Blood – composition and functions. What role does blood play in the body?

In line with its mission, the Editorial Board of MedTvoiLokony makes every effort to provide reliable medical content supported by the latest scientific knowledge. The additional flag “Checked Content” indicates that the article has been reviewed by or written directly by a physician. This two-step verification: a medical journalist and a doctor allows us to provide the highest quality content in line with current medical knowledge.

Our commitment in this area has been appreciated, among others, by by the Association of Journalists for Health, which awarded the Editorial Board of MedTvoiLokony with the honorary title of the Great Educator.

Blood is an extremely vital part of the human body. Responsible for cell nourishment, oxygenation, and the release of metabolic products from the tissues. In short, blood is an irreplaceable fluid, even by the latest inventions of medicine, which is absolutely necessary for the proper functioning of our body and our internal organs. What is the composition of the blood?

Blood – role in the body

It is the blood flow that determines the proper functioning of our organs. In the body of a healthy adult human there are about 5 liters of life-giving fluid. Blood is the life-giving fluid for a reason. If a large amount of it is lost, a transfusion is necessary. If not done quickly enough, the injured person may even die.

Blood is a highly coveted fluid, and hospitals and blood donation stations are constantly complaining about the lack of it. The medicine of the XNUMXst century can bring us the solution. Unfortunately, at the moment, synthetic blood is just a pipe dream, and scientists believe that human blood cannot be replaced with anything else. What should be the correct blood composition?

See also: Will blood be mass produced?

Blood – composition

The composition of blood is primarily red blood cells, also called erythrocytes, white blood cells called leukocytes, platelets called thrombocytes, and plasma, which is the liquid part in which the above-mentioned cells are suspended. Blood cells are not long-lived cells and must be constantly replaced and replenished. In a fetus, these cells form in the liver. After birth, blood cell formation is performed by the bone marrow, which makes them from immortal stem cells.

The blood is also composed of leukocytes (white blood cells) – they have a protective function. They constitute a barrier against infections and eliminate bacteria. They annihilate foreign proteins and are an important factor in the fight against parasites. One of their more important functions is also the elimination of blood clots. They take part in the destruction of bacteria, cells, cancer and fungi, and T lymphocytes (which are also white blood cells) are responsible for the proper functioning of the immune system.

Plasma – based on water, which accounts for 90% of its structure. Other components include sodium, potassium, chloride ions, fatty acids, urea, hormones, cholesterol, vitamins, proteins, glucose and metabolic products. Plasma is responsible for the transport of nutrients, participation in the body’s defense reactions, and maintaining a constant pressure and pH of cells.

Erythrocytes (red blood cells) – their main component is hemoglobin. Thanks to its ability to capture oxygen molecules and combine them with iron, it enables the transfer of this oxygen to all cells of our body. In the same process, carbon dioxide is taken to the lungs, from where it is excreted.

Thrombocytes (platelets) – it is this element of the blood that is responsible for blood clotting. Together with fibrinogen dissolved in plasma, in the event of an injury, they form a kind of barrier at the site of vessel damage, which stops the flow of erythrocytes. This is how a clot is formed.

Also read: Leukopenia and other disorders of the blood composition. What are they characterized by and what do they testify to?

Blood – functions

The composition of the blood is important, but no less important are its functions. Blood performs many important tasks in our body. Its main function is the transport of oxygen and nutrients to the cells and the excretion of the end products of the transformation, e.g. carbon dioxide and urea. Except that blood is responsible for the transport of hormones and other substances between cells.

Another task that blood has to do is regulate the pH value. Blood protects the body against foreign bodies and antigens thanks to antibodies and phagocytes (food cells). The constant flow of blood makes us warm-blooded. Blood also protects our body from cuts by clotting it. In addition, our blood, through the constant pressure exerted on the walls of blood vessels, also serves as a support. Thanks to this, the blood can be responsible for organ movement (e.g. during an erection).

See also: What is thick blood?

A blood cell kit containing educational toys may be useful as a teaching aid. The set is available on Medonet Market at an attractive price.

Blood – arising

In our body, new and new blood elements are constantly being created and at the same time replace old components that break down and destroy. With each passing day, millions of red cells, white cells, and platelets are formed. As for the blood counts, these are mainly produced in the bone marrow, but also in the spleen, lymph nodes, and the reticuloendothelial system. The process of their formation is known as haemopoiesis and includes:

  1. erythropoiesis, or red blood cell production;
  2. leukopoiesis, or production of white blood cells;
  3. thrombopoiesis, i.e. the production of platelets.

