhydric alcohol.

Glucose with Cu (OH) 2 gives a blue solution (copper gluconate)

2. Glucose - aldehyde.

a) Reacts with an ammonia solution of silver oxide to form a silver mirror:

CH 2 OH-(CHOH) 4 -CHO + Ag 2 O> CH 2 OH-(CHOH) 4 -COOH + 2Ag

gluconic acid

b) With copper hydroxide gives a red precipitate Cu 2 O

CH 2 OH-(CHOH) 4 -CHO + 2Cu(OH) 2 > CH 2 OH-(CHOH) 4 -COOH + Cu 2 Ov + 2H 2 O

gluconic acid

c) It is reduced by hydrogen to form a six-hydric alcohol (sorbitol)

CH 2 OH-(CHOH) 4 -CHO + H 2 > CH 2 OH-(CHOH) 4 -CH 2 OH

3. Fermentation

a) Alcoholic fermentation (to obtain alcoholic beverages)

C 6 H 12 O 6 > 2CH 3 -CH 2 OH + 2CO 2 ^

ethanol

b) Lactic acid fermentation (souring of milk, fermentation of vegetables)

C 6 H 12 O 6 > 2CH 3 -CHOH-COOH

lactic acid

1.3 Biological significance of glucose

Glucose is a necessary component of food, one of the main participants in the body's metabolism, is very nutritious and easily absorbed. When it is oxidized, more than a third of the energy used in the body is released - fats, but the role of fats and glucose in the energy of different organs is different. The heart uses fatty acids as fuel. Skeletal muscles need glucose to “start”, but nerve cells, including brain cells, work only on glucose. Their need is 20-30% of the generated energy. Nerve cells need energy every second, and the body receives glucose when eating. Glucose is easily absorbed by the body, so it is used in medicine as a strengthening remedy. Specific oligosaccharides determine the blood type. In the confectionery business for the manufacture of marmalade, caramel, gingerbread, etc. Of great importance are the processes of fermentation of glucose. So, for example, when pickling cabbage, cucumbers, milk, lactic acid fermentation of glucose occurs, as well as when ensiling feed. In practice, alcoholic fermentation of glucose is also used, for example, in the production of beer. Cellulose is the starting material for the production of silk, cotton wool, and paper.

Carbohydrates are indeed the most common organic substances on Earth, without which the existence of living organisms is impossible.

In a living organism, in the process of metabolism, glucose is oxidized with the release of a large amount of energy:

C 6 H 12 O 6 + 6O 2 ??? 6CO 2 +6H 2 O+2920kJ

2. The biological role of glucose in the body

Glucose is the main product of photosynthesis and is formed in the Calvin cycle. In humans and animals, glucose is the main and most universal source energy to ensure metabolic processes.

2.1 Glucose catabolism

Glucose catabolism is the main supplier of energy for the vital processes of the body.

Aerobic breakdown of glucose is its ultimate oxidation to CO 2 and H 2 O. This process, which is the main pathway for glucose catabolism in aerobic organisms, can be expressed by the following summary equation:

C 6 H 12 O 6 + 6O 2 > 6CO 2 + 6H 2 O + 2820 kJ / mol

Aerobic breakdown of glucose includes several stages:

* aerobic glycolysis - the process of oxidizing glucose with the formation of two molecules of pyruvate;

* the general path of catabolism, including the conversion of pyruvate to acetyl-CoA and its further oxidation in the citrate cycle;

* the chain of electron transfer to oxygen, coupled with dehydrogenation reactions that occur during the breakdown of glucose.

In certain situations, the provision of oxygen to tissues may not meet their needs. For example, in the initial stages of intense muscle work under stress, heart rate may not reach the desired frequency, and the oxygen demand of muscles for aerobic glucose breakdown is high. In such cases, a process is activated that proceeds without oxygen and ends with the formation of lactate from pyruvic acid.

This process is called anaerobic breakdown, or anaerobic glycolysis. Anaerobic breakdown of glucose is energetically inefficient, but it is this process that can become the only source of energy for a muscle cell in the situation described. In the future, when the supply of oxygen to the muscles is sufficient as a result of the transition of the heart to an accelerated rhythm, anaerobic decay switches to aerobic.

Aerobic glycolysis is the process of oxidizing glucose to pyruvic acid in the presence of oxygen. All enzymes that catalyze the reactions of this process are localized in the cytosol of the cell.

1. Stages of aerobic glycolysis

In aerobic glycolysis, 2 stages can be distinguished.

1. Preparatory stage, during which glucose is phosphorylated and split into two molecules by phosphotriose. This series of reactions takes place using 2 ATP molecules.

