Chemical composition and functions of blood. Functions and composition of blood. The composition of human blood plasma and its functions

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 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 interferes with the body's work.

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.

It is unthinkable to talk about blood without taking into account its main components, which determine the unique properties of this liquid tissue of the body.

Blood components

Typically, blood makes up 7-8% of a person's body weight; in adults it is 4.5-6 liters. Blood is a fluid that carries out: transporting oxygen and nutrients to our cells, getting rid of carbon dioxide, ammonia and other waste (see). In addition, it plays an important role in our immune system, maintaining a relatively constant body temperature. Blood is a highly specialized tissue consists of more than 4000 different types of components. The most important of them four main components of blood:, , and . All these components are contained in the blood of people regardless of their racial, ethnic and religious differences.

red blood cells

Red blood cells or erythrocytes, are relatively large cells without nuclei. Red blood cells usually make up 40-50% of the total blood volume. They carry oxygen from the lungs to every cell in the tissues of the body and carry away carbon dioxide. Red blood cells are continuously produced in the bone marrow from stem cells. in the amount of about 2-3 million cells per second. 95% of the erythrocyte is occupied hemoglobin- a gas transport protein molecule. Each red blood cell contains about 270 million iron-rich hemoglobin molecules. People who are anemic usually have a lack of red blood cells and therefore feel tired due to lack of oxygen. The red color of blood is primarily determined by the oxygen in red blood cells. The human fetal hemoglobin molecule (fetal hemoglobin) differs from the adult hemoglobin molecule in the number of amino acid chains. Fetal hemoglobin has three chains, while adults have only two. As a consequence, the fetal hemoglobin molecule binds and transports relatively more oxygen to the cells of the body.

White cells, leukocytes

platelets

platelets, or records, are non-nuclear fragments of cells that work in the blood coagulation system at the site of vascular damage. They stick to the site of damage and “patch” the site of rupture of the vessel. Platelets secrete virtually all of the proteins needed to form a blood clot. Thirteen different clotting factors, in addition to platelets, are required for blood to clot, to form a clot. The coagulation system is launched according to the cascade principle - one factor triggers another, and so on.

Platelets are not equally effective in clotting blood throughout the day. The circadian rhythm of the body system (internal biological clock) causes platelet activation to peak in the morning. This is one of the main reasons that heart attacks and strokes are more common in the morning.

Recent studies have shown that platelets also help fight infections by releasing proteins that kill invading bacteria and some other microorganisms. In addition, platelets stimulate the immune system. Individual platelets are approximately 1/3 the size of an erythrocyte. The service life of platelets is 9-10 days. Like red blood cells and white blood cells, platelets are formed in the bone marrow from a common precursor, the stem cell.

Plasma

A yellowish biological fluid in which sugars, fats, proteins and salts are dissolved and erythrocytes, leukocytes and platelets are weighed. Typically, 55% of our blood volume is plasma. As the heart pumps blood to cells throughout the body, the plasma carries nourishment to the cells and removes waste products from metabolism. Plasma contains blood clotting factors, sugars, lipids, vitamins, minerals, hormones, enzymes, antibodies, and other proteins. It is likely that plasma contains some of each of the proteins that are synthesized by the body - so far Approximately 500 proteins have been identified in human plasma.

Blood functions

1. Transport

  • Dissolved gases (eg oxygen, carbon dioxide)
  • Metabolic waste products (e.g. water, urea)
  • Hormones
  • Enzymes
  • Nutrients (such as glucose, amino acids, trace elements (vitamins and minerals), fatty acids, glycerol)
  • Plasma proteins
  • Blood cells (including white blood cells - leukocytes, erythrocytes - red blood cells, and platelets).

2. Maintains body temperature

3. Provides physiological pH range:

The pH of the blood must be in the range of 6.8 to 7.4, otherwise it starts to damage the cells.

4. Removes toxins from the body

Toxins are removed from the blood through the kidneys and sweat

5. Fluid and electrolyte regulation

Excess salt is removed from the body with urine - up to 10 g / day

The main components of blood and its functions - video

Blood is a liquid form of connective tissue that is in constant motion. Thanks to this, many of its functions are provided - nutritional, protective, regulatory, humoral and others. Normally, blood cells make up about 45%, the rest is plasma. In the article, we will consider which particles include vital connective tissue, as well as their main functions.

Blood functions

Blood cells are very important for the normal functioning of the whole organism. Violation of this composition leads to the development of various diseases.

Blood functions:

  • humoral - the transfer of substances for regulation;
  • respiratory - responsible for the transfer of oxygen to the lungs and other organs, the removal of carbon dioxide;
  • excretory - ensures the elimination of harmful metabolic products;
  • thermoregulatory - transfer and redistribution of heat in the body;
  • protective - helps to neutralize pathogenic microorganisms, participates in immune reactions;
  • homeostatic - maintaining all metabolic processes at a normal level;
  • nutritional - the transfer of nutrients from organs, where they are synthesized to other tissues.

All these functions are provided by leukocytes, erythrocytes, platelets and some other elements.

Red blood cells, or erythrocytes, are biconvex disc-shaped transport cells. Such a cell consists of hemoglobin and some other substances, due to which oxygen is transported through the bloodstream to all tissues. Red blood cells take oxygen in the lungs, then carry it to the organs, returning from there already with carbon dioxide.

The formation of red blood cells takes place in the red bone marrow of the long bones of the arms and legs (in childhood) and in the bones of the skull, spine and ribs (in adults). The total lifespan of one cell is about 90–120 days, after which the bodies undergo hemolysis, which takes place in the tissues of the spleen and liver, and are excreted from the body.

Under the influence of various diseases, there is a violation of the formation of red blood cells and a distortion of their shape. This causes a decrease in their performance of their functions.

Red blood cells are the main transporter of oxygen in the body.

Important! The study of the quantity and quality of erythrocytes acts as an important diagnostic value.

Leukocytes are called white blood cells that perform a protective function. There are several types of these cells, differing in purpose, structure, origin and some other characteristics.

Leukocytes are formed in the red bone marrow and lymph nodes. Their role in the body is to protect against viruses, bacteria, fungi and other pathogens.

Neutrophils

Neutrophils are one of the groups of blood cells. These cells are among the most numerous. They make up to 96% of all leukocytes.

When a focus of infection enters the body, these bodies quickly move to the place of localization of a foreign microorganism. Due to rapid reproduction, these cells quickly neutralize viruses, bacteria and fungi, as a result of which they die. This phenomenon in medicine is called phagocytosis.

Eosinophils

The concentration of eosinophils in the blood is lower, but they perform an equally important protective function. After entering the body of foreign cells, eosinophils quickly move to eliminate them to the affected area. They easily penetrate the tissues of blood vessels, absorb uninvited guests.

Another important function is the binding and absorption of some allergy mediators, including histamine. That is, eosinophils perform an anti-allergic role. In addition, they effectively fight helminths and helminthic invasions.

Monocytes

Functions of monocytes:

  • neutralization of microbial infections;
  • restoration of damaged tissues;
  • protection against the formation of tumors;
  • phagocytosis of affected and dead tissues;
  • toxic effect on helminthic invasions that have entered the body.


Monocytes are important blood cells that perform a protective function

Monocytes are responsible for the synthesis of the interferon protein. It is interferon that blocks the spread of viruses, contributes to the destruction of the shell of pathogens.

Important! The life cycle of monocytes is short and is three days. After that, the cells penetrate into tissues, where they turn into tissue macrophages.

Basophils

Like other blood cells, basophils are produced in the tissues of the red bone marrow. After synthesis, they enter the human bloodstream, where they stay for about 120 minutes, after which they are transferred to cellular tissues, where they perform their main functions, they stay from 8 to 12 days.

The main role of these cells is to identify and neutralize allergens in a timely manner, stop their spread throughout the body, and call other granulocytes to the place where foreign bodies spread.

In addition to participating in allergic reactions, basophils are responsible for blood flow in thin capillaries. The role of cells in protecting the body from viruses and bacteria, as well as in the formation of immunity is very small, despite the fact that their main function is phagocytosis. This type of leukocyte takes an active part in the process of blood clotting, increases vascular permeability, and is actively involved in the contraction of certain muscles.

Lymphocytes are the most important cells of the immune system, performing a number of complex tasks. These include:

  • production of antibodies, destruction of pathogenic microflora;
  • the ability to distinguish between "own" and "foreign" cells in the body;
  • elimination of mutating cells;
  • providing sensitization of the body.

