In this article we will consider the properties of blood plasma. Blood is of great importance in the metabolic processes of the human body. It includes plasma and shaped elements suspended in it: erythrocytes, platelets and leukocytes, which occupy about 40-45%, the elements that make up the plasma account for 55-60%.
What is plasma?
Blood plasma is a liquid with the same viscous structure of light yellow color. If you consider it as a suspension, you can detect blood cells. Plasma is usually clear, but eating fatty foods can make it cloudy.
What are the main properties of plasma? More on that later.
Plasma composition and functions of its parts
Most of the plasma composition (92%) is occupied by water. In addition, it contains substances such as amino acids, glucose, proteins, enzymes, minerals, hormones, fat, and fat-like substances. The main protein is albumin. It has a low molecular weight and occupies more than 50% of the total volume of proteins.
The composition and properties of plasma are of interest to many medical students, andThe following information will be helpful to 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, large-molecular globulins, which are produced by the organs of the liver and the immune system, are secreted in the plasma. There are 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, it can lose this sign and become insoluble, as a result of which a blood clot appears where the vessel was 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 a lot of 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 self-regulate.
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 ensure blood clotting, the transport of nutrients.
Also thanks to themthe functioning of acid-base hemostasis occurs, the aggregate state of the blood is maintained. Albumin is synthesized in the liver. Cells and tissues are nourished, bile substances are transported, as well as a reserve of amino acids. Let's single out the main chemical properties of plasma:
- Drug components are delivered with albumins.
- α-globulins activate protein production, transport hormones, microelements, lipids.
- β-globulins transport cations of elements such as iron, zinc, phospholipids, steroid hormones and bile sterols.
- G-globulins contain antibodies.
- Fibrinogen affects blood clotting.
The most significant physical and chemical properties of blood, as well as its components (including plasma properties) are as follows:
- osmotic and oncotic pressure;
- suspension stability;
- colloidal stability;
- viscosity and specific gravity.
Osmotic pressure
Osmotic pressure is directly related to the concentration of molecules of dissolved substances in the plasma, the sum of the osmotic pressures of different ingredients in its composition. This pressure is a hard homeostatic constant, which in a he althy person is approximately 7.6 atm. It carries out the transition of the solvent from less concentrated to more saturated through a semi-permeable membrane. It plays a significant role in the dispersal of water between cells and the internal environment of the body. The main properties of plasma will be discussed below.
Oncotic pressure
Oncotic pressure is an osmotic type pressure created in a colloidal solution by proteins (another name is colloidal osmotic pressure). 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 the 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 difference 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 protein. Their decrease in plasma leads to water loss, tissue edema, and their increase leads to water retention in the blood.
Suspension properties
The suspension properties of plasma are interrelated with the colloidal stability of proteins in its composition, that is, with the preservation of cellular elements in a state of suspension. The indicator of these blood properties is estimated by the erythrocyte sedimentation rate (ESR) in the immovable blood volume. The following relationship is observed: the more albumins are contained in comparison with less stable colloidal particles, the higher the suspension properties of blood. Ifthe level of fibrinogen, globulins and other unstable proteins increases, the ESR increases and the suspension capacity decreases.
Colloid stability
The colloidal stability of plasma is determined by the properties of hydration of protein molecules and the presence on their surface of a double layer of ions that create a phi-potential (surface), which includes a zeta potential (electrokinetic), located at the junction between the colloidal particle and the surrounding liquid her. It determines the possibility of sliding 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 value is much greater for albumin in the plasma, and its stability is most often determined by these proteins.
Viscosity
Viscosity of blood - its ability to resist the flow of fluid during the movement of particles with the help of internal friction. On the one hand, these are complex relationships between macromolecules of colloids and water, on the other hand, between formed elements and plasma. The viscosity of plasma is higher than that of water. The more it contains large molecular proteins (lipoproteins, fibrinogen), the stronger the plasma viscosity. In general, this property of blood is reflected in the total peripheral vascular resistance to blood flow, that is, it determines the functioning of the heart and blood vessels.
Specific gravity
The specific gravity of blood is related to the number of red blood cells and their content of hemoglobin, the structure of plasma. In an adultof 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, specific gravity increases due to fluid loss, profuse sweating during physical labor and high air temperature.
We looked at the properties of plasma and blood.
