Advertising on the portal

Red blood cell: structure, shape and functions. Features of the structure of red blood cells

The site provides reference information for informational purposes only. Diagnosis and treatment of diseases must be carried out under the supervision of a specialist. All drugs have contraindications. Consultation with a specialist is required!

Blood is a liquid connective tissue that fills the entire human cardiovascular system. Its amount in the adult human body reaches 5 liters. It consists of a liquid part called plasma and formed elements such as leukocytes, platelets and red blood cells. In this article we will talk specifically about red blood cells, their structure, functions, method of formation, etc.

What are red blood cells?

This term comes from two words “ erythos" And " kytos", which translated from Greek means " red" And " container, cage" Erythrocytes are red blood cells in the blood of humans, vertebrates, and some invertebrate animals, which are responsible for a wide variety of very important functions.

Red cell formation

These cells are formed in the red bone marrow. Initially, the process of proliferation occurs ( tissue proliferation by cell proliferation). Then from hematopoietic stem cells ( cells - the founders of hematopoiesis) a megaloblast is formed ( large red corpuscle containing a nucleus and a large amount of hemoglobin), from which in turn an erythroblast is formed ( nucleated cell), and then the normocyte ( normal sized body). As soon as a normocyte loses its nucleus, it immediately turns into a reticulocyte - the immediate predecessor of red blood cells. The reticulocyte enters the bloodstream and transforms into an erythrocyte. It takes about 2 - 3 hours to transform it.

Structure

These blood cells are characterized by a biconcave shape and a red color, due to the presence of a large amount of hemoglobin in the cell. It is hemoglobin that makes up the bulk of these cells. Their diameter varies from 7 to 8 microns, but their thickness reaches 2 - 2.5 microns. Mature cells lack a nucleus, which significantly increases their surface area. In addition, the absence of a nucleus ensures rapid and uniform penetration of oxygen into the body. The lifespan of these cells is about 120 days. The total surface area of ​​human red blood cells exceeds 3000 square meters. This surface is 1500 times larger than the surface of the entire human body. If you place all the red cells of a person in one row, you can get a chain whose length will be about 150,000 km. The destruction of these bodies occurs mainly in the spleen and partially in the liver.

Functions

1. Nutritious: carry out the transfer of amino acids from the organs of the digestive system to the cells of the body;


2. Enzymatic: are carriers of various enzymes ( specific protein catalysts);
3. Respiratory: this function is carried out by hemoglobin, which is capable of attaching to itself and releasing both oxygen and carbon dioxide;
4. Protective: bind toxins due to the presence of special substances of protein origin on their surface.

Terms used to describe these cells

  • Microcytosis– the average size of red blood cells is smaller than normal;
  • Macrocytosis– the average size of red blood cells is larger than normal;
  • Normocytosis– the average size of red blood cells is normal;
  • Anisocytosis– the sizes of red blood cells vary significantly, some are too small, others are very large;
  • Poikilocytosis– the shape of the cells varies from regular to oval, crescent-shaped;
  • Normochromia– red blood cells are colored normally, which is a sign of a normal level of hemoglobin in them;
  • Hypochromia– red blood cells are faintly colored, indicating that they contain less hemoglobin than normal.

Sedimentation Rate (ESR)

Erythrocyte sedimentation rate or ESR is a fairly well-known indicator of laboratory diagnostics, which means the rate of separation of uncoagulated blood, which is placed in a special capillary. The blood is divided into 2 layers - lower and upper. The bottom layer consists of settled red blood cells, but the top layer is plasma. This indicator is usually measured in millimeters per hour. The value of ESR directly depends on the gender of the patient. In normal conditions, in men this figure ranges from 1 to 10 mm/hour, but in women it ranges from 2 to 15 mm/hour.

When the indicators increase, we are talking about disturbances in the functioning of the body. There is an opinion that in most cases, ESR increases against the background of an increase in the ratio of large and small protein particles in the blood plasma. As soon as fungi, viruses or bacteria enter the body, the level of protective antibodies immediately increases, which leads to changes in the ratio of blood proteins. It follows that ESR increases especially often against the background of inflammatory processes such as joint inflammation, tonsillitis, pneumonia, etc. The higher this indicator, the more pronounced the inflammatory process. With mild inflammation, the rate increases to 15 - 20 mm/hour. If the inflammatory process is severe, then it jumps to 60 - 80 mm/hour. If during the course of therapy the indicator begins to decrease, it means that the treatment was chosen correctly.