Immune cells are divided into T-lymphocytes, B-lymphocytes and NK-lymphocytes. Each group performs its own function.

T-lymphocytes

By the level of these bodies in the blood, one or another immune disorder can be determined. An increase in their number indicates an increased activity of natural defense, which indicates immunoproliferative disorders. A low level indicates immune dysfunction. During a laboratory study, the number of T-lymphocytes and other formed elements is taken into account, thanks to which it is possible to establish a diagnosis.

B-lymphocytes

Cells of this species have a specific function. Their activation occurs only in those conditions when certain types of pathogens enter the body. These can be strains of a virus, some kind of bacterial infection, proteins, or other chemicals. If the pathogen is of a different nature, B-lymphocytes do not have any effect on it. That is, the main function of these bodies is the synthesis of antibodies and the implementation of the humoral defense of the body.


Lymphocytes are the main immune defenders

NK lymphocytes

This type of antibody can react to any pathogenic microorganisms, in front of which T-lymphocytes are powerless. Because of this, NK-lymphocytes are called natural killers. It is these bodies that effectively fight cancer cells. To date, active research is underway on this blood cell in the field of cancer treatment.

platelets

Platelets are small, but very important blood cells, without which stopping bleeding and wound healing would be impossible. These bodies are synthesized by splitting off small particles of the cytoplasm from large structural formations - megakaryocytes located in the red bone marrow.

Platelets take an active part in the process of blood clotting, so that wounds and abrasions tend to heal. Without this, any damage to the skin or internal organs would be fatal to humans.

When a vessel is damaged, platelets quickly stick together, forming blood clots that prevent further bleeding.

Important! In addition to wound healing, platelets help nourish the vascular walls, take an active part in regeneration, synthesize substances that catalyze the division and growth of skin cells during wound healing.

The norm of formed elements in the blood

To perform all the necessary functions of the blood, the number of all formed elements in it must meet certain standards. These figures vary with age. In the table you can find data on which numbers are considered normal.

Any deviations from the norm serve as a reason for further examination of the patient. To exclude false indicators, it is important for a person to follow all recommendations for donating blood for a laboratory test. The test should be taken in the morning on an empty stomach. In the evening before visiting the hospital, it is important to give up spicy, smoked, salty foods and alcoholic beverages. Blood sampling is carried out exclusively in the laboratory using sterile devices.

Regular testing and timely detection of certain disorders will help to diagnose various pathologies in time, carry out treatment, and maintain health for many years.

Any changes in the blood composition in humans have a high diagnostic value for establishing the cause of the disease and identifying the pathogen.

Blood, in essence, is a suspension, which is divided into liquid plasma and formed elements. On average, the constituents of the blood are 40% of their elements distributed in the plasma. The formed elements are 99% red blood cells (ἐρυθρός - red). The ratio of volume (RBC) to total blood capacity is called HCT (hematocrit). With the loss of an impressive volume of fluid by blood, they talk about. This condition occurs when the percentage of plasma falls below 55%.

The causes of blood pathology can be:

  • Diarrhea;
  • Vomit;
  • burn disease;
  • Dehydration of the body from hard work, as a result of sports and prolonged exposure to heat.

According to the peculiarities of the response of leukocytes to the ongoing changes, they make a conclusion about the presence of an infection and its variety, determine the stages of the pathological process, the body's susceptibility to the prescribed treatment. The study of the leukoformula makes it possible to detect tumor pathologies. With a detailed decoding of the leukocyte formula, it is possible to establish not only the presence of leukemia or leukopenia, but to clarify what type of oncology a person suffers from.

Of no small importance is the detection of an increased influx of leukocyte precursor cells into the peripheral blood. This indicates a perversion of the synthesis of leukocytes, leading to oncology of the blood.

In humans (PLT) are small cells, devoid of a nucleus, whose task is to maintain the integrity of the bloodstream. PLT are capable of sticking together, sticking to various surfaces, forming blood clots when the walls of blood vessels are destroyed. Platelets in the blood assist leukocytes in the elimination of foreign agents, increasing the lumen of the capillaries.

In the body of a child, blood occupies up to 9% of body weight. In an adult, the percentage of the most important connective tissue of the body drops to seven, which is at least five liters.

