What chemical elements does a human being consist of? What does a person consist of, each component of it? What is in the composition of blood, bones, skin, hair, muscles
Introduction.
Elemental composition of organisms.
Molecules and ions that make up the human body, their content and functions.
Levels of structural organization of chemical compounds of living organisms.
General patterns of metabolism and energy in the human body.
Features of the flow of metabolic processes in various conditions of the body.
Introduction. What does biochemistry do?
Biochemistry studies the chemical processes occurring in living systems. In other words, biochemistry studies the chemistry of life. This science is relatively young. She was born in the 20th century. Conventionally, the course of biochemistry can be divided into three parts.
General biochemistry deals with the general laws of the chemical composition and metabolism of various living beings from the smallest microorganisms to humans. It turned out that these patterns are largely repeated.
Private biochemistry deals with the features of chemical processes occurring in certain groups of living beings. For example, biochemical processes in plants, animals, fungi and microorganisms have their own characteristics, and in some cases very significant ones.
functional biochemistry deals with the peculiarities of biochemical processes occurring in individual organisms, associated with the characteristics of their lifestyle. The direction of functional biochemistry, investigating the effect of physical exercises on the body of an athlete is called biochemistry of sports orsports biochemistry.
Development physical education and sport requires from athletes and coaches good knowledge in the field of biochemistry. This is due to the fact that without understanding how the body works at the chemical, molecular level, it is difficult to hope for success in modern sports. Many training and recovery methods are based in our time on a deep understanding of how the body works at the subcellular and molecular level. Without a deep understanding of biochemical processes, it is impossible to fight with doping - an evil that can ruin the sport.
Elemental composition of organisms
The human body includes chemical elements that are also found in inanimate nature. However, in terms of quantity chemical elements living organisms differ significantly from inanimate nature. For example, the quantitative content of iron and silicon in inanimate nature is significantly higher than in living organisms. A characteristic distinguishing feature of living organisms is a high carbon content, which is associated with the predominance of organic compounds in them.
The human body consists of structural elements: C-carbon, O-oxygen, H-hydrogen, N-nitrogen, Ca-calcium, Mg-magnesium, Na-sodium, K-potassium, S-sulfur, P-phosphorus, Cl-chlorine . For example, H 2 O, a water molecule, consists of two hydrogen atoms and one oxygen atom. 70-80% human body is made up of water. However, the fluids in the human body, in its cells, in its blood include, in addition to water, 0.9% NaCl salt, the molecule of which consists of sodium and chlorine. All biochemical processes occur precisely in a 0.9% aqueous solution of common salt, which is called saline. Therefore, even drugs for injections and droppers are dissolved in saline.
The human body contains about 3 kg of minerals, which is 4% of body weight. Mineral composition organism is very diverse and in it you can find almost the entire periodic table.
Minerals are distributed in the body extremely unevenly. in blood, muscles, internal organs the mineral content is low - about 1%. But in the bones, the share of minerals accounts for about half of the mass. Tooth enamel is 98% mineral.
The forms of existence of mineral substances in the body are also diverse.
First, they occur in the bones in the form of insoluble salts.
Secondly, mineral elements can be part of organic compounds.
Thirdly, mineral elements can be found in the body in the form of ions.
The daily need for minerals is small and they enter the body with food. Their amount is usually sufficient in food. However, in rare cases, they may not be enough. For example, in some areas there is not enough iodine, in others there is an excess of magnesium and calcium.
Minerals are excreted from the body in three ways in the composition of urine, the intestines - in the composition of feces and with sweat - the skin.
The biological role of these substances of these substances is very diverse.
About 90 elements of the D.I. table were found in the human and animal body. Mendeleev. Biogenic chemical elements- chemical elements present in living organisms. According to their quantitative content, they are usually divided into several groups:
Macronutrients.
Microelements.
Ultramicroelements.
If the mass fraction of an element in the body exceeds 10 -2%, then it should be considered macronutrient. Share trace elements in the body is 10 -3 -10 -5%. If the content of an element is below 10-5%, it is considered ultramicroelement. Of course, such a gradation is conditional. Through it, magnesium enters the intermediate region between macro- and microelements.
Minerals in the human body are in different states. In accordance with this, their action is also manifested.
One from forms - this is when they are an integral part of organic substances. So, for example, sulfur is part of the amino acids cysteine and methionine, iron is integral part hemoglobin, iodine - thyroid hormone - thyroxine, phosphorus is present in a variety of organic compounds - ATP, ADP, other nucleotides, nucleic acids, phosphatides (lecithins and cephalins), various esters with hexoses, trioses, etc.
Second form - these are strong insoluble deposits of salts of carbonate, calcium and magnesium phosphate, fluoride and other salts in hard tissues - in bones, teeth, horns, hooves, feathers, etc. They make up their mineral backbone.
And third form - minerals dissolved in tissue fluids. This group of minerals provides a number of conditions necessary for the preservation of the vital processes of the body. These conditions include osmotic pressure, the reaction of the environment, the colloidal state of proteins, the state of the nervous system, etc. These conditions, in turn, depend on the amount of mineral elements, their ratio, and the qualitative characteristics of the latter.
The whole variety of substances of the animal and plant world is built from a relatively small number of initial components. These are the chemical elements chemical substances. Of the 107 known chemical elements, 60 have been found in living organisms, however, only 22 are found in concentrations that make it possible not to consider this element as an accidental impurity. All chemical elements found in living organisms are divided into three groups according to their concentration in cells:
Macronutrients: C, H, O, N, P, S, Cl, Na, K, Ca.
They account for more than 0.01%. The number of macronutrients is shown in the table; Trace elements: Fe, Mg, Zn, Cu, Co, J, Br, V, F, Mo, Al, Si, etc.
They account for from 0.01 to 0.000001%;
Ultramicroelements: Hg, Au, Ag, Ra, etc. They account for less than 0.000001%.
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Macronutrients make up about 99.9% of the mass of the cell and can be divided into two groups. Main biogenic chemical elements (oxygen, carbon, hydrogen, nitrogen) make up 98% of the mass of all living cells. They form the basis of organic compounds, and also form water, which is present in all living systems in significant quantities. The second group of macronutrients includes phosphorus, potassium, sulfur, chlorine, calcium, magnesium, sodium, iron, totaling 1.9%. They are extremely important for ensuring the vital activity of organisms; without them, the existence of any living beings is impossible.
sodium and potassium found in the body in the form of ions. Sodium ions are found outside the cells, while potassium ions are concentrated inside the cell. These ions play an important role in creating osmotic pressure and cell potential, which are necessary for the normal functioning of the myocardium.