In addition to inflammatory diseases, an increase in ESR is also possible with some non-inflammatory ailments, namely:

  • Malignant formations;
  • Severe diseases of the liver and kidneys;
  • Severe blood pathologies;
  • Frequent blood transfusions;
  • Vaccine therapy.
The rate often increases during menstruation, as well as during pregnancy. The use of certain medications can also cause an increase in ESR.

Hemolysis - what is it?

Hemolysis is the process of destruction of the membrane of red blood cells, as a result of which hemoglobin is released into the plasma and the blood becomes clear.

Modern experts distinguish the following types of hemolysis:
1. According to the nature of the flow:

  • Physiological: destruction of old and pathological forms of red cells occurs. The process of their destruction is noted in small vessels, macrophages ( cells of mesenchymal origin) bone marrow and spleen, as well as in liver cells;
  • Pathological: against the background of a pathological condition, healthy young cells are destroyed.
2. By place of origin:
  • Endogenous: hemolysis occurs inside the human body;
  • Exogenous: hemolysis occurs outside the body ( for example, in a vial of blood).
3. According to the mechanism of occurrence:
  • Mechanical: noted with mechanical ruptures of the membrane ( for example, a bottle of blood had to be shaken);
  • Chemical: noted when red blood cells are exposed to substances that tend to dissolve lipids ( fat-like substances) membranes. Such substances include ether, alkalis, acids, alcohols and chloroform;
  • Biological: noted when exposed to biological factors ( poisons of insects, snakes, bacteria) or due to transfusion of incompatible blood;
  • Temperature: at low temperatures, ice crystals form in red blood cells, which tend to rupture the cell membrane;
  • Osmotic: occurs when red blood cells enter an environment with a lower osmotic content than blood ( thermodynamic) pressure. Under this pressure, cells swell and burst.

Red blood cells

The total number of these cells in human blood is simply enormous. So, for example, if your weight is about 60 kg, then there are at least 25 trillion red blood cells in your blood. The figure is very large, so for practicality and convenience, experts calculate not the overall level of these cells, but their number in a small amount of blood, namely in 1 cubic millimeter. It is important to note that the norms for the content of these cells are determined by several factors at once - the patient’s age, his gender and place of residence.


Normal red blood cell count

Clinical tests help determine the level of these cells ( general) blood test.
  • In women - from 3.7 to 4.7 trillion per liter;
  • In men - from 4 to 5.1 trillion per liter;
  • In children over 13 years old - from 3.6 to 5.1 trillion per liter;
  • In children aged 1 to 12 years - from 3.5 to 4.7 trillion per liter;
  • In children aged 1 year - from 3.6 to 4.9 trillion per liter;
  • In children at six months - from 3.5 to 4.8 trillion per liter;
  • In children at 1 month - from 3.8 to 5.6 trillion per liter;
  • In children on the first day of their life - from 4.3 to 7.6 trillion per 1 liter.
The high level of cells in the blood of newborns is due to the fact that during intrauterine development their bodies need more red blood cells. This is the only way the fetus can receive the amount of oxygen it needs under conditions of relatively low oxygen concentration in the mother’s blood.

Level of red blood cells in the blood of pregnant women

Most often, the number of these cells during pregnancy decreases slightly, which is completely normal. Firstly, during gestation, a woman’s body retains a large amount of water, which enters the blood and dilutes it. In addition, the bodies of almost all expectant mothers do not receive enough iron, as a result of which the formation of these cells again decreases.

Increased level of red blood cells in the blood

A condition characterized by an increase in the level of red blood cells in the blood is called erythremia , erythrocytosis or polycythemia .

