An exudate is a fluid released by an

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

'to (ooze out) sweat' (' 'out' and ' 'to sweat').

Medicine

An exudate is any

fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...

that filters from the

circulatory system In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart ...

into

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...

s or areas of

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

. It 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 is composed of serum,

fibrin Fibrin (also called Factor Ia) is a fibrous protein, fibrous, non-globular protein involved in the Coagulation, clotting of blood. It is formed by the action of the protease thrombin on fibrinogen, which causes it to polymerization, polymerize. ...

, and

leukocytes White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...

. Exudate may ooze from cuts or from areas of infection or inflammation.

Types

* Purulent or suppurative exudate consists of plasma with both active and dead

neutrophils Neutrophils are a type of phagocytic white blood cell and part of innate immunity. More specifically, they form the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. Their functions vary in different ...

fibrinogen Fibrinogen (coagulation factor I) is a glycoprotein protein complex, complex, produced in the liver, that circulates in the blood of all vertebrates. During tissue and vascular injury, it is converted Enzyme, enzymatically by thrombin to fibrin ...

, and

necrotic Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who is ...

parenchymal cells. This kind of exudate is consistent with more severe infections, and is commonly referred to as

pus Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during infections, regardless of cause. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collect ...

. * Fibrinous exudate is composed mainly of

and

. It is characteristic of rheumatic carditis, but is seen in all severe injuries such as

strep throat Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by ''Streptococcus pyogenes'', a Gram-positive bacteria, gram-positive, group A str ...

and

bacterial pneumonia Bacterial pneumonia is a type of pneumonia caused by bacterial infection. Types Gram-positive '' Streptococcus pneumoniae'' () is the most common bacterial cause of pneumonia in all age groups except newborn infants. ''Streptococcus pneumoniae ...

. 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. * Catarrhal exudate is seen in the nose and throat and is characterized by a high content of mucus. * Serous exudate (sometimes classified as serous

transudate Transudate is extravascular fluid with low protein content and a low specific gravity (< 1.012). It has low nucleated cell counts (less than 500 to 1000 per microliter) and the primary cell types are mononuclear leukocyte, mononuclear cells: macrop ...

) 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 Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...

. (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. Types of exudates: serous, serosanguineous, sanguineous, hemorrhaging and purulent drainage. *Serous: Clear straw colored liquid that drains from the wound. This is a normal part of the healing process. *Serosanguineous: Small amount of blood is present in the drainage; it is pink in color due to the presence of red blood cells mixed with serous drainage. This is a normal part of the healing process. *Sanguineous: This type of drainage contains red blood due to trauma of blood vessels, this may occur while cleaning the wound. Sanguineous drainage is abnormal. *Hemorrhaging: This type of drainage contains frank blood from a leaking blood vessel. This will require emergency treatment to control the bleed. This type of drainage is abnormal. *Purulent drainage: This type of drainage is malodorous and can be yellow, gray, or greenish in color. This is an indication of an infection.

Exudates vs. transudates

There is an important distinction between transudates and exudates. Transudates are caused by disturbances of

hydrostatic Hydrostatics is the branch of fluid mechanics that studies fluids at hydrostatic equilibrium and "the pressure in a fluid or exerted by a fluid on an immersed body". The word "hydrostatics" is sometimes used to refer specifically to water and o ...

colloid osmotic pressure Oncotic pressure, or colloid osmotic-pressure, is a type of osmotic pressure induced by the plasma proteins, notably albumin, in a blood vessel's plasma (or any other body fluid such as blood and lymph) that causes a pull on fluid back into ...

, 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 Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

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 A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the inn ...

permeability changes in relation to

body cavities A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid. The two largest human body cavities are the ventral body cavity, a ...

. For example, the specific gravity of the transudate is usually less than 1.012 and a protein content of less than 2 g/100 mL (2 g%). 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.

Plant exudates

Plant exudates include saps,

gums The gums or gingiva (: gingivae) consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health. Structure The gums are part of the soft tissue lining of the ...

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...

, and

resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...

. Sometimes

nectar Nectar is a viscous, sugar-rich liquid produced by Plant, plants in glands called nectaries, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to an ...

is considered an exudate. Plant seeds exudate a variety of molecules into the spermosphere, and roots exudate into the

rhizosphere The rhizosphere is the narrow region of soil or Substrate (biology), substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Pore space in soil, Soil pores in the rhizosphere can ...

; these exudates include acids, sugars,

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...

and

ectoenzyme An exoenzyme, or extracellular enzyme, is an enzyme that is secreted by a cell (biology), cell and functions extracellular, outside that cell. Exoenzymes are produced by both prokaryotic and eukaryotic cells and have been shown to be a crucial co ...

s, and collectively account for 40% of root carbon. Exudation of these compounds has various benefits to the plant and to the

microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

of the rhizosphere.

References

External links

* {{Authority control Cardiovascular physiology Body fluids

Medicine

Types

Exudates vs. transudates

Plant exudates

See also

References

External links