In this article, we consider the properties of blood plasma.Blood is of great importance in the metabolic processes of the human body. It includes plasma and suspended elements in it: red blood cells, platelets and leukocytes, which occupy about 40-45%, the elements entering into the plasma account for 55-60%.
What is plasma?
Plasma of blood is a liquid with the same typeviscous structure of light yellow color. If you consider it as a suspension, you can detect blood cells. Plasma is usually transparent, but eating fatty foods can make it cloudy.
What are the main properties of plasma? About this further.
The composition of the plasma and the function of its parts
Большая часть состава плазмы (92 %) занята водой.In addition, it contains substances such as amino acids, glucose, proteins, enzymes, minerals, hormones, fat, and also fat-like substances. The main protein is albumin. It has a low molecular weight and occupies more than 50% in the entire volume of proteins.
The composition and properties of plasma are of interest to many medical students, and the following information will be useful for them.
Proteins take part in metabolism and synthesis, regulate oncotic pressure, are responsible for the safety of amino acids, carry various kinds of substances.
Also in the composition of the plasma emit large-molecule globulins, which are produced by the organs of the liver and the immune system. Differ alpha, beta and gamma globulins.
Fibrinogen - a protein that is formed in the liver,has the property of solubility. Due to the influence of thrombin, this sign can be lost and become insoluble, as a result of which a blood clot appears where the vessel has been damaged.
Blood plasma, in addition to the above, contains proteins: prothrombin, transferrin, haptoglobin, complement, thyroxin-binding globulin and C-reactive protein.
Functions of blood plasma
It performs many functions, among which stand out:
- transport - transfer of metabolic products and blood cells;
- binding of liquid media located outside the circulatory system;
- contact - provides communication with tissues in the body using extravascular fluids, which allows the plasma to perform self-regulation.
Physical and chemical properties of plasma
Blood plasma is rich in platelets.It is used in medicine as a stimulator of regeneration and healing of body tissues. The proteins that make up the plasma provide blood clotting, transport nutrients.
Also thanks to them, there is a functioningacid-base hemostasis, the aggregative state of the blood is maintained. Albumin synthesis is performed in the liver. They feed on cells and tissues, transport bile substances, as well as a reserve of amino acids. Select the main chemical properties of the plasma:
- Albumin is delivered medicinal ingredients.
- α-globulins activate the production of proteins, transport hormones, microelements, lipids.
- β-globulins transport the cations of elements such as iron, zinc, phospholipids, steroid hormones and bile sterols.
- G-globulins contain antibodies.
- Coagulation of blood depends on fibrinogen.
The most significant properties of blood of a physicochemical nature, as well as its components (including properties of a plasma) are the following:
- osmotic and oncotic pressure;
- suspension stability;
- colloidal stability;
- viscosity and specific gravity.
Osmotic pressure
Osmotic pressure is directly related toconcentration of molecules of dissolved substances in plasma, the sum of osmotic pressures of various ingredients in its composition. This pressure is a hard homeostatic constant, which in a healthy person is about 7.6 atm. It transitions the solvent from less concentrated to more saturated through a semi-impermeable membrane. Plays a significant role in the dispersion of water between the cells and the internal environment of the body. The main properties of plasma are discussed below.
Oncotic pressure
Oncotic pressure is pressureosmotic type, created in a colloidal solution by proteins (another name is colloid-osmotic). Since plasma proteins have poor permeability to the tissue environment through the capillary walls, the oncotic pressure that they create retains water in the blood. In this case, the osmotic pressure is the same in the tissue fluid and plasma, and oncotic pressure is much higher in the blood. In addition, the reduced concentration of proteins in the tissue fluid is due to the fact that they are washed out by the lymph from the extracellular environment; between tissue fluid and blood there is a drop in protein saturation and oncotic pressure. Since plasma contains the highest content of albumin, oncotic pressure in it is created mainly by this type of proteins. Reducing them in plasma leads to the loss of water, tissue edema, and an increase leads to water retention in the blood.
Suspension properties
The plasma suspension properties are interrelated withcolloidal stability of proteins in its composition, that is, with the preservation of cellular elements in suspension. The indicator of these properties of blood is estimated by the erythrocyte sedimentation rate (ESR) in the immovable blood volume. The following relationship is observed: the more albumin there is in comparison with less stable colloidal particles, the higher the suspension properties of blood. If the level of fibrinogen, globulins and other unstable proteins increases, the ESR increases and the suspension capacity decreases.
Colloid stability
Plasma colloid stability is determinedthe properties of hydration of protein molecules and the presence on their surface of a double layer of ions creating a phi potential (surface), which includes a zeta potential (electrokinetic) located at the junction between the colloidal particle and the liquid surrounding it. It makes it possible for particles to slip in a colloidal solution. The higher the zeta potential, the stronger the protein particles repel each other, and on this basis the stability of the colloidal solution is determined. Its size is much higher in albumin in the plasma, and its stability is most often determined by these proteins.
Viscosity
Blood viscosity - ability to resistfluid flow during the movement of particles using internal friction. On the one hand, it is a complex relationship between macromolecules of colloids and water, on the other - between formed elements and plasma. Plasma viscosity is higher than that of water. The more it contains macromolecular proteins (lipoproteins, fibrinogen), the stronger the plasma viscosity. In general, this property of blood is reflected in the general peripheral vascular resistance to blood flow, that is, it causes the functioning of the heart and blood vessels.
Specific gravity
The proportion of blood is related to the amounterythrocyte and hemoglobin content in them, plasma structure. In an adult, a middle-aged person ranges from 1.052 to 1.064. Due to the different content of red blood cells in men, this figure is higher. In addition, the proportion increases due to fluid loss, excessive sweating during physical labor and high air temperature.
We considered the properties of plasma and blood.