Potassium. About 90% of potassium is inside the cells. It, together with other salts, provides osmotic pressure; involved in the transfer nerve impulses;regulation of water-salt metabolism; promotes the removal of water, and, consequently, toxins from the body; maintains the acid-base balance of the internal environment of the body; participates in the regulation of the activity of the heart and other organs; necessary for the functioning of a number of enzymes.
Potassium is well absorbed from the intestines, and its excess is quickly removed from the body with urine. The daily requirement for potassium in an adult is 2000-4000 mg. It increases with profuse sweating, with the use of diuretics, diseases of the heart and liver. Potassium is not a deficient nutrient in the diet, and with a varied diet, potassium deficiency does not occur. Potassium deficiency in the body appears when the function of the neuromuscular and cardiovascular systems is impaired, drowsiness, lowering blood pressure, and cardiac arrhythmias. In such cases, a potassium diet is prescribed.
Most potassium comes from plant foods. Its rich sources are apricots, prunes, raisins, spinach, seaweed, beans, peas, potatoes, other vegetables and fruits (100 - 600 mg / 100 g of product). Less potassium is found in sour cream, rice, bread made from premium flour (100 - 200 mg / 100 g).
Sodium found in all tissues and body fluids. He is involved in maintaining osmotic pressure in tissue fluids and blood; in the transmission of nerve impulses; regulation of acid-base balance, water-salt metabolism; increases the activity of digestive enzymes.
calcium and magnesium are found mainly in inert tissue in the form of insoluble salts. These salts give bones hardness. In addition, in ionic form, they play an important role in muscle contraction.
Calcium. It is the main structural component of bones and teeth; is part of the nuclei of cells, cell and tissue fluids, is necessary for blood clotting. Calcium forms compounds with proteins, phospholipids, organic acids; participates in the regulation of the permeability of cell membranes, in the transmission of nerve impulses, in the molecular mechanism of muscle contractions, controls the activity of a number of enzymes. Thus, calcium performs not only plastic functions, but also affects many biochemical and physiological processes in the body.
Calcium is a hard-to-digest element. Calcium compounds entering the human body with food are practically insoluble in water. The alkaline environment of the large intestine promotes the formation of indigestible calcium compounds, and only the action of bile acids ensures its absorption.
The assimilation of calcium by tissues depends not only on its content in foods, but also on its ratio with other food components and, first of all, with fats, magnesium, phosphorus, and proteins. With an excess of fat, there is competition for bile acids and a significant part of the calcium is excreted from the body through the large intestine. Absorption of calcium is adversely affected by an excess of magnesium; the recommended ratio of these elements is 1:0.5. The strongest bones are obtained with a Ca:P ratio of 1:1.7. This ratio is approximately the same in strawberries and walnuts. If the amount of phosphorus exceeds the level of calcium in food by more than 2 times, then soluble salts are formed, which are extracted by blood from bone tissue . Calcium enters the walls of blood vessels, which causes their fragility, as well as into the tissues of the kidneys, which can contribute to the occurrence of kidney stones. For adults, the recommended ratio of calcium and phosphorus in food is 1:1.5. The difficulty in maintaining this ratio is due to the fact that most commonly consumed foods are much richer in phosphorus than in calcium. Phytin and oxalic acid, contained in a number of plant products, have a negative effect on the absorption of calcium. These compounds form insoluble salts with calcium.
The daily requirement for calcium in an adult is 800 mg, and in children and adolescents - 1000 mg or more.
With insufficient intake of calcium or in violation of its absorption in the body (with a lack of vitamin D), a state of calcium deficiency develops. There is an increased excretion of it from bones and teeth. In adults, osteoporosis develops - demineralization of bone tissue, in children, the formation of the skeleton is disturbed, rickets develops.
The best sources of calcium are milk and dairy products, various cheeses and cottage cheese (100-1000 mg / 100 g of product), green onions, parsley, beans. Significantly less calcium is found in eggs, meat, fish, vegetables, fruits, berries (20-40 mg / 100 g of product).
Magnesium.,
With a lack of magnesium, the absorption of food is disrupted, growth is delayed, calcium is deposited in the walls of blood vessels, and a number of other pathological phenomena develop. In humans, a lack of magnesium ions, due to the nature of nutrition, is extremely unlikely. However, large losses of this element can occur with diarrhea.
Phosphorus plays an important role in the body. It is an integral part of the salts that make up the bones. Phosphoric acid plays an extremely important role in energy metabolism. Phosphorus. Phosphorus is found in all tissues of the body, especially muscles and the brain. This element is involved in all life processes of the body. : synthesis and breakdown of substances in cells; regulation of metabolism; is a part of nucleic acids and a number of enzymes; needed for the formation of ATP.
Phosphorus is found in body tissues and food products in the form of phosphoric acid and its organic compounds (phosphates). Its main mass is in the bone tissue in the form of calcium phosphate, the rest of the phosphorus is part of the soft tissues and fluids. In the muscles, the most intensive exchange of phosphorus compounds occurs. Phosphoric acid is involved in the construction of the molecules of many enzymes, nucleic acids, etc.
With a long-term deficiency of phosphorus in the diet, the body uses its own phosphorus from bone tissue. This leads to demineralization of bones and a violation of their structure - rarefaction. When the body is depleted of phosphorus, mental and physical performance decreases, loss of appetite, apathy is noted.
The daily requirement for phosphorus for adults is 1200 mg. It increases with great physical or mental stress, with certain diseases.
A large amount of phosphorus is found in animal products, especially in the liver, caviar, as well as in cereals and legumes. Its content in these products ranges from 100 to 500 mg per 100 g of product. Cereals (oatmeal, pearl barley) are a rich source of phosphorus, they contain 300-350 mg of phosphorus / 100 g. However, phosphorus compounds are absorbed from plant products worse than when eating food of animal origin.
Sulfur. The importance of this element in nutrition is determined, first of all, by the fact that it is part of proteins in the form of sulfur-containing amino acids. (methionine and cystine), and is also an integral part of some hormones and vitamins.
As a component of sulfur-containing amino acids, sulfur is involved in the processes of protein metabolism, and the need for it increases sharply during pregnancy and body growth, accompanied by the active inclusion of proteins in the resulting tissues, as well as during inflammatory processes. Sulfur-containing amino acids, especially in combination with vitamins C and E, have a pronounced antioxidant effect. Along with zinc and silicon, sulfur determines the functional state of hair and skin.
