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Diagram of the exchange of water and mineral salts.
Exchange of mineral salts The importance of water and its exchange in the body Water-salt metabolism- this is a set of processes of distribution of water and minerals between the extra- and intracellular spaces of the body, as well as between the body and the external environment. Water exchange in the body is inseparably linked with mineral (electrolyte) metabolism. The distribution of water between the water spaces of the body depends on the osmotic pressure of liquids in these spaces, which is largely determined by their electrolyte composition. From quantitative and quality composition The flow of all vital processes depends on the mineral substances in body fluids. Mechanisms involved in regulation
water-salt metabolism , are characterized by high sensitivity and accuracy. Maintaining the constancy of osmotic, volume and ionic balance of extra- and intracellular body fluids using reflex mechanisms is called water-electrolyte homeostasis. Changes in water and salt consumption, excessive loss of these substances, etc. accompanied by changes in composition
internal environment and are perceived by the corresponding receptors. The synthesis of information entering the central nervous system ends with the fact that the kidney, the main effector organ regulating water-salt balance, receives nervous or humoral stimuli that adapt its work to the needs of the body.
Water necessary for any animal organism and performs the following functions: 1) is mandatory
integral part
protoplasm of cells, tissues and organs; The body of an adult is 50-60% water, i.e. it reaches 40-45 l; 2) is a good solvent and carrier of many minerals and nutrients, metabolic products; 3) accepts
Active participation
in many metabolic reactions (hydrolysis, swelling of colloids, oxidation of proteins, fats, carbohydrates);
4) reduces friction between contacting surfaces in the human body;
5) is the main component of water-electrolyte homeostasis, being part of plasma, lymph and tissue fluid;
6) participates in the regulation of human body temperature;
7) provides flexibility and elasticity of fabrics; for an adult person in water at rest is 35-40 ml per kilogram of body weight, i.e. with a mass of 70 kg - an average of about 2.5 liters. This amount of water enters the body from the following sources:
1) water consumed as drinking (1-1.1 l) and with food (1-1.1 l);
2) water, which is formed in the body as a result of chemical transformations of nutrients (0.3-0.35 l).
The main organs that remove water from the body are the kidneys, sweat glands, lungs and intestines. Under normal conditions, the kidneys remove 1.1.5 liters of water per day in the form of urine. At rest, the sweat glands secrete 0.5 liters of water per day through the skin in the form of sweat (more during intense work and in hot weather). The lungs at rest exhale 0.35 liters of water per day in the form of water vapor (with increased and deepening breathing - up to 0.8 liters/day). 100-150 ml of water is excreted through the intestines with feces per day. The ratio between the amount of water entering the body and the amount removed from it is water balance . For the normal functioning of the body, it is important that the influx of water completely covers the consumption, otherwise, as a result of water loss, water loss occurs. serious violations life activity. A loss of 10% of water leads to the condition dehydration(dehydration), with a loss of 20% water occurs death. With a lack of water in the body, fluid moves from the cells into the interstitial space, and then into the vascular bed. Both local and general disturbances of water metabolism in tissues can manifest themselves in the form of edema and dropsy. Edema is called the accumulation of fluid in the tissues, dropsy is the accumulation of fluid in the cavities of the body. The fluid that accumulates in tissues during edema and in cavities during dropsy is called transudate. It is transparent and contains 2-3% protein. Edema and dropsy of various localizations are designated by special terms: swelling of the skin and subcutaneous tissue - anasarca (Greek ana - above and sarcos - meat), dropsy of the peritoneal cavity - ascites (Greek ascos - bag), pleural cavity- hydrothorax, cavities of the cardiac membrane - hydropericardium, cavities of the vaginal membrane of the testicle - hydrocele. Depending on the causes and mechanisms of development, cardiac or congestive edema, renal edema, cachectic, toxic, traumatic edema, etc. are distinguished.
Exchange of mineral salts
The body needs a constant supply of not only water, but also mineral salts. They enter the body with food and water, with the exception of table salt, which is specially added to food. In total, about 70 were found in the body of animals and humans. chemical elements, of which 43 are considered irreplaceable (essential; lat. essentia - essence).
The body's need for various minerals not the same. Some elements, called macronutrients, are introduced into the body in significant quantities (in grams and tenths of a gram per day). Macroelements include sodium, magnesium, potassium, calcium, phosphorus, and chlorine. Other elements - microelements(iron, manganese, cobalt, zinc, fluorine, iodine, etc.) are needed by the body in extremely small quantities (in micrograms - thousandths of a milligram).
Functions of mineral salts:
1) are biological constants of homeostasis;
2) create and maintain osmotic pressure in the blood and tissues (osmotic balance);
3) maintain the constancy of the active blood reaction
(pH=7.36 – 7.42);
4) participate in enzymatic reactions;
5) participate in water-salt metabolism;
6) ions of sodium, potassium, calcium, chlorine play an important role in the processes of excitation and inhibition, muscle contraction, and blood clotting;
7) are an integral part of bones (phosphorus, calcium), hemoglobin (iron), the hormone thyroxine (iodine), gastric juice (hydrochloric acid), etc.;
8) are integral components of all digestive juices, which are secreted in large quantities.
Let us briefly consider the metabolism of sodium, potassium, chlorine, calcium, phosphorus, iron and iodine.