The most common causes of this condition are:

  • Polycystic kidney disease ( a disease in which cysts appear in both kidneys and gradually enlarge);
  • COPD (chronic obstructive pulmonary disease - bronchial asthma, emphysema, chronic bronchitis);
  • Pickwick's syndrome ( obesity, accompanied by pulmonary insufficiency and arterial hypertension, i.e. persistent increase in blood pressure);
  • Hydronephrosis ( persistent progressive expansion of the renal pelvis and calyces against the background of impaired urine outflow);
  • A course of steroid therapy;
  • Congenital or acquired myeloma ( tumors from bone marrow elements). A physiological decrease in the level of these cells is possible in the periods between 17.00 and 7.00, after meals and when taking blood in a lying position. You can find out about other reasons for a decrease in the level of these cells by consulting a specialist.

    Red blood cells in urine

    Normally, there should be no red blood cells in the urine. Their presence in the form of single cells in the field of view of the microscope is allowed. Being present in urine sediment in very small quantities, they may indicate that the person was involved in sports or performed hard physical work. In women, a small amount of them can be observed with gynecological ailments, as well as during menstruation.

    A significant increase in their level in the urine can be noticed immediately, since the urine in such cases acquires a brown or red tint. The most common cause of the appearance of these cells in the urine is considered to be kidney and urinary tract diseases. These include various infections, pyelonephritis ( inflammation of kidney tissue), glomerulonephritis ( kidney disease characterized by inflammation of the glomerulus, i.e. olfactory glomerulus), kidney stones, and adenoma ( benign tumor) prostate gland. It is also possible to identify these cells in urine in cases of intestinal tumors, various blood clotting disorders, heart failure, and smallpox ( contagious viral pathology), malaria ( acute infectious disease), etc.

    Red blood cells often appear in the urine and during therapy with certain medications such as methenamine. The fact of the presence of red blood cells in the urine should alert both the patient and his attending physician. Such patients require a repeat urine test and a complete examination. A repeat urine test should be taken using a catheter. If a repeated analysis once again establishes the presence of numerous red cells in the urine, then the urinary system is examined.

The red blood cell, the structure and functions of which we will consider in our article, is the most important component of blood. It is these cells that carry out gas exchange, ensuring respiration at the cellular and tissue level.

Red blood cell: structure and functions

The circulatory system of humans and mammals is characterized by the most perfect structure compared to other organisms. It consists of a four-chambered heart and a closed system of blood vessels through which blood continuously circulates. This tissue consists of a liquid component - plasma, and a number of cells: erythrocytes, leukocytes and platelets. Each cell plays its role. The structure of a human red blood cell is determined by the functions it performs. This refers to the size, shape and number of these blood cells.

Features of the structure of red blood cells

Red blood cells have the shape of a biconcave disc. They are not able to move independently in the bloodstream, like leukocytes. They reach tissues and internal organs thanks to the work of the heart. Red blood cells are prokaryotic cells. This means that they do not contain a formal core. Otherwise they would not be able to transport oxygen and carbon dioxide. This function is performed due to the presence of a special substance inside the cells - hemoglobin, which also determines the red color of human blood.

The structure of hemoglobin

The structure and functions of red blood cells are largely determined by the characteristics of this particular substance. Hemoglobin contains two components. These are an iron-containing component called heme and a protein called globin. For the first time, the English biochemist Max Ferdinand Perutz managed to decipher the spatial structure of this chemical compound. For this discovery he was awarded the Nobel Prize in 1962. Hemoglobin is a member of the group of chromoproteins. These include complex proteins consisting of a simple biopolymer and a prosthetic group. For hemoglobin, this group is heme. This group also includes plant chlorophyll, which ensures the process of photosynthesis.

How does gas exchange occur?

In humans and other chordates, hemoglobin is located inside red blood cells, and in invertebrates it is dissolved directly in the blood plasma. In any case, the chemical composition of this complex protein allows the formation of unstable compounds with oxygen and carbon dioxide. Blood saturated with oxygen is called arterial. It is enriched with this gas in the lungs.

From the aorta it goes to the arteries, and then to the capillaries. These small vessels are suitable for every cell of the body. Here, red blood cells give up oxygen and add the main product of respiration - carbon dioxide. With the flow of blood, which is already venous, they return to the lungs. In these organs, gas exchange occurs in the smallest bubbles - alveoli. Here hemoglobin detaches carbon dioxide, which is removed from the body through exhalation, and the blood is again saturated with oxygen.