Chlorine. This element is involved in the formation of gastric juice, the formation of plasma, activates a number of enzymes. This nutrient is easily absorbed from the intestines into the blood. The ability of chlorine to be deposited in the skin, to linger in the body with excessive intake, and to be excreted with sweat in significant quantities is interesting. The excretion of chlorine from the body occurs mainly with urine (90%) and sweat.
Violations in the exchange of chlorine lead to the development of edema, insufficient secretion of gastric juice, etc. A sharp decrease in the content of chlorine in the body can lead to a serious condition, even death. An increase in its concentration in the blood occurs with dehydration of the body, as well as with a violation of the excretory function of the kidneys.
The daily requirement for chlorine is approximately 5000 mg. Chlorine enters the human body mainly in the form of sodium chloride when added to food.
Magnesium. This element is required for the activity of a number of key enzymes. , providing the body's metabolism. Magnesium is involved in maintaining the normal function of the nervous system and heart muscles; has a vasodilating effect; stimulates bile secretion; increases the motor activity of the intestine, which contributes to the removal of toxins from the body (including cholesterol).
Magnesium absorption is hindered by the presence of phytin and excess fat and calcium in food. The daily requirement for magnesium is not precisely defined; it is believed, however, that a dose of 200-300 mg / day prevents the manifestation of deficiency (it is assumed that about 30% of magnesium is absorbed).
With a lack of magnesium, the absorption of food is disturbed, growth is delayed, and calcium is deposited in the walls of blood vessels.
Iron is part of hema, component part hemoglobin. This element is necessary for the biosynthesis of compounds that provide respiration, hematopoiesis; it participates in immunobiological and redox reactions; is part of the cytoplasm, cell nuclei and a number of enzymes.
Iron assimilation is prevented by oxalic acid and phytin. For the assimilation of this nutrient, vitamin B 12 is required. Ascorbic acid also contributes to the absorption of iron, since iron is absorbed in the form of a divalent ion.
A lack of iron in the body can lead to the development of anemia, gas exchange, cellular respiration, that is, the fundamental processes that ensure life, are disrupted. The development of iron deficiency states is facilitated by: insufficient intake of iron in an assimilated form, a decrease in the secretory activity of the stomach, a deficiency of vitamins (especially B 12, folic and ascorbic acids) and a number of diseases that cause blood loss. The iron requirement of an adult (14 mg/day) is met in excess by the normal diet. However, when bread from fine flour containing little iron is used in food, iron deficiency is very often observed in urban residents. At the same time, it should be taken into account that grain products rich in phosphates and phytin form sparingly soluble compounds with iron and reduce its assimilation by the body.
Iron is a widespread element. It is found in offal, meat, eggs, beans, vegetables, berries. However, in an easily digestible form, iron is found only in meat products, liver (up to 2000 mg / 100 g of product), egg yolk.
trace elements (manganese, copper, zinc, cobalt, nickel, iodine, fluorine) make up less than 0.1% of the mass of living organisms. However, these elements are necessary for the life of organisms. trace elements contained in very low concentrations. Their need per day is micrograms, that is, millionths of a gram. Of these, there are irreplaceable and conditionally irreplaceable.
Indispensable: Ag-silver, Co-cobalt, Cu-copper, Cr-chromium, F-fluorine, Fe - iron, I-iodine, Li - lithium, Mn - manganese, Mo - molybdenum, Ni - nickel, Se - selenium, Si - silicon, V - vanadium, Zn - zinc.
Conditionally indispensable: B - boron, Br - bromine.
Possibly indispensable: Al - aluminum, As - arsenic, Cd - cadmium, Pb - lead, Rb - rubidium.
Manganese has a beneficial effect on nervous system, contributes to the production of neurotransmitters - substances responsible for the transmission of impulses between the fibers of the nervous tissue, also contributes to the normal development of bones, strengthens the immune system, contributes to the normal course of the digestive process of insulin and fat metabolism. In addition, the process of metabolism of vitamins A, C and group B can only occur normally if there is a sufficient amount of manganese in the body. Thanks to manganese, the normal process of cell formation and growth, the growth and restoration of cartilage, the fastest healing of tissues, good brain function and proper metabolism are ensured, and it has excellent antioxidant properties. This element regulates the balance of blood sugar, and also contributes to the normal process of milk production in lactating women. Optimal manganese content can be achieved through the use of raw vegetables, fruits and herbs.
The role of copper in the body huge. First of all, it takes an active part in the construction of many of the proteins and enzymes we need, as well as in the processes of growth and development of cells and tissues. Copper is necessary for the normal process of hematopoiesis and the functioning of the immune system. Copper- is part of the oxidative enzymes involved in the synthesis of cytochromes.
Zinc- is part of the enzymes involved in alcoholic fermentation, in the composition insulin
Cobalt affects the physiological and pathophysiological state of the human body. There is information about its effect on the metabolism of carbohydrates and lipids, on the function of the thyroid gland, the state of the myocardium. Vitamin B12 contains cobalt.
For the human body and animals nickel is an essential nutrient, but scientists know little about its biological role. In animal and plant organisms, it is involved in enzymatic reactions, and in birds it accumulates in feathers. We have it in the liver and kidneys, pancreas, pituitary gland and lungs. Nickel affects the processes of hematopoiesis, preserves the structure of nucleic acids and cell membranes; participates in the exchange of vitamins C and B12, calcium and other substances.
Iodine very important for normal growth and development of children and adolescents: it is involved in the formation of bone and cartilage tissue, protein synthesis, stimulates mental abilities, improves performance and reduces fatigue. In the body, iodine is involved in the synthesis of thyroxine and triiodothyronine, hormones necessary for the normal functioning of the thyroid gland.
Fluorine necessary for the formation of tooth enamel, iodine is part of the thyroid hormones, cobalt is an integral part of vitamin B12.
To ultramicroelements include a large number of chemical elements (lithium, silicon, tin, selenium, titanium, mercury, gold, silver, and many others), which in total make up less than 0.01% of the cell mass. For a number of ultramicroelements, their biological significance has been established, for others not. Perhaps the accumulation of some of them in the cells and tissues of humans and other organisms is random and is associated with anthropogenic pollution of the environment. On the other hand, it is possible that the biological significance of a number of ultramicroelements has not yet been revealed.
