necrosis

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necrosis

1. the death of one or more cells in the body, usually within a localized area, as from an interruption of the blood supply to that part
2. death of plant tissue due to disease, frost, etc.

Necrosis

 

the death within the living organism of individual organs or their component tissues or cells.

A necrosis is classified according to the pathological condition that causes it. Thus, frostbite and burns can cause traumatic necrosis; neurotropic necrosis arises with syringomyelia and the nervous form of leprosy; infarcts and gangrene are associated with circulatory, or ischemic, necrosis; caseous necroses occurring in tuberculosis and syphilis are forms of septic necrosis; and fibrinoid necrosis associated with allergic diseases is a type of allergic necrosis.

Necrosis is accompanied by characteristic changes in the cell and in the intercellular substances. The nucleus shrinks and coagulates, a process known as pycnosis, and the cytoplasm breaks up into clumps. The cell eventually lyses, that is, it degenerates and dissolves. The lysis is due to the activation of the lysosomal hydrolytic enzymes, such as ribonuclease, deoxyribonuclease, and acid phosphatase. The activation of the lysosomes occurs as a result of an increase in the permeability of the cell membranes, changes in the osmotic equilibrium, and acidosis—an abnormal increase in the intracellular hydrogen-ion concentration. Fibrinoid changes appear in the connective tissue, and nerve fibers become fragmented and disintegrate into clumps.

The clinical and morphological manifestations and further consequences of necrosis depend on the localization and distribution of the necrosis and on the mechanisms and conditions of origin. The following types of advanced necrotic conditions can develop: dry necrosis, such as Zenker’s degeneration of infected muscles; colliquative, or liquefactive, necrosis, which occurs for example, when a focus of softening arises in the brain in response to cerebral hemorrhage; gangrene; and bed sores. Necrotic tissue tears away; then, either connective tissue grows through it or the necrotic tissue undergoes autolytic or purulent liquefaction. Finally, the necrotic tissue becomes encapsulated and petrified.

The two most serious consequences of necrosis are a loss of function owing to the death of the structural elements of the necrotic tissues or organs and poisoning caused by the actual presence of a necrotic focus and by the inflammation that arises in response to this presence.

V. V. SEROV

necrosis

[nə′krō·səs]
(medicine)
Death of a cell or group of cells as a result of injury, disease, or other pathologic state.
References in periodicals archive ?
Table 1 Complications following Locked Plating Complication Amount Varus Malunion 16 Loss of Humeral Height 16 Avascular Necrosis 6 Implant Penetration 1
The collection of secondary complications to sickle cell anemia that are unique to this patient, including stroke, pain crises, avascular necrosis of the left hip, hypertension, priapism, Tinea-like skin lesions on the upper extremities, and iron overload will be discussed next in order to gain greater understanding of the pathophysiology of sickle cell anemia.
Due to the lack of blood flow in her bones she developed avascular necrosis in her hip joint and right shoulder.
In their review, no cases of avascular necrosis were observed in any of the four reviewed trials of low-dose glucocorticoids used in treating rheumatoid arthritis.
Virik K, Karapetis C, Droufakou S, Harper P Avascular necrosis of bone: the hidden risk of glucocorticoids used as antiemetics in cancer chemotