Blood – it is the fluid by which the human body lives. It circulates in the body, warming, cooling, nourishing, protecting and cleansing it from toxic substances. Due to the peculiarities of human blood, it – a link between all organs of the body, capable of instantly closing any cracks in the walls of blood vessels and updating the system. On average, a person weighing 60 kg has 5 liters of blood circulating in the body. The heart easily drives all this amount of blood through the body in 1 minute. Blood plays a very important role in human life: it supplies nutrients and warms all points of the body.
Features of human blood – transporter of oxygen and carbon dioxide
The air we breathe is a vital substance for the body. It is needed for energy production. Thanks to the characteristics of human blood, oxygen is transported from the lungs to all cells.
The hemoglobin molecules found in red blood cells carry oxygen. Each red blood cell, shaped like a curved disk, is capable of carrying about three hundred million hemoglobin molecules. They are able not only to carry oxygen, but also to release it, for example, into working muscle cells. On the way back, red blood cells deliver carbon dioxide, which is produced by burning sugar, back to the lungs. After that, red blood cells again bind with oxygen and transport it to the tissues.
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The diagram shows the process of gas exchange in the alveoli and transport of oxygen by hemoglobin |
Hemoglobin molecules also carry nitric oxide in addition to oxygen. Without this gas, blood pressure would constantly change. Hemoglobin also regulates the amount of oxygen delivered to tissues via nitric oxide. It is surprising that such a "regulation" possible thanks to just one molecule.
Features of human blood – perfectly designed cages
Red blood cells make up the majority of all blood cells. There are about 30 billion of them in the blood of an adult, they give color to our blood. Due to their exceptional flexibility, red blood cells can squeeze through capillaries and very small openings without getting stuck in them. In diameter, capillaries are, as a rule, from four to five micrometers, and erythrocytes – about 7.5 micrometers. In diabetics, red blood cells lose their flexibility, causing them to "clog" delicate tissues in the eyes of patients, resulting in blindness.
Features of human blood – automatic emergency system
The life span of a red blood cell is 120 days. After that, the erythrocytes "eliminate" spleen. This loss is replenished through the constant formation of new cells. Under normal conditions, 2.5 million red blood cells appear in the body per second. The peculiarity of human blood is that, if necessary, their number increases – regulated by a hormone called erythropoietin. For example, as a result of a large loss of blood, the loss is immediately replenished. In addition, the rate of regeneration increases with a constant decrease in oxygen levels, for example, when climbing to a high altitude.
Features of human blood – ideal transport system
The blood fluid is called plasma, and it carries not only blood cells, but also other substances in the body. Plasma – clear yellowish liquid, accounting for 5% of normal body weight. 90% plasma – it is water, in addition to which the plasma also contains salts, minerals, carbohydrates, fats, and hundreds of different types of proteins. Some of the proteins in the blood carry out the transport function – bind fats and transport them to tissues. If such proteins could not carry fats, the latter would simply swim randomly throughout the body, leading to serious health problems.
Hormones in plasma play the role of special couriers. This is another feature of human blood. They facilitate communication between organs and cells through chemical signals. The most abundant hormone in plasma is albumin. It binds fats such as cholesterol, hormones, bilirubin or drugs and leaves harmful substances in the liver while carrying other nutrients. and hormones to the places where they are needed.
Just one protein is able to distinguish between fats, hormones and drugs, as well as determine the places to which they need to be transferred, as well as the quantities in which they are needed. And this is just one of tens of thousands of biochemical processes occurring in the body.
Features of human blood – special controls
Nutritients must penetrate the walls of the vessels through which they are transported to the target tissues. Despite the fact that there are tiny holes in the walls of the vessels, the substances themselves do not pass through them – This requires blood pressure. However, nutrients that pass into the tissues in larger quantities than necessary lead to the appearance of inflammation in the tissues. The peculiarity of human blood also lies in the fact that there are special mechanisms for balancing blood pressure and outflow of fluid back into the blood. Albumin is responsible for this – it is larger than the above openings, it can suck up water like a sponge.
On the other hand, substances from the blood should not enter the brain without proper control, as some of them can damage nerve cells (neurons). Therefore, the brain is protected from unauthorized access of such substances: the pores are closed by dense layers of cells, and all substances must pass through this layer, as through a checkpoint, so that the brain receives a balanced supply of nutrients.
Features of human blood – body thermostat
In addition to toxins, red blood cells, vitamins and other substances, blood also carries heat – by-product of energy production in cells. The distribution and balancing of heat in the body depending on the outside temperature is vital. If there were no heat distribution system in the body, during the use of the muscles of the hands, our hands would overheat, and the rest of the body – cooled, which would have a negative effect on the metabolism.
Therefore, heat is evenly distributed in the body, for which the circulatory system is responsible. Blood vessels under the skin increase in volume, which allows excess heat to escape, and the sweating system is also activated. When the outside temperature is low, the blood vessels under the skin constrict, causing the amount of blood in the area where cooling occurs to decrease to minimize cooling.
All processes occurring in the blood are complex and closely intertwined. Everything is thought out to the smallest detail, so even a small breakdown in this mechanism can lead to serious consequences.
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