2. Stage associated with the synthesis of ATP. As a result of this series of reactions, phosphotrioses are converted to pyruvate. The energy released at this stage is used to synthesize 10 moles of ATP.

2. Reactions of aerobic glycolysis

The conversion of glucose-6-phosphate into 2 molecules of glyceraldehyde-3-phosphate

Glucose-6-phosphate, formed as a result of ATP-assisted phosphorylation of glucose, is converted to fructose-6-phosphate during the next reaction. This reversible isomerization reaction proceeds under the action of the enzyme glucose phosphate isomerase.

Pathways of glucose catabolism. 1 - aerobic glycolysis; 2, 3 - general path of catabolism; 4 - aerobic breakdown of glucose; 5 - anaerobic breakdown of glucose (framed); 2 (circled) - stoichiometric coefficient.

Conversion of glucose-6-phosphate to triose phosphates.

Conversion of glyceraldehyde-3-phosphate to 3-phosphoglycerate.

This part of aerobic glycolysis includes the reactions associated with the synthesis of ATP. The most complex reaction in this series of reactions is the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate. This transformation is the first oxidation reaction during glycolysis. The reaction is catalyzed by glyceraldehyde-3-phosphate dehydrogenase, which is a NAD-dependent enzyme. The significance of this reaction lies not only in the fact that a reduced coenzyme is formed, the oxidation of which in the respiratory chain is associated with the synthesis of ATP, but also in the fact that the free energy of oxidation is concentrated in the macroergic bond of the reaction product. Glyceraldehyde-3-phosphate dehydrogenase contains a cysteine residue in the active center, the sulfhydryl group of which is directly involved in catalysis. Oxidation of glyceraldehyde-3-phosphate leads to the reduction of NAD and the formation with the participation of H 3 PO 4 of a high-energy anhydride bond in 1,3-bisphosphoglycerate at position 1. In the next reaction, high-energy phosphate is transferred to ADP with the formation of ATP

The formation of ATP in this way is not associated with the respiratory chain, and it is called substrate ADP phosphorylation. The formed 3-phosphoglycerate no longer contains a macroergic bond. In the following reactions, intramolecular rearrangements occur, the meaning of which boils down to the fact that a low-energy phosphoester passes into a compound containing a high-energy phosphate. Intramolecular transformations consist in the transfer of a phosphate residue from position 3 in phosphoglycerate to position 2. Then a water molecule is split off from the resulting 2-phosphoglycerate with the participation of the enolase enzyme. The name of the dehydrating enzyme comes from the reverse reaction. As a result of the reaction, a substituted enol is formed - phosphoenolpyruvate. The resulting phosphoenolpyruvate is a macroergic compound, the phosphate group of which is transferred in the next reaction to ADP with the participation of pyruvate kinase (the enzyme is also named after the reverse reaction in which pyruvate is phosphorylated, although such a reaction does not take place in this form).

Conversion of 3-phosphoglycerate to pyruvate.

3. Oxidation of cytoplasmic NADH in the mitochondrial respiratory chain. Shuttle systems

NADH, formed during the oxidation of glyceraldehyde-3-phosphate in aerobic glycolysis, undergoes oxidation by the transfer of hydrogen atoms into the mitochondrial respiratory chain. However, cytosolic NADH is unable to transfer hydrogen to the respiratory chain because the mitochondrial membrane is impermeable to it. The transfer of hydrogen through the membrane occurs with the help of special systems called "shuttle". In these systems, hydrogen is transported through the membrane with the participation of pairs of substrates bound by the corresponding dehydrogenases, i.e. on both sides of the mitochondrial membrane is a specific dehydrogenase. 2 shuttle systems are known. In the first of these systems, hydrogen is transferred from NADH in the cytosol to dihydroxyacetone phosphate by the enzyme glycerol-3-phosphate dehydrogenase (NAD-dependent enzyme, named after the reverse reaction). The glycerol-3-phosphate formed during this reaction is further oxidized by the enzyme of the inner mitochondrial membrane - glycerol-3-phosphate dehydrogenase (FAD-dependent enzyme). Then protons and electrons from FADH 2 pass to ubiquinone and further along the CPE.

