The term necrosis is an uncoordinated cell death in which a cell group dies. Common causes of necrosis are a sudden lack of oxygen in an organ (for example, when heart attack), bacterial toxins, burns, burns, or mechanical damage. Typically necrosis attracts an inflammatory reaction to - usually the dead tissue is replaced by scar tissue.
A small necrosis of the body can be replaced by functional tissue in good defensive position. In these cases heals the affected tissue and acquires its original state.
If there is necrosis (Greek. Nekros = dead), going to the affected cells proteins based and parts of cells or tissue dissolve themselves. This is done by enzymes - special proteins that can perform a wide variety of reactions. Disintegrates a cell enzymes enter also into the surrounding tissue and trigger a inflammatory response out.
Scientists distinguish several Nekrosetypen:
A Clotting or coagulation necrosis arises when a certain area of an organ is no longer supplied with blood. This is the case for example during a heart attack. Cells break down and release cell constituents freely, some of which pass over into the blood and leave them there to prove. This one uses, for example in a suspected heart attack: find certain proteins in the blood, supports this is the Diagnosis. Even in organs such as the liver, spleen or kidney Gerinnungsnekrosen may occur. Another cause of coagulation necrosis: A corrosive substance as acid or alkali comes into contact with the skin or mucous membrane and damages the cells.
In the special form the coagulation, the so-called fibrillo-granular necrosis, performs infection with microorganisms such as the tuberculosis pathogen Mycobacterium tuberculosis cell death. The affected tissue is soft and crumbly and resembles in consistency desiccated cream cheese. Therefore, doctors refer to this as Nekrosetyp cheesy necrosis.
At a fibrinoid necrosis perish collagen fibers or elastic fibers, for example in Vessel walls. Frequently a so-called autoimmune reaction triggers this type of cell death. A typical example is vasculitis, in which immune cells against the body's own tissue judge. Also a particular form of stomach ulcers or intestinal ulcers (peptic ulcer which) leads to a fibrinoid necrosis.
To a colliquative necrosis (Erweichungsnekrose) can occur in organs that contain little protein, but much fat. This includes asking for the brain. The affected area of the necrosis is soft and liquefies. Midst of the non-damaged tissue is created (so-called. Pseudocyst) a cavity with the liquid content and the cell remains. Also, on the pancreas, a necrosis of this type as in severe inflammation (pancreatitis) can form.
at vascular occlusions (In the legs for example, in "Raucherbein" or the diabetic foot) sometimes a special form of necrosis, gangrene develops due to the insufficient supply of blood. Only a Gerinnungsnekrose developed - later in the liquefied dead tissue more or less.