1) Sodium enters the body mainly in the form of table salt. It is the only mineral salt that is added to food. Plant foods are low in table salt. The daily requirement for table salt for an adult is 10-15 g. Sodium is actively involved in maintaining osmotic balance and fluid volume in the body and affects the growth of the body. Together with potassium, sodium regulates the activity of the heart muscle, significantly changing its excitability. Symptoms of sodium deficiency: weakness, apathy, muscle twitching, loss of muscle tissue contractility.
2) Potassium enters the body with vegetables, meat, and fruits. Its daily norm is 1 g. Together with sodium, it participates in the creation of bioelectric membrane potential (potassium-sodium pump), maintains the osmotic pressure of intracellular fluid, and stimulates the formation of acetylcholine. With a lack of potassium, inhibition of assimilation processes (anabolism), weakness, drowsiness, and hyporeflexia (decreased reflexes) are observed.
3) Chlorine enters the body in the form of table salt. Chlorine anions, together with sodium cations, are involved in creating the osmotic pressure of blood plasma and other body fluids. Chlorine is also included in of hydrochloric acid gastric juice. No symptoms of chlorine deficiency have been found in humans.
4) Calcium enters the body with dairy products, vegetables (green leaves). Contained in bones along with phosphorus and is one of the most important biological constants of blood. The normal calcium content in human blood is 2.25-2.75 mmol/l (9-11 mg%). A decrease in calcium leads to involuntary muscle contractions (calcium tetany) and death due to respiratory arrest. Calcium is necessary for blood clotting. The daily requirement for calcium is 0.8 g.
5) Phosphorus enters the body with dairy products, meat, and cereals. The daily requirement for it is 1.5 g. Together with calcium, it is found in bones and teeth, and is part of high-energy compounds (ATP, creatine phosphate, etc.). The deposition of phosphorus in the bones is possible only in the presence of vitamin D. With a lack of phosphorus in the body, demineralization of the bones is observed.
6) Iron enters the body with meat, liver, beans, and dried fruits. The daily requirement is 12-15 mg. It is a component of blood hemoglobin and respiratory enzymes. The human body contains 3 g of iron, of which 2.5 g is found in red blood cells as a component of hemoglobin, the remaining 0.5 g is part of the body's cells. Lack of iron disrupts hemoglobin synthesis and, as a result, leads to anemia.
7) Iodine comes with drinking water enriched with it when flowing through rocks or with table salt with the addition of iodine. The daily requirement is 0.03 mg. Participates in the synthesis of thyroid hormones. Lack of iodine in the body leads to endemic goiter - an increase in thyroid gland(some regions of the Urals, Caucasus, Pamirs, etc.).
Disorders of mineral metabolism can lead to a disease in which stones of different sizes, structures and chemical composition(renal stone disease - nephrolithiasis). It can also contribute to the formation of stones in the gall bladder and bile ducts (cholelithiasis).
Vitamins and their meaning
Vitamins(Latin vita - life + amines) - essential substances supplied with food that are necessary to maintain the vital functions of the body. Currently, more than 50 vitamins are known.
The functions of vitamins are diverse:
1) they are biological catalysts and actively interact with enzymes and hormones;
2) many of them are coenzymes, i.e. low molecular weight components of enzymes;
3) take part in the regulation of the metabolic process in the form of inhibitors or activators;
4) some of them play a certain role in the formation of hormones and mediators;
5) certain vitamins reduce inflammation and promote the restoration of damaged tissue;
6) promote growth, improve mineral metabolism, resistance to infections, protect against anemia, increased bleeding;
7) provide high performance.
Diseases that develop in the absence of vitamins in food are called avitaminosis. Functional disorders that occur with partial vitamin deficiency are hypovitaminosis. Diseases caused by excessive consumption of vitamins are called hypervitaminosis.
Vitamins are usually designated by letters of the Latin alphabet, chemical and physiological names (the physiological name is given depending on the nature of the action of the vitamin). For example, vitamin C - ascorbic acid, antiscorbutic vitamin, vitamin K - vikasol, antihemorrhagic, etc.
According to solubility, all vitamins are divided into 2 large groups: water-soluble- B vitamins, vitamin C, vitamin P, etc.; fat-soluble- vitamins A, D, E, K, F.
Let's take a brief look at some of the vitamins from these groups.
Water-soluble vitamins.
1) Vitamin C - ascorbic acid, antiscorbutic. The daily requirement is 50-100 mg. In the absence of vitamin C, a person develops scurvy (scurvy): bleeding and loosening of the gums, tooth loss, hemorrhages in the muscles and joints. Bone tissue becomes more porous and fragile (fractures may occur). There is general weakness, lethargy, exhaustion, and decreased resistance to infections.
2) Vitamin B 1- thiamine, antineurin. The daily requirement is 2-3 mg. In the absence of vitamin B 1, beriberi disease develops: polyneuritis, impaired heart function and gastrointestinal tract.
3) Vitamin B 2- riboflavin (lactoflavin), antiseborrheic. The daily requirement is 2-3 mg. With vitamin deficiency in adults, damage to the eyes, oral mucosa, lips, atrophy of the papillae of the tongue, seborrhea, dermatitis, weight loss is observed; in children - growth retardation.
4) Vitamin B 3 - pantothenic acid, antidermatitis. The daily requirement is 10 mg. Vitamin deficiency causes weakness, fatigue, dizziness, dermatitis, damage to the mucous membranes, and neuritis.