Such chemical reactions are due to the presence of ferrous iron in heme. As a result of combination and decomposition, oxy- and carbhemoglobin are sequentially formed. But the complex protein of erythrocytes can also form stable compounds. For example, during incomplete combustion of fuel, carbon monoxide is released, which forms carboxyhemoglobin with hemoglobin. This process leads to the death of red blood cells and poisoning of the body, which can be fatal.

What is anemia

Shortness of breath, noticeable weakness, tinnitus, noticeable pallor of the skin and mucous membranes may indicate an insufficient amount of hemoglobin in the blood. The norm of its content varies depending on gender. In women, this figure is 120 - 140 g per 1000 ml of blood, and in men it reaches 180 g/l. The hemoglobin content in the blood of newborns is the highest. It exceeds this figure in adults, reaching 210 g/l.

Lack of hemoglobin is a serious disease called anemia or anemia. It can be caused by a lack of vitamins and iron salts in food, addiction to alcohol, the influence of radiation pollution and other negative environmental factors on the body.

A decrease in the amount of hemoglobin can also be due to natural factors. For example, in women, anemia can be caused by the menstrual cycle or pregnancy. Subsequently, the amount of hemoglobin normalizes. A temporary decrease in this indicator is also observed among active donors who often donate blood. But an increased number of red blood cells is also quite dangerous and undesirable for the body. It leads to an increase in blood density and the formation of blood clots. An increase in this indicator is often observed in people living in high mountain areas.

It is possible to normalize hemoglobin levels by consuming foods containing iron. These include liver, tongue, cattle, rabbit, fish, black and red caviar. Products of plant origin also contain the necessary microelement, but the iron they contain is much more difficult to absorb. These include legumes, buckwheat, apples, molasses, red peppers and herbs.

Shape and size

The structure of red blood cells is characterized primarily by their shape, which is quite unusual. It really resembles a disk, concave on both sides. This shape of red blood cells is not accidental. It increases the surface of red blood cells and ensures the most effective penetration of oxygen into them. This unusual shape also helps to increase the number of these cells. Thus, normally 1 cubic mm of human blood contains about 5 million red blood cells, which also contributes to the best gas exchange.

The structure of frog red blood cells

Scientists have long established that human red blood cells have structural features that ensure the most efficient gas exchange. This applies to form, quantity, and internal content. This is especially obvious when the structure of human and frog red blood cells is compared. In the latter, red blood cells are oval in shape and contain a nucleus. This significantly reduces the content of respiratory pigments. Frog red blood cells are much larger than human ones, and therefore their concentration is not so high. For comparison: if a person has more than 5 million of them per cubic mm, then in amphibians this figure reaches 0.38.

Evolution of red blood cells

The structure of human and frog erythrocytes allows us to draw conclusions about the evolutionary transformations of such structures. Respiratory pigments are also found in the simplest ciliates. In the blood of invertebrates they are contained directly in the plasma. But this significantly increases the thickness of the blood, which can lead to the formation of blood clots inside the vessels. Therefore, over time, evolutionary transformations went towards the appearance of specialized cells, the formation of their biconcave shape, the disappearance of the nucleus, a decrease in their size and an increase in concentration.

Ontogenesis of red blood cells

An erythrocyte, the structure of which has a number of characteristic features, remains viable for 120 days. Subsequently, they are destroyed in the liver and spleen. The main hematopoietic organ in humans is the red bone marrow. It continuously produces new red blood cells from stem cells. Initially they contain a nucleus, which as it matures is destroyed and replaced by hemoglobin.

Features of blood transfusion

There are often situations in a person's life that require a blood transfusion. For a long time, such operations led to the death of patients, and the real reasons for this remained a mystery. Only at the beginning of the 20th century was it established that the culprit was the erythrocyte. The structure of these cells determines human blood groups. There are four of them in total, and they are distinguished according to the AB0 system.

Each of them is distinguished by a special type of protein substances contained in red blood cells. They are called agglutinogens. People with the first blood group do not have them. From the second - they have agglutinogens A, from the third - B, from the fourth - AB. At the same time, the blood plasma contains agglutinin proteins: alpha, beta, or both at the same time. The combination of these substances determines the compatibility of blood groups. This means that the simultaneous presence of agglutinogen A and agglutinin alpha in the blood is impossible. In this case, red blood cells stick together, which can lead to the death of the body.

