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| | + | {{frontpage |
| | + | |pagetitle =Acute Inflammation |
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| | + | |contenttitle = Content |
| | + | |contentbody =<big><b> |
| | + | <categorytree mode=pages>Acute Inflammation</categorytree> |
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| − | ==Fluids==
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| − | ===Serous===
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| − | * Serous fluids are formed due to mild vascular injury in an organ or in vessels underlying a
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| − | surface.
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| − | * The fluid is clear to cloudy fluid.
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| − | ** Little protein is present.
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| − | * Examples:[[Image:hand burn injury.jpg|right|thumb|150px|<small><center>'''Burn injury'''. (Courtesy of T. Scase)</center></small>]]
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| − | ** Vesicles of the skin.
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| − | ** Many inflammations in joints.
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| − | ===Catarrhal===
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| − | * Catarrhal inflammation is a mild form of inflammation.
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| − | * Occurs on mucous membranes where there are many mucus cells.
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| − | * The consistency of catarrhal exudate varies from water to gelatinous.
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| − | * Colour varies from cloudy to pinkish.
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| − | * This form of exudation is essentially a shedding of epithelium containing many mucus cells, neutrophils, some RBCs, and flecks of fibrin.
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| − | * Common in mild forms of rhinitis, tracheitis, bronchitis, gastritis and enteritis.
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| − | ===Fibrinous===
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| − | * Fibrinous exudation occurs in more severe endothelial injury.
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| − | ** Injury results in the escape of fibrinogen, which is converted to fibrin.
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| − | * The fibrin formed appears as a yellowish coagulation on the surface of or within a tissue.
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| − | ** Common in the lungs and on serous surfaces.
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| − | * In hollow organs the fluid may coagulate to form casts of the lumen.
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| − | * Fibrin will peel off from the underlying tissue without causing damage to it.
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| − | ===Diptheritic===
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| − | * Diphtheritic exudate a more severe form of fibrinous exudate in which there is considerable necrosis of the underlying tissues.
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| − | * Diptheritic exudate is firmly adherent to the underlying tissue.
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| − | ** Attempts at removal cause tearing of this tissue>
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| − | * Commonly seen with internal surface fungal infections.
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| − | ** E.g. in the nose of the dog and the guttural pouch of the horse.
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| − | ** Fungal toxins penetrate the underlying tissue causing coagulation necrosis.
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| − | ===Haemorrhagic===
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| − | * This is a severe acute to peracute inflammation in which haemorrhage is the main component.
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| − | * Seen in the lymph nodes, lungs and intestine in severe inflammation.
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| − | ===Purulent===
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| − | * In purulent inflammation, pus is the predominant feature.
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| − | ** Pus is an admixture of dead and dying neutrophils with necrotic cells and a pyogenic agent.
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| − | *** Proteolytic enzymes released by the dying neutrophils lyse tissue cells to produce a fluid.
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| − | * Colour varies depending upon the agent.
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| − | ** May be white, yellow, green or brown.
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| − | * An abscess is a circumscribed sphere of pus surrounded by a pyogenic membrane.
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| − | ** The pyogenic membrane is composed of capillaries bringing neutrophils into the sphere.
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| − | ** This rapidly becomes enveloped by a fibrous tissue capsule.
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| − | *** A local connective tissue response attempting to wall off the purulent irritant from nearby normal tissue.
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| − | | |
| − | ===Functions of Exudate=== | |
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| − | # Dilutes the toxic agent, reducing its effect upon the tissue cells.
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| − | # The protein components may contain antibodies which attack or coat (opsonise) the irritant.
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| − | #* This makes the irritant more digestible to neutrophils and macrophages.
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| − | # Exudates may contain fibrin.
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| − | #* This is very sticky - immobilises the irritant.
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| − | #* Provides a framework over which the leukocytes crawl to reach the irritant.
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| − | #* Fibrin is also chemotactic to neutrophils, bringing more of these cells into the injured area.
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| − | # Exudate on a suface will wash away the irritant.
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| − | #* E.g the skin and alimentary track.
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| − | # Brings the irritant to the lymph nodes, via the lymphatics, for further processing or antigen presentation.
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| − | #* Preferably within white blood cells such as macrophages and neutrophils.
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| − | #* Local lymph nodes may also be inflamed following inflammation of a tissue which drains into them.
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| − | ===Sequelae to Exudation===
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| − | * Catarrhal and serous exudationresolve when the irritant is overcome.
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| − | ** Alternatively, they may progress to a more serious reaction.
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| − | * Fibrinous exudates may also resolve if the fibrin is digested by macrophages.
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| − | ** In the pleural and peritoneal cavities, the fibrin may become rganised into fibrous tissue, producing adhesions between the visceral surface.
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| − | * Diphtheritic inflammation will only repair by scar formation.
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| − | * If haemorrhagic lesions are widespread, they most commonly associated with acute deaths.
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| − | ** For example in acute viral, bacterial or toxic diseases.
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| − | * If the exudation is strictly localised, for example in brusing, then repair may occur.
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| − | * The resolution of abscesses depends upon their location.
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| − | ** If the abscess is near to a surface it will rupture onto it.
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| − | ** This is beneficial in the skin where it discharges to the exterior, hopefully getting rid of the pyogenic organism.
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| − | ** If the abscess is in deeper tissues, there is extensive fibrous capsule formation.
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| − | *** The fluid becomes inspissated due to withdrawal of water content.
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| − | *** Macrophages digest the necrotic remains.
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| − | *** Fibrous tissue organises the interior.
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| − | *** The very end result is a fibrous scar.
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| | [[Category:Inflammation]] | | [[Category:Inflammation]] |