The ratio of the above blood components may change due to illness, or as a result of other circumstances.


The reasons for changes in the composition of the blood in an adult and a child can be:

  • Unbalanced diet;
  • Age;
  • Physiological conditions;
  • Climate;
  • Bad habits.

Excessive consumption of fat provokes the crystallization of cholesterol on the walls of blood vessels. Excess protein, due to the passion for meat products, is excreted from the body in the form of uric acid. Excessive coffee consumption provokes erythrocytosis, hyperglycemia, and the composition of human blood changes.

An imbalance in the intake or absorption of iron, folic acid and cyanocobalamin leads to a drop in hemoglobin. Fasting causes an increase in bilirubin.

Men, whose lifestyle involves higher physical exertion, compared to women, need more oxygen, which is manifested in an increase in the number of RBC and hemoglobin concentration.

The load on the body of the elderly is gradually decreasing, leading down the blood counts.

Highlanders, who are constantly in conditions of lack of oxygen, compensate for it by increasing the level of RBC and HB. The excretion of an increased amount of toxins from the body of a smoker is accompanied by leukocytosis.

You can optimize blood counts during illness. First of all, you need to establish a nutritious diet. Get rid of bad habits. Limit coffee consumption, fight weakness through moderate physical activity. The blood will thank the owner, who is ready to fight for the preservation of health. This is how the composition of human blood looks like if you disassemble it by its components.

The essence of this function is reduced to the following process: in case of damage to a medium or thin blood vessel (when squeezing or incising the tissue) and the occurrence of external or internal bleeding, a blood clot forms at the site of the destruction of the vessel. It is he who prevents significant blood loss. Under the influence of released nerve impulses and chemicals, the lumen of the vessel is reduced. If it so happens that the endothelial lining of the blood vessels has been damaged, the collagen underlying the endothelium is exposed. Platelets that circulate in the blood quickly stick to it.

Homeostatic and protective functions

Studying the blood, its composition and functions, it is worth paying attention to the process of homeostasis. Its essence boils down to maintaining the water-salt and ion balance (a consequence of osmotic pressure), and maintaining the pH of the internal environment of the body.

As for the protective function, its essence is to protect the body through immune antibodies, phagocytic activity of leukocytes and antibacterial substances.

Blood system

To include the heart and blood vessels: blood and lymphatic. The key task of the blood system is the timely and complete supply of organs and tissues with all the elements necessary for life. The movement of blood through the vascular system is provided by the pumping activity of the heart. Delving into the topic: “The meaning, composition and functions of blood”, it is worth determining the fact that the blood itself moves continuously through the vessels and therefore is able to support all the vital functions discussed above (transport, protective, etc.).

The key organ in the blood system is the heart. It has the structure of a hollow muscular organ and is divided into left and right halves by means of a vertical solid partition. There is one more partition - horizontal. Its task is to divide the heart into 2 upper cavities (atria) and 2 lower cavities (ventricles).

Studying the composition and functions of human blood, it is important to understand the principle of the action of circulatory circles. There are two circles of movement in the blood system: large and small. This means that the blood inside the body moves through two closed systems of vessels that connect to the heart.

The aorta extending from the left ventricle acts as the starting point of the great circle. It is she who gives rise to small, medium and large arteries. They (arteries), in turn, branch into arterioles, ending in capillaries. The capillaries themselves form a wide network that permeates all tissues and organs. It is in this network that the return of nutrients and oxygen to cells occurs, as well as the process of obtaining metabolic products (including carbon dioxide).

From the lower part of the body, blood enters from the upper, respectively, to the upper. It is these two hollow veins that complete the systemic circulation, entering the right atrium.

Regarding the pulmonary circulation, it is worth noting that it begins with the pulmonary trunk, which extends from the right ventricle and carries venous blood to the lungs. The pulmonary trunk itself is divided into two branches, which go to the right and left arteries, are divided into smaller arterioles and capillaries, which subsequently pass into venules, forming veins. The key task of the pulmonary circulation is to ensure the regeneration of the gas composition in the lungs.

Studying the composition of blood and the functions of blood, it is easy to conclude that it is extremely important for tissues and internal organs. Therefore, in the event of serious blood loss or impaired blood flow, a real threat to human life appears.

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