Exudate
From The Art and Popular Culture Encyclopedia
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An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can apply to plants as well as animals. Its composition varies but generally includes water and the dissolved solutes of the main circulatory fluid such as sap or blood. In the case of blood it will contain some or all plasma proteins, white blood cells, platelets, and in the case of local vascular damage: red blood cells. In plants, it can be a healing and defensive response to repel insect attack, or it can be an offensive habit to repel other incompatible or competitive plants. Organisms that feed on exudate are known as exudativores; for example, the Vampire Bat exhibits hematophagy, and the Pygmy marmoset is an obligate gummivore< (primarily eats tree gum).
In humans, exudate can be a pus like or clear fluid. When an injury occurs, leaving skin exposed it leaks out of the blood vessels and into nearby tissues. The fluid includes cells, proteins, or solid material or more specifically is composed of serum, fibrin, and white blood cells. Exudate may ooze from cuts or from areas of infection or inflammation. The purpose is to keep the injury moist, helping to keep it from becoming infected.
It is also important dealing with the control of exudate, removal of unhealthy tissue is key to improvement of the wound's healing process. A good wound cover keeps the wound moist and absorbs exudate at the same time. Thus, locking it inside the cover to prevent maceration. Again, the absorption and retention of the wound are vital towards the healing process and keeping the wound safe. Exudate depurates the wound but the pus, liquid, ext. is left on the skin so it is important for the exudate to be removed carefully. Biatain foam is a type of cover that is made specifically for cleaning these types of injuries. These may be used for up to seven days, controlling all leakage and absorption of the wound.
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Etymology
Exudate is derived from exude, "to ooze," from the Latin exsūdāre, "to (ooze) out like sweat" (ex- "out" and sūdāre "to sweat").
Types
- Purulent or suppurative exudate consists of plasma with both active and dead neutrophils, fibrinogen, and necrotic parenchymal cells. This kind of exudate is consistent with more severe infections, and is commonly referred to as pus.
- Fibrinous exudate is composed mainly of fibrinogen and fibrin. It is characteristic of rheumatic carditis, but is seen in all severe injuries such as strep throat and bacterial pneumonia. Fibrinous inflammation is often difficult to resolve due to blood vessels growing into the exudate and filling space that was occupied by fibrin. Often, large amounts of antibiotics are necessary for resolution.
- Catarhal exudate is seen in the nose and throat and is characterized by a high content of mucus.
- Serous exudate (sometimes classified as serous transudate) is usually seen in mild inflammation, with relatively low protein. Its consistency resembles that of serum, and can usually be seen in certain disease states like tuberculosis. (See below for difference between transudate and exudate)
- Malignant (or cancerous) pleural effusion is effusion where cancer cells are present. It is usually classified as exudate.
Plant exudates
Plant exudates include saps, gums, latex, resin, and sometimes nectar is considered an exudate.
Plant roots exude a variety of molecules into the rhizosphere, including acids, sugars, polysaccharides and ectoenzymes; this can account for 40% of root carbon. Exudation of these compounds has various benefits to the plant and to the microorganisms of the rhizosphere
Exudates vs. transudates
There is an important distinction between transudates and exudates. Transudates are caused by disturbances of hydrostatic or colloid osmotic pressure, not by inflammation. They have a low protein content in comparison to exudates. Medical distinction between transudates and exudates is through the measurement of the specific gravity of extracted fluid. Specific gravity is used to measure the protein content of the fluid. The higher the specific gravity, the greater the likelihood of capillary permeability changes in relation to body cavities. For example, the specific gravity of the transudate is usually less than 1.012 and a protein content of less than 2 gm/100mL (2 gm%). Rivalta test may be used to differentiate an exudate from a transudate. It is not clear if there is a distinction in the difference of transudates and exudates in plants.
See also
