What is the composition of human blood? Blood is one of the tissues of the body, consisting of plasma (the liquid part) and cellular elements. Plasma is a homogeneous transparent or slightly cloudy liquid with a yellow tint, which is the intercellular substance of blood tissues. Plasma consists of water in which substances (mineral and organic) are dissolved, including proteins (albumins, globulins and fibrinogen). Carbohydrates (glucose), fats (lipids), hormones, enzymes, vitamins, individual constituents of salts (ions) and some metabolic products.

Together with the plasma, the body removes metabolic products, various poisons and antigen-antibody immune complexes (which occur when foreign particles enter the body as a protective reaction to remove them) and all unnecessary that prevents the body from working.

Composition of blood: blood cells

The cellular elements of the blood are also heterogeneous. They consist of:

• erythrocytes (red blood cells);
• leukocytes (white blood cells);
• platelets (platelets).

Erythrocytes are red blood cells. They transport oxygen from the lungs to all human organs. It is erythrocytes that contain an iron-containing protein - bright red hemoglobin, which attaches oxygen from the inhaled air to itself in the lungs, after which it gradually transfers it to all organs and tissues of various parts of the body.

Leukocytes are white blood cells. Responsible for immunity, i.e. for the ability of the human body to resist various viruses and infections. There are different types of leukocytes. Some of them are aimed directly at the destruction of bacteria or various foreign cells that have entered the body. Others are involved in the production of special molecules, the so-called antibodies, which are also necessary to fight various infections.

Platelets are platelets. They help the body stop bleeding, that is, they regulate blood clotting. For example, if you damaged a blood vessel, then a blood clot will appear at the site of damage over time, after which a crust will form, respectively, the bleeding will stop. Without platelets (and with them a number of substances that are found in blood plasma), clots will not form, so any wound or nosebleed, for example, can lead to a large loss of blood.

Blood composition: normal

As we wrote above, there are red blood cells and white blood cells. So, normally, erythrocytes (red blood cells) in men should be 4-5 * 1012 / l, in women 3.9-4.7 * 1012 / l. Leukocytes (white blood cells) - 4-9 * 109 / l of blood. In addition, in 1 µl of blood there are 180-320 * 109 / l of platelets (platelets). Normally, the volume of cells is 35-45% of the total blood volume.

The chemical composition of human blood

Blood washes every cell of the human body and every organ, therefore it reacts to any changes in the body or lifestyle. Factors affecting the composition of the blood are quite diverse. Therefore, in order to correctly read the results of the tests, the doctor needs to know about bad habits and physical activity of a person, and even about the diet. Even the environment and that affects the composition of the blood. Everything related to metabolism also affects blood counts. For example, consider how a regular meal changes blood counts:

• Eating before a blood test to increase the concentration of fat.
• Fasting for 2 days will increase bilirubin in the blood.
• Fasting more than 4 days will reduce the amount of urea and fatty acids.
• Fatty foods will increase your potassium and triglyceride levels.
• Eating too much meat will increase your urate levels.
• Coffee increase the level of glucose, fatty acids, leukocytes and erythrocytes.

The blood of smokers differs significantly from the blood of people leading a healthy lifestyle. However, if you lead an active lifestyle, before taking a blood test, you need to reduce the intensity of training. This is especially true when it comes to hormone testing. Various medications also affect the chemical composition of the blood, so if you have taken something, be sure to tell your doctor about it.

Blood (haema, sanguis) is a liquid tissue consisting of plasma and blood cells suspended in it. The blood is enclosed in a system of vessels and is in a state of continuous movement. Blood, lymph, interstitial fluid are 3 internal environments of the body that wash all cells, delivering them the substances necessary for life, and carry away the end products of metabolism. The internal environment of the body is constant in its composition and physico-chemical properties. The constancy of the internal environment of the body is called homeostasis and is a necessary condition for life. Homeostasis is regulated by the nervous and endocrine systems. The cessation of blood flow during cardiac arrest leads the body to death.

Blood functions:

Transport (respiratory, nutritional, excretory)

Protective (immune, protection against blood loss)

Thermoregulating

Humoral regulation of functions in the body.

QUANTITY OF BLOOD, PHYSICO-CHEMICAL PROPERTIES OF BLOOD

Quantity

Blood makes up 6-8% of body weight. Newborns have up to 15%. On average, a person has 4.5 - 5 liters. Blood circulating in the vessels peripheral , part of the blood is contained in the depot (liver, spleen, skin) - deposited . The loss of 1/3 of the blood leads to the death of the organism.

Specific gravity(density) of blood - 1,050 - 1,060.

It depends on the amount of red blood cells, hemoglobin and proteins in the blood plasma. It increases with thickening of the blood (dehydration, exercise). A decrease in the specific gravity of blood is observed with the influx of fluid from the tissues after blood loss. In women, the specific gravity of the blood is slightly lower, because they have a lower number of red blood cells.