5) Vitamin B 6- pyridoxine, antidermatitis (adermin). The daily requirement is 2-3 mg. Synthesized by the microflora of the large intestine. With vitamin deficiency, dermatitis is observed in adults. In infants, a specific manifestation of vitamin deficiency is seizures (convulsions) of the epileptiform type.
6) Vitamin B 12- cyanocobalamin, antianemic. The daily requirement is 2-3 mcg. Synthesized by the microflora of the large intestine. Affects hematopoiesis and protects against pernicious anemia.
7) Vitamin Sun - folic acid(folacin), antianemic. Daily requirement - 3 mg. Synthesized in the large intestine by microflora. Affects the synthesis of nucleic acids, hematopoiesis and protects against megaloblastic anemia.
8) Vitamin P- rutin (citrine), a capillary-strengthening vitamin. The daily requirement is 50 mg. Reduces the permeability and fragility of capillaries, enhances the effect of vitamin C and promotes its accumulation in the body.
9) Vitamin PP- nicotinic acid (nicotinamide, niacin), antipellagric. Daily requirement - 15 mg. Synthesized in the large intestine from the amino acid tryptophan. Protects against pellagra: dermatitis, diarrhea (diarrhea), dementia (mental disorders).
Fat-soluble vitamins.
1) Vitamin A- retinol, antixerophthalmic. The daily requirement is 1.5 mg. Promotes growth and protects against night or night blindness (hemeralopia), dry cornea (xerophthalmia), softening and necrosis of the cornea (keratomalacia). The precursor to vitamin A is carotene, found in plants: carrots, apricots, parsley leaves.
2) Vitamin D - calciferol, antirachitic. The daily requirement is 5-10 mcg, for infants - 10-25 mcg. Regulates the exchange of calcium and phosphorus in the body and protects against rickets. The precursor of vitamin D in the body is 7-dehydro-cholesterol, which, under the influence ultraviolet rays in tissues (skin) it is converted into vitamin D.
3) Vitamin E- tocopherol, antisterile vitamin. The daily requirement is 10-15 mg. Provides reproductive function and normal pregnancy.
4) Vitamin K- vikasol (phylloquinone), an antihemorrhagic vitamin. The daily requirement is 0.2-0.3 mg. Synthesized by the microflora of the large intestine. Enhances the biosynthesis of prothrombin in the liver and promotes blood clotting.
5) Vitamin F- a complex of unsaturated fatty acids (linoleic, linolenic, arachidonic) is necessary for normal fat metabolism in the body. Daily requirement - 10-12 g.
Nutrition
Nutrition- difficult process receipt, digestion, absorption and assimilation by the body of nutrients necessary to cover its energy expenditure, construction and renewal of cells, tissues and regulation of functions. During feeding nutrients enter digestive organs, undergo various changes under the influence of digestive enzymes, enter the circulating fluids of the body and thus turn into factors of its internal environment.
Nutrition ensures the normal functioning of the body, provided it is supplied with the necessary amount of proteins, fats, carbohydrates, vitamins, minerals and water in the ratios necessary for the body. At balanced diet The main focus is on the so-called essential food components, which are not. are synthesized in the body itself and must be supplied to it in the required quantities with food. These components include essential amino acids, essential fatty acid, vitamins. Many minerals and water are also essential components. Almost optimal for nutrition healthy person is the ratio of proteins, fats and carbohydrates in the diet, close to 1:1:4.6.
ILLUSTRATIONS
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Figure 262 Diagram of the course of the peritoneum
Figure 263 Organs abdominal cavity
Control questions
1. general characteristics internal organs and digestive system.
2. Oral cavity, its structure.
3. The structure of the tongue and teeth.
4. Salivary glands, composition, properties and significance of saliva.
5. Regulation of salivation.
6. Structure and functions of the pharynx and esophagus.
7. Structure of the stomach.
8. Methods for studying the secretion of gastric juice.
9. Composition, properties and significance of gastric juice.
10. Regulation of gastric secretion and the mechanism of food transfer from the stomach to the duodenum.
11. The structure of the small intestine.
12. Composition, properties and significance of intestinal juice.
13. Types of intestinal digestion.
14. Absorption of proteins, fats, carbohydrates, water and mineral salts.
15 The structure of the large intestine.
16. Digestion in the large intestine.
17. The role of colon microflora in digestion.
18. Peritoneum.
19. Structure and functions of the liver.
20. Bile, its composition and significance.
21. Structure of the pancreas.
22. Composition, properties and significance of pancreatic juice.
23. General characteristics of metabolism in the body.
24. Protein metabolism.
25. Fat metabolism.
26. Carbohydrate metabolism.
27. General characteristics of water-salt metabolism. The importance of water and its exchange in the body.
28. Exchange of mineral salts.
29. Vitamins and their significance.
internal environment in an adult it is 60%, and in a newborn - 75% of body weight. It is the environment in which metabolic processes take place in cells, organs and tissues. A continuous supply of water to the body is one of the main conditions for maintaining its vital functions. About 70% of all water in the body is part of the protoplasm of cells, making up the so-called intracellular water. Extracellular water included in fabric or interstitial fluid(about 25%) and blood plasma water(around 5%). The balance of water consists of its consumption and excretion. With food, a person receives about 750 ml of water per day, in the form of drinks and clean water- about 630 ml. About 320 ml of water is formed during the metabolic process during the oxidation of proteins, carbohydrates and fats. When evaporating from the surface of the skin and alveoli of the lungs, about 800 ml of water is released per day. The same amount is necessary to dissolve osmotically excreted by the kidney active substances at maximum urine osmolarity. 100 ml of water is excreted in feces. Therefore, the minimum daily requirement is about 1700 ml of water.
The supply of water is regulated by its need, manifested by a feeling of thirst, which depends on the osmotic concentration of substances in liquids and their volume. This feeling occurs when the drinking center of the hypothalamus is stimulated.
The body needs a constant supply of not only water, but also mineral salts (the regulation of water-salt metabolism is described in Chapter 8).
Mineral salts.Sodium(Na+) is the main cation in extracellular fluids. Its content in the extracellular environment is 6-12 times higher than the content in cells. Sodium in the amount of 3-6 g per day enters the body in the form of table salt and is absorbed mainly in the small intestine. The role of sodium in the body is diverse. It is involved in maintaining the acid-base state, osmotic pressure of extracellular and intracellular fluids, takes part in the formation of the action potential, and influences the activity of almost all body systems; he is given great importance in the development of a number of diseases. In particular, sodium is believed to mediate the development arterial hypertension due to both an increase in the volume of extracellular fluid and an increase in microvascular resistance. The sodium balance in the body is mainly maintained by the activity of the kidneys (see Chapter 8).
The most important sources of sodium are table salt, canned meat, feta cheese, cheese, pickles, tomatoes, sauerkraut, salty fish. With a lack of table salt, dehydration, loss of appetite, vomiting, and muscle cramps occur; in case of overdose - thirst, depression, vomiting. Constant excess sodium increases blood pressure.
Potassium(K+) is the main cation in intracellular fluid. The cells contain 98% potassium. Potassium is absorbed in the small and large intestines. Potassium is of particular importance due to its potential-forming role at the level of maintaining the resting membrane potential. Potassium also takes an active part in regulating the balance of the acid-base state of cells. It is a factor in maintaining osmotic pressure in cells. Regulation of its excretion is carried out mainly by the kidneys (see Chapter 8).
Potatoes with skin, garlic, parsley, pumpkin, zucchini, dried apricots, apricots, raisins, prunes, bananas, apricots, legumes, meat, and fish are richest in potassium.
With potassium deficiency, loss of appetite, arrhythmia, and decreased blood pressure are observed; in case of overdose - muscle weakness, impairment heart rate and kidney function.
Calcium(Ca 2+) has high biological activity. It is the main structural component of skeletal bones and teeth, containing about 99% of all Ca 2+. IN large quantities Children need calcium due to intensive bone growth. Calcium is absorbed mainly into the duodenum in the form of monobasic salts of phosphoric acid. Approximately 3/4 of calcium is excreted digestive tract, where endogenous calcium enters with secretions digestive glands, and */ 4 - kidneys. The role of calcium in the functioning of the body is great. Calcium takes part in the generation of the action potential, in the initiation of muscle contraction, is a necessary component of the blood coagulation system, and increases reflex excitability spinal cord and has a sympathicotropic effect.
The main suppliers of calcium are milk and dairy products, cheese, liver, fish, egg yolk, raisins, cereals, dates.
With calcium deficiency, muscle cramps, pain, spasms, rigidity appear, in children - bone deformation, in adults - osteoporosis, in athletes - cramps, tinnitus, hypotension. In case of overdose, loss of appetite, weight, weakness, fever and constipation are noted. Regulation is carried out mainly by hormones - thyrocalcitonin, parathyroid hormone and vitamin Z) 3 (see Chapter 10).
Magnesium(Mg 2+) is contained in an ionized state in blood plasma, erythrocytes, and in bone tissue in the form of phosphates and bicarbonates. Magnesium has an antispasmodic and vasodilating effect, stimulates intestinal motility and increases the secretion of bile. It is part of many enzymes that release energy from glucose, stimulating enzyme activity, and has a calming effect on the heart and nervous system.
Magnesium is found in wholemeal bread, cereals (buckwheat, whole grain rice, cereals), chicken egg, beans, peas, bananas, spinach. Milk and dairy products contain small amounts of magnesium, but are well absorbed.
With magnesium deficiency, seizures are observed, muscle pain, dizziness, apathy, depression. A lack of magnesium increases the calcium content in the heart and skeletal muscles, which leads to heart rhythm disturbances and other diseases. In case of overdose, respiratory and central nervous system functions are inhibited.
Chlorine(SG) is involved in the formation of gastric juice, enters the human body as part of table salt and, together with sodium and potassium, participates in the creation of membrane potential and conduction of nerve impulses, supports acid-base balance, promotes the transport of carbon dioxide by red blood cells. Chlorine can be deposited in the skin and linger in the body if taken in excess.
Chlorine is mainly found in table salt, canned meat, cheese, and feta cheese.
With chlorine deficiency, sweating, diarrhea, insufficient secretion of gastric juice are observed, and edema develops. An increase in chlorine content occurs when the body is dehydrated and when the excretory function of the kidneys is impaired.
