From Latin necrosis, which in turn derives from a Greek word, the necrosis is the degeneration of a tissue by death his cells. This mortality is produced by the action of a harmful agent that generates a irreparable injury.
Necrosis can be caused by trauma, ischemia (when the blood supply to the tissue is insufficient), the action of a chemical or toxic substance, an infection or a certain disease. It is important to bear in mind that, once necrosis has occurred, it is irreversible.
There are many other causes that can become the origin of necrosis. Specifically, this can be produced as a result of the important imbalances that someone experiences in terms of nutrition, individuals being affected by substances or infectious agents of different types or the occurrence of various genetic alterations.
All this without forgetting that necrosis can have its original cause in what are the exposure to certain ionizing radiation and in relevant variations of thermal type.
Cells have a great capacity for adaptation. Before a stimulus, can undergo various changes: atrophy (the decrease in the size of the organ), hypertrophy (the enlargement of the organ), metaplasia (the exchange of one fabric for another) or hyperplasia (an increase in the number of cells in the organ).
When the adaptation mechanisms are not sufficient, the cell dies, either by necrosis or by apoptosis (the cell loses its anchorage, reduces its cytoplasm and fragments its genetic material).
There are different types of necrosis depending on the lesion, such as coagulative necrosis (generated by ischemia), the fat necrosis, the gangrenous necrosis and the necrosis with liquefaction, among other.
In the case of fat-type necrosis, we must emphasize that, in turn, it is divided into two. Thus, on the one hand, there would be the traumatic type that, as its name indicates, has its origin in a trauma of some importance. And on the other, we would find that it occurs as a result of a series of changes in the cell, which is the one that, by itself, decides that it has to die.
Necrosis with liquefaction we can establish, for its part, that it is the one whose main consequences are the fact that the area that is necrotic becomes completely liquefied.
In addition to the types of necrosis exposed, the so-called caseous necrosis should not be overlooked either. In various pathologies such as, for example, tuberculosis makes an appearance that is identified by the fact that the necrotic area acquires a white appearance similar to that of a cheese.
When necrosis affects a considerable area of the body, we speak of gangrene. In these cases, the decomposition of organic tissues usually affects the extremities and, in the most extreme cases, requires the amputation of the affected limb.
Gangrene can be dry (due to lack of circulation), damp (from a bacterial infection) or frothy (when a strong odor is emitted from the affected tissue).