Blood viscosity 3- 5, exceeds the viscosity of water by 3 - 5 times (the viscosity of water at a temperature of + 20 ° C is taken as 1 conventional unit).

Plasma viscosity - 1.7-2.2.

Blood viscosity depends on the number of red blood cells and plasma proteins (mainly

fibrinogen) in the blood.

The rheological properties of blood depend on the viscosity of the blood - the speed of blood flow and

peripheral blood resistance in the vessels.

Viscosity has a different value in different vessels (highest in venules and

veins, lower in arteries, lowest in capillaries and arterioles). If

viscosity would be the same in all vessels, then the heart would have to develop

30-40 times more power to push blood through the entire vascular

Viscosity increases with thickening of the blood, dehydration, after physical

loads, with erythremia, some poisonings, in venous blood, with the introduction

drugs - coagulants (drugs that enhance blood clotting).

Viscosity decreases with anemia, with the influx of fluid from tissues after blood loss, with hemophilia, with fever, in arterial blood, with the introduction heparin and other anticoagulants.

Environment reaction (pH) - fine 7,36 - 7,42. Life is possible if the pH is between 7 and 7.8.

The condition in which there is an accumulation of acid equivalents in the blood and tissues is called acidosis (acidification), At the same time, blood pH decreases (less than 7.36). acidosis may be :

gas - with the accumulation of CO 2 in the blood (CO 2 + H 2 O<->H 2 CO 3 - accumulation of acid equivalents);

metabolic (accumulation of acid metabolites, for example, in diabetic coma, the accumulation of acetoacetic and gamma-aminobutyric acids).

Acidosis leads to CNS inhibition, coma and death.

The accumulation of alkaline equivalents is called alkalosis (alkalinization)- an increase in pH greater than 7.42.

Alkalosis can also be gas , with hyperventilation of the lungs (if too much CO 2 is excreted), metabolic - with the accumulation of alkaline equivalents and excessive excretion of acidic ones (uncontrollable vomiting, diarrhea, poisoning, etc.) Alkalosis leads to overexcitation of the central nervous system, muscle cramps and death.

Maintaining the pH is achieved through blood buffer systems that can bind hydroxyl (OH-) and hydrogen ions (H +) and thus keep the blood reaction constant. The ability of buffer systems to counteract the pH shift is explained by the fact that when they interact with H+ or OH-, compounds are formed that have a weakly pronounced acidic or basic character.

The main buffer systems of the body:

protein buffer system (acidic and alkaline proteins);

hemoglobin (hemoglobin, oxyhemoglobin);

bicarbonate (bicarbonates, carbonic acid);

phosphate (primary and secondary phosphates).

Osmotic blood pressure = 7.6-8.1 atm.

It is being created mostly sodium salts and other mineral salts dissolved in the blood.

Due to osmotic pressure, water is distributed evenly between cells and tissues.

Isotonic solutions solutions are called, the osmotic pressure of which is equal to the osmotic pressure of the blood. In isotonic solutions, erythrocytes do not change. Isotonic solutions are: saline 0.86% NaCl, Ringer's solution, Ringer-Locke's solution, etc.

in a hypotonic solution(the osmotic pressure of which is lower than in the blood), water from the solution goes into the red blood cells, while they swell and collapse - osmotic hemolysis. Solutions with higher osmotic pressure are called hypertensive, erythrocytes in them lose H 2 O and shrivel.

oncotic blood pressure due to plasma proteins (mainly albumin) Normally is 25-30 mmHg Art.(average 28) (0.03 - 0.04 atm.). Oncotic pressure is the osmotic pressure of blood plasma proteins. It is part of the osmotic pressure (is 0.05% of

osmotic). Thanks to him, water is retained in the blood vessels (vascular bed).

With a decrease in the amount of proteins in the blood plasma - hypoalbuminemia (with impaired liver function, hunger), oncotic pressure decreases, water leaves the blood through the wall of blood vessels into the tissues, and oncotic edema occurs ("hungry" edema).

ESR- sedimentation rate of erythrocytes, expressed in mm/h. At men ESR is normal - 0-10 mm/hour , among women - 2-15 mm/hour (in pregnant women up to 30-45 mm / hour).

ESR increases in inflammatory, purulent, infectious and malignant diseases, it is normally increased in pregnant women.

BLOOD COMPOSITION

Formed elements of the blood - blood cells, make up 40 - 45% of the blood.

Blood plasma is a liquid intercellular substance of blood, it makes up 55-60% of blood.

The ratio of plasma and blood cells is called hematocritindicator, because it is determined using hematocrit.

When blood stands in a test tube, the formed elements settle to the bottom, and the plasma remains on top.