What is Rh factor

The structure of the human red blood cell determines the performance of another function - determining the Rh factor. This sign is also necessarily taken into account during blood transfusion. In Rh-positive people, a special protein is located on the red blood cell membrane. There are a majority of such people in the world - more than 80%. Rh negative people do not have this protein.

What is the danger of mixing blood with different types of red blood cells? During the pregnancy of an Rh-negative woman, fetal proteins may enter her blood. In response to this, the mother’s body will begin to produce protective antibodies that neutralize them. During this process, the red blood cells of the Rh-positive fetus are destroyed. Modern medicine has created special drugs that prevent this conflict.

Red blood cells are red blood cells whose main function is to transport oxygen from the lungs to cells and tissues and carbon dioxide in the opposite direction. This role is possible due to its biconcave shape, small size, high concentration and presence of hemoglobin in the cell.

Red blood cells are highly specialized anucleate blood cells. Their core is lost during the maturation process. Red blood cells have the shape of a biconvex disk. On average, their diameter is about 7.5 microns, and the thickness at the periphery is 2.5 microns. Thanks to this shape, the surface of red blood cells for the diffusion of gases increases. In addition, their plasticity increases. Due to their high plasticity, they are deformed and easily pass through capillaries. Old and pathological red blood cells have low plasticity. Therefore, they are retained in the capillaries of the reticular tissue of the spleen and destroyed there.

The membrane of erythrocytes and the absence of a nucleus ensures their main function - the transport of oxygen and participation in the transfer of carbon dioxide. The erythrocyte membrane is impermeable to cations except potassium, and its permeability to chlorine anions, bicarbonate anions and hydroxyl anions is a million times greater. In addition, it allows oxygen and carbon dioxide molecules to pass through well. The membrane contains up to 52% protein. In particular, glycoproteins determine the blood group and provide its negative charge. It has a built-in Na–K–ATPase, which removes sodium from the cytoplasm and pumps in potassium ions. Chemoprotein makes up the bulk of red blood cells hemoglobin. In addition, the cytoplasm contains the enzymes carbonic anhydrase, phosphatases, cholinesterase and other enzymes.

Functions of red blood cells:

1. Transfer of oxygen from the lungs to the tissues.

2. Participation in the transport of CO 2 from tissues to the lungs.

3. Transport of water from tissues to the lungs, where it is released in the form of steam.

4. Participation in blood coagulation, releasing erythrocyte coagulation factors.

5. Transfer of amino acids on its surface.

6. Participate in the regulation of blood viscosity due to plasticity. As a result of their ability to deform, the viscosity of blood in small vessels is less than in large ones.

One microliter of a man’s blood contains 4.5-5.0 million red blood cells (4.5-5.0*10 12 /l). Women 3.7-4.7 million (3.7-4.7 * 10 12 / l).

The number of red blood cells is counted in Goryaev's cell. To do this, blood in a special capillary melanger (mixer) for red blood cells is mixed with a 3% sodium chloride solution in a ratio of 1:100 or 1:200. A drop of this mixture is then placed in a mesh chamber. It is created by the middle projection of the chamber and the cover glass. Chamber height 0.1 mm. On the middle protrusion there is a grid applied, forming large squares. Some of these squares are divided into 16 small ones. Each side of a small square has a size of 0.05 mm. Therefore, the volume of the mixture over the small square will be 1/10 mm * 1/20 mm * 1/20 mm = 1/4000 mm 3.

After filling the chamber, under a microscope, count the number of red blood cells in those 5 large squares that are divided into small ones, i.e. in 80 small ones. Then the number of red blood cells in one microliter of blood is calculated using the formula:

X = 4000*a*b/b.

Where a is the total number of red blood cells obtained during counting; b – the number of small squares in which the counting was carried out (b = 80); c – blood dilution (1:100, 1:200); 4000 is the reciprocal of the volume of liquid above the small square.

