The Occurrence / Mechanisms of Edema

Edema or swollen is increased extracellular fluid volume and extravascular (interstitial fluid) are accompanied by abnormal accumulation of fluid in the sidelines of the tissue and serous cavities (loose connective tissue and body cavities). Edema can be local and general.

Localized edema, as happens only in the abdominal cavity (hydroperitoneum or ascites), the chest cavity (hydrothorax), under the skin (subcutaneous edema or anasarca hidops), pericardium of the heart, (hydropericardium) or in the lungs (pulmonary edema ). While edema is characterized by the occurrence of edema fluid collection in many places, called general edema.

Edema fluid, transudates termed, has a specific gravity and low protein content, clear colorless or yellowish clear, and it is a watery liquid or like gelatin when it contains within it a number of plasma fibrinogen.

The cause of edema is the presence of congestion, lymphatic obstruction, increased capillary permeability, hipoproteinemia, colloid osmotic pressure and sodium and water retention.

Mechanisms of Edema

1. Congestion

On the condition that clogged veins (congestion), an increase in intravascular hydrostatic pressure (the pressure that drives blood flow in vascular, by the work of the heart pump) causing leakage of plasma fluid into the interstitium. Plasma fluid will fill the sidelines of loose connective tissue and body cavities (edema).

2. Lymphatic obstruction

In the event of interruption of the nodes in an area (obstruction / blockage), the body fluid derived from blood plasma and the metabolism goes into the lymph channels will be buried (lymphoedema). Lymphoedema is often caused by radical mastectomy to remove a malignant tumor in the breast or the result of a malignant tumor infiltrated lymph nodes and channels. In addition, the channel and inguinal glands are inflamed due to filarial infestation can also cause edema of the scrotum and legs (disease filariasis / elephantiasis).

3. Increased capillary permeability

Capillary endothelium is a semi-permeable membrane that can be traversed by water and electrolytes freely, whereas plasma protein can only be through little or limited. Blood osmotic pressure greater than in lymph.
Power depends on the permeability of these substances that bind to the endothelial cells. In certain circumstances, for example due to the influence of the work of the endothelial toxin, can increase capillary permeability. As a result, plasma proteins exit the capillaries, so that the colloidal osmotic pressure of blood decreases, and vice versa interstitium fluid osmotic pressure increases. This resulted in the more fluid that leaves the capillaries and causing edema. Increased capillary permeability may occur in conditions of severe infections and anaphylactic reactions.

4. Hipoproteinemia

The reduced amount of blood protein (hipoproteinemia) cause low water holding capacity of the remaining plasma proteins, so that the liquid plasma vascular leak out, as the edema fluid. Hipoproteinemia condition may result from chronic blood loss by Haemonchus contortus worms that suck the blood in the gastric mucous glands (abomasum) and caused damage to the kidneys that cause symptoms of albuminuria (proteinuria, blood protein albumin out with urine) prolonged. This usually results in edema Hipoproteinemia general.

5. Colloid osmotic pressure

Colloid osmotic pressure in the tissues usually very small, so it can not resist osmotic pressure contained in the blood. But in certain circumstances the amount of protein in the tissue can be raised, for example, if increased capillary permeability. In this case the osmotic pressure can cause tissue edema.
Plasma fluid filtration also got resistance from line pressure (tissue tension). This pressure varies in different tissues. In a tenuous subcutis tissue such as eyelids, the pressure is very low, therefore the place is easily arise edema.

6. Sodium and water retention

Sodium retention occurs when the urinary excretion of sodium is smaller than that in (intake). Because sodium concentration rises, there will be hipertonia. Hipertonia causes water to be detained, so the amount of extracellular fluid and extravascular (interstitium fluid) increases. The result is edema.
Sodium and water retention can be caused by hormonal factors (increased aldosterone in hepatic cirrhosis and nephrotic syndrome and in patients who received treatment with ACTH, testosterone, progesterone or estrogen).
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