What is blood, everyone knows. We see it when we injure the skin, for example, if we cut or prick. We know it's thick and red. But what is blood made of? Not everyone knows this. Meanwhile, its composition is complex and heterogeneous. It's not just red liquid. It is not the plasma that gives it its color, but the shaped particles that are in it. Let's see what our blood is.
What is blood made of?
The entire volume of blood in the human body can be divided 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 that is in the hematopoietic organs and tissues. Naturally, it constantly circulates through the body, and therefore this division is formal. Human blood consists of two components - plasma and shaped particles that are in it. These are erythrocytes, leukocytesand platelets. They differ from each other not only in structure, but also in their function in the body. Some particles more, some less. In addition to uniform components, various antibodies and other particles are found in human blood. Normally, blood is sterile. But with pathological processes of an infectious nature, bacteria and viruses can be found in it. So, what does blood consist of, and what are the ratios of these components? This question has long been studied, and science has accurate data. In an adult, the volume of the plasma itself is from 50 to 60%, and the shaped components - from 40 to 50% of all blood. Is it important to know? Of course, knowing the percentage of erythrocytes or leukocytes in the blood, one can assess the state of human he alth. The ratio of formed particles to the total volume of blood is called hematocrit. Most often, it does not focus 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, heavy components sink to the bottom, while the plasma, on the contrary, rises up. It's like the blood is shedding. After that, laboratory assistants can only calculate what part is occupied by one or another component. In medicine, such analyzes are widely used. Currently, they are made on automatic hematology analyzers.
Blood plasma
Plasma is the liquid component of the blood, which contains suspended cells, proteins and other compounds. According to her theydelivered to organs and tissues. What is blood plasma made of? About 85% is water. The remaining 15% are organic and inorganic substances. There are also gases in the blood plasma. This, of course, is carbon dioxide and oxygen. Inorganic substances account for 3-4%. These are anions (PO43-, HCO3-, SO4 2-) and cations (Mg2+, K+, Na +). Organic substances (approximately 10%) are divided into nitrogen-free (cholesterol, glucose, lactate, phospholipids) and nitrogen-containing substances (amino acids, proteins, urea). Also, biologically active substances are found in the blood plasma: enzymes, hormones and vitamins. They account for about 1%. Histologically, plasma is nothing more than interstitial fluid.
Erythrocytes
So, what does human blood consist of? In addition to plasma, it also contains shaped particles. Red blood cells, or erythrocytes, are perhaps the largest group of these components. Erythrocytes in a 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 called hemoglobin. It plays a key role in the process of gas exchange. These particles transport oxygen and carbon dioxide. It is the protein hemoglobin that makes the blood red.
Platelets
What does human blood consist of, exceptplasma and erythrocytes? It contains platelets. They matter a lot. These small non-nuclear cells, only 2-4 micrometers in diameter, play a critical role in thrombosis and homeostasis. Platelets are disc-shaped. They circulate freely in the bloodstream. But their distinguishing feature is the ability to sensitively respond to vascular damage. This is their main function. When the wall of a blood vessel is injured, 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 megakaryocyte precursors. They are in the bone marrow. In total, up to 10 thousand platelets are formed from one megakaryocyte. This is quite a large number. The lifespan of platelets is 9 days. Of course, they can last even less, as they die during the clogging of the damage in the blood vessel. Old platelets are broken down in the spleen by phagocytosis and in the liver by Kupffer cells.
Leukocytes
White blood cells, or leukocytes, are agents of the body's immune system. This is the only particle of those that is part of the blood, which can leave the bloodstream and penetrate into the tissues. This ability actively contributes to the performance of its main function - protection from alien agents. Leukocytes destroy pathogenic proteins and other compounds. They participate in immune responses, while producing T-cells that can recognize viruses, foreign proteins and other substances. Lymphocytes also secrete B cells,producing 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 that indicates the developing inflammation.
Hematopoietic organs
So, having analyzed the composition and functions of blood, it remains to find 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 hematopoiesis. The most important of them 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. In these organs, its immunological control is also exercised.
