Such a topic as the composition of blood and blood functions definitely deserves attention, since it reveals one of the foundations of the full-fledged work of the whole human body. Understanding the value of blood flow is important because of its significant effect on all key processes in the body.
What is blood
Blood is understood as the liquid internal environment of the body, which ensures the constancy of key biochemical and physiological parameters, while making a humoral connection between organs. When studying blood, its composition and functions, it is important to understand the essence of two basic terms:
- peripheral blood (it consists of plasma);
- shaped elements (are inside the blood in suspension).
Blood can also be defined as a peculiar form of tissue, characterized by several features: its components are of various origins, this body fluid is in constant motion, all blood elements are formed and destroyed outside the bloodstream itself.
Within the framework of the topic: “Blood system, composition and functions”, it is worth noting that this system includes the organs of blood formation and hemorrhage (liver, bone marrow, lymph nodes, spleen), as well as peripheral blood.
Blood composition
A large half of the blood - 60% - is plasma, and only 40% is filled with elements such as red blood cells, white blood cells and platelets. A viscous thick liquid (plasma) contains substances that are important for the life of the body. They move through tissues and organs, providing the desired chemical reaction and the full activity of the entire nervous system. Hormones produced by the endocrine glands enter the plasma and are then carried throughout the body by blood flow. Antibodies - enzymes that protect the body from various types of threats - are contained in plasma.
Red blood cells
Considering the composition and basic functions of the blood, it is necessary to pay attention to red blood cells. These are red blood cells that determine the color of blood. By its structure, the red blood cell is very similar to a thin sponge, in the pores of which there is hemoglobin. On average, each red blood cell is able to carry 267 million particles of hemoglobin, which "swallows" carbon dioxide and oxygen, entering into a connection with them.
Going deep into the topic: “Composition and functions of the blood: red blood cells”, it must be understood that these particles can carry a large amount of hemoglobin due to the nuclear-free structure. As for the size of the red blood cell, they reach 8 micrometers in length and 3 micrometers in width. Moreover, the number of red blood cells is, without exaggeration, huge: every second more than 2 million of these particles are formed in the bone marrow, their total mass in the body is approximately 26 trillion.
White blood cells
These elements are also integral components of the blood flow. White blood cells are called white blood cells, the size of which may vary. They have a rounded irregular shape. Since white blood cells are particles that have a nucleus, they are able to move independently. They are much smaller than red blood cells, but leukocytes are actively involved in the function of protecting the body from infections. Blood composition and blood functions cannot be complete without white blood cells.
White blood cells have special enzymes that can bind and break down decay products and foreign protein substances, as well as absorb dangerous microorganisms. In addition, some forms of white blood cells can produce antibodies - protein particles that perform one of the important functions: the defeat of any foreign microorganisms that enter the blood, mucous membranes and other tissues or organs.
Platelets
These blood plates move in close proximity to the walls of blood vessels. Their main function is the restoration of blood vessels in case of damage. If you use medical terminology, then we can say that platelets are actively involved in providing hemostasis (blood coagulation). One cubic millimeter on average accounts for more than 500 thousand of these particles. Platelets live less than other elements of the blood - from 4 to 7 days.
They move freely with the blood flow and are delayed only in those places where the blood flow goes into a more relaxed state (spleen, liver, subcutaneous tissue). At the time of activation, the platelet shape becomes spherical, with the formation of pseudopodia (special outgrowths). It is with the help of pseudopodia that these blood elements are able to connect with each other and fix at the site of damage to the vessel wall.
Blood composition and blood function should be considered only taking into account the action of platelets.
Lymphocytes
This term refers to small mononuclear cells. Lymphocytes for the most part are up to 10 microns in size. The nuclei of such cells are round and dense, and the cytoplasm consists of small granules and is painted in a bluish color. With a superficial study, you can notice that all lymphocytes have the same appearance. This does not change the following fact - they differ in the properties of the cell membrane and their functions.
These mononuclear blood elements fall 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 that performs several important functions. For example, with their participation, the process of synthesizing macrophage activation factors and interferon growth factors, as well as B cells, takes place. Inductive T cells, which are involved in stimulating the formation of antibodies, can also be distinguished. On the example of the action of various categories of lymphocytes, the relationship of the composition and function of blood is clearly visible.
As for 0-cells, they are significantly different from the rest, because they do not have surface antigens. Some of these blood elements act as "natural killers", destroying those cells that have a cancerous structure or are infected with a virus.
Blood plasma
The composition of blood plasma includes water (90-90%) and solids: proteins, fats, glucose, various salts, metabolic products, vitamins, hormones, etc. One of the key properties of plasma is osmotic pressure. Plasma also 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 fluids that are located outside the blood vessels.
Plasma in constant contact with the kidneys, liver and other organs, thereby maintaining homeostasis - the constancy of the internal environment of the body.
Physico-chemical properties of blood
Studying such a topic 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 is on average 6-8% of his body weight. In men, this figure reaches 5-6 liters, in women - from 4 to 5. It is this amount of blood that passes through the heart 1 thousand times daily. It is worth knowing that blood does not completely fill the vascular system, a significant part of it remains free. The density of the 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 the blood is determined by the ratio of hydroxyl and hydrogen ions. Such a hydrogen indicator as pH (concentration of hydrogen ions) determines this activity. Changes in blood pH, in which the body can function, fluctuate in the range of 7.0-7.8. If there is a shift in the active reaction of the blood to the acidic side, then this condition can be defined as acidosis. Its development is due to an 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 is a consequence of a decrease in the concentration of hydrogen ions and an increase in the concentration of hydroxyl ions OH.
Blood transport function
This is one of the key tasks that blood flow performs. The following functions can be attributed to the process of transporting various elements:
- trophic: transfer to all parts of the body of nutrients, trace elements and vitamins;
- regulatory: transportation of hormones and other substances that are part of the humoral system of regulation of the body;
- 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: metabolic products are transferred to the excretory organs.
Hemostasis
The essence of this function is reduced to the following process: in the case of damage to the medium or thin blood vessel (when squeezing or incision of the tissue) and the occurrence of external or internal bleeding, a blood clot forms at the site of destruction of the vessel. It is he who prevents significant blood loss. Under the influence of the 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 under the endothelium is exposed. Platelets that circulate in the blood quickly adhere to it.
Homeostatic and protective functions
When studying blood, its composition and functions, it is worth paying attention to the process of homeostasis. Its essence is to maintain water-salt and ionic balance (a consequence of osmotic pressure), and maintain the pH of the internal environment of the body.
As for the protective function, its essence is to protect the body through immune antibodies, the phagocytic activity of leukocytes and antibacterial substances.
Blood system
To the circulatory system can include the heart and blood vessels: 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 vascular system is ensured through the injection activity of the heart. Going deeper into the topic: “The Importance, Composition, and Functions of Blood”, it is worthwhile to determine the fact that the blood itself directly 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 is divided into left and right halves by means of a vertical whole septum. There is another 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 blood circulation circles. Two circles of movement function in the blood system: large and small. This means that the blood inside the body moves through two closed systems of blood 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 with capillaries. 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 cells, as well as the process of obtaining metabolic products (including carbon dioxide).
From the lower torso, blood enters the lower vena cava, from the upper, respectively, to the upper. It is these two hollow veins that complete the large circle of blood circulation, falling into the right atrium.
Regarding the pulmonary 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 lung. The pulmonary arteries are divided into smaller arterioles and capillaries, which subsequently pass into the venules that form the 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 blood functions, it is not difficult to conclude that it is extremely important for tissues and internal organs. Therefore, in case of serious blood loss or impaired blood flow, a real threat to human life appears.