Causes of hydrodynamic factor edema. Oncotic factor of edema
Factor. contributing to the development of edema, can becomedecrease in tissue pressure, which occurs when the amount of collagen in the connective tissue is reduced and its looseness is increased, as is the case with inflammation. The fact that swelling occurs first of all in the fiber under the eyes, on the scrotum, labia is due to the looseness of the connective tissue and its weak resistance in these areas. Low pressure in the pleural cavity facilitates the development of hydrothorax in heart failure.
Disturbance of lymphodynamics may also lead to the inclusion ofhydrodynamic factor and the development of edema, if normal drainage of intercellular fluid through lymphatic vessels is disrupted. In this case, the liquid and proteins released from the capillary do not return back through the lymphatic vessels to the bloodstream, but accumulate in the interstitial environment. Lymph outflow disturbance is observed when lymphatic vessels are clogged with thrombi, parasites (filariasis), malignant tumor cells, as well as when they are squashed by scars, neighboring tissues, fluid, enlarged lymph nodes.
The narrowing of these vessels can be congenital, as it is found whencongenital hypoplasia of lymphatic vessels. In these situations, local edema is formed. Outflow of lymph from the tissue into the bloodstream is impeded by an increase in central venous pressure, which can also affect the fluid retention in the tissues. Dynamic lymphatic insufficiency (increased lymphatic formation with limited possibility of its outflow) can occur during fasting, nephrotic syndrome, etc. In such cases, generalized edema often develops. With prolonged disturbance of the lymph drainage in the tissues irreversible fibrotic changes of the skin and subcutaneous tissue occur, the deformation of the organ (elephantia) develops.
The hydrodynamic factor is important in the development of stagnant, lymphogenous and other edema.
Oncotic factor. Edema can occur with a decreaseoncotic blood pressure (hyponionia of the blood) and / or an increase in the oncotic pressure of the intercellular fluid. Hypoonkia of blood is a consequence of hypoproteinemia or a decrease in the albumin-globulin coefficient.
Due to the direct dependencies oncotic pressure of blood plasma fromconcentration of albumin in it, the inclusion of an oncotic factor occurs when the content of primarily albumin falls. The oncotic effect of globulins due to the large size of their molecules and less hydrophilicity is significantly lower than that of albumins, so hyperglobulinemia in hypoalbuminemia can not fully compensate for reduced oncotic blood plasma pressure. Thus, hypoalbuminemia leads to a decrease in oncotic pressure, regardless of changes in the concentration of globulins in the blood plasma. Even with a normal total amount of protein in the blood plasma, a decrease in the albumin-globulin coefficient leads to the development of hypone- nia of the blood.
Hypoproteinemia occurs when the protein synthesis is disturbedhepatitis and cirrhosis of the liver, protein starvation, loss of protein in the urine in the case of nephrotic syndrome, with excessive release of protein with feces, when there is a violation of its digestion and absorption. Hypononkia of blood plasma and hyperonkia of intercellular fluid can occur with increasing permeability of the vascular wall and entering the tissue of a protein-rich filtrate. Hyperonkia in tissues develops with the enhancement of catabolic processes with an increase in the number of finely dispersed substances that have high hydrophilicity. The ability of proteins to retain water depends on the ionic medium - the concentration of H +, C1
Hyponionia of the blood plasma increases filtration pressure on allalong the vascular bed, so giponokoticheskie edema are often generalized, but they appear faster where there is a low tissue pressure. Oncotic factor has an initial significance in the development of nephrotic, cachectic and other edema.