The glycerol phosphate shuttle system works in white muscle cells and hepatocytes. However, mitochondrial glycerol-3-phosphate dehydrogenase is absent in cardiac muscle cells. The second shuttle system, which involves malate, cytosolic and mitochondrial malate dehydrogenases, is more universal. In the cytoplasm, NADH reduces oxaloacetate to malate, which, with the participation of the carrier, passes into mitochondria, where it is oxidized to oxaloacetate by NAD-dependent malate dehydrogenase (reaction 2). The NAD reduced during this reaction donates hydrogen to the mitochondrial CPE. However, oxaloacetate formed from malate cannot exit the mitochondria into the cytosol on its own, since the mitochondrial membrane is impermeable to it. Therefore, oxaloacetate is converted to aspartate, which is transported to the cytosol, where it is again converted to oxaloacetate. The conversion of oxaloacetate to aspartate and vice versa is associated with the addition and elimination of an amino group. This shuttle system is called malate-aspartate. The result of her work is the regeneration of cytoplasmic NAD+ from NADH.

Both shuttle systems differ significantly in the amount of ATP synthesized. In the first system, the P/O ratio is 2, since hydrogen is introduced into the CPE at the level of KoQ. The second system is energetically more efficient, since it transfers hydrogen to the CPE through mitochondrial NAD+ and the P/O ratio is close to 3.

4. ATP balance during aerobic glycolysis and breakdown of glucose to CO 2 and H 2 O.

ATP output during aerobic glycolysis

The formation of fructose-1,6-bisphosphate from one glucose molecule requires 2 ATP molecules. Reactions associated with the synthesis of ATP occur after the breakdown of glucose into 2 molecules of phosphotriose, i.e. in the second step of glycolysis. At this stage, 2 reactions of substrate phosphorylation occur and 2 ATP molecules are synthesized. In addition, one molecule of glyceraldehyde-3-phosphate is dehydrogenated (reaction 6), and NADH transfers hydrogen to the mitochondrial CPE, where 3 ATP molecules are synthesized by oxidative phosphorylation. In this case, the amount of ATP (3 or 2) depends on the type of shuttle system. Therefore, the oxidation to pyruvate of one molecule of glyceraldehyde-3-phosphate is associated with the synthesis of 5 ATP molecules. Given that 2 phosphotriose molecules are formed from glucose, the resulting value must be multiplied by 2 and then subtract 2 ATP molecules consumed in the first stage. Thus, the output of ATP during aerobic glycolysis is (5×2) - 2 = 8 ATP.

The release of ATP during the aerobic breakdown of glucose to end products as a result of glycolysis produces pyruvate, which is further oxidized to CO 2 and H 2 O in the OPC. Now we can evaluate the energy efficiency of glycolysis and OPC, which together make up the process of aerobic breakdown of glucose to end products. Thus, the yield of ATP when 1 mol of glucose is oxidized to CO 2 and H 2 O is 38 mol of ATP. In the process of aerobic breakdown of glucose, 6 dehydrogenation reactions occur. One of them occurs in glycolysis and 5 in the GPC. Substrates for specific NAD-dependent dehydrogenases: glyceraldehyde-3-phosphate, zhiruvate, isocitrate, β-ketoglutarate, malate. One dehydrogenation reaction in the citrate cycle under the action of succinate dehydrogenase occurs with the participation of the FAD coenzyme. The total amount of ATP synthesized by oxidative phosphorylation is 17 mol of ATP per 1 mol of glyceraldehyde phosphate. To this must be added 3 mol of ATP synthesized by substrate phosphorylation (two reactions in glycolysis and one in the citrate cycle). Considering that glucose breaks down into 2 phosphotrioses and that the stoichiometric coefficient of further transformations is 2, the resulting value must be multiplied by 2, and subtract from the result 2 mol of ATP used in the first stage of glycolysis.

Anaerobic breakdown of glucose (anaerobic glycolysis).

Anaerobic glycolysis is the process of breaking down glucose to form lactate as an end product. This process proceeds without the use of oxygen and therefore does not depend on the functioning of the mitochondrial respiratory chain. ATP is formed by substrate phosphorylation reactions. The overall equation of the process:

C 6 H 12 0 6 + 2 H 3 P0 4 + 2 ADP \u003d 2 C 3 H 6 O 3 + 2 ATP + 2 H 2 O.

anaerobic glycolysis.

During anaerobic glycolysis, all 10 reactions identical to aerobic glycolysis occur in the cytosol. Only reaction 11, where pyruvate is reduced by cytosolic NADH, is specific for anaerobic glycolysis. The reduction of pyruvate to lactate is catalyzed by lactate dehydrogenase (the reaction is reversible, and the enzyme is named after the reverse reaction). This reaction ensures the regeneration of NAD+ from NADH without the participation of the mitochondrial respiratory chain in situations associated with insufficient oxygen supply to cells.

2.2 Significance of glucose catabolism

The main physiological purpose of glucose catabolism is to use the energy released in this process for the synthesis of ATP.

