Blood composition and function of human blood

Such a topic as the composition of the blood and the function of blood is unequivocally worthy of attention, since it reveals one of the foundations of the full-fledged work of the entire human body. To understand the value of blood flow is important because of its significant influence on all key processes occurring in the body.

What is blood

Under the blood is to understand the liquid internal environment of the body, which ensures the consistency of key biochemical and physiological parameters, while carrying out a humoral connection between organs. Studying the blood, its composition and functions, it is important to understand the essence of the two main terms:

- peripheral blood (it consists of plasma);

- Formal elements (are inside the blood in a suspended state).

Blood can also be defined as a unique form of tissue, characterized by several features: its constituents have different origins, this fluid environment of the body is in constant motion, all elements of blood are formed and destroyed outside the bloodstream itself.

Within the framework of the topic: "Blood system, composition and functions" it is worth noting that the system includes hemopoiesis and blood destruction (liver, bone marrow, lymph nodes, spleen), as well as peripheral blood.

Composition of blood

The major part of the blood - 60% - is plasma, and only 40% are filled with elements such as red blood cells, leukocytes and platelets. Viscous thick liquid (plasma) contains substances that are important for the life of the body. They move through tissues and organs, providing the necessary chemical reaction and full-fledged activity of the entire nervous system. Produced by the glands of internal secretion, hormones enter the plasma and then spread throughout the body with blood. Antibodies - enzymes that protect the body from various types of threats - are contained in the plasma.

Erythrocytes

Considering the composition and main functions of blood, it is necessary to pay attention to red blood cells. These are the red blood cells that determine the color of the blood. In its structure, the erythrocyte is very similar to a thin sponge, in the pores of which there is hemoglobin. On average, each erythrocyte is able to carry 267 million hemoglobin particles, "swallowing" carbon dioxide and oxygen, joining them with a compound.

Deepening into the topic: "The composition and function of the blood: red blood cells," it must be understood that these particles can carry a large amount of hemoglobin due to a non-nuclear structure. As for the size of the erythrocyte, they reach 8 micrometers in length and 3 micrometers in width. The number of red blood cells without exaggeration is enormous: every second more than 2 million of these particles form in the bone marrow, their total mass in the body is approximately 26 trillion.

Leukocytes

These elements are also integral parts of the blood flow. White blood cells are called leukocytes, the size of which may vary. They have a rounded irregular shape. Because leukocytes are particles that have a nucleus, they are able to move independently. They are much less than red blood cells, but leukocytes are actively involved in the function of protecting the body from infections. The composition of blood and blood functions can not be complete without white blood cells.

Leukocytes possess special enzymes that are capable of binding and splitting decay products and foreign protein substances, as well as absorbing harmful microorganisms. In addition, some forms of leukocytes can produce antibodies - protein particles, performing one of the important functions: the defeat of any foreign microorganisms that have got into the blood, mucous membranes and other tissues or organs.

Platelets

These blood plates move in close proximity to the walls of the vessels. Their main function is the restoration of the vessels in case of damage. If we use medical terminology, then we can say that platelets are actively involved in providing hemostasis (blood clotting). One cubic millimeter on average accounts for more than 500 thousand of these particles. Platelets live less than other elements of blood - from 4 to 7 days.

They move freely together with the blood flow and are retained only in those places where the flow of blood passes into a calmer state (spleen, liver, subcutaneous tissue). At the time of activation, the form of platelets becomes spherical, and pseudopodia (special outgrowths) are formed. It is through the use of pseudopodia that these elements of blood are able to connect to each other and to be fixed at the site of damage to the vessel wall.

The composition of blood and blood functions should be considered only with account of the action of platelets.

Lymphocytes

This term means small single-nucleated cells. Lymphocytes in their majority have a size of up to 10 microns. The nuclei of such cells are round and dense, and the cytoplasm consists of small granules and is colored bluish. With a superficial study, you can see that all the lymphocytes have the same appearance. This does not change the following fact - they differ in the properties of the cell membrane and its functions.

These mononuclear elements of blood are divided into three main categories: 0-cells, B-cells and T-cells. The function of B-lymphocytes is to serve as precursors to cells that form antibodies. In turn, T cells provide the transformation of B-leukocytes. It is worth noting that T-lymphocytes are a specific group of cells of the immune system, which performs several important functions. For example, with their participation, the process of synthesizing macrophage activation factors and growth factors of interferons, as well as B cells, occurs. It is possible to isolate and inductor T cells, which participate in stimulating the formation of antibodies. On the example of the action of various categories of lymphocytes, the relationship between blood composition and function is clearly visible.

