Blood plays an extremely important role in the metabolic processes of the human body. It contains a plasma and shaped elements suspended in it:
- erythrocytes - red blood cells in which hemoglobin is contained;
- white blood cells - white blood cells, the main function of which is protective;
- platelets - blood platelets intended for blood coagulation.
Shaped elements occupy 40–45%, and plasma - 55-60% of the total blood volume. This ratio is called hematocrit (hematocrit).
Blood plasma is a liquid with a uniform viscous texture of light yellow color. If it is presented as a suspension, blood cells are detected there. Plasma is most often clear, but after eating fatty foods it may become cloudy. We will understand in this article how the blood plasma differs from serum.
Plasma composition
Water occupies a significant place in the plasma composition (about 92%). In addition, it contains the following substances:
- glucose;
- proteins;
- amino acids;
- fat and similar substances;
- enzymes;
- hormones;
- minerals.
Albumin is the main protein in the plasma, having a small molecular weight. It makes up more than 50% of the total protein volume. Formed in the liver.
The functions of the main protein
Albumin performs the following functions:
- transport - the transfer of hormones, fatty acids, ions, drugs, bilirubin;
- participates in the metabolism;
- conducts protein synthesis;
- controls oncotic pressure of plasma and blood serum;
- preserves amino acids.
If the plasma albumin level changes, this becomes an additional sign of diagnosis. Protein concentration helps to determine the condition of the liver, since its decrease is a characteristic sign of chronic diseases of this organ.
Other proteins
Other plasma proteins are large-molecular globulins produced in the organs of the immune system and liver. The following types are distinguished: alpha, beta and gamma globulins.
Alpha-globulins combine thyroxine and bilirubin, stimulate the production of proteins, transfer hormones, vitamins, lipids and trace elements.
Beta-globulins provide a connection of iron, vitamins and cholesterol, are responsible for the transportation of phospholipids, hormones, sterols, etc.
Gamma globulins bind histamine and take part in immunological reactions, therefore they are called antibodies (immunoglobulins). They are represented by five classes: IgA, IgD, IgE, IgG, IgM. The chemical composition of plasma and blood serum is unique.
They are produced in the liver, spleen, bone marrow, lymph nodes and have various biological properties and structure, differing methods of antigen communication, stimulation of the work of immune proteins, differentiate by their ability to pass through the placenta and avidity, that is, the speed of connection with the antigen and strength. IgG make up 80% of immunoglobulins. Only they can penetrate the placenta, have high avidity. Initially, IgM is synthesized in the fetus and appears first in the blood serum after most of the vaccinations.
Fibrinogen is a soluble protein formed in the liver. When exposed to thrombin, it becomes insoluble fibrin, due to which a blood clot forms in the damaged area of the vessel. What distinguishes blood plasma from serum is of interest to many. About it further.
In addition, blood plasma also includes proteins such as transferrin, complement, haptoglobin, prothrombin, C-reactive protein and thyroxin-binding globulin.
Non-protein components
Non-protein components include:
- organic nitrogen-free (lipids, carbohydrates, ketones, lactate, glucose, pyruvic acid, cholesterol, minerals);
- organic with a nitrogen content (urea nitrogen, amino acid nitrogen, creatine, indican, creatinine, bilirubin, low molecular weight peptides);
- inorganic: cations of magnesium, sodium, calcium, potassium, anions of iodine and chlorine.
Protein and Plasma Functions
Proteins perform the following functions:
- provide stable functioning of the immune system;
- support self-regulation of the body and the state of aggregation of blood;
- transport nutrients;
- take part in blood coagulation.
Plasma itself performs many functions, including:
- carries out the transportation of blood cells, metabolic products;
- binds liquid media outside the circulatory system;
- provides contact with body tissues through extravascular fluids, thereby realizing self-regulation.
Receiving plasma and serum
Most often, transfusion now requires not so much whole blood as its components and plasma. It is extracted from whole blood by centrifugation, that is, separation of the liquid part from the formed elements by hardware. After this, blood cells are returned to the donor. The duration of this procedure is forty minutes. In this case, blood loss is much less, and after two weeks you can re-donate plasma, but no more than twelve times a year.
Venous blood is taken in the morning on an empty stomach. At the same time, factors that can affect the result of the analysis should be taken into account: emotional arousal, excessive physical exertion, ingestion of food or alcohol before the study, smoking, etc. In order to exclude their effects, it is necessary to fulfill the following conditions for donor preparation:
- blood is taken after fifteen minutes of rest;
- the patient should sit (lying blood is taken from seriously ill people);
- smoking, drinking alcohol and food are excluded before the study.
Blood serum
Here is the definition of blood serum. It is a clear liquid with a yellowish tinge that separates from the blood clot after it coagulates. If the serum of a person or an animal is immunized with certain antigens, it is possible to obtain its immune variety, which is used in the diagnosis, prevention and treatment of various diseases. The color of the serum may also be red due to hemolysis - a process in which the destruction of red blood cells occurs with the release of hemoglobin. The icteric color indicates an increase in the value of bilirubin.
In serum, unlike plasma, there is no fibrinogen, but it contains all antibodies that can fight pathogens. In order to get it, you need to put blood taken sterile for 30-60 minutes in a thermostat, peel a clot from the tube wall using a Pasteur pipette and put it in the refrigerator for several hours (best of all for a day). After it has settled, the serum is drained or aspirated into a sterile tube. We examined the determination of blood serum, but what is the difference between it and plasma?
Difference from plasma
The main differences between serum and plasma are as follows:
- Blood plasma is a complex biological medium, the liquid part of the blood remaining after the removal of the formed elements, and serum is the liquid fraction of coagulated blood and is obtained by adding coagulants to it to help the blood coagulate.
- In blood serum, unlike plasma, a number of proteins, such as antihemophilic globulin and fibrinogen, are absent, as a result of which it cannot coagulate from coagulase, including microbial.
This is the difference between blood plasma and serum.
Thus, donor plasma is used in the transfusion and preparation of serum, which is further used for the prevention and treatment of infectious diseases, as a diagnostic method for identifying microorganisms obtained during the analysis. Serum has a more noticeable effect, like the introduction of a vaccine, since the immunoglobulins contained in it neutralize the action of harmful microorganisms and their metabolic products, and contribute to the early formation of passive immunity.
Now it is clear how plasma differs from serum.