About 5 liters of blood circulate continuously in the body of an adult. From the heart, it is carried throughout the body by a fairly branched vascular network. The heart needs about a minute, or 70 beats, to pass all the blood, which supplies all parts of the body with vital elements.
How does the circulatory system work?
It delivers the oxygen received by the lungs and the nutrients produced in the food tract to where they are needed. The blood also transports hormones to their destination and stimulates the removal of waste products from the body. In the lungs, it is enriched with oxygen, and carbon dioxide from it is released into the air when a person exhales. It carries the products of cell decay to the excretory organs. In addition, the blood ensures that the body always remains evenly warm. If a person has cold feet or hands, it means they don't have enough blood supply.
Erythrocytes and leukocytes
These are cells with their own special qualities and "tasks". red blood cells(erythrocytes) are formed in the bone marrow and are constantly updated. There are 5 million red blood cells in 1 mm3 of blood. Their task is to deliver oxygen to different cells throughout the body. White blood cells - leukocytes (6-8 thousand in 1 mm3). They inhibit pathogens that have entered the body. When the white bodies themselves are affected by the disease, the body loses its protective functions, and a person can even die from a disease such as influenza, which, with a normal defense system, quickly copes. The white blood cells of an AIDS patient are affected by the virus - the body can no longer resist disease on its own. Each cell, leukocyte or erythrocyte, is a living system, and all the processes occurring in the body are displayed on its vital activity.
What does blood type mean?
The composition of blood differs in people like appearance, hair and skin color. How many blood groups are there? There are four of them: O (I), A (II), B (III) and AB (IV). The proteins contained in erythrocytes and plasma influence which group a particular blood belongs to.
Antigen proteins in erythrocytes are called agglutinogens. Plasma proteins are called agglutinins. There are two types of agglutinogens: A and B, agglutinins are also divided - a and b.
Here's what's going on. Let's take 4 people, for example, Andrey, Alla, Alexei and Olga. Andrei has blood type A with A agglutinogens in cells and agglutinins in plasma. Alla has group B: agglutinogens B and agglutinins a. Alexeigroup AB: the features of the 4th blood group are that it contains agglutinogens A and B, but there are no agglutinins at all. Olga has group O - she does not have agglutinogens at all, but there are agglutinins a and b in the plasma. Each organism treats other agglutinogens as a foreign aggressor.
Compatibility
If Andrei with group A is transfused with blood of group B, its agglutinins will not accept a foreign substance. These cells will not be able to move freely throughout the body. This means that they will not be able to deliver oxygen to organs such as the brain, and this is life-threatening. The same thing happens if you connect A and B groups. Substances B will repel substances A, and for the O (I) group, both A and B are not suitable. To prevent errors, patients are pre-tested for a blood group before transfusion. People with type I blood are considered the best donors - it will suit anyone. How many blood groups there are - they all positively perceive the blood of group O, it does not contain agglutinogens in erythrocytes that others might not "like". Such people (like Olga in our case) are universal donors. The AB group contains both A- and B-proteins, it can combine with the rest. Therefore, a patient with blood group 4 (AB), with the necessary transfusion, can safely receive any other. That's why people like Aleksey are called "universal consumers".
Nowadays, when transfusing a patient, they try to use exactly the blood type that thepatient, and only in emergency cases, you can use the universal first. In any case, you must first check them for compatibility so as not to harm the patient.
What is the Rh factor?
Some people's red bodies contain a protein called the Rh factor, so they are Rh positive. Those who do not have this protein are said to have a negative Rh factor, and they are allowed to transfuse only exactly the same blood. Otherwise, their immune system will reject it after the first transfusion.
It is very important to determine the Rh factor during pregnancy. If the mother has a second negative group, and the father has a positive one, the child can inherit the father's Rh factor. In this case, antibodies accumulate in the mother's blood, which can lead to the destruction of red blood cells. The second positive group of the fetus creates a Rh conflict that is dangerous to the life and he alth of the child.
Genetic transmission of the group
Just like the shade of hair, the blood of a person will inherit from his parents. But this does not mean at all that the child will have the same composition as both or any of the parents. Sometimes this question unknowingly becomes the cause of family quarrels. In fact, the inheritance of blood is subject to certain laws of genetics. To figure out which and how many blood groups exist during the formation of a new life, the table below will help.
For example, if the mother has type 4 blood and the father has type 1, the child will not have the same blood as the mother. According to the table, hebe both the second and the third group.
Inheritance of a child's blood type:
| Mother's blood type | Paternal blood type | |||
| I | II | III | IV | |
| I | I | I, II | I, III | II, III |
| II | I, II | I, II | I, II, III, IV | II, III, IV |
| III | I, III | I, II, III, IV | I, III | II, III, IV |
| IV | II, III | II, III, IV | II, III, IV | II, III, IV |
| Possible genetic variants in a child | ||||
The Rh factor is also inherited. If, for example, both or one of the parents has a second positive group, then the baby can be born with both positive and negative Rh. If each of the parents has a negative Rh, then the laws of heredity work. The child may have the first or second negative group.
Dependence on human origin
How many blood groups exist, what is their ratio among different peoples, depends on the place of their origin. There are so many in the worldpeople are tested to determine the blood type, which provided an opportunity for researchers to trace how the frequency of one or another varies depending on the geographical location. In the US, 41% of Caucasians have type A blood, compared to 27% of African Americans. Almost all Indians in Peru are of group I, and in Central Asia, group III is the most common. Why these differences exist is not well understood.
Susceptibility to certain diseases
But scientists have noticed some interesting relationships between blood cells and certain diseases. People with type I blood, for example, are more at risk of developing ulcers. And people who have the second group are at risk of developing stomach cancer. It is very strange, but the proteins that determine the composition of the blood are very similar to the proteins found on the surface of individual pathogenic bacteria and viruses. If a person becomes infected with a virus with surface proteins similar to their own, the immune system may accept them as their own and allow them to multiply unhindered.
For example, the surface proteins of the microorganisms that cause bubonic plague are very similar to those of the I blood group. Scientific researchers suspect that such people may be particularly susceptible to this infection. Scientists believe that the disease originated in Southeast Asia and spread to the west. When it reached Europe, it destroyed a fourth of its population in the 14th century: then the disease was called the "black death". Lives in Central Asiathe smallest number of people with I blood group. Therefore, it was precisely this group that was "flawed" in areas where the plague was particularly rampant, and people with other groups were more likely to survive. Scientists believe that there is a dependence of diseases on the composition of the blood. The study of this version will help in the future to decipher the genesis of ailments and reveal the secrets of human survival.