Lithium helps to reduce nervous excitability, improves the general condition in diseases of the nervous system, has anti-allergic and anti-anaphylactic effects, has some effect on neuroendocrine processes, takes part in carbohydrate and lipid metabolism, improves immunity, neutralizes the effects of radiation and salts heavy metals on the body, as well as the effect of ethyl alcohol.
Silicon participates in the body's absorption of more than 70 mineral salts and vitamins, promotes the absorption of calcium and bone growth, prevents osteoporosis, stimulates the immune system. Silicon is necessary for healthy hair, improves the condition of nails and skin, strengthens connective tissues and blood vessels, reduces the risk of cardiovascular disease, strengthens joints - cartilage and tendons.
It is known that tin improves growth processes, is one of the components of the gastric enzyme gastrin, affects the activity of flavin enzymes (biocatalysts of some redox reactions in the body), plays an essential role in the proper development of bone tissues.
Selenium- participates in the regulatory processes of the body. Selenium, being a part of the enzyme glutathione peroxidase, prevents blood clots from settling on the walls of blood vessels, due to which it is an antioxidant and prevents the development of atherosclerosis. Not so long ago it was found that the lack of selenium leads to the development of cancer.
Titanium is a permanent component of the body and performs certain vital functions: it increases erythropoiesis, catalyzes the synthesis of hemoglobin, immunogenesis, stimulates phagocytosis and activates the reactions of cellular and humoral immunity.
Mercury has a certain biotic effect and has a stimulating effect on vital processes (in quantities corresponding to physiological, i.e., normal for humans, concentrations). There is information about the presence of mercury in the nuclear fraction of living cells and about the importance of this metal in the realization of the information embedded in DNA and its transmission with the help of transfer RNA. In simpler terms, the complete removal of mercury from the body is apparently undesirable, and the same 13 mg, "embedded" in us by nature, should always be contained in a person (which, by the way, is in full agreement with the Clark-Vernadsky law on the general dispersion of elements mentioned above) .
Goldandsilver have a bactericidal effect Many microelements and ultramicroelements in large quantities toxic to humans.
Lack or excess in the diet of any mineral substances causes a violation of the metabolism of proteins, fats, carbohydrates, vitamins, which leads to the development of a number of diseases. The most common consequence of a discrepancy in the amount of calcium and phosphorus in the diet is dental caries, bone thinning. With a lack of fluoride in drinking water, tooth enamel is destroyed, iodine deficiency in food and water leads to thyroid diseases. Thus, minerals are very important for the elimination and prevention of a number of diseases.
The presented tables show the characteristic (typical) symptoms of a deficiency of various chemical elements in the human body:
In accordance with the recommendation of the dietary commission of the US National Academy of Sciences, the daily intake of chemical elements with food should be at a certain level (Table 5.2). The same number of chemical elements must be excreted daily from the body, since their content in it is relatively constant.
The role of minerals in the human body is extremely diverse, despite the fact that they are not an essential component of nutrition. Mineral substances are contained in protoplasm and biological fluids, play a major role in ensuring the constancy of osmotic pressure, which is necessary condition for the normal functioning of cells and tissues. They are part of complex organic compounds (for example, hemoglobin, hormones, enzymes), are a plastic material for building bone and dental tissue. In the form of ions, mineral substances are involved in the transmission of nerve impulses, provide blood clotting and other physiological processes of the body.
ions macro-andtrace elements actively transported enzymes through the cell membrane. Only in the composition of enzymes, ions of macro- and microelements can perform their function. Therefore, foods and medicinal herbs are preferred over chemotherapy drugs for the treatment of hypomicroelementosis. In addition, given that the human body takes the microelement exactly as much as it needs from products and plants, this helps to avoid hypermicroelementosis. And the excess of macro- and microelements in the body is much more dangerous than their lack. When calcium chemicals are used, calcium deposits are typical in the mammary glands, gallbladder, liver, kidneys, in general, anywhere, but not in the bones
Enzymes are small particles that actively ensure the operation of all functional systems. They produce digestion, for example, salivary amylase (diastase) digests potato and cereal starches, pancreatic lipase digests fats, chymotrypsin digests proteins, etc. In addition, enzymes “pull” the necessary substances through cell membranes, for example, active transport of calcium, sodium, chlorine and other ions is carried out in the kidneys, and, therefore, they regulate the calcium composition of bones and blood pressure. The enzyme lysozyme "kills" harmful microbes. The cytochrome P-450 enzyme is involved in many biochemical reactions, for example, it decomposes chemical drugs and removes them from cells, oxidizes cholesterol to steroid hormones (i.e. produces hormones), etc. There are thousands of these little hard workers, enzymes, in the body, and there are no biochemical and physiological transformations in which they would not participate. Like a functional element of the microcirculation of an organ, so enzyme- this is the primary element, the fundamental principle of any processes, and this should always be taken into account in the treatment of the disease. It is very important to know that there are no enzymes in chemical medicine, but herbs and foods do. For example, horseradish roots contain the enzyme lysozyme. In addition, there are enzymes in honey, for example, invertase, diastase, catalase, phosphatase, peroxidase, lipase, etc. Honey is undesirable to melt and heat above 38 0, because then the enzymes break down.
Part enzyme includes several protein molecules interconnected and representing in the microcosm a huge size and two small parts, one of them is a vitamin, the second is a microelement. That is why herbal treatment is preferable to chemistry, because the herb contains proteins, vitamins, and microelements - this harmonious composition of the enzyme was created by the Creator. Natural foods, such as honey, contain all 22 essential amino acids that are needed for protein synthesis. Honey contains macronutrients, all essential trace elements except fluorine, iodine and selenium, as well as almost all conditionally essential trace elements. Conversely, chemical medicines produced by industry are associated in a special and incomprehensible way with the father of industry, Cain. And the consequence of such a connection is the deprivation of pharmacological agents consisting of one chemical formula, of all the wealth of the world created by the Creator, one of the small industrious first particles of which is enzyme.
The human body is not yet fully understood. But scientists were able to answer the question of what the human body consists of.
- Carbon boasts not only the largest number of chemical compounds in the periodic table, (the most famous of them are coal and oil). It also occupies an honorable second place in our list.
- Hydrogen like oxygen, which is a constituent element of air and drinking water. And it also applies to the main components of the human body. 10% of our weight is hydrogen.
- Although nitrogen also found in air, it is better known as a heat transfer fluid, in liquid form. Still, its mysteriously evaporating gases should not be misleading - 3% of our body mass is made up of nitrogen.