FORMED BLOOD ELEMENTS

Erythrocytes (red blood cells), leukocytes (white blood cells), platelets (red blood plates).

erythrocytes are red blood cells without a nucleus

the shape of a biconcave disc, 7-8 microns in size.

They are formed in the red bone marrow, live for 120 days, are destroyed in the spleen (“erythrocyte graveyard”), liver, and macrophages.

Functions:

1) respiratory - due to hemoglobin (transfer of O 2 and CO 2);

nutritional - can transport amino acids and other substances;

protective - able to bind toxins;

enzymatic - contain enzymes. Quantity erythrocytes are normal

in men in 1 ml - 4.1-4.9 million.

in women in 1 ml - 3.9 million.

in newborns in 1 ml - up to 6 million.

in the elderly in 1 ml - less than 4 million.

An increase in the number of red blood cells is called erythrocytosis.

Types of erythrocytosis:

1.Physiological(normal) - in newborns, residents of mountainous areas, after eating and exercise.

2. Pathological- with violations of hematopoiesis, erythremia (hemoblastoses - tumor diseases of the blood).

A decrease in the number of red blood cells in the blood is called erythropenia. It can be after blood loss, impaired formation of red blood cells

(iron deficiency, B!2 deficiency, folic acid deficiency anemia) and increased destruction of red blood cells (hemolysis).

HEMOGLOBIN (Hb) is a red respiratory pigment found in erythrocytes. Synthesized in the red bone marrow, destroyed in the spleen, liver, macrophages.

Hemoglobin consists of a protein - globin and 4 heme molecules. gem- non-protein part of Hb, contains iron, which combines with O 2 and CO 2. One hemoglobin molecule can attach 4 O 2 molecules.

The norm of the amount of Hb in the blood in men up to 132-164 g/l, in women 115-145 g/l. Hemoglobin decreases - with anemia (iron deficiency and hemolytic), after blood loss, increases - with blood clotting, B12 - folic deficiency anemia, etc.

Myoglobin is muscle hemoglobin. Plays an important role in the supply of O 2 to skeletal muscles.

Functions of hemoglobin: - respiratory - transport of oxygen and carbon dioxide;

enzymatic - contains enzymes;

buffer - is involved in maintaining the pH of the blood. Hemoglobin compounds:

1.physiological compounds of hemoglobin:

but) Oxyhemoglobin: Hb + O 2<->NIO 2

b) Carbohemoglobin: Hb + CO 2<->HCO 2 2. pathological hemoglobin compounds

a) Carboxyhemoglobin- connection with carbon monoxide, formed during carbon monoxide (CO) poisoning, irreversible, while Hb is no longer able to carry O 2 and CO 2: Hb + CO -> HbO

b) Methemoglobin(Met Hb) - connection with nitrates, the connection is irreversible, formed during poisoning with nitrates.

HEMOLYSIS - this is the destruction of red blood cells with the release of hemoglobin to the outside. Types of hemolysis:

1. Mechanical hemolysis - can occur when shaking a test tube with blood.

2. Chemical hemolysis - with acids, alkalis, etc.

Z. Osmotic hemolysis - in a hypotonic solution, the osmotic pressure of which is lower than in the blood. In such solutions, water from the solution goes into the erythrocytes, while they swell and collapse.

4. Biological hemolysis - with a transfusion of an incompatible blood type, with snake bites (venom has a hemolytic effect).

Hemolyzed blood is called "lacquer", the color is bright red. hemoglobin enters the blood. Hemolyzed blood is unsuitable for analysis.

leukocytes- these are colorless (white) blood cells, containing a nucleus and protoplasm. They are formed in the red bone marrow, live 7-12 days, are destroyed in the spleen, liver, and macrophages.

Functions of leukocytes: immune defense, phagocytosis of foreign particles.

Properties of leukocytes:

Amoeba mobility.

Diapedesis - the ability to pass through the wall of blood vessels in the tissue.

Chemotaxis - movement in tissues to the focus of inflammation.

The ability to phagocytosis - the absorption of foreign particles.

In the blood of healthy people at rest white blood cell count ranges from 3.8-9.8 thousand in 1 ml.

An increase in the number of white blood cells in the blood is called leukocytosis.

Types of leukocytosis:

Physiological leukocytosis (normal) - after eating and exercise.

Pathological leukocytosis - occurs with infectious, inflammatory, purulent processes, leukemia.

Decrease in the number of leukocytes called in the blood leukopenia, can be with radiation sickness, exhaustion, aleukemic leukemia.

The percentage of types of leukocytes among themselves is called leukocyte count.

Blood is a red liquid connective tissue that is constantly in motion and performs many complex and important functions for the body. It constantly circulates in the circulatory system and carries the gases and substances dissolved in it necessary for metabolic processes.