Aerobic breakdown of glucose occurs in many organs and tissues and serves as the main, although not the only, source of energy for life. Some tissues are most dependent on glucose catabolism for energy. For example, brain cells consume up to 100 g of glucose per day, oxidizing it aerobically. Therefore, insufficient supply of glucose to the brain or hypoxia are manifested by symptoms indicating a violation of brain functions (dizziness, convulsions, loss of consciousness).

Anaerobic breakdown of glucose occurs in muscles, in the first minutes of muscle work, in erythrocytes (which lack mitochondria), as well as in various organs under conditions of limited oxygen supply, including tumor cells. The metabolism of tumor cells is characterized by the acceleration of both aerobic and anaerobic glycolysis. But predominant anaerobic glycolysis and an increase in lactate synthesis serve as an indicator of an increased rate of cell division with insufficient provision of them with a system of blood vessels.

In addition to the energy function, the process of glucose catabolism can also perform anabolic functions. Glycolysis metabolites are used to synthesize new compounds. Thus, fructose-6-phosphate and glyceraldehyde-3-phosphate are involved in the formation of ribose-5-phosphate, a structural component of nucleotides; 3-phosphoglycerate can be involved in the synthesis of amino acids such as serine, glycine, cysteine (see section 9). In the liver and adipose tissue, acetyl-CoA, formed from pyruvate, is used as a substrate for the biosynthesis of fatty acids and cholesterol, and dihydroxyacetone phosphate as a substrate for the synthesis of glycerol-3-phosphate.

Recovery of pyruvate to lactate.

2.3 Regulation of glucose catabolism

Since the main significance of glycolysis is the synthesis of ATP, its rate should correlate with the energy expenditure in the body.

Most of the reactions of glycolysis are reversible, with the exception of three catalyzed by hexokinase (or glucokinase), phosphofructokinase, and pyruvate kinase. Regulatory factors that change the rate of glycolysis, and hence the formation of ATP, are aimed at irreversible reactions. An indicator of ATP consumption is the accumulation of ADP and AMP. The latter is formed in a reaction catalyzed by adenylate kinase: 2 ADP - AMP + ATP

Even a small consumption of ATP leads to a noticeable increase in AMP. The ratio of the level of ATP to ADP and AMP characterizes the energy status of the cell, and its components serve as allosteric regulators of the rate of both the general path of catabolism and glycolysis.

Essential for the regulation of glycolysis is a change in the activity of phosphofructokinase, because this enzyme, as mentioned earlier, catalyzes the slowest reaction of the process.

Phosphofructokinase is activated by AMP but inhibited by ATP. AMP, by binding to the allosteric center of phosphofructokinase, increases the affinity of the enzyme for fructose-6-phosphate and increases the rate of its phosphorylation. The effect of ATP on this enzyme is an example of homotropic schüsterism, since ATP can interact with both the allosteric site and the active site, in the latter case as a substrate.

At physiological values of ATP, the active center of phosphofructokinase is always saturated with substrates (including ATP). An increase in the level of ATP relative to ADP reduces the reaction rate, since under these conditions ATP acts as an inhibitor: it binds to the allosteric center of the enzyme, causes conformational changes, and reduces the affinity for its substrates.

Changes in the activity of phosphofructokinase contribute to the regulation of the rate of glucose phosphorylation by hexokinase. A decrease in phosphofructokinase activity at a high level of ATP leads to the accumulation of both fructose-6-phosphate and glucose-6-phosphate, and the latter inhibits hexokinase. It should be recalled that hexokinase in many tissues (with the exception of the liver and pancreatic β-cells) is inhibited by glucose-6-phosphate.

High ATP levels slow down the cycle citric acid and the respiratory chain. Under these conditions, the process of glycolysis also slows down. It should be recalled that the allosteric regulation of the OPC and respiratory chain enzymes is also associated with a change in the concentration of such key products as NADH, ATP, and some metabolites. So, NADH, accumulating if it does not have time to be oxidized in the respiratory chain, inhibits some allosteric enzymes of the citrate cycle.

Regulation of glucose catabolism in skeletal muscle.

2.4 Synthesis of glucose in the liver (gluconeogenesis)

Some tissues, such as the brain, need a constant supply of glucose. When the intake of carbohydrates in the composition of food is not enough, the glucose content in the blood is maintained within the normal range for some time due to the breakdown of glycogen in the liver. However, glycogen stores in the liver are low. They significantly decrease by 6-10 hours of fasting and are almost completely exhausted after a daily fast. In this case, de novo glucose synthesis begins in the liver - gluconeogenesis.

Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate substances. Its main function is to maintain blood glucose levels during periods of prolonged fasting and intense physical exertion. The process proceeds mainly in the liver and less intensively in the cortical substance of the kidneys, as well as in the intestinal mucosa. These tissues can provide the synthesis of 80-100 g of glucose per day. The brain during fasting accounts for most of the body's need for glucose. This is due to the fact that brain cells are not able, unlike other tissues, to provide energy needs due to the oxidation of fatty acids. In addition to the brain, tissues and cells in which the aerobic pathway of decay is impossible or limited, such as erythrocytes (they lack mitochondria), cells of the retina, adrenal medulla, etc., need glucose.

The primary substrates for gluconeogenesis are lactate, amino acids, and glycerol. The inclusion of these substrates in gluconeogenesis depends on the physiological state of the organism.

Lactate is a product of anaerobic glycolysis. It is formed in all conditions of the body in red blood cells and working muscles. Thus, lactate is constantly used in gluconeogenesis.

Glycerol is released during the hydrolysis of fats in adipose tissue during fasting or during prolonged physical exertion.

Amino acids are formed as a result of the breakdown of muscle proteins and are included in gluconeogenesis during prolonged fasting or prolonged muscular work.

2.5 Synthesis of glucose from lactate

Lactate formed in anaerobic glycolysis is not a metabolic end product. The use of lactate is associated with its conversion in the liver to pyruvate. Lactate as a source of pyruvate is important not only during fasting, but during the normal functioning of the body. Its conversion to pyruvate and further use of the latter is a way to utilize lactate. Lactate, formed in intensively working muscles or in cells with a predominant anaerobic way of glucose catabolism, enters the bloodstream and then to the liver. In the liver, the NADH/NAD+ ratio is lower than in the contracting muscle; therefore, the lactate dehydrogenase reaction proceeds in the opposite direction, i.e. towards the formation of pyruvate from lactate. Further, pyruvate is included in gluconeogenesis, and the resulting glucose enters the bloodstream and is absorbed by skeletal muscles. This sequence of events is called the "glucose-lactate cycle" or "Cori cycle". The Corey cycle performs 2 important functions: 1 - ensures the utilization of lactate; 2 - prevents the accumulation of lactate and, as a consequence, a dangerous decrease in pH (lactic acidosis). Part of the pyruvate formed from lactate is oxidized by the liver to CO 2 and H 2 O. The energy of oxidation can be used to synthesize ATP, which is necessary for gluconeogenesis reactions.

Corey cycle (glucose lactate cycle). 1 - receipt of layugat from the contracting muscle with blood flow to the liver; 2 - synthesis of glucose from lactate in the liver; 3 - the flow of glucose from the liver with blood flow into the working muscle; 4 - the use of glucose as an energy substrate by the contracting muscle and the formation of lactate.

Lactic acidosis. The term "acidosis" means an increase in the acidity of the body's environment (decrease in pH) to values that are outside the normal range. Acidosis either increases proton production or decreases proton excretion (in some cases both). Metabolic acidosis occurs with an increase in the concentration of intermediate metabolic products (acidic in nature) due to an increase in their synthesis or a decrease in the rate of decay or excretion. If the acid-base state of the body is disturbed, buffer compensation systems are quickly activated (after 10-15 minutes). Pulmonary compensation ensures the stabilization of the ratio of HCO 3 -/H 2 CO 3 , which normally corresponds to 1:20, and decreases with acidosis. Pulmonary compensation is achieved by increasing the volume of ventilation and, consequently, by accelerating the removal of CO 2 from the body. However, the main role in the compensation of acidosis is played by renal mechanisms with the participation of ammonia buffer. One of the causes of metabolic acidosis may be the accumulation of lactic acid. Normally, lactate in the liver is converted back to glucose by gluconeogenesis or oxidized. In addition to the liver, other consumers of lactate are the kidneys and the heart muscle, where lactate can be oxidized to CO 2 and H 2 O and used as an energy source, especially during physical work. The level of lactate in the blood is the result of a balance between the processes of its formation and utilization. Short-term compensated lactic acidosis occurs quite often even in healthy people with intense muscular work. In untrained people, lactic acidosis during physical work occurs as a result of a relative lack of oxygen in the muscles and develops quite quickly. Compensation is carried out by hyperventilation.

With uncompensated lactic acidosis, the content of lactate in the blood increases to 5 mmol / l (normally up to 2 mmol / l). In this case, the pH of the blood can be 7.25 or less (normally 7.36-7.44). An increase in blood lactate may be due to a disorder in pyruvate metabolism.