- Even if it is only 1.5%, calcium- important metal in our body. It is he who gives strength to our bones and teeth.
- Phosphorus, as a luminous substance, is known to everyone. But not everyone knows that it is thanks to phosphorus in the body that DNA is formed, the basis of human life.
- Potassium, with a modest 0.2%, takes little part in the processes of the body. It belongs to the electrolytes that our body needs, first of all, during sports. Its deficiency can cause a feeling of exhaustion and convulsions.
- Can sulfur, with its unpleasant appearance and smell, be important for our body? Yes, that's right. Sulfur - essential component amino acids and coenzymes.
- First sulfur, now chlorine. You might think that our body consists of some poisons. Of course, there is no elemental chlorine in our body, but there is chloride. And it is vitally important for us, since it is contained, for example, in blood plasma.
- Sodium we consume primarily in the form of sodium chloride, also known as salt. The element is important for the protection of cells and the movement of nerve signals.
- Magnesium vital for all organisms on earth, naturally for us humans, too.
Despite its small fraction of 0.05% of our body weight, a lack of magnesium leads to distinctly tangible consequences: Nervousness, headaches, fatigue and muscle cramps are just some of them. - The male body contains more gland than female. One of the reasons for this is the difference in nutrition. The other is women lose iron during menstruation. Therefore, the average mass of this element in the human body varies from 2 to 5 grams.
- Cobalt- an integral part of vitamin B12, which is necessary for human existence. An overdose of cobalt leads to numerous diseases, including cancerous tumors.
- For microorganisms copper lethal even in small quantities, but a person needs it for the formation of vital enzymes. Heavy metal makes up 0.05% of our body weight. We get it through vegetables, chocolate and nuts.
- Zinc refers to the elements that all living things on earth need. It is important for metabolism and is found in many important enzymes.
- Iodine- a component of the hormones thyroxine and triiodothyronine, which are produced by the thyroid gland. Lack of iodine can cause severe metabolic disorders.
- Selenium refers to essential trace elements. At the same time, in case of an overdose, it is highly toxic, so its use as a dietary supplement causes great discussion in the circles of scientists.
- Before today not fully understood to what extent fluorine necessary for our body. Undeniable fact is big part of the fluorine is found in bones and teeth. Fluorine, like selenium, is highly toxic in overdose.
The human body contains more than 40 elements of the periodic system of Mendeleev. The largest amounts in tissues are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. These substances are called organogens, because they are part of the organic components of cells. Less in the cells of sodium, potassium, calcium, magnesium, manganese, cobalt, iron, copper, selenium. All of these elements must be supplied to the body from the external environment. Organogens combine with each other and with other elements, forming proteins, nucleic acids, lipids, carbohydrates and other complex substances.
Carbon is the center of organic compounds. It forms stable molecules of various configurations with a large number of functional groups.
Nitrogen is often erroneously called lifeless because it does not support combustion, but life is impossible without this element, since it is part of proteins, nucleic acids and many other compounds that form the basis of the life of the body. Nitrogen easily changes valency; in the body it is in a tri- or pentavalent state. With a change in valence, nitrogen gains or loses an electron, which determines its role in metabolism.
Oxygen is involved in the formation of acid, alcohol and other groups in organic compounds. Without it, biochemical processes are impossible. Thanks to the reaction with oxygen, respiration is carried out in the cells, energy processes necessary for life take place.
Hydrogen is not only a plastic component of organic compounds, but also a "fuel" for the plant and animal world: when it combines with oxygen, a large amount of energy is released.
Sulfur takes part in the formation of easily oxidized thiol groups, disulfide bridges, which stabilize the structure of certain sections of protein molecules. It is one of the components of the processes of neutralization of toxic substances.
Phosphorus is widely present in the body both in free form and in combination with various substances (proteins, fats, carbohydrates). It is part of phospholipins, phosphoproteins, ATP, GTP mononucleotides, and is part of the blood buffer system. Phosphorus in the body is involved in the activation of various compounds, in the formation of the skeletal system and teeth.
Living matter consists of substances that have huge molecules (macromolecules), due to which they acquire both stability and high reactivity. Such compounds are proteins, nucleic acids, lipids, carbohydrates. MSS vital processes are connected with them.
No less important role in living matter is played by water and minerals. Salts and water make up about 2/3 of the human body. Most of the mineral substances account for the share of bones, which include not soluble-million and code salt - calcium phosphate. Fluids in the body of humans and animals are solutions of electrolytes. They ensure the constancy of osmotic pressure and liquid phases of the body, acid-base balance in tissues. These processes are dominated by sodium and potassium cations, chloride anions, carbonates, and phosphates.
Mineral substances that make up living organisms are conventionally divided into three groups: macro-, micro- and ultramicroelements. Macroelements include those chemical elements whose content exceeds 0.001% (O, C, H, Ca, K, N, P, S, Mg, Na, Cl, Fe, etc.). If the content of a chemical element in the body is from 0.001 to 0.000001%, then it is classified as a microelement (Cu, Mn, Co, etc.). Substances that are in even smaller quantities are called ultramicroelements (Pb, V, Au, Hg, etc.).
Water. With a few exceptions (bones, tooth enamel), they are the predominant component in the cell structure. Water serves as a natural solvent for many substances, and also as a dispersion medium, which plays an important role in the colloidal system of the cytoplasm. All chemical processes in the body occur in the aquatic environment, water is directly involved in many reactions. In addition, it removes various substances from the body.
The importance of water for the life of the organism is eloquently evidenced by the fact that the loss of even a fifth of it inevitably leads to death.
STRUCTURE OF A CELL
A cell is one of the forms of organization of living matter, which underlies the structure and development of plants and animals.
The sizes, shape and structure of the cells that make up the organs and tissues are different. They depend on the stage of development and function of the cell, their species, etc. Basically, the diameter of the cells ranges from 1 micron to several centimeters. However, some of them are large, for example, nerve cells with long processes reaching 1 m. The most typical cells are spherical, oval, cylindrical, and cubic. The number of cells in the body and even in its individual organs can be huge, for example, the human cerebral cortex contains 14-15 billion nerve cells, and in the blood - up to 25 billion red blood cells.
In their structure, the cells of plants, animals and humans, like atoms, are similar to each other. Each of them contains in the middle a dense formation - the nucleus, which floats in the "semi-liquid" cytoplasm. The cell is surrounded by a cell membrane.