For quick calculations with a large number of tests, use photovoltaic erythrohemometers. The principle of their operation is based on determining the transparency of a suspension of red blood cells using a beam of light passing from a source to a light-sensitive sensor. Photoelectric calorimeters. An increase in the number of red blood cells in the blood is called erythrocytosis or erythremia ; decrease - erythropenia or anemia . These changes can be relative or absolute. For example, a relative decrease in their number occurs when water is retained in the body, and an increase occurs when dehydration occurs. An absolute decrease in the content of red blood cells, i.e. anemia, observed with blood loss, hematopoietic disorders, destruction of red blood cells by hemolytic poisons or transfusion of incompatible blood.

Hemolysis - This is the destruction of the red blood cell membrane and the release of hemoglobin into the plasma. As a result, the blood becomes clear.

The following types of hemolysis are distinguished:

1. By place of origin:

· Endogenous, i.e. in the body.

· Exogenous, outside of it. For example, in a bottle of blood, a heart-lung machine.

2. By character:

· Physiological. It ensures the destruction of old and pathological forms of red blood cells. There are two mechanisms. Intracellular hemolysis occurs in macrophages of the spleen, bone marrow, and liver cells. Intravascular– in small vessels from which hemoglobin is transferred to liver cells using the plasma protein haptoglobin. There, hemoglobin heme is converted into bilirubin. About 6-7 g of hemoglobin is destroyed per day.

· Pathological.

3. According to the mechanism of occurrence:

· Chemical. Occurs when red blood cells are exposed to substances that dissolve membrane lipids. These are alcohols, ether, chloroform, alkalis, acids, etc. In particular, when poisoned with a large dose of acetic acid, severe hemolysis occurs.

· Temperature. At low temperatures, ice crystals form in red blood cells, destroying their shell.

· Mechanical. Observed during mechanical ruptures of membranes. For example, when shaking a bottle of blood or pumping it with a heart-lung machine.

· Biological. Occurs under the influence of biological factors. These are hemolytic poisons of bacteria, insects, and snakes. As a result of transfusion of incompatible blood.

· Osmotic. Occurs when red blood cells enter an environment with an osmotic pressure lower than that of blood. Water enters the red blood cells, they swell and burst. The sodium chloride concentration at which 50% of all red blood cells are hemolyzed is a measure of their osmotic stability. It is determined in the clinic to diagnose liver diseases and anemia. Osmotic resistance must be at least 0.46% NaCl.

When red blood cells are placed in a medium with a higher osmotic pressure than blood, plasmolysis occurs. This is the shrinkage of red blood cells. It is used to count red blood cells.

Red blood cells as a concept appear in our lives most often in school during biology lessons in the process of becoming familiar with the principles of functioning of the human body. Those who did not pay attention to that material at that time may subsequently come into close contact with red blood cells (and these are erythrocytes) already in the clinic during an examination.

You will be sent to, and the results will be of interest in the level of red blood cells, since this indicator relates to the main indicators of health.

The main function of these cells is to supply oxygen to the tissues of the human body and remove carbon dioxide from them. Their normal quantity ensures the proper functioning of the body and its organs. When the level of red cells fluctuates, various disorders and failures appear.

Erythrocytes are red blood cells of humans and animals containing hemoglobin.
They have a specific biconcave disk shape. Because of this special shape, the total surface area of ​​these cells is up to 3000 m² and is 1500 times larger than the surface of the human body. For an ordinary person, this figure is interesting because a blood cell performs one of its main functions precisely with its surface.

For reference. The larger the total surface area of ​​red blood cells, the better for the body.
If red blood cells had the usual spherical shape for cells, then their surface area would be 20% less than the existing one.

Due to their unusual shape, red cells can:

  • Transport more oxygen and carbon dioxide.
  • Pass through narrow and curved capillary vessels. Red blood cells lose their ability to travel to the most remote areas of the human body with age, as well as with pathologies associated with changes in shape and size.

One cubic millimeter of blood from a healthy person contains 3.9-5 million red blood cells.

The chemical composition of red blood cells looks like this:

  • 60% – water;
  • 40% – dry residue.

The dry residue of the bodies consists of:

  • 90-95% – hemoglobin, red blood pigment;
  • 5-10% - distributed between lipids, proteins, carbohydrates, salts and enzymes.

Blood cells lack cellular structures such as a nucleus and chromosomes. Red blood cells reach a nuclear-free state through successive transformations in the life cycle. That is, the hard component of the cells is reduced to a minimum. The question is, why?

