What is blood, everyone knows. We see it when we injure the skin, for example, if we cut ourselves or pricked ourselves. We know that it is thick and red. But what does blood consist of? Not everyone knows this. Meanwhile, its composition is complex and heterogeneous. It is not just a red liquid. The color does not give it at all to the plasma, but the shaped particles that are in it. Let's see what our blood is.
What does blood consist 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 blood located in the blood-forming organs and tissues. Naturally, it constantly circulates throughout the body, and therefore the separation is formal. Human blood consists of two components - plasma and the 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 the function performed in the body. There are more particles, some less. In addition to the shaped components, various antibodies and other particles are found in the blood of a person. Normal 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 in what proportions are these components? This issue has long been studied, and science has accurate data. In an adult, the volume of the plasma itself is from 50 to 60%, and of 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
white blood cells in the blood, you can give an assessment of the state of human health. The ratio of the shaped particles to the total blood volume is called the hematocrit. 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 up. Blood stratifies, as it were. After this, the laboratory technicians can only calculate which part is occupied by this or that component. In medicine, such analyzes are widespread. Currently, they are made on automatic
hematological analyzers.
Blood plasma
Plasma is the liquid component of the blood in which suspended cells, proteins, and other compounds are located. On it they are delivered to organs and tissues. What does
blood plasma consist of
? About 85% is water. The remaining 15% are organic and inorganic substances. Also in the blood plasma are gases. This, of course, is carbon dioxide and oxygen.
Inorganic substances account for 3-4%. These are anions (PO
4 3- , HCO
3- , SO
4 2- ) and cations (Mg
2+ , K
+ , Na
+ ). Organic substances (approximately 10%) are divided into nitrogen-free (cholesterol, glucose, lactate, phospholipids) and nitrogen-containing substances (amino acids, proteins, urea). Biologically active substances are also found in blood plasma: enzymes, hormones and vitamins. They account for about 1%. From the point of view of histology, plasma is nothing but intercellular fluid.
Red blood cells
So what does human blood consist of? In addition to plasma, shaped particles are also found in it. Red blood cells, or red blood cells, are perhaps the largest group of these components. Red blood cells in a mature state do not have a nucleus. In shape they resemble biconcave disks. 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 hemoglobin protein that makes blood red.
Platelets
What does human blood consist of, other than plasma and red blood cells? It contains platelets. They are of great importance. These small nuclear-free cells with a diameter of only 2-4 micrometers play a decisive role in thrombosis and homeostasis. Platelets are disc-shaped. They circulate freely in the bloodstream. But their distinctive feature is the ability to sensitively respond to damage to blood vessels. This is their main function. When injuring the walls 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 form after the fragmentation of their larger megakaryocyte precursors. They are located in the bone marrow. In total, up to 10 thousand platelets are formed from one megakaryocyte. This is a fairly large amount. Platelet life is 9 days. Of course, they can exist even less, since they die during the clogging of the damage in the blood vessel. Old platelets disintegrate in the spleen during phagocytosis and in the liver using Kupffer cells.
White blood cells
White blood cells, or white blood cells, are agents of the body’s immune system. This is the only particle of those that are part of the blood, which can leave the bloodstream and penetrate into the tissues. This ability actively contributes to the fulfillment of its main function - protection against foreign agents. White blood cells destroy pathogenic proteins and other compounds. They participate in immune responses, producing T cells that can recognize viruses, foreign proteins, and other substances. Also, lymphocytes secrete B cells producing antibodies and macrophages that devour large pathogenic cells. When diagnosing diseases, it is very important to know the composition of the blood. It is the increased number of leukocytes in it that indicates developing inflammation.
Hematopoietic organs
So, having analyzed the composition and
functions of the 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 destruction of old cells and, accordingly, the formation of new ones. This occurs in the blood. The most important of them in humans is bone marrow. It is located in the long tubular and pelvic bones. Blood is filtered in the spleen and liver. In these organs, its immunological control is also carried out.