The cell consists of many elements, the totality of which has a certain meaning not only for itself, but also for the whole organism as a whole. If the structure of the cell is somehow disturbed, then its functions will change, it will lose its properties as an organized unit and die.
The content of the cell is very complex system various components. The scheme of the cell structure, obtained using an electron microscope, is shown in Figure 1.
cytoplasmic membrane. The internal environment of the cell is different from the external one. The cell membrane serves as a natural barrier between them, the main function of which is to regulate the metabolism between the cell and the environment (Fig. 2).
The cytoplasmic membrane ensures the constancy of the composition of the intracellular contents. In its structure, the membrane is a viscous lipid phase (lipid layer) with proteins immersed in it. The lipid layer consists mainly of phospholipids, cholesterol, glycolipids and is a double layer of molecules. In this case, the long fatty acid residues of one and the other layer of lipid molecules face each other and form a liquid hydrophobic phase, and the hydrophilic groups of these lipids (choline, phosphoric acid, ethanolamine, etc.) are located outside. The structure of the membrane determines its main property - selective permeability, i.e., regulation of the entry into the cell of the necessary nutrients and removal of metabolic products from it. Such selectivity ensures the constancy of the internal environment of the cell, maintains the desired osmotic pressure, pH value, etc.
The proteins that make up the membrane are located on the periphery (peripheral) or penetrate its entire thickness (integral).
The functions of membrane proteins are diverse. Some of them are enzymes that catalyze many important reactions, others transport various substances (fatty acids, cholesterol) through the membrane. A special group of proteins forms "pores" in the membrane for the transfer of ions (hydrogen, sodium, potassium, etc.). Superficially located proteins and hydrophilic groups of lipids are associated with carbohydrates and form sites that can "recognize" other cells or substances. Such areas are called receptors. By connecting with specific receptors, substances (for example, hormones) transmit their signals into the cell. The membranes are elastic and have the ability to spontaneously restore their integrity when damaged.
Cytoplasm. The inner space of the cell is filled with cytoplasm, in which the organelles of the cell are located. The cytoplasm is penetrated by numerous channels, which are called the endoplasmic reticulum (reticulum).
Endoplasmic reticulum is an extension of the nuclear membrane. It is a network of membranes that form tubules and vesicles; through the endoplasmic reticulum, various substances are transported from the cell to the external environment and vice versa, the processes of synthesis and decay of chemicals take place here.
There are two types of reticulum - smooth and rough. The “roughness” of the latter is due to numerous small spherical particles located on its surface - ribosomes.
Ribosomes - small dense granules of small sizes. They consist of two parts (subunits) of a rounded shape, the connection of which can be figuratively represented in the form of a mushroom or figure eight. They are scattered throughout the cell. Some of them are associated with the endoplasmic reticulum, others are in a free state in the cytoplasmic matrix. Ribosomes perform essential function- participate in the process of protein synthesis.
golgi apparatus represented by thin flat sacs. It plays a dual role: it participates in the synthesis of carbohydrate components of glycoproteins and carries out the removal of finished molecules from the cell.
Mitochondria(from the Greek mitos - thread, сhondrion - grain, grain) are large organelles of the cell, shaped like a bean grain.
Mitochondria are surrounded by two membranes formed by proteins and lipids of various nature. The inner membrane has many protrusions directed inward - cristae, which are more numerous than
to cell respiration. The internal space of mitochondria is filled with a fine-grained viscous substance. Mitochondria - in the highest degree specialized particles: it is in them that the processes of respiration and oxidation of various substances take place. Their main function is to beat the prisoner organic matter ah energy and accumulate it in the phosphate bonds of adenosine triphosphate (ATP), which is necessary for the implementation various processes vital activity. Mitochondria are called "power substations"
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Another feature of mitochondria should also be noted. DNA has been found in their matrix. In addition, there are ribosomes and a number of other substances necessary for the synthesis of membrane proteins, the bulk of which are enzymes involved in the formation of ATP,
Other important organelles of the cell - lysosomes(from Greek 1u515 - dissolution, zota - body). These structures are membrane-bound bodies containing proteolytic enzymes. An intact lysosomal membrane is very strong and resistant to enzymes. They are dangerous for the cell and are enclosed, as it were, in a sac formed by a membrane. The purpose of lysosomes is diverse: they are able to break down already used proteins, fats, carbohydrates and their intermediate products. The membrane of lysosomes is semi-permeable and prevents the release of enzymes into the cytoplasm if this is not necessary. When, as a result of any impact, the integrity of the lysosome membrane is violated, the lysosomal enzymes destroy the cell.
Plant cells contain plastids - small granules with a double membrane in which the synthesis and accumulation of organic substances occurs. These include chloroplasts, leukoplasts, and chromoplasts. Chloroplasts contain the green pigment chlorophyll, which is able to synthesize the energy of sunlight. In chloroplasts, solar energy is converted into chemical energy, which is stored in the form of chemical bonds of various nutrients formed during photosynthesis. Leucoplasts are colorless plastids, they accumulate starch and other substances. Chromoplasts contain various pigments that determine the color of fruits, vegetables, and flowers.
If the metabolism is disturbed, then such a violation is expressed in the form of a change in chemical constancy at the level of cells of a tissue, organ, or even the organism as a whole. Accordingly, the manifestations of many diseases can be characterized by their influence on the change of chemical compounds at all these levels. However, before speaking directly about such changes, it is advisable to briefly consider the chemical composition of the organs and tissues of the human body, touching in passing on those sources that building material, from which the body draws resources and energy, that is, nutrients.
continuous wear human body requires constant updating constituent elements. This explains the constant need for an influx of food. For 70 years of life, a person eats more than 2.5 tons of proteins, about 2 tons of fats, about 10 tons of carbohydrates, drinks more than 50,000 liters of water. All living things are characterized by organic molecules, and their composition mainly includes carbon, as well as various amounts of hydrogen, oxygen, nitrogen and a small percentage of phosphorus, sulfur, iron and some other elements. Carbon is the most important element in all living systems.
The cells of the human body are built, it would seem, from simple chemical components - proteins, carbohydrates, fats, nucleic acids. However, these components, connecting with each other, can form and form complex complexes. Yes, in many cell structures includes lipoproteins, glucoproteins, etc. An important chemical component of the vital activity of all cells is adenosine triphosphoric acid - universal source energy for various metabolic processes.