Blood – blood group

It should be mentioned that on the surface of red blood cells there are proteins called antigens that make up the two basic blood group systems.

Blood groups – AB0 system

In the case of a person possessing A antigens, their blood group will be marked with the letter “A” and those with B-antigens with the letter “B”. When a person has both antigens then their blood flu is labeled ‘AB’. It also happens that the antigens may not be present at all, which means that we are dealing with blood group zero, which in turn is marked with the number “0”.

In addition, each antigen corresponds to specific antibodies (or no antibodies) found in the plasma. Their task is to destroy foreign antigens if they appear in the blood and to clump “non-native” blood cells. This is crucial during blood transfusions. When a person is given the wrong blood type, antibodies come into play. This reaction, called serological, can lead to severe complications and even death.

Needless to say, that people with blood group 0 can be universal donorsTherefore, their blood can be given to anyone without fear, but people with the AB group are the best recipients, so they can accept any blood because they do not have antibodies.

More on this topic: Blood groups – characteristics, inheritance, serological conflict [EXPLAIN]

Blood groups – Rh system

In addition to the aforementioned antigens, proteins also known as the D antigen can also be found on the surface of the erythrocytes. When they are present, it is a sign that we are dealing with the blood group Rh +. On the other hand, if they are not, we are dealing with the blood group Rh-.

It should be mentioned here that the Rh factor may be the cause of a serological conflict between the mother and the fetus, when the mother is Rh- and her baby is Rh +. This causes the D-antigen from the fetal erythrocytes to enter the mother’s bloodstream, where it triggers a protective reaction and the production of anti-D antibodies. If the second baby is Rh + in the next pregnancy, anti-D antibodies from the mother’s bloodstream into the fetus’ blood start destroying their blood cells.

Find out more: Determination of the blood group. Why is it worth it? [WE EXPLAIN]

Blood – diseases

By observing changes in the blood picture, it is possible to recognize various diseases, as well as determine their degree of advancement. Important blood tests include the determination of Biernacki’s reaction, which consists in measuring the depletion of red blood cells in a specific unit of time in the presence of an anticoagulant, which finally allows to determine the presence of inflammation.

It’s worth mentioning that not all diseases change the blood picture, but there are also diseases that directly affect the blood and its components. These diseases include: haemophilia, leukemia and anemia (anemia). In the case of the latter, there is an insufficient supply of oxygen to the body (hypoxia). In hemophilia, however, there is a bleeding disorder, which in turn results in excessive and profuse bleeding.

As for leukemia, in this disease there is too much production of white blood cells, which enter the bloodstream in an immature form. For this reason, the remaining number of blood cells is reduced both in the bone marrow and in the blood itself.

If we are talking about it, it should be added that the excessive production of blood cells is called cytosis or a branch, and depending on the type of cell, it is referred to as erythrocytosis or leukocytosis (it is divided into subtypes, i.e. eosinophilia, monocytosis, basophilia, neutrophilia, lymphocytosis and thrombocytosis).

When it comes to the deficiency of red blood cells, we deal with erythropenia (anemia), in the case of the deficiency of white blood cells – leukopenia (and here, depending on the subtype, we can distinguish between: eosinopenia, basopenia, neutropenia, monocytopenia, lymphopenia), and the deficiency of platelets is thrombocytopenia. A blood smear can identify changes in cell proportions as well as gain valuable information on the severity and type of disease.

It should also be mentioned that insufficient blood supply or its lack may result in cell damage or even death. When we are dealing with a high blood deficiency, for example due to a sudden loss of blood as a result of an accident, it is significant that there is a shock. In turn, blood clots can cause blockages, clots or heart attacks (e.g. cerebral infarction). In order to prevent such situations, drugs that inhibit blood clotting, such as aspirin, heparin or acenocoumarol, are used.

we recommend: Basic blood tests – meaning, interpretation

Blood – healing wounds

Sealing is a process in which specific chemical and mechanical processes are involved. The damaged vessel begins to narrow, limiting blood leakage. Then, in the place where the wound appeared, platelets accumulate, which cover the wound, resulting in the formation of the so-called plate pin. Then the collected plates release chemical compounds to stimulate the action of the so-called. coagulation factors that are found in plasma. Fibrinogen in a damaged vessel is transformed into fibrin, i.e. a fibrous mesh, designed to stop the outflow of blood from the wound or its flow through the vessel. As a result, a clot is formed, commonly known as a scab.

See also: Prothrombin time, which is how fast blood clots

Leave a Reply