Phosphorus(R) - vital important substance, is part of bone tissue and is the main part of the nuclei of cells of the nervous system, especially the brain. It is actively involved in the metabolism of proteins, fats and carbohydrates; necessary for the formation of bones and teeth, the normal functioning of the nervous system and heart muscle; takes part in the synthesis of enzymes, proteins and nucleic acids (DNA and RNA). Phosphorus is found in body tissues and food products in the form of phosphoric acid and organic compounds(phosphates).
Phosphorus is found in products of animal origin: milk, cottage cheese, cheese, liver, meat, eggs; V wheat bran, wholemeal bread, sprouted wheat; Various cereals, potatoes, legumes, dried fruits, nuts, sunflower seeds, seafood and, especially, fish are rich in phosphorus.
Phosphorus deficiency occurs when long fasting(the body consumes phosphorus contained in tissues). Symptoms: weakness, subsequent loss of appetite, bone pain, metabolic disorders in the myocardium. With an excess of phosphorus, the level of calcium in the blood decreases, and heart rhythm disturbances are possible. Excess phosphorus can develop in children who are on artificial feeding. Parathyroid hormone and thyrocalcitonin take part in the regulation (see Chapter 10).
Sulfur(S) is part of proteins, cartilage tissue, hair, nails, and is involved in collagen synthesis. It is necessary for the neutralization in the liver of toxic substances coming from the large intestine as a result of putrefaction.
The most important source of sulfur is protein products: meat, fish, dairy products, eggs, legumes.
The daily requirement, deficiency and overdose have not been reliably established. It is believed that the daily requirement is compensated by the usual diet.
Iron(Fe) is a major constituent of many body tissues and some enzymes. A significant amount of iron is contained in red blood cells, about 70% in hemoglobin. The main physiological significance of iron is participation in the process of hematopoiesis, transport of oxygen and carbon dioxide, and ensuring cellular respiration. Iron can be deposited in the body. Such “depots” for it are the spleen, liver and bone marrow.
Iron is especially necessary for girls entering puberty and young children. A lack of iron in the body can lead to the development of anemia and suppression of the body's defenses. Iron is found in meat, liver (especially pork), heart, brain, egg yolk, porcini mushrooms, beans, peas, garlic, horseradish, beets, carrots, tomatoes, pumpkin, white cabbage, lettuce, spinach.
Iron deficiency reduces the activity of respiratory enzymes, which can lead to tissue respiration disorders and the development of iron deficiency anemia(anemia). Many fad diets aimed at fast weight loss, lead to iron deficiency. Excess iron can impair the functions of the liver and digestive system.
Iodine(I -) participates in the formation of thyroxine - the thyroid hormone, helps reduce cholesterol levels in the blood, and increases the absorption of calcium and phosphorus by the body.
The largest amount of iodine is found in seaweed (seaweed), sea fish, eggs, meat, milk, vegetables (beets, carrots, lettuce, cabbage, potatoes, onions, celery, tomatoes), fruits (apples, plums, grapes). It must be remembered that during long-term storage of food products containing iodine and their heat treatment, up to 60% of iodine is lost.
Lack of iodine in the body leads to hypothyroidism, enlargement of the thyroid gland (goiter), childhood- to cretinism (stunted growth and decreased intelligence). Excess iodine leads to hyperthyroidism ( toxic goiter). For prevention, take iodized salt (see Chapter 10).
Copper(Ci) participates in the formation of a number of enzymes and hemoglobin, promotes the absorption of iron in the intestines, and the release of energy from fats and carbohydrates; Copper ions take part in the oxidation reactions of substances in the body. The copper content in the human body is associated with gender, age, daily and seasonal temperature fluctuations, and inflammatory diseases.
Copper is found in meat, liver, seafood (squid, crabs, shrimp), all vegetables, melons and legumes, nuts, cereals (oatmeal, buckwheat, millet, etc.), mushrooms, fruits (apples, pears, apricots, plums), berries (strawberries, strawberries, cranberries, gooseberries, raspberries, etc.).
Lack of copper in diseases of scarlet fever, diphtheria, Botkin's disease, and pulmonary tuberculosis complicates their course. Pregnant women with copper deficiency are more likely to experience toxicosis. Lack of copper in food reduces the activity of oxidative enzymes and leads to various forms anemia (anemia). An overdose of copper leads to poisoning.
Fluorine(F -) is found in small quantities in all tissues of the body, but its main role is participation in the formation of dentin, tooth enamel and bone tissue. The main source of fluoride is drinking water. Fluoride in sufficient quantities found in food products - fish, liver, lamb, nuts, oatmeal, tea and fruits. Vegetables rich in fluoride include lettuce, parsley, celery, potatoes, white cabbage, carrots, and beets.
A sharp decrease in fluoride in drinking water leads to caries and tooth decay, increased content has a depressing effect on thyroid gland and leads to the development of fluorosis (spotty lesions of the teeth).
Zinc(Zn 2+) is involved in the synthesis of proteins, RNA, in the formation of most enzymes and hematopoiesis, is in skeletal system, skin and hair, is an integral part of the male sex hormone - testosterone, promotes wound healing, increases immunity, takes part in the mechanism cell division, normalizes carbohydrate metabolism. Chronic psycho-emotional stress, alcohol, and smoking impair the absorption of zinc. A deficiency of zinc in the diet can lead to infertility, anemia, skin diseases, slower growth of nails and hair loss, increased growth of tumors, delayed sexual development, slowed growth during puberty.
