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%.
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.
Most of the composition of the plasma (92%) is occupied by water. 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 the plasma are of interest to many medical students, and the following information will be useful to them.
Proteins take part in the metabolism and synthesis, regulate oncotic pressure, are responsible for the safety of amino acids, carry various kinds of substances.
Also in the plasma are large-molecule globulins, which are produced by the organs of the liver and the immune system. There are alpha, beta and gamma globulins.
Fibrinogen - a protein that is formed in the liver,has the solubility property. Because of the influence of thrombin, it can lose this sign and become insoluble, resulting in a blood clot where the vessel has been damaged.
Blood plasma, in addition to the above, contains proteins: prothrombin, transferrin, haptoglobin, complement, thyroxine-binding globulin and C-reactive protein.
It performs a lot of functions, among which are:
- transport - the transfer of metabolic products and blood cells;
- binding of liquid media located outside the circulatory system;
- contact - provides communication with tissues in the body with the help of extravascular fluids, which allows the plasma to perform self-regulation.
Plasma of blood is rich in platelets. It is used in medicine as a stimulant for the regeneration and healing of body tissues. Proteins that make up the plasma provide blood clotting, transportation of nutrients.
Also thanks to them the functioningacid-base hemostasis, the aggregate state of blood is maintained. Albumin synthesis is performed in the liver. The cells and tissues are fed, the transportation of bile substances is carried out, as well as the reserve of amino acids. Let us single out the main chemical properties of plasma:
The most significant properties of blood of a physico-chemical nature, as well as its components (including the properties of plasma) are the following:
osmotic and oncotic pressure;
- Suspension resistance;
- colloid stability;
- viscosity and specific gravity.
Osmotic pressure is directly related tothe concentration in the plasma of molecules of dissolved substances, the sum of the osmotic pressures of various ingredients in its composition. This pressure is a rigid homeostatic constant, which in a healthy person is approximately 7.6 atm. It transfers the solvent from the less concentrated to the more saturated by means of a semi-impermeable membrane. It plays an important role in the dispersal of water between cells and the internal environment of the body. The main properties of plasma are discussed below.
Oncotic pressure is the pressureosmotic type, which is created in colloidal solution by proteins (also known as colloid osmotic). Since plasma proteins have poor permeability to the tissue medium through the capillary walls, the oncotic pressure that they create creates water in the blood. In this case, the osmotic pressure is the same in the tissue fluid and plasma, and the oncotic pressure is much higher in the blood. In addition, a reduced concentration of proteins in the tissue fluid is due to the fact that they are washed out by lymph from the extracellular environment; between the tissue fluid and blood there is a difference in protein saturation and oncotic pressure. Since the plasma contains the highest content of albumins, the oncotic pressure in it is mainly created by this type of protein. Reducing them in plasma leads to loss of water, edema of tissues, and increase - to a delay in the blood of water.
Suspension properties of plasma are interrelated withcolloidal stability of proteins in its composition, that is, with the preservation of cellular elements in a suspended state. The indicator of these blood properties is estimated by the rate of erythrocyte sedimentation (ESR) in the real blood volume. The following relationship is observed: the more albumins are contained in comparison with the less stable colloidal particles, the higher the suspension properties of the blood. If the level of fibrinogen, globulins and other unstable proteins increases, the ESR increases and the suspension capacity decreases.
The colloidal stability of the plasma is deterministicthe properties of the hydration of protein molecules and the presence on their surface of a double layer of ions that create a fi-potential (surface), in which a zeta potential (electrokinetic) is located at the junction between the colloidal particle and the liquid surrounding it. It determines the possibility of slipping particles 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 magnitude is much higher in albumins in the plasma, and its stability is most often determined by these proteins.
The viscosity of blood - the ability to resist itThe flow of a liquid during the movement of particles by means of internal friction. On the one hand, these are complex relationships between macromolecules of colloids and water, on the other - between shaped elements and plasma. The viscosity of the plasma is higher than that of water. The more it contains large-molecular proteins (lipoproteins, fibrinogen), the higher the viscosity of the plasma. In general, this property of blood is reflected in the overall peripheral vascular resistance to the blood flow, that is, determines the functioning of the heart and blood vessels.
The specific gravity of blood is related to the numbererythrocyte and the content of hemoglobin in them, the structure of the plasma. The average adult varies from 1.052 to 1.064. Due to the different content of erythrocytes in men, this indicator is higher. In addition, the specific gravity increases due to fluid loss, abundant sweating during physical labor activity and high air temperature.
We examined the properties of plasma and blood.