For reference. Nature created red cells in such a way that, having a standard size of 7-8 microns, they pass through the smallest capillaries with a diameter of 2-3 microns. The absence of a hard core allows it to “squeeze” through the thinnest capillaries in order to bring oxygen to all cells.

Formation, life cycle and destruction of red cells

Red blood cells are formed from previous cells that originate from stem cells. Red cells originate in the bone marrow of flat bones - the skull, spine, sternum, ribs and pelvic bones. In the case when, due to illness, the bone marrow is not able to synthesize red blood cells, they begin to be produced by other organs that were responsible for their synthesis in fetal development (liver and spleen).

Note that, having received the results of a general blood test, you may encounter the designation RBC - this is the English abbreviation for red blood cell count - the number of red blood cells.

For reference. Red blood cells (RBCs) are produced (erythropoiesis) in the bone marrow under the control of the hormone erythropoietin (EPO). Cells in the kidneys produce EPO in response to decreased oxygen delivery (as in anemia and hypoxia), as well as increased androgen levels. What is important here is that in addition to EPO, the production of red blood cells requires a supply of constituents, mainly iron, vitamin B 12 and folic acid, which are supplied either through food or as supplements.

Red blood cells live for about 3-3.5 months. Every second, from 2 to 10 million of them decay in the human body. Cell aging is accompanied by a change in their shape. Red blood cells are most often destroyed in the liver and spleen, forming breakdown products - bilirubin and iron.

Read also on the topic

What are reticulocytes in the blood and what can be learned from their analysis

In addition to natural aging and death, the breakdown of red blood cells (hemolysis) can occur for other reasons:

  • due to internal defects - for example, with hereditary spherocytosis.
  • under the influence of various unfavorable factors (for example, toxins).

When destroyed, the contents of the red cell are released into the plasma. Extensive hemolysis can lead to a decrease in the total number of red blood cells moving in the blood. This is called hemolytic anemia.

Tasks and functions of red blood cells

The main functions of blood cells are:
  • Movement of oxygen from the lungs to tissues (with the participation of hemoglobin).
  • Transfer of carbon dioxide in the opposite direction (with the participation of hemoglobin and enzymes).
  • Participation in metabolic processes and regulation of water-salt balance.
  • Transfer of fatty organic acids into tissues.
  • Providing tissue nutrition (red blood cells absorb and transport amino acids).
  • Directly involved in blood clotting.
  • Protective function. Cells are able to absorb harmful substances and transfer antibodies - immunoglobulins.
  • The ability to suppress high immunoreactivity, which can be used to treat various tumors and autoimmune diseases.
  • Participation in the regulation of the synthesis of new cells - erythropoiesis.
  • Blood cells help maintain acid-base balance and osmotic pressure, which are necessary for biological processes in the body.

By what parameters are red blood cells characterized?

Main parameters of a detailed blood test:

  1. Hemoglobin level
    Hemoglobin is a pigment found in red blood cells that helps with gas exchange in the body. An increase and decrease in its level is most often associated with the number of blood cells, but it happens that these indicators change independently of each other.
    The norm for men is from 130 to 160 g/l, for women – from 120 to 140 g/l and 180–240 g/l for infants. A lack of hemoglobin in the blood is called anemia. The reasons for an increase in hemoglobin levels are similar to the reasons for a decrease in the number of red cells.
  2. ESR – erythrocyte sedimentation rate.
    The ESR indicator can increase in the presence of inflammation in the body, and its decrease is due to chronic circulatory disorders.
    In clinical studies, the ESR indicator gives an idea of ​​the general condition of the human body. Normally, ESR should be 1-10 mm/hour in men, and 2-15 mm/hour in women.

With a reduced number of red cells in the blood, the ESR increases. A decrease in ESR occurs with various erythrocytosis.

Modern hematological analyzers, in addition to hemoglobin, red blood cells, hematocrit and other conventional blood tests, can also take other indicators called red blood cell indices.

  • MCV– average volume of erythrocytes.

A very important indicator that determines the type of anemia based on the characteristics of red cells. High MCV levels indicate hypotonic plasma abnormalities. A low level indicates a hypertensive state.