Disorders of pyruvate metabolism in lactic acidosis. 1 - violation of the use of pyruvate in gluconeogenesis; 2 - violation of pyruvate oxidation. glucose biological catabolism gluconeogenesis

Thus, during hypoxia resulting from a disruption in the supply of tissues with oxygen or blood, the activity of the pyruvate dehydrogenase complex decreases and the oxidative decarboxylation of pyruvate decreases. Under these conditions, the equilibrium of the reaction pyruvate - lactate is shifted towards the formation of lactate. In addition, during hypoxia, ATP synthesis decreases, which consequently leads to a decrease in the rate of gluconeogenesis, another pathway for lactate utilization. An increase in lactate concentration and a decrease in intracellular pH negatively affect the activity of all enzymes, including pyruvate carboxylase, which catalyzes the initial reaction of gluconeogenesis.

The occurrence of lactic acidosis is also facilitated by violations of gluconeogenesis in liver failure of various origins. In addition, hypovitaminosis B 1 may be accompanied by lactic acidosis, since the derivative of this vitamin (thiamine diphosphate) performs a coenzyme function in the PDC during the oxidative decarboxylation of pyruvate. Thiamine deficiency can occur, for example, in alcoholics with a disturbed diet.

So, the reasons for the accumulation of lactic acid and the development of lactic acidosis can be:

activation of anaerobic glycolysis due to tissue hypoxia of various origins;

liver damage (toxic dystrophy, cirrhosis, etc.);

violation of the use of lactate due to hereditary defects in gluconeogenesis enzymes, insufficiency of glucose-6-phosphatase;

violation of the MPC due to defects in enzymes or hypovitaminosis;

the use of a number of drugs, such as biguanides (gluconeogenesis blockers used in the treatment of diabetes mellitus).

2.6 Synthesis of glucose from amino acids

Under conditions of starvation, part of the proteins in muscle tissue breaks down to amino acids, which are then included in the process of catabolism. Amino acids that catabolize into pyruvate or citrate cycle metabolites can be considered as potential precursors of glucose and glycogen and are called glycogenic. For example, oxaloacetate, formed from aspartic acid, is an intermediate product of both the citrate cycle and gluconeogenesis.

Of all the amino acids entering the liver, approximately 30% is accounted for by alanine. This is due to the fact that during the breakdown of muscle proteins, amino acids are formed, many of which are converted immediately to pyruvate or first to oxaloacetate, and then to pyruvate. The latter turns into alanine, acquiring an amino group from other amino acids. Alanine from the muscles is transported by the blood to the liver, where it is again converted to pyruvate, which is partially oxidized and partially included in glucose neogenesis. Therefore, there is the following sequence of events (glucose-alanine cycle): muscle glucose > muscle pyruvate > muscle alanine > liver alanine > liver glucose > muscle glucose. The whole cycle does not lead to an increase in the amount of glucose in the muscles, but it solves the problems of transporting amine nitrogen from the muscles to the liver and prevents lactic acidosis.

Glucose-alanine cycle

2.7 Synthesis of glucose from glycerol

Glycerol can only be used in tissues that contain the enzyme glycerol kinase, such as the liver, kidneys. This ATP-dependent enzyme catalyzes the conversion of glycerol to β-glycerophosphate (glycerol-3-phosphate). When glycerol-3-phosphate is included in gluconeogenesis, it is dehydrogenated by NAD-dependent dehydrogenase to form dihydroxyacetone phosphate, which is then converted into glucose.

The conversion of glycerol to dihydroxyacetone phosphate

Thus, we can say that the biological role of glucose in the body is very large. Glucose is one of the main energy source of our body. It is an easily digestible source of valuable nutrition that increases the energy reserves of the body and improves its functions. The main value in the body is that it is the most versatile source of energy for metabolic processes.

In the human body, the use of hypertonic glucose solution promotes vasodilation, increased contractile activity of the heart muscle and an increase in urine volume. As a general tonic, glucose is used in chronic diseases that are accompanied by physical exhaustion. The detoxifying properties of glucose are due to its ability to activate the functions of the liver to neutralize poisons, as well as a decrease in the concentration of toxins in the blood as a result of an increase in the volume of circulating fluid and increased urination. In addition, in animals it is deposited in the form of glycogen, in plants - in the form of starch, the polymer of glucose - cellulose is the main component of the cell membranes of all higher plants. In animals, glucose helps to survive frosts.

In short, glucose is one of the vital substances in the life of living organisms.

List of used literature

1. Biochemistry: a textbook for universities / ed. E.S. Severina - 5th ed., - 2014. - 301-350 st.

2. T.T. Berezov, B.F. Korovkin Biological Chemistry.

3. Clinical endocrinology. Guide / N. T. Starkova. - 3rd edition, revised and expanded. - St. Petersburg: Peter, 2002. - S. 209-213. - 576 p.

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What is glucose?

