What is blood, everyone knows.We see it when we injure the skin, for example, if we have cut or pricked ourselves. We know that it is thick and red. But what is the blood? Not everyone knows this. Meanwhile, its composition is complex and heterogeneous. It is not just a red liquid. The color is attached to it not by the plasma at all, but by the shaped particles that are in it. Let's see what our blood is.
What is the blood?
Весь объем крови в организме человека можно devide into two parts. Of course, this division is conditional. The first part is peripheral, that is, the one that flows in the arteries, veins and capillaries, the second is the blood in the blood-forming organs and tissues. Naturally, it constantly circulates in the body, and therefore the separation is formal. Human blood consists of two components - plasma and shaped particles that are in it. These are red blood cells, white blood cells and platelets. They differ from each other not only in structure, but also in their function in the body. Some more particles, some less. In addition to the form components, various antibodies and other particles are detected in human blood. Normal blood is sterile. But with the pathological processes of an infectious nature, bacteria and viruses can be detected in it. So, what is the blood, and in what proportions are these components? This question has long been studied, and science has accurate data. In an adult, the volume of the plasma itself ranges from 50 to 60%, and the formed components - from 40 to 50% of all blood. Is it important to know? Of course, knowing the percentage of red blood cells or leukocytes in the blood, it is possible to assess the state of human health. The ratio of the shaped particles to the total blood volume is called the hematocrit number. Most often, it focuses not on all components, but only on red blood cells. This indicator is determined using a graduated glass tube into which blood is placed and centrifuged. In this case, the heavy components sink to the bottom, and the plasma, on the contrary, rises. The blood is stratified. After that, laboratory assistants can only calculate what part of a particular component. In medicine, such analyzes are widespread. Currently they are made on automatic hematology analyzers.
Blood plasma
Plasma is the liquid component of blood in whichthere are weighted cells, proteins and other compounds. On it they are delivered to the organs and tissues. What is the blood plasma? About 85% is water. The remaining 15% are organic and inorganic substances. Also in the blood plasma are gases. This, of course, carbon dioxide and oxygen. Inorganic substances account for 3-4%. These are anions (PO
43-, HCO
3-CO
42-) and cations (Mg
2+To
+, On
+).Organic substances (approximately 10%) are divided into nitrogen-free substances (cholesterol, glucose, lactate, phospholipids) and nitrogen-containing substances (amino acids, proteins, urea). Also in the blood plasma are detected biologically active substances: enzymes, hormones and vitamins. They account for about 1%. From the point of view of histology, plasma is nothing but an intercellular fluid.
Erythrocytes
Итак, из чего состоит кровь человека?In addition to plasma, it also contains shaped particles. Red blood cells, or red blood cells, are perhaps the largest group of these components. Red blood cells in the mature state do not have a nucleus. In shape, they resemble biconcave discs. The period of their life is 120 days, after which they are destroyed. It occurs in the spleen and liver. Red blood cells contain an important protein - hemoglobin. It plays a key role in the gas exchange process. In these particles, oxygen and carbon dioxide are transported. It is protein hemoglobin that makes blood red.
Platelets
What does human blood consist of, other than plasma andred blood cells? There are platelets in it. They are of great importance. These small, nuclear-free cells with a diameter of only 2-4 micrometers play a crucial role in thrombosis and homeostasis. Platelets are disc-shaped. They circulate freely in the bloodstream. But their distinguishing feature is the ability to be sensitive to vascular damage. This is their main function. When injuring the wall of a blood vessel, they, connecting with each other, “close up” the damage, forming a very dense clot that prevents blood from flowing out. Platelets are formed after the fragmentation of their larger precursors of megakaryocytes. They are in the bone marrow. Just from one megakaryocyte forms up to 10 thousand platelets. This is quite a large number. The life span of platelets is 9 days. Of course, they can survive even less, as they die during a blockage of damage in a blood vessel. Old platelets break down in the spleen during phagocytosis and in the liver with Kupffer cells.
Leukocytes
White blood cells, or leukocytes, are agentsthe body's immune system. This is the only particle that is part of the blood that can leave the bloodstream and penetrate into the tissue. This ability actively contributes to the implementation of its main function - protection from foreign agents. Leukocytes destroy pathogenic proteins and other compounds. They participate in immunity reactions, producing T-cells capable of recognizing viruses, foreign proteins and other substances. Lymphocytes also secrete B cells that produce antibodies, and macrophages that devour large pathogenic cells. It is very important when diagnosing diseases to know the composition of the blood. It is the increased number of leukocytes in it indicates a developing inflammation.
Hematopoiesis
So, having analyzed the composition and function of blood, it remainsfind out where its main particles are formed. They have a short lifespan, so you need to constantly update them. The physiological regeneration of blood components is based on the processes of destruction of old cells and, accordingly, the formation of new ones. It occurs in the organs of blood formation. The most important of these in humans is the bone marrow. It is located in the long tubular and pelvic bones. The blood is filtered in the spleen and liver. Immunological control is also carried out in these organs.