The structure of the blood

What is blood? This is a tissue that consists of plasma and special blood cells that are in it in the form of a suspension. Plasma is a clear yellowish liquid that makes up more than half of the total volume of blood. . It contains three main types of shaped elements:

• erythrocytes - red cells that give the blood a red color due to the hemoglobin in them;
• leukocytes - white cells;
• platelets are platelets.

Arterial blood, which comes from the lungs to the heart and then spreads to all organs, is enriched with oxygen and has a bright scarlet color. After the blood gives oxygen to the tissues, it returns through the veins to the heart. Deprived of oxygen, it becomes darker.

Approximately 4 to 5 liters of blood circulate in the circulatory system of an adult. Approximately 55% of the volume is occupied by plasma, the rest is accounted for by formed elements, while the majority are erythrocytes - more than 90%.

Blood is a viscous substance. Viscosity depends on the amount of proteins and red blood cells in it. This quality affects blood pressure and movement speed. The density of blood and the nature of the movement of formed elements determine its fluidity. Blood cells move in different ways. They can move in groups or singly. RBCs can move either individually or in whole "stacks", like stacked coins, as a rule, create a flow in the center of the vessel. White cells move singly and usually stay near the walls.

Plasma is a liquid component of a light yellow color, which is due to a small amount of bile pigment and other colored particles. Approximately 90% it consists of water and approximately 10% of organic matter and minerals dissolved in it. Its composition is not constant and varies depending on the food taken, the amount of water and salts. The composition of substances dissolved in plasma is as follows:

• organic - about 0.1% glucose, about 7% proteins and about 2% fats, amino acids, lactic and uric acid and others;
• minerals make up 1% (anions of chlorine, phosphorus, sulfur, iodine and cations of sodium, calcium, iron, magnesium, potassium.

Plasma proteins take part in the exchange of water, distribute it between the tissue fluid and blood, give blood viscosity. Some of the proteins are antibodies and neutralize foreign agents. An important role is given to the soluble protein fibrinogen. He takes part in the process of blood coagulation, turning under the influence of coagulation factors into insoluble fibrin.

In addition, plasma contains hormones that are produced by endocrine glands, and other bioactive elements necessary for the functioning of body systems.

Plasma devoid of fibrinogen is called blood serum. You can read more about blood plasma here.

red blood cells

The most numerous blood cells, making up about 44-48% of its volume. They have the form of discs, biconcave in the center, with a diameter of about 7.5 microns. The shape of the cells ensures the efficiency of physiological processes. Due to the concavity, the surface area of ​​the sides of the erythrocyte increases, which is important for gas exchange. Mature cells do not contain nuclei. The main function of red blood cells is the delivery of oxygen from the lungs to the tissues of the body.

Their name is translated from Greek as "red". Red blood cells owe their color to a very complex protein, hemoglobin, which is able to bind with oxygen. Hemoglobin consists of a protein part called globin and a non-protein part (heme) containing iron. It is thanks to iron that hemoglobin can attach oxygen molecules.

Red blood cells are produced in the bone marrow. The term of their full maturation is approximately five days. The lifespan of red cells is about 120 days. RBC destruction occurs in the spleen and liver. Hemoglobin is broken down into globin and heme. What happens to globin is unknown, but iron ions are released from heme, return to the bone marrow and go to the production of new red blood cells. Heme without iron is converted into the bile pigment bilirubin, which enters the digestive tract with bile.

A decrease in the level of red blood cells in the blood leads to a condition such as anemia, or anemia.

Leukocytes

Colorless peripheral blood cells that protect the body from external infections and pathologically altered own cells. White bodies are divided into granular (granulocytes) and non-granular (agranulocytes). The former include neutrophils, basophils, eosinophils, which are distinguished by their reaction to different dyes. To the second - monocytes and lymphocytes. Granular leukocytes have granules in the cytoplasm and a nucleus consisting of segments. Agranulocytes are devoid of granularity, their nucleus usually has a regular rounded shape.

Granulocytes are produced in the bone marrow. After maturation, when granularity and segmentation are formed, they enter the blood, where they move along the walls, making amoeboid movements. They protect the body mainly from bacteria, are able to leave the vessels and accumulate in the foci of infections.

Monocytes are large cells that form in the bone marrow, lymph nodes, and spleen. Their main function is phagocytosis. Lymphocytes are small cells that are divided into three types (B-, T, O-lymphocytes), each of which performs its own function. These cells produce antibodies, interferons, macrophage activating factors, and kill cancer cells.

platelets

Small non-nuclear colorless plates, which are fragments of megakaryocyte cells located in the bone marrow. They can be oval, spherical, rod-shaped. Life expectancy is about ten days. The main function is participation in the process of blood coagulation. Platelets secrete substances that take part in a chain of reactions that are triggered when a blood vessel is damaged. As a result, the fibrinogen protein turns into insoluble fibrin strands, in which blood elements become entangled and a blood clot forms.