"Metabolic Disorders: Prevention",
M.A. Zhukovsky
Proteins are the main component of any living cell. Their most important function is catalytic, since any chemical reaction in the cell proceeds with the participation of biological catalysts - enzymes. Any enzyme is a protein. The structural function of proteins is also very important. They ensure the reproduction of the main structural elements of organs and tissues. The problem is that proteins...
Carbohydrates are the main fuel for cells. Oxidized, carbohydrates release energy, which is consumed by the cell for all life processes. Carbohydrates account for about 50-60% of the diet in terms of calories. The human body is not able to synthesize carbohydrates from inorganic substances and receives them with various food products, mainly of plant origin. In nutrition, the main carbohydrate that has nutritional value, ...
As a source of energy, cells use not only carbohydrates, but also fats. During the breakdown of fats, a significant amount of it is released. And the energy value fats are much higher than carbohydrates. Fat provides more than 2 times more calories than glucose. Nevertheless, the energy supply of the body is still mainly determined by carbohydrates, since lipids also have a number of ...
Nucleic acids are a relatively recently discovered and studied group of compounds that play an extremely important role. These chemical compounds store and transmit hereditary information. They mediate the synthesis of all body proteins. There are two types of nucleic acids: deoxyribonucleic (DNA) and ribonucleic (RNA). DNA is found mainly in the nucleus of the cell, RNA - in the cytoplasm and nucleus. The importance of nucleic acids is...
It must be taken into account that each of the described links of biosynthesis is catalyzed by certain enzymes and is supplied with energy by ATP molecules. Perhaps, here it is immediately worth noting the possible development of deviations in protein synthesis due to a violation in hereditary information. Their causes may be different: the sequence of amino acids in the DNA molecule may be disturbed, another option is this DNA molecule itself ...
Lesson Objectives
1. Expansion and deepening of students' knowledge about the role of metals in the life of the human body.
2. Development of independent work skills; the ability to use the knowledge gained earlier in the study of biology and chemistry; work with tables compare, analyze, draw conclusions.
3. Education of respect for nature and human health, a sense of collectivism, respect for each other, responsibility for the common cause.
Equipment and materials
1. Demo material: table " Chemical composition human body"; cards with pictures for drawing up the scheme "Penetration of lead ions into the human body."
2. Handout: tables "Chemical composition of the human body", "Influence of metals on the vital activity of the human body", "Crossroads"; homework text.
3. K practical work: solutions of salts of lead and protein, test tubes, pipettes, tripods.
4. Video film "Transport in the city".
5. Excerpts from literary works about the effect of metals on the human body.
6. On the board - an epigraph: “Nature does not recognize jokes; she is always truthful, always serious, always strict; she is always right, while mistakes and delusions come from people ”(W. Goethe).
DURING THE CLASSES
I. Organizational moment
Chemistry teacher. In the last lesson, we finished studying the topic "Metals", during which we considered metals as elements of inanimate nature. You know that the role of metals in inanimate nature is very great: they include 92 of the 114 chemical elements included in periodic table. Today, with the help of a biology teacher, we will talk about the role of metals in wildlife.
Biology teacher. All living organisms, including humans, belong to wildlife, so we will get acquainted with the role of metals in wildlife using the example of the human body. ( The teacher asks the students to formulate lesson topic, writes it on the board, and students write it in notebooks.)
Today we will recall what you learned about metals in chemistry lessons and about the human body in biology lessons in the 8th grade, generalize and expand this knowledge and apply it to clarify the role of metals in the human body. You will work in teams, so each of you has the opportunity to receive two grades - for individual work and group work. For correct answers to questions in chemistry and biology, you will receive two types of tokens. Three tokens of the same type will allow you to get an "excellent" grade, two tokens - "good". In addition, each correct answer will bring your team 1 point (incorrect answers do not count), all points are entered in the team table. Grades for group work will be posted after checking homework and final summing up the lesson. Grades for individual work - today at the end of the lesson.
II. Knowledge update
Chemistry teacher. Nature has created many living organisms - simple and complex, similar and completely different from each other. Together with inanimate nature they formed a complex but harmonious system - the nature of the Earth. As an epigraph to our lesson, we have chosen the words of the great German poet Goethe. ( The teacher draws the attention of students to the epigraph written on the board, reads the first part of it..) However, man, by his activity, violates the harmony of nature, thereby causing harm not only environment but also to their own health. ( The teacher reads the second part of the epigraph.) A century and a half later, the words of the poet received, unfortunately, full confirmation.
III. Main part
Biology teacher. The composition of the cells of living organisms, including humans, includes organic and inorganic substances. They are listed in the tables "Chemical composition of the human body", which everyone has on the table. Chemical elements and their compounds, necessary for the normal functioning of the body in relatively large quantities, are called macronutrients, and elements required by organisms in extremely small quantities - trace elements. Among the macronutrients there are both non-metals - oxygen, carbon, hydrogen, nitrogen, phosphorus and chlorine, as well as metals. Name them using the data in Table. 1. Among the microelements there are also non-metals and metals. Using the table, try to name them. From the data in the table it can be seen how diverse the metals that make up the human body are.
Chemistry teacher. In what form are metals found in the cells of the human body? Let's remember what is the biological role of the metals studied in chemistry lessons. To do this, we use the generalizing tables in the chemistry notebook. ( Students repeat the biological role of sodium, potassium, calcium, magnesium, iron. You get tokens for correct answers.)
Biology teacher. Now look at the table. 2. How would you title it? ( Students get acquainted with the contents of the table, offer its name, enter it above the table and paste the table into workbooks.) What conclusion can be drawn from the contents of this table? Obviously, metals are necessary for the cells of the human body for normal functioning. Both excess and deficiency of metals have a negative effect on the body, and some metals can even have toxic effect. (The conclusion is written in a notebook.)
Chemistry teacher. We tried to find confirmation of this in various literary sources. Try to use your tables to determine the effect of which metals in question.
Table 1. Chemical composition of the human body
Height - 170 cm. Body weight - 70 kg. |
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body composition |
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Substance |
Weight, kg |
% to body weight |
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Chemical elements in human cells |
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In % to dry weight |
In % to dry weight |
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Oxygen |
65 |
Manganese |
0,0003 |
1. Quote from the article “Help Came Through the Internet” from Readers Digest, October 1996:
“A young student studying chemistry at Peking University suddenly developed dizziness, severe intestinal spasms, and burning pains in her hands and feet. Then her hair began to fall out. Her parents rushed her to the hospital, but the girl plunged into a coma.