Glucose is also called "grape sugar", since the largest amount of it is found in grape juice. There is also a fairly high content in all ripe fruits and berries, in addition, glucose is part of sugar and honey.

"Grape sugar" is a colorless crystalline compound in powder form, highly soluble in water and having a sweet taste. The melting point fluctuates within 146 degrees. This compound belongs to the group of polyhydric alcohols and monosaccharides, that is, those groups of substances that, upon hydrolysis (dissolution in water), do not decompose into simpler constituent molecules.

The use of glucose is very extensive.

Glucose is formed during photosynthesis in the green parts of plants, and from it, in turn, glycogen is synthesized, which, when interacting with creatine phosphate, is transformed into adenosine triphosphoric acid (ATP), which is the main energy supplier.

The benefits of "grape sugar" for the body

Consider the chemical properties of glucose, its application in various fields.

Since it is a monosaccharide, immediately after eating glucose, it is quickly absorbed in the intestines, after which processes are carried out aimed at oxidizing it, in order to release free and so necessary energy for our body. In addition, it is very nutritious and is the main source of energy for the adequate functioning of the brain. In fact, the energy that is formed in the process of oxidation is about one third of the total energy of a living organism.

Glucose: properties and uses

However, as with everything, balance is also needed here. Everything is good in moderation: so, with a lack of energy, we become lethargic, we lose concentration, our attention decreases. Conversely, with an increase in its level, the synthesis of the main hormone-antagonist of glucose, the pancreatic hormone insulin, increases, which leads, accordingly, to a decrease in the level of sugar concentration in the blood. If these interactions are violated, such an endogenous disease as diabetes mellitus develops.

Being a small compound, natural sugar is involved in the formation of more complex compounds, such as, for example, starch and glycogen. It is these polysaccharides that form the basis for cartilage, ligaments and hair.

How does it accumulate?

Our body is quite thrifty, so it “lays off” glycogen (the main carbohydrate reserve) for unforeseen situations (for example, heavy physical exertion). Glucose accumulates in muscle tissue, in the blood (with a concentration equal to 0.1-0.12% of total sugar) and in individual cells. Now it becomes quite obvious that the level of sugar rises after eating and decreases with exercise and fasting. This leads to the development of such a pathological condition as hypoglycemia, with the development and increase in the degree of excitability, anxiety, accompanied by muscle tremors and fainting.

The use of glucose in sports

It is used as a means to increase the level of endurance, provides the highest level of performance for athletes and athletes, since its calorie content is almost two times lower than that of fatty foods. But at the same time, it oxidizes much faster, thereby ensuring a fairly rapid intake of “fast carbohydrate” into the blood, which is so necessary after exhausting workouts or competitions. To achieve these goals, glucose is used in the form of tablets, infusion and injection solutions, or an isotonic solution (dissolved in water).

Indications for the use of glucose will be diverse.

Glucose is very important for bodybuilders, because with its lack, not only a decline in strength is observed, the deterioration of cellular and, as a result, tissue metabolism, but also the possibility of gaining body weight is significantly reduced. Why is this happening?

After all, the athlete in this situation deliberately consumes a huge amount of sugar, so why then do we observe weight loss? The paradox is that at the same time, bodybuilders are training a lot. In addition, huge doses of glucose significantly increase cholesterol levels, and also contribute to the development of such endocrine pathology as diabetes mellitus. Glucose is deposited in the form of fatty compounds, which, in fact, the athlete fights.

The structure, properties, use of glucose have been studied for a long time.

Rules of use

There are rules for the use of this sugar: before the start of a workout, you should not get carried away with sugary drinks, as this threatens to faint as a result of a sharp drop in glucose concentration due to insulin production. The most optimal intake of glucose immediately after the end of classes, during the so-called carbohydrate window. To prepare the above isotonic drink, you need to take 14 glucose tablets, each weighing 0.5 grams, and a liter of plain purified boiled water. Next, you need to dilute the sugar in a liquid and take it every 15-20 minutes for an hour.

Application in industry

Food industry: as a substitute for sucrose, as a raw material for the production of dietary products.
Confectionery industry: part of sweets, chocolate, cakes; production of molasses necessary for the preparation of marmalade and gingerbread.
The production of ice cream is based on the ability of glucose to lower the level of freezing of this product, while increasing its density and hardness.
Production of bakery food products: creates favorable conditions for fermentation processes, which entails an improvement not only taste properties but also organoleptic.

What is another use of glucose tablets?

Application in medicine

Natural sugar has detoxifying and metabolic properties, on which its use in medical practice is based.