Blood functions

It is unlikely that anyone doubts that blood is necessary for the body, but why it is needed, perhaps not everyone can answer. This liquid tissue performs several functions, including:

1. Protective. The main role in protecting the body from infections and damage is played by leukocytes, namely neutrophils and monocytes. They rush and accumulate at the site of damage. Their main purpose is phagocytosis, that is, the absorption of microorganisms. Neutrophils are microphages and monocytes are macrophages. Other types of white blood cells - lymphocytes - produce antibodies against harmful agents. In addition, leukocytes are involved in the removal of damaged and dead tissues from the body.
2. Transport. Blood supply affects almost all processes in the body, including the most important - respiration and digestion. With the help of blood, oxygen is transferred from the lungs to the tissues and carbon dioxide from the tissues to the lungs, organic substances from the intestines to the cells, end products, which are then excreted by the kidneys, transport of hormones and other bioactive substances.
3. Temperature regulation. A person needs blood to maintain a constant body temperature, the norm of which is in a very narrow range - about 37 ° C.

Conclusion

Blood is one of the tissues of the body, which has a certain composition and performs a number of important functions. For normal life, it is necessary that all components are in the blood in the optimal ratio. Changes in the composition of the blood, detected during the analysis, make it possible to identify the pathology at an early stage.

The ancients said that the secret is hidden in the water. Is it so? Let's think. The two most important fluids in the human body are blood and lymph. The composition and functions of the first, we will consider in detail today. People always remember about diseases, their symptoms, the importance of maintaining a healthy lifestyle, but they forget that blood has a huge impact on health. Let's talk in detail about the composition, properties and functions of blood.

Introduction to the topic

To begin with, it is worth deciding what blood is. Generally speaking, this is a special type of connective tissue, which in its essence is a liquid intercellular substance that circulates through the blood vessels, bringing useful substances to each cell of the body. Without blood, a person dies. There are a number of diseases, which we will discuss below, that spoil the properties of the blood, leading to negative or even fatal consequences.

The body of an adult contains approximately four to five liters of blood. It is also believed that the red liquid makes up a third of a person's weight. 60% is plasma and 40% is formed elements.

Composition

The composition of the blood and the functions of the blood are numerous. Let's start with the composition. Plasma and formed elements are the main components.

The formed elements, which will be discussed in detail below, consist of erythrocytes, platelets and leukocytes. What does plasma look like? It resembles an almost transparent liquid with a yellowish tint. Almost 90% of plasma consists of water, but it also contains mineral and organic substances, proteins, fats, glucose, hormones, amino acids, vitamins and a variety of products of the metabolic process.

Blood plasma, the composition and functions of which we are considering, is the necessary environment in which the formed elements exist. Plasma is made up of three main proteins - globulins, albumins and fibrinogen. Interestingly, it even contains gases in a small amount.

red blood cells

The composition of the blood and the functions of the blood cannot be considered without a detailed study of erythrocytes - red cells. Under a microscope, they were found to resemble concave discs in appearance. They do not have nuclei. The cytoplasm contains the protein hemoglobin, which is important for human health. If it is not enough, the person falls ill with anemia. Since hemoglobin is a complex substance, it consists of heme pigment and globin protein. Iron is an important structural element.

Erythrocytes perform the most important function - they carry oxygen and carbon dioxide through the vessels. It is they that nourish the body, help it live and develop, because without air a person dies in a few minutes, and the brain, with insufficient work of red blood cells, can experience oxygen starvation. Although the red cells themselves do not have a nucleus, they still develop from nuclear cells. The latter mature in the red bone marrow. As they mature, red cells lose their nucleus and become shaped elements. Interestingly, the life cycle of red blood cells is about 130 days. After that, they are destroyed in the spleen or liver. Bile pigment is formed from hemoglobin protein.

platelets

Platelets have neither color nor nucleus. These are cells of a rounded shape, which outwardly resemble plates. Their main task is to ensure sufficient blood clotting. One liter of human blood can contain from 200 to 400 thousand of these cells. The site of platelet formation is the red bone marrow. Cells are destroyed in case of even the slightest damage to blood vessels.

Leukocytes

Leukocytes also perform important functions, which will be discussed below. First, let's talk about their appearance. Leukocytes are white bodies that do not have a fixed shape. The formation of cells occurs in the spleen, lymph nodes and bone marrow. By the way, leukocytes have nuclei. Their life cycle is much shorter than that of red blood cells. They exist for an average of three days, after which they are destroyed in the spleen.

Leukocytes perform a very important function - they protect a person from a variety of bacteria, foreign proteins, etc. Leukocytes can penetrate through thin capillary walls, analyzing the environment in the intercellular space. The fact is that these small bodies are extremely sensitive to various chemical secretions that are formed during the decay of bacteria.