With a lack of zinc, wounds heal poorly, there is a loss of appetite, taste and olfactory sensitivity weaken, ulcers appear in the mouth, on the tongue, and pustules form on the skin. In case of overdose, the risk of poisoning increases. In large quantities, zinc has a carcinogenic effect, and therefore it is not recommended to store water and food products in galvanized containers.
Zinc is found in walnuts, seafood, meat, poultry, in all vegetables, especially garlic and onions, legumes, cereals (especially oatmeal). The digestibility of zinc from animal products is over 40%, and from plant products - up to 10%.
The regulation of most microelements has practically not been studied.
Water is an integral part of all cells and tissues and is found in the body in the form saline solutions. The body of an adult is 50-65% water, in children - 80% or more. In different organs and tissues, the water content per unit mass is not the same. It is least found in bones (20%) and adipose tissue (30%). Muscles contain 70% water, internal organs- 75-85% of their mass. The water content in the blood is the highest and most constant (92%).
Depriving the body of water and mineral salts causes severe impairment and death. Complete fasting, but when taking water, is tolerated by a person for 40-45 days, without water - only 5-7 days. During mineral starvation, despite sufficient intake of other nutrients and water into the body, animals experienced loss of appetite, refusal to eat, emaciation and death.
At normal temperature and humidity external environment The daily water balance of an adult is 2.2-2.8 l. About 1.5 liters of liquid comes in the form of drunk water, 600-900 ml in food products and 300-400 ml is formed as a result of oxidative reactions. The body loses approximately 1.5 liters per day with urine, 400-600 ml with sweat, 350-400 ml with exhaled air and 100-150 ml with feces.
The exchange of mineral salts in the body is of great importance for its life. They are found in all tissues, accounting for approximately 0.9% of the total human body weight. The cells contain many minerals (potassium, calcium, sodium, phosphorus, magnesium, iron, iodine, sulfur, chlorine and others). The normal functioning of tissues is ensured not only by the presence of certain salts in them, but also by their strictly defined quantitative ratios. If there is an excess intake of mineral salts into the body, they can be deposited in the form of reserves. Sodium and chlorine are deposited in subcutaneous tissue, potassium - in skeletal muscles, calcium and phosphorus - in bones.
Physiological significance mineral salts are diverse. They make up the bulk of bone tissue, determine the level of osmotic pressure, participate in the formation of buffer systems and influence metabolism. The role of minerals in the processes of excitation of nervous and muscle tissue, in the emergence of electrical potentials in cells, as well as in blood coagulation and the transfer of oxygen is great.
All mineral elements necessary for the body come with food and water. Most mineral salts are easily absorbed into the blood; They are eliminated from the body mainly through urine and sweat. With intense muscle activity, the need for certain minerals increases.
And briefly about the importance of vitamins that do not perform an energetic or plastic function, being constituent components enzyme systems, play the role of catalysts in metabolic processes. They are substances of a chemical nature necessary for normal metabolism, growth, development of the body, maintaining high performance and health.
Vitamins are divided into water-soluble (group B, C, P, etc.) and.
fat-soluble (A, D, E, K). Sufficient intake of vitamins into the body depends on proper diet nutrition and normal function digestive processes; some vitamins (K, B) are synthesized by bacteria in the intestines. Insufficient intake of vitamins into the body (hypovitaminosis) or their complete absence (avitaminosis) leads to disruption of many functions.
ENERGY EXCHANGE
The body must maintain an energy balance of energy intake and expenditure. Living organisms receive energy in the form of its potential reserves accumulated in the chemical bonds of molecules of carbohydrates, fats and proteins. During the process of biological oxidation, this energy is released and used primarily for the synthesis of ATP.
ATP reserves in cells are small, so they must be constantly restored. This process is carried out by oxidation of nutrients. The energy reserve in food is expressed by its calorie content, i.e., the ability to release a certain amount of energy during oxidation. Energy consumption depends on age and gender, the nature and amount of work performed, time of year, health status and other factors.
The intensity of energy metabolism in the body is determined using calorimetry. Energy exchange can be determined using direct and indirect calorimetry methods.
Direct calorimetry is based on measuring the heat generated by the body and is carried out using special chambers (calorimeters). This heat determines the amount of energy expended. Direct calorimetry is the most accurate method, but it requires long-term observations, bulky special equipment and is unacceptable in many types of professional and sports activities.
It is much easier to determine energy expenditure using indirect calorimetry methods. One of them (indirect respiratory calorimetry) is based on the study of gas exchange, i.e., on determining the amount of oxygen consumed by the body and carbon dioxide exhaled during this time. For this purpose, various gas analyzers are used.
Different nutrients require different amounts of oxygen to oxidize. The amount of energy released when 1 liter of oxygen is used is called its caloric equivalent. When oxidizing carbohydrates, the caloric equivalent is 5.05 kcal, when oxidizing fats - 4.7 kcal and proteins - 4.85 kcal.
The body usually oxidizes a mixture of nutrients, so the caloric equivalent of O ranges from 4.7 to 5.05 kcal. With an increase in carbohydrates in the oxidized mixture, the caloric equivalent increases, and with an increase in fat, it decreases.
