Blood plasma

Plasma of blood is a liquid extracellular part of the blood flow, which is about 60% of the blood. By consistency, it can be a transparent or slightly yellowish hue (due to particles of bile pigment or other organic elements), and blood plasma is also unclear as a result of the intake of fatty foods. The plasma contains protein substances, electrolytes, amino acids, hormones, carbohydrates and lipids, as well as vitamins, enzymes, certain gases dissolved in the plasma, the products of the decomposition and exchange of the above parts.

The composition can vary in the ratio of the elements quite often, since it is influenced by many factors, especially the human diet. However, the amount of proteins, cations, glucose is almost invariable, since normal functioning of blood depends on these elements. Changes in the level of glucose or cations, significantly removed from the limits of the norm, can become detrimental not only for human health, but also for his life (for example, dehydration). Frequent and relatively safe changes are subjected to quantitative indicators of uric acid, phosphate, neutral lipids.

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What is the function of blood plasma?

Plasma of blood has very diverse functions: it transports blood cells, metabolic products and nutritional elements. Plasma of blood connects and carries out dispatching of extravascular fluids (liquid media working on the circulatory system, that is, intercellular fluid). Through extravascular fluids, blood plasma contacts the tissues of organs, and thus maintains the biological stability of all systems - homeostasis. In addition, blood plasma performs an extremely important function for the blood - maintains a balanced pressure (the distribution of liquid media in the blood outside and inside the cell membranes). The main role in providing normal osmosis in the body is played by mineral salts, the pressure level should be within 770 kPa (7.5-8 atm). A small part of the osmotic function is carried out by proteins - 1/200 from the whole process. The plasma of blood has an osmotic pressure identical to the pressure in the blood cells, that is, it is balanced. For medical purposes a person can be infused with an isotonic solution having a pressure similar to that of blood. If it has a lower concentration, it is called hypotonic, it is intended for erythrocytes, for their hemolysis (they swell and disintegrate). If the blood plasma loses its liquid component, the salts in it are concentrated, the lack of water is compensated from through the erythrocyte membranes. Such "salty" mixtures are usually called hypertonic. Both those and others are used as compensation when the plasma of blood has insufficient quantity.

Plasma of blood: composition, concentration and functional roles of constituent elements

Plasma of blood consists of proteins, which are the main part, although they make up only 6-8% of the total mass. Proteins have their own subtypes: 

• Albumins are protein substances with a low molecular weight, they are up to 5%; 
• Globulins are protein substances, large-molecular, they make up to 3%; 
• Fibrinogen - a globular protein, they make up to 0.4%.

Functions of plasma protein elements: 

• Water balance (homeostasis); 
• Support of the aggregate state of blood flow; 
• Acid-basic homeostasis; 
• Stability of the immune system; 
• Transportation of nutrients and other substances; 
• Participation in the process of blood clotting.

Albumin synthesizes the liver. Albumins supply cells and tissues, regulate oncotic pressure, reserve amino acids and help synthesize proteins, transport bile substances - sterols (cholesterol), pigments (bilirubin), and salts of bile acids, heavy metals. Albumins are involved in the delivery of medicinal components (sulfonamides, antibiotics).

Globulins are divided into fractions - A-globulins, B-globulins and G-globulins. 

• A-globulins activate the production of proteins - components of blood serum (glycoproteins), providing almost 60% glucose. A-globulins carry the transportation of hormones, lipids, microelements, some vitamins. A-globulins are plasminogen, erythropoietin and prothrombin. 
• B-globulins transport bile sterols, phospholipids, steroid hormones, cations of iron, zinc and other metals. To transfer to beta-globulin transferrin, which binds iron molecules, deionizes them and carries them to tissues (liver and bone marrow). Also, beta-globulin is hemopexin, which helps to bind iron to ferritin, steroid-binding globulin and lipoproteins. 
• G-globulins have antibodies in their group, which are divided into five classes: IgG, IgA, IgM, IgD, IgE-globulin of the immune system, which protect the body from invading viruses and infections. Gamma-globulin is also the agglutinins of blood, due to which blood is determined by groups. G-globulins are synthesized, produced in the spleen, in the cells of the liver, in the bone marrow and lymph nodes.
• Fibrinogen is a soluble protein element, through which blood can be folded. When fibrinogen combines with thrombin, it is transformed into fibrin - an insoluble form, so blood clots form. Fibrinogen is produced (synthesized) in the liver.

Any acute inflammatory process can provoke an increase in the number of plasma proteins, especially the inflammatory inhibitors of proteases (antitrypsins), glycopeptides, and also C-reactive proteins. Monitoring the level of C-reactive protein makes it possible to track the dynamics of a person's condition in acute inflammation, for example, with rheumatoid arthritis.

The plasma of blood contains in its composition organic non-protein substances:

Group I:

These are nitrogen-containing substances: 

• 50% of the compounds are urea nitrogen; 
• 25% of the compounds - amino acid nitrogen; 
• Low molecular weight amino acid residues (peptides); 
• Creatinine; 
• Creatine; 
• Bilirubin; 
• Indikan.

The pathology of the kidneys, extensive burns are often accompanied by azotemia - a high level of nitrogen-containing elements.

Group II:

• These are nitrogen-free substances of organic origin: 
• Lipids, carbohydrates, the products of their metabolism and disintegration (metabolism), such as lactate, pyruvic acid (PVC), glucose, ketones, cholesterol. 
• Mineral elements of blood.

Inorganic elements that contain plasma blood take up no more than 1% of the total composition. These are the cations Na +, K +, Ca2 +, Mg2 + and Cl-, HP042-, HC03-, that is, the anions. The ions contained in the plasma maintain the normal state of the body cells, regulate the acid-base balance (pH).

In medical practice, infusion of physiological environments to the patient is used in case of severe blood loss, extensive burns or to support the work of the organs. These plasma substitutes perform a temporary compensatory function. Thus, the isotonic solution of NaC (0.9%) is equal to the osmotic pressure with pressure in the bloodstream. Ringer's mixture is much more adaptable to blood, since it contains ions besides NaCl - CaCl2 + KC1 +, so it is both isotonic and ionic with respect to blood. And due to the fact that NaHC03 is included in it, such a liquid can be considered equal to blood by acid-base balance. Another option - the Ringer-Locke mixture is close to the composition of natural plasma due to the fact that it contains glucose. All physiological compensation fluids are designed to maintain a level of normal, balanced blood pressure in situations associated with bleeding, dehydration, including after surgery.

Plasma of blood is an important component of blood, without which the functions of many organs and systems are difficult, and sometimes impossible. This complex biological environment performs a lot of useful functions - providing a salt balance necessary for the vital activity of cells, carrying out transport, protective, excretory and humoral functions.