The monosaccharide is available in the following forms:

Glucose tablets. Instructions for use says that it contains 0.5 grams of dry matter dextrose. When administered orally (through the mouth), it has a vasodilating and sedative effect, replenishing the energy reserves of the body, thereby contributing to an increase in the intellectual level of development and physical activity person.
In the form of a solution for infusion injections. One liter of 5% glucose solution accounts for 50.0 grams of dry matter dextrose, 10% solution, respectively, contain 100.0 g, 20% mixture - 200.0 g of active ingredient. It should be taken into account that a 5% saccharide solution is isotonic to blood plasma, so its administration as an infusion contributes to the normalization of the acid-base balance and water-electrolyte balance.
The solution in the form of intravenous injections increases the osmotic pressure of the blood, dilates blood vessels, increases the outflow of fluid from the tissues, increases urination, which, in turn, ensures the activation of metabolic processes in the liver and the normalization of the contractile activity of the heart muscle.

Indications for use

Instructions for the use of glucose indicate that the indications for use are:

Low concentration of blood sugar levels (phenomena of hypoglycemia, hypoglycemic coma).
Significant mental (intellectual) and physical stress.
For speedy recovery during the rehabilitation period after surgery or protracted diseases.
As a complex therapy for decompensation of pathological processes, presented in the form of cardiac insufficiency, intestinal pathologies, hemorrhagic diathesis, or diseases affecting the liver or kidneys.
collapsible state.
Shock state of any genesis.
Dehydration regardless of the source of origin.
The period of intoxication with narcotic drugs, various chemical compounds.
In pregnant women to increase weight gain in the fetus.

special instructions

For glucose, the instructions for use confirm that concentrated solutions (10%, 25%, 40%) are used only for intravenous administration at the same time no more than 20-50 milliliters, with the exception of emergency situations in the form of massive blood loss, hypoglycemia. In these cases, up to 300 milliliters per day is infused. The doctor must remember, and the patient must take into account the synergistic interaction (mutual reinforcing effect on each other) of glucose and ascorbic acid. Tablet preparations are taken in a dosage of 1-2 pieces with an increase of up to 10, depending on the need.

It is imperative to take into account that dextrose has the ability to weaken the action of glycosides for the heart by the fact that they are inactivated and oxidized. Accordingly, you need to take a break between the methods of these funds. Also, the effectiveness of the following drugs is reduced by glucose:

nystatin;
analgesics;
streptomycin;
adrenomimetic agents.

If a person has hyponatremia and renal failure, then it is necessary to take glucose with caution, to constantly monitor the indicators of central hemodynamics. According to indications, it is prescribed during pregnancy and lactation. Children under 5 years of age are not prescribed a tablet form for the reason that they cannot yet dissolve the tablet under the tongue. Glucose is often prescribed for alcohol intoxication and various poisonings.

Contraindications to the use of glucose

Do not prescribe the drug when a person has:

diabetes;
any pathological condition accompanied by a drop in blood sugar levels;
cases of individual intolerance (development of the phenomena of drug or food allergies).

Conclusion

You need to understand that you need a reasonable use of both glucose and all foods, drugs. Otherwise, it threatens with a failure in the regulation, in particular of the endocrine system, a decrease in the level of not only working capacity and physical activity, but also the quality of life.

We have considered glucose - a representative of monosaccharides. The chemical structure, properties, application are described in detail.

What is glucose? Obtaining glucose and its properties. Why is glucose needed in the human body?

What is glucose. General information?

The role of glucose in the human body

Glucose - indications and contraindications for use

Contraindications - to whom glucose is dangerous

Glucose fermentation

Glucose: about the harm it brings to the body. What is dangerous in excess quantities

What is dangerous lack of glucose

Glucose: about contraindications. Who should not use it and why?

Glucose: about the beneficial properties of a monosaccharide

What foods are high in glucose

What is glucose?

Properties of glucose

What are the benefits of glucose?

Various conversions of glucose into energy

The use of pure glucose

The norm of glucose in the blood

Chemical composition

Significance in the life of animals and humans

Surplus and deficiency

Use of glucose

Who benefits from glucose

Release form

Contraindications and side effects

Unusual uses of glucose

Definition

Physical properties of glucose

Chemical properties of glucose

glucose and food

Hormones-regulators

How to measure blood glucose?

Excess blood glucose

Low blood glucose

Glucose and medicine

Application

Properties of glucose

What are the benefits of glucose?

Various conversions of glucose into energy

The use of pure glucose

The norm of glucose in the blood

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Similar Documents

What is glucose?

The benefits of "grape sugar" for the body

Glucose: properties and uses

How does it accumulate?

The use of glucose in sports

Rules of use

Application in industry

Application in medicine

Indications for use

special instructions

Contraindications to the use of glucose

Conclusion