The value of the caloric equivalent of O is determined by the level of the respiratory coefficient (RK) - the relative volume of exhaled carbon dioxide to the volume of absorbed oxygen (CO / O). The DC value depends on the composition of the oxidized substances. For the oxidation of carbohydrates it is 1.0, for the oxidation of fats - 0.7 and proteins - 0.8. When a mixture of nutrients is oxidized, its value ranges from 0.8-0.9.
In the second method of indirect calorimetry (alimentary calorimetry), the calorie content of food taken is taken into account and body weight is monitored. Constancy of body weight indicates a balance between the flow of energy resources into the body and their expenditure. However, significant errors are possible when using this method; In addition, it does not allow determining energy expenditure over short periods of time.
Depending on the activity of the body and the impact of environmental factors on it, three levels of energy metabolism are distinguished: basal metabolism, energy expenditure at rest and energy expenditure at rest. various types labor.
The basal metabolic rate is the amount of energy that the body expends when fully muscle rest, 12-14 hours after eating and at an ambient temperature of 20-22°C. In an adult, it is on average 1 kcal per 1 kg of body weight per 1 hour. In people with a body weight of 70 kg, the basal metabolism is on average about 1700 kcal. Its normal fluctuations are! 10%. In women, the basal metabolism is slightly lower than in men; It is higher in children than in adults.
Energy expenditure in a state of relative rest exceeds the value of the basal metabolism. This is due to the influence of digestion processes on energy exchange, thermoregulation outside the comfort zone and energy expenditure on maintaining the posture of the human body.
Energy consumption for various types of work is determined by the nature of human activity. Daily energy expenditure in such cases includes the amount of basal metabolism and the energy required to perform a specific type of work. By the nature of production activities and the amount of energy consumption adult population can be divided into 4 groups: 1) people of mental work, their daily energy consumption is 2200-3000 kcal; 2) people performing mechanized work and spending - 146
2300-3200 kcal per day; 3) people of partially mechanized labor with a daily energy consumption of 2500-3400 kcal; 4) people of non-mechanized heavy physical labor, whose energy expenditure reaches 3500-4000 kcal. During sports activities, energy consumption can be 4500-5000 kcal or more. This circumstance should be taken into account when drawing up the diet of athletes, which should ensure replenishment of expended energy.
Not all the energy released in the body is spent on mechanical work. Most of it turns into heat. The amount of energy that goes into doing work is called the coefficient useful action(efficiency). In humans, the efficiency does not exceed 20-25%. Efficiency during muscular activity depends on the power, structure and tempo of movements, on the number of muscles involved in the work and the degree of training of the person.
internal environment in an adult it is 60% of body weight, and in a newborn - 75%. It is the environment in which metabolic processes take place in cells, organs and tissues. A continuous supply of water to the body is one of the main conditions for maintaining its vital functions. The bulk (about 71%) of all water in the body is part of the protoplasm of cells, making up the so-called intracellular water. Extracellular water is part of tissue, or interstitial, fluid (about 21%) and blood plasma water (about 8%). The balance of water consists of its consumption and excretion. A person receives about 750 ml of water per day with food, and about 630 ml in the form of drinks and clean water. About 320 ml of water is formed during the metabolic process during the oxidation of proteins, carbohydrates and fats. When evaporating from the surface of the skin and alveoli of the lungs, about 800 ml of water is released per day. The same amount is necessary to dissolve osmotically active substances excreted by the kidney at maximum urine osmolarity. 100 ml of water is excreted in feces. Therefore, the minimum daily requirement is about 1700 ml of water.
The supply of water is regulated by its need, manifested by a feeling of thirst. This feeling occurs when the drinking center of the hypothalamus is stimulated.
The body needs a constant supply of not only water, but also mineral salts. Most important have sodium, potassium, calcium.
Sodium is the main cation in extracellular fluids. Its content in the extracellular environment is 6-12 times higher than the content in cells. Sodium in the amount of 3-6 g per day enters the body in the form of NaCl and is absorbed mainly in the small intestine. The role of sodium in the body is diverse. It is involved in maintaining the balance of the acid-base state, the osmotic pressure of extracellular and intracellular fluids, takes part in the formation of the action potential, and influences the activity of almost all body systems. It is of great importance in the development of a number of diseases. In particular, sodium is believed to mediate the development of arterial hypertension by both increasing extracellular fluid volume and increasing microvascular resistance. The sodium balance in the body is mainly maintained by the activity of the kidneys.
Potassium is the main cation in intracellular fluid. The cells contain 98% potassium. The human DV in potassium is 2-3 g. The main source of potassium in food is foods plant origin. Potassium is absorbed in the intestines. Potassium is of particular importance due to its potential-forming role both at the level of maintaining the membrane potential and in the generation of the action potential. Potassium also takes an active part in regulating the acid-base balance. It is a factor in maintaining osmotic pressure in cells. Its excretion is regulated primarily by the kidneys.
Calcium has high biological activity. It is the main structural component of skeletal bones and teeth, containing about 99% of all Ca 2+. An adult should receive 800-1000 mg of calcium per day from food. Children need more calcium due to rapid bone growth. Calcium is absorbed primarily in duodenum in the form of monobasic salts of phosphoric acid. Approximately 3/4 of calcium is excreted by the digestive tract, where endogenous calcium enters with the secretions of the digestive glands, and 1/4 by the kidneys. The role of calcium in the functioning of the body is great. Calcium takes part in the generation of the action potential, plays a certain role in the initiation of muscle contraction, is a necessary component of the blood coagulation system, increases the reflex excitability of the spinal cord and has a sympathicotropic effect.
Oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus make up the bulk of living matter.
In the body, elements found in small quantities also play a significant role in the implementation of life activities. They are called microelements. Microelements with high biological activity include iron, copper, zinc, cobalt, molybdenum, selenium, chromium, nickel, tin, silicon, fluorine, vanadium. In addition, many other elements are found in the body in small quantities, the biological role of which has not been established. In total, about 70 elements were found in the body of animals and humans.
Most biologically significant microelements are included in enzymes, vitamins, hormones, and respiratory pigments.
Vitamins do not have significant plastic and energetic significance and are not characterized by generality chemical nature. They are found in food products in small quantities, but have a pronounced effect on the physiological state of the body, often being a component of enzyme molecules. Sources of vitamins for humans are food products of plant and animal origin - they are found either in finished form or in the form of provitamins, from which vitamins are formed in the body. Some vitamins are synthesized by intestinal microflora. In the absence of any vitamin or its precursor, pathological condition, called vitamin deficiency, in less expressed form it is observed with a lack of vitamin - hypovitaminosis. The absence or deficiency of a certain vitamin causes a disease characteristic only of the absence of this vitamin. Avitaminosis and hypovitaminosis can occur not only in the absence of vitamins in food, but also when their absorption is impaired due to diseases of the gastrointestinal tract. The state of hypovitaminosis can also occur with the usual intake of vitamins from food, but with increased consumption (during pregnancy, intensive growth), as well as in the case of suppression of intestinal microflora by antibiotics.
Based on solubility, all vitamins are divided into two groups: water-soluble (B vitamins, vitamin C and vitamin P) and fat-soluble (vitamins A, D, E and K).
Regulation of fat metabolism.
Increasing the concentration of glucose in the blood reduces the breakdown of lipids and activates their synthesis. A decrease in blood glucose concentration, on the contrary, inhibits lipid synthesis and increases their breakdown. Thus, the relationship between fat and carbohydrate metabolism aimed at meeting the body's energy needs.
Adrenal medulla hormone - adrenaline, somatotropic pituitary hormone, thyroid hormone - thyroxine with long-term influence they reduce fat depot.
The metabolism is influenced by the sympathetic nervous system (it inhibits the synthesis of lipids and enhances their breakdown) and the parasympathetic nervous system (promotes fat deposition).
Nervous influences on fat metabolism are controlled by the hypothalamus.
Water is an integral part of all human cells and tissues. Water in an adult makes up 60% of body weight, and in a newborn – 75%. It is the environment in which metabolic processes take place in cells, organs and tissues. A continuous supply of water to the body is one of the main conditions for maintaining its vital functions.
The bulk - 71% of all water in the body - is part of the protoplasm of cells, making up intracellular water.
Extracellular water included in tissue fluid(about 21%) and blood plasma water (about 8%).
The water depot is subcutaneous tissue.
The balance of water consists of its consumption and excretion. A person receives about 750 ml of water per day with food, and about 630 ml in the form of drinks and clean water. About 320 ml of water is formed during the metabolic process during the oxidation of proteins, carbohydrates and fats. When evaporating from the surface of the skin and alveoli of the lungs, about 800 ml of water is released per day. 100 ml of water is excreted with feces. Therefore, the minimum daily requirement is about 1700 ml of water.
The supply of water is regulated by its need, manifested by a feeling of thirst. This feeling occurs when the drinking center of the hypothalamus is stimulated.
The body needs a constant supply of not only water, but also mineral salts. The most important are sodium, potassium and calcium.
Sodium (Na+) is the main cation in extracellular fluids. Its content in the extracellular environment is 6–12 times higher than the content in cells. Sodium in the amount of 3 - 6 g per day enters the body in the form of NaCl and is absorbed mainly in the small intestine. The role of sodium in the body is diverse. It is involved in maintaining the osmotic pressure of extracellular and intracellular fluids, takes part in the formation of the action potential, and influences the activity of almost all body systems. The sodium balance in the body is maintained mainly by the activity of the kidneys.
Potassium (K+) is the main cation in intracellular fluid. The cells contain 98% potassium. The daily requirement for potassium is 2-3 g. The main source of potassium in food is products of plant origin. Potassium is absorbed in the intestines. Potassium is of great importance in the life of the body because it maintains membrane potential and generates action potential. It is also involved in the regulation of acid-base balance and maintains osmotic pressure in cells. Its excretion is regulated primarily by the kidneys.
Calcium (Ca 2+) has high biological activity. It is the main structural component of skeletal bones and teeth, containing about 99% of all calcium. An adult should receive 800-1000 mg of calcium per day from food. Children need large amounts of calcium due to rapid bone growth. Calcium is absorbed primarily in the duodenum. Approximately ¾ of calcium is excreted through the digestive tract and ¼ through the kidneys. Calcium takes part in the generation of the action potential, plays a certain role in muscle contraction, is a necessary component of the blood coagulation system, and increases the reflex excitability of the spinal cord.
Elements found in small quantities also play a significant role in the body. They are called microelements. These include: iron, copper, zinc, cobalt, molybdenum, selenium, chromium, nickel, tin, silicon, fluorine, vanadium. Most biologically significant microelements are included in enzymes, vitamins, and hormones.