According to doctors, dizziness and cutting pains in the palms and feet, as well as in the joints, indicated a serious neuralgic disorder. However, spinal puncture revealed no abnormalities. Tests for arsenic and lead poisoning also came back negative.”
2. Quote from Valentin Rasputin's story "Live for a century - love a century":
(Students work with tables and come to the conclusion that the first quote refers to thallium poisoning, and the second refers to zinc.)
Biology teacher. I would especially like to dwell on the harmful effects of heavy metals on the human body. One of the "suppliers" of heavy metals, such as lead, copper, chromium, is road transport, or rather its exhaust gases. Let's watch a short video a fragment of the video film "Transport in the city" is shown). This picture is typical for all major cities, including Chelyabinsk. Let's take a closer look at the effect of lead ions on the human body. In table. 2 says that lead, even in small amounts, causes anemia, kidney failure, and brain diseases. In addition, lead can replace calcium in bones. How can lead ions enter the human body? Let's draw up a scheme "Penetration of lead ions into the human body." One student will do this work at the blackboard, using magnetic cards with pictures, the rest will draw up a diagram in a notebook and accompany it with the appropriate notes.
table 2
chemical element |
metal shortage |
excess metal |
Deficiency leads to mental disorder. |
Excess causes general lethargy, impaired breathing and heart rhythm, weakness, drowsiness, loss of appetite, thirst, and dermatitis of the face and hands. |
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It maintains the normal excitability of muscle cells in humans, maintains the acid-base balance in the body, takes part in the regulation of cardiac activity (calms), retains water in the body. |
Excess leads to disruption water balance, blood clotting, impaired renal function, cardiovascular system, as well as to general violation metabolism. |
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Regulates protein and carbohydrate metabolism, affects the processes of photosynthesis and plant growth. Necessary for the normal functioning of all muscles, especially the heart, promotes the release of excess sodium, ridding the body of excess water and eliminating swelling. |
With an excess, there is an increase in motor activity, a violation of the heart rhythm, a violation of carbohydrate, fat and protein metabolism. |
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It exhibits antiseptic and vasodilating effects, lowers blood pressure and cholesterol levels in the blood, plays big role in cancer prevention. It has a beneficial effect on the digestive organs. |
The increased content leads to a violation of mineral metabolism. An imbalance in magnesium metabolism causes increased mortality from cardiovascular diseases and diseases of the gastrointestinal tract. |
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It is necessary for the processes of hematopoiesis, metabolism, to reduce vascular permeability, normal growth of the skeleton, has a beneficial effect on the state of the nervous system, and has an anti-inflammatory effect. |
With an excess of calcium, cystitis occurs. If calcium enters the body in the form of cement dust, then the respiratory organs suffer, the excitability of the nervous system and the olfactory analyzer decreases in children. |
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Strontium |
Influences the process of bone formation. |
With an excess of strontium, bone tissue, liver, and blood are affected; there is increased fragility of bones, hair loss. |
Aluminum |
Contained in the lungs, liver, bones, brain; acts on the digestive and nervous system. |
Excess leads to a violation of mineral metabolism. |
Included in the blood and muscle tissue, is a catalyst for many reactions; part of insulin, involved in protein metabolism. |
At high concentrations, it is a mutagen and an oncogene. |
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It is a biological competitor of zinc, in excess it reduces the activity of digestive enzymes, disrupts the function of the pancreas, carbohydrate metabolism, affects the kidneys and inhibits bone growth, increases the risk of bone fractures. |
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In excess, it affects the central nervous system, concentrates in the kidneys, disrupts their activity; accumulates in the cells of the brain and the membrane of the mouth. |
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| Barium | In excess, it affects bone tissue, bone marrow and liver, the nervous system, and leads to bone fragility due to the displacement of calcium. | |
In excess, it affects the peripheral nervous system, gastrointestinal tract and kidneys. Thallium, a biological competitor of potassium due to the similarity between ions, accumulates in hair, bones, kidneys, muscles. characteristic feature thallium poisoning - hair loss. |
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Excess causes anemia, kidney failure, brain disease. Able to replace calcium in the bones. |
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Excess leads to the development of Wilson's disease, a violation of the liver. |
Chemistry teacher. It has been established that the content of lead ions is especially high in areas adjacent to roads. This was tested by the students of our school. You have tables on your tables. "Crossroads". It presents the results of studies of soil samples taken at the intersection of Dovator and Fedorov streets. As can be seen from the table data the largest number lead ions are found near the road itself, the smallest - at a distance of about 100 m. Let's check by experience how lead ions affect living organisms. To do this, we will do a laboratory experiment "Interaction of lead salts with protein." Write the conclusion in a notebook. ( Students perform a laboratory experiment, independently draw a conclusion, write it down in a notebook.)
Table 3. "Crossroads"
Number of cars (for 15 minutes) |
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The amount of harmful (gaseous) emissions |
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The presence of lead ions: |
black precipitate with NaS solution; |
Dustiness: |
In the park - moderate; at the crossroads - very strong; |
V. Homework
Biology teacher. Today we considered the influence of certain metals on the vital activity of the human body, but did not pay enough attention to the problem of the penetration of metal ions into it. You will consider this problem while doing your homework. ( Homework varying degrees groups of students get difficulties; lists of students of each group are distributed along with the text of homework).
1st group. Consider the methods of penetration of sodium, potassium, calcium and iron ions into the human body, using the text of a chemistry textbook. Present the results in the form of a table in a chemistry notebook.
2nd group. Familiarize yourself with the contents of the labels and instructions on the preparations household chemicals, present your assumptions in the form of a table.
3rd group. Using reference and additional literature, draw up schemes for the penetration of selenium ions and heavy metals - copper, cadmium, mercury into the human body.
V. Independent work
Chemistry teacher. At the end of our lesson, we invite you to do a little independent work. Each of you will receive a card with a text. Using Table 1, try to determine what metal is being discussed, enter its name instead of dots in the card. ( At the end of the work, students conduct a mutual check, the results are entered in the command table..)
VI. Summing up the lesson
Chemistry teacher. Our lesson is almost over. It remains to remember once again what you learned today, and answer a few questions, draw a final conclusion and write it down in a notebook. (Students read the questions written on the board, answer them, discuss the conclusion, write it in a notebook.)
The biology teacher sums up the lesson, announces the total score for the teams, comments on the individual work of students, and grades the number of tokens.