  • MSN– average hemoglobin content in an erythrocyte. The normal value of the indicator when studied in the analyzer should be 27 - 34 picograms (pg).
  • ICSU– average concentration of hemoglobin in erythrocytes.

The indicator is interconnected with MCV and MCH.

  • RDW- distribution of red blood cells by volume.

The indicator helps differentiate anemia depending on its values. The RDW indicator, together with the MCV calculation, decreases in microcytic anemias, but it must be studied simultaneously with the histogram.

Red blood cells in urine

An increased level of red cells is called hematuria (blood in the urine). This pathology is explained by the weakness of the capillaries of the kidneys, which allow red blood cells to pass into the urine, and failures in the filtration of the kidneys.

Hematuria can also be caused by microtrauma to the mucous membrane of the ureters, urethra or bladder.
The maximum level of blood cells in the urine in women is no more than 3 units in the field of view, in men - 1-2 units.
When analyzing urine according to Nechiporenko, red blood cells in 1 ml of urine are counted. The norm is up to 1000 units/ml.
A reading of more than 1000 U/ml may indicate the presence of stones and polyps in the kidneys or bladder and other conditions.

Norms for the content of red blood cells in the blood

The total number of red blood cells contained in the human body as a whole and the number of red cells coursing through the system blood circulation are different concepts.

The total number includes 3 types of cells:

  • those that have not yet left the bone marrow;
  • located in the “depot” and waiting to be released;
  • plying through blood channels.

Transport function of blood.

It involves the transfer of various substances in the blood. A specific feature of blood is the transport of O 2 and CO 2. Gas transport is carried out by red blood cells and plasma.

Characteristics of red blood cells.(Er).

Form: 85% Er is a biconcave disk, easily deformed, which is necessary for its passage through the capillary. Red blood cell diameter = 7.2 – 7.5 µm.

More than 8 microns – macrocytes.

Less than 6 microns – microcytes.

Quantity:

M – 4.5 – 5.0 ∙ 10 12/l. . - erythrocytosis.

F – 4.0 – 4.5 ∙ 10 12/l. ↓ - erythropenia.

Membrane Er easily permeable for the anions HCO 3 – Cl, as well as for O 2, CO 2, H +, OH -.

Low permeability for K +, Na + (1 million times lower than for anions).

Properties of erythrocytes.

1) Plasticity– ability to undergo reversible deformation. As we age, this ability decreases.

The transformation of Er into spherocytes leads to the fact that they cannot pass through the capillary and are retained in the spleen and are phagocytosed.

Plasticity depends on the properties of the membrane and the properties of hemoglobin, on the ratio of various lipid fractions in the membrane. The ratio of phospholipids and cholesterol, which determine the fluidity of membranes, is especially important.

This ratio is expressed as a lipolytic coefficient (LC):

Normally LC = cholesterol / lecithin = 0.9

↓ cholesterol → ↓ membrane resistance, the fluidity property changes.

Lecithin → permeability of the erythrocyte membrane.

2) Osmotic stability of the erythrocyte.

R osm. in erythrocytes is higher than in plasma, which ensures cell turgor. It is created by a high intracellular concentration of proteins, more than in plasma. In a hypotonic solution, Er swells, in a hypertonic solution they shrink.

3) Providing creative connections.

Red blood cells carry various substances. This ensures intercellular interaction.

It has been shown that when the liver is damaged, red blood cells begin to intensively transport nucleotides, peptides, and amino acids from the bone marrow to the liver, helping to restore the structure of the organ.

4) The ability of red blood cells to settle.

Albumin– lyophilic colloids, create a hydration shell around the red blood cell and keep them in suspension.

Globulins – lyophobic colloids– reduce the hydration shell and the negative surface charge of the membrane, which contributes to increased erythrocyte aggregation.

The ratio of albumins and globulins is the protein coefficient of BC. Normal

BC = albumin / globulin = 1.5 – 1.7

With a normal protein ratio, ESR in men is 2 – 10 mm/hour; in women 2 – 15 mm/hour.

5) Aggregation of red blood cells.

When blood flow slows and blood viscosity increases, red blood cells form aggregates that lead to rheological disorders. This happens:

1) with traumatic shock;

2) post-infarction collapse;