As for the 0-cells, they differ significantly from the others, since they do not have surface antigens. Some of these elements of blood perform the function of "natural killers", destroying those cells that have a cancerous structure or are infected with a virus.

Blood plasma

The composition of the blood plasma is water (90-90%) and solids: proteins, fats, glucose, various salts, metabolic products, vitamins, hormones, etc. One of the key properties of plasma is the osmotic pressure. Also, the plasma carries nutrients, blood cells and metabolic products. Studying the composition and functions of blood plasma , you can see that It serves as a link between liquids that are outside the blood vessels.

Plasma on a regular basis contacts with the kidneys, liver and other organs, thereby supporting homeostasis - the constancy of the internal environment of the body.

Physicochemical properties of blood

Studying a topic such as the composition, properties and functions of blood, it is worth paying attention to certain facts. The volume of blood in the body of an adult on average is 6-8% of his body weight. In men, this indicator reaches 5-6 liters, in women - from 4 to 5. This is the amount of blood that passes through the heart every thousand times. It is worth knowing that the blood does not fill the vascular system completely, a significant part of it remains free. The density of blood depends on the number of red blood cells in it and is approximately 1,050-1,060 g / cm ³ . Viscosity reaches 5 conventional units.

The active reaction of blood is caused by the ratio of hydroxyl and hydrogen ions. This activity is determined by such a hydrogen index as pH (concentration of hydrogen ions). Changes in blood pH, in which the body can function, range from 7.0 to 7.8. If there is a shift in the active reaction of the blood to the acidic side, then a similar condition can be defined as acidosis. Its development is due to the increase in the level of hydrogen ions. If the reaction shifts to the alkaline side, then it makes sense to talk about alkalosis. This change in pH results from a decrease in the concentration of hydrogen ions and an increase in the concentration of OH hydroxyl ions.

Transport function of blood

This is one of the key tasks that blood flow performs. The following functions can be assigned to the process of transportation of various elements:

- trophic: transfer to all parts of the body of nutrients, microelements and vitamins;

- regulatory: transportation of hormones and other substances that enter the humoral system of body regulation;

- respiratory: transfer of respiratory gases O2 and CO2 from the lungs to the tissues and in the opposite direction;

- thermoregulatory: removal of excess heat from the brain and internal organs to the skin;

- excretory: the products of metabolism are transferred to the organs of excretion.

Hemostasis

The essence of this function is reduced to the following process: in the case of damage to the middle or thin blood vessel (when squeezing or cutting the tissue) and the occurrence of external or internal bleeding, a blood clot forms at the site of the vessel's destruction. 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 happened that the endothelial lining of the blood vessels was damaged, the collagen located beneath the endothelium is exposed. Platelets adhere to it quickly enough to circulate in the blood.

Homeostatic and protective functions

Studying the blood, its composition and functions, it is worth paying attention to the process of homeostasis. The essence of it is reduced to the preservation of 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

The circulatory system can include the heart and blood vessels: the blood and lymph. 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 system of blood vessels is provided by the injection of the heart. Deepening in the topic: "The meaning, composition and function of the blood," it is necessary to determine the fact that the blood itself moves through the vessels continuously and therefore is capable of supporting 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 divides it into the left and right halves by means of a vertical integral septum. There is another partition - horizontal. Its task is to divide the heart into 2 upper cavities (atria) and 2 lower (ventricles).

Studying the composition and function of human blood, it is important to understand the principle of the action of the circulatory system. In the blood system there are two circles of motion: large and small. This means that the blood inside the body moves along two closed systems of vessels that connect to the heart.

As the starting point of the large circle appears the aorta that extends from the left ventricle. It gives rise to small, medium and large arteries. They (arteries), in turn, branch into arterioles, terminating with capillaries. Directly the capillaries themselves form a wide network that permeates all tissues and organs. It is in this network that nutrients and oxygen are released to the cells, as well as the process of obtaining metabolic products (carbon dioxide including).

From the lower part of the trunk blood enters the lower hollow vein, from the upper, respectively, to the upper. It is these two hollow veins that complete the large circle of circulation, reaching the right atrium.

Concerning the small circle of blood circulation, it is worth noting that it begins with a pulmonary trunk, extending from the right ventricle and carrying venous blood into the lungs. The pulmonary trunk itself is divided into two branches that go to the right and left lungs. Pulmonary arteries are divided into smaller arterioles and capillaries, which later turn into venules that form veins. The key task of the small circle of blood circulation is to ensure the regeneration of the gas composition in the lungs.

Studying the composition of the blood and the function of blood, it is easy to come to the conclusion that it is extremely important for tissues and internal organs. Therefore, in case of serious blood loss or blood flow disturbance, a real threat to human life appears.