Speaking figuratively and clearly, one can imagine the work of leukocytes as follows: getting into the intercellular space, they analyze the environment and look for bacteria or decay products. Having found a negative factor, leukocytes approach it and absorb it into themselves, that is, they absorb it, then inside the body the harmful substance is split with the help of secreted enzymes.

It will be useful to know that these white blood cells have intracellular digestion. At the same time, protecting the body from harmful bacteria, a large number of leukocytes die. Thus, the bacterium is not destroyed and decay products and pus accumulate around it. Over time, new white blood cells absorb it all and digest it. It is interesting that I. Mechnikov was very carried away by this phenomenon, who called the white shaped elements phagocytes, and gave the name phagocytosis to the very process of absorption of harmful bacteria. In a broader sense, this word will be used in the sense of the general defensive reaction of the body.

blood properties

Blood has certain properties. There are three main ones:

1. Colloidal, which directly depend on the amount of protein in the plasma. It is known that protein molecules can retain water, therefore, thanks to this property, the liquid composition of the blood is stable.
2. Suspension: also associated with the presence of protein and the ratio of albumin and globulins.
3. Electrolyte: affect osmotic pressure. Depend on the ratio of anions and cations.

Functions

The work of the human circulatory system is not interrupted even for a minute. In every second of time, blood performs a number of important functions for the body. Which ones? Experts identify four main functions:

1. Protective. It is clear that one of the main functions is to protect the body. This happens at the level of cells that repel or destroy foreign or harmful bacteria.
2. Homeostatic. The body works properly only in a stable environment, so consistency plays a huge role. Maintaining homeostasis (balance) means controlling the water-electrolyte balance, acid-base balance, etc.
3. Mechanical is an important function that ensures the health of organs. It consists in the turgor tension that the organs experience during a rush of blood.
4. Transport is another function, which lies in the fact that the body receives everything it needs through the blood. All useful substances that come with food, water, vitamins, injections, etc. do not directly diverge to the organs, but through the blood, which nourishes all body systems equally.

The last function has several sub-functions that are worth considering separately.

Respiratory is that oxygen is transferred from the lungs to the tissues, and carbon dioxide from the tissues to the lungs.

Nutritional subfunction refers to the delivery of nutrients to the tissues.

The excretory subfunction is to transport waste products to the liver and lungs for their further excretion from the body.

No less important is thermoregulation, on which body temperature depends. The regulatory subfunction is to transport hormones - signaling substances that are necessary for all body systems.

The composition of the blood and the functions of the formed elements of the blood determine the health of a person and his well-being. Deficiency or excess of certain substances can lead to mild ailments such as dizziness or to serious illnesses. Blood performs its functions clearly, the main thing is that the products of transportation are useful for the body.

Blood types

The composition, properties and functions of blood, we examined in detail above. Now it's time to talk about blood groups. Belonging to a particular group is determined by a set of specific antigenic properties of red blood cells. Each person has a certain blood type, which does not change throughout life and is innate. The most important grouping is the division into four groups according to the "AB0" system and into two groups according to the Rh factor.

In the modern world, blood transfusion is very often required, which we will discuss below. So, for the success of this process, the blood of the donor and the recipient must match. However, not everything is decided by compatibility, there are interesting exceptions. People with blood type I can be universal donors for people with any blood type. Those with IV blood group are universal recipients.

It is quite possible to predict the blood type of the future baby. To do this, you need to know the blood group of the parents. A detailed analysis will make it possible to guess the future blood type with a high probability.

Blood transfusion

A blood transfusion may be required for a number of diseases or for large blood loss in case of severe injury. Blood, the structure, composition and functions of which we have examined, is not a universal liquid, therefore it is important to timely transfuse the nominal group that the patient needs. With a large blood loss, internal blood pressure drops and the amount of hemoglobin decreases, and the internal environment ceases to be stable, that is, the body cannot function normally.

The approximate composition of blood and the functions of blood elements were known in antiquity. Then the doctors were also engaged in transfusion, which often saved the life of the patient, but the mortality rate from this method of treatment was incredibly high due to the fact that there was no concept of compatibility of blood groups at that time. However, death could occur not only as a result of this. Sometimes death occurred due to the fact that donor cells stuck together and formed lumps that clogged blood vessels and disrupted blood circulation. This effect of transfusion is called agglutination.

Blood diseases

The composition of the blood, its main functions affect the overall well-being and health. If there are any violations, various diseases can occur. Hematology deals with the study of the clinical picture of diseases, their diagnosis, treatment, pathogenesis, prognosis and prevention. However, blood diseases can also be malignant. Oncohematology is engaged in their study.

One of the most common diseases is anemia, in which case it is necessary to saturate the blood with iron-containing products. Its composition, quantity and functions are affected by this disease. By the way, if the disease is started, you can end up in the hospital. The concept of "anemia" includes a number of clinical syndromes that are associated with a single symptom - a decrease in the amount of hemoglobin in the blood. Very often this occurs against the background of a decrease in the number of red blood cells, but not always. Anemia should not be understood as one disease. Often it is just a symptom of another disease.

Hemolytic anemia is a blood disease in which the body is massive destruction of red blood cells. Hemolytic disease in newborns occurs when there is an incompatibility between mother and child in terms of blood type or Rh factor. In this case, the mother's body perceives the formed elements of the child's blood as foreign agents. For this reason, children most often suffer from jaundice.

Hemophilia is a disease that is manifested by poor blood clotting, which, with minor tissue damage without immediate intervention, can lead to death. The composition of the blood and the functions of the blood may not be the cause of the disease, sometimes it lies in the blood vessels. For example, in hemorrhagic vasculitis, the walls of microvessels are damaged, which causes the formation of microthrombi. This process affects the kidneys and intestines most of all.

animal blood

The composition of the blood and the functions of the blood in animals have their own differences. In invertebrates, the proportion of blood in the total body weight is approximately 20-30%. It is interesting that in vertebrates the same figure reaches only 2-8%. In the world of animals, blood is more diverse than in humans. Separately, it is worth talking about the composition of the blood. The functions of blood are similar, but the composition can be completely different. There is iron-containing blood that flows in the veins of vertebrates. It is red in color, similar to human blood. Iron-containing blood based on hemerythrin is characteristic of worms. Spiders and various cephalopods are naturally rewarded with blood based on hemocyanin, that is, their blood contains not iron, but copper.

Animal blood is used in different ways. National dishes are prepared from it, albumin and medicines are created. However, in many religions it is forbidden to eat the blood of any animal. Because of this, there are certain techniques for slaughtering and preparing animal food.

As we have already understood, the most important role in the body is assigned to the blood system. Its composition and functions determine the health of every organ, brain and all other body systems. What should be done to be healthy? It's very simple: think about what substances your blood carries through the body every day. Is it the right healthy food, in which the rules of preparation, proportions, etc. are observed, or is it processed food, food from fast food stores, tasty, but unhealthy food? Pay special attention to the quality of the water you drink. The composition of blood and the functions of blood largely depend on its composition. What is the fact that the plasma itself is 90% water. Blood (composition, functions, metabolism - in the article above) is the most important fluid for the body, remember this.

Blood, together with lymph and interstitial fluid, constitutes the internal environment of the body, in which the vital activity of all cells and tissues takes place.

Peculiarities:

1) is a liquid medium containing shaped elements;

2) is in constant motion;

3) constituent parts are mainly formed and destroyed outside of it.

Blood, together with hematopoietic and blood-destroying organs (bone marrow, spleen, liver and lymph nodes), makes up an integral blood system. The activity of this system is regulated by neurohumoral and reflex ways.

Thanks to the circulation in the vessels, blood performs the following important functions in the body:

14. Transport - blood transports nutrients (glucose, amino acids, fats, etc.) to the cells, and the end products of metabolism (ammonia, urea, uric acid, etc.) - from them to the excretory organs.

15. Regulatory - carries out the transfer of hormones and other physiologically active substances that affect various organs and tissues; regulation of the constancy of body temperature - the transfer of heat from organs with its intensive formation to organs with less intense heat production and to places of cooling (skin).

16. Protective - due to the ability of leukocytes to phagocytosis and the presence in the blood of immune bodies that neutralize microorganisms and their poisons, destroy foreign proteins.

17. Respiratory - delivery of oxygen from the lungs to the tissues, carbon dioxide - from the tissues to the lungs.

In an adult, the total amount of blood is 5-8% of body weight, which corresponds to 5-6 liters. The volume of blood is usually denoted in relation to body weight (ml / kg). On average, it is 61.5 ml/kg for men and 58.9 ml/kg for women.

Not all blood circulates in the blood vessels at rest. About 40-50% of it is in the blood depots (spleen, liver, blood vessels of the skin and lungs). Liver - up to 20%, spleen - up to 16%, subcutaneous vascular network - up to 10%

The composition of the blood. Blood consists of formed elements (55-58%) - erythrocytes, leukocytes and platelets - and a liquid part - plasma (42-45%).

red blood cells- specialized non-nuclear cells with a diameter of 7-8 microns. Formed in the red bone marrow, destroyed in the liver and spleen. There are 4–5 million erythrocytes in 1 mm3 of blood. The structure and composition of erythrocytes are determined by their function - gas transport. The shape of erythrocytes in the form of a biconcave disk increases contact with the environment, thus contributing to the acceleration of gas exchange processes.

Hemoglobin has the ability to easily bind and split off oxygen. By attaching it, it becomes oxyhemoglobin. Giving oxygen in places with a low content, it turns into reduced (reduced) hemoglobin.

Skeletal and cardiac muscles contain muscle hemoglobin - myoglobin (an important role in supplying oxygen to working muscles).

Leukocytes, or white blood cells, according to morphological and functional features, are ordinary cells containing a nucleus and protoplasm of a specific structure. They are produced in the lymph nodes, spleen and bone marrow. In 1 mm 3 of human blood there are 5-6 thousand leukocytes.

Leukocytes are heterogeneous in their structure: in some of them, the protoplasm has a granular structure (granulocytes), in others there is no granularity (agronulocytes). Granulocytes make up 70-75% of all leukocytes and are divided depending on the ability to stain with neutral, acidic or basic dyes into neutrophils (60-70%), eosinophils (2-4%) and basophils (0.5-1%). Agranulocytes - lymphocytes (25-30%) and monocytes (4-8%).

Functions of leukocytes:

1) protective (phagocytosis, production of antibodies and destruction of toxins of protein origin);

2) participation in the breakdown of nutrients

platelets- plasma formations of oval or round shape with a diameter of 2-5 microns. In the blood of humans and mammals, they do not have a nucleus. Platelets are formed in the red bone marrow and in the spleen, and their number ranges from 200,000 to 600,000 per 1 mm3 of blood. They play an important role in the process of blood clotting.

The main function of leukocytes is immunogenesis (the ability to synthesize antibodies or immune bodies that neutralize microbes and their metabolic products). Leukocytes, having the ability to amoeboid movements, adsorb antibodies circulating in the blood and, penetrating through the walls of blood vessels, deliver them to the tissues to the foci of inflammation. Neutrophils, containing a large number of enzymes, have the ability to capture and digest pathogenic microbes (phagocytosis - from the Greek Phagos - devouring). The cells of the body are also digested, degenerating in the foci of inflammation.

Leukocytes are also involved in recovery processes after tissue inflammation.

Protecting the body from bleeding. This function is carried out due to the ability of blood to clot. The essence of blood coagulation is the transition of the fibrinogen protein dissolved in the plasma into an undissolved protein - fibrin, which forms threads glued to the edges of the wound. Blood clot. (thrombus) blocks further bleeding, protecting the body from blood loss.

The transformation of fibrogen into fibrin is carried out under the influence of the thrombin enzyme, which is formed from the prothrombin protein under the influence of thromboplastin, which appears in the blood when platelets are destroyed. The formation of thromboplastin and the conversion of prothrombin to thrombin proceed with the participation of calcium ions.

Blood groups. The doctrine of blood groups arose in connection with the problem of blood transfusion. In 1901, K. Landsteiner discovered agglutinogens A and B in human erythrocytes. Blood plasma contains agglutinins a and b (gamma globulins). According to the classification of K. Landsteiner and J. Jansky, depending on the presence or absence of agglutinogens and agglutinins in the blood of a particular person, 4 blood groups are distinguished. This system was called ABO. Blood groups in it are indicated by numbers and those agglutinogens that are contained in the erythrocytes of this group.

Group antigens are hereditary innate properties of blood that do not change throughout a person's life. There are no agglutinins in the blood plasma of newborns. They are formed during the first year of a child's life under the influence of substances supplied with food, as well as produced by the intestinal microflora, to those antigens that are not in his own erythrocytes.

Group I (O) - there are no agglutinogens in erythrocytes, plasma contains agglutinins a and b

Group II (A) - erythrocytes contain agglutinogen A, plasma - agglutinin b;

Group III (B) - agglutinogen B is in erythrocytes, agglutinin a is in plasma;

Group IV (AB) - agglutinogens A and B are found in erythrocytes, there are no agglutinins in plasma.

Among the inhabitants of Central Europe, blood type I occurs in 33.5%, group II - 37.5%, group III - 21%, group IV - 8%. 90% of Native Americans have I blood type. More than 20% of the population of Central Asia have III blood group.

Agglutination occurs when an agglutinogen with the same agglutinin occurs in the human blood: agglutinogen A with agglutinin a or agglutinogen B with agglutinin b. When incompatible blood is transfused, as a result of agglutination and their subsequent hemolysis, hemotransfusion shock develops, which can lead to death. Therefore, a rule was developed for the transfusion of small amounts of blood (200 ml), which took into account the presence of agglutinogens in the donor's erythrocytes and agglutinins in the recipient's plasma. Donor plasma was not taken into account because it was highly diluted with recipient plasma.

According to this rule, blood of group I can be transfused to people with all blood types (I, II, III, IV), therefore people with the first blood group are called universal donors. Blood of group II can be transfused to people with II and IY blood groups, blood of group III - from III and IV, Blood of group IV can only be transfused to people with the same blood type. At the same time, people with IV blood group can be transfused with any blood, so they are called universal recipients. If it is necessary to transfuse large amounts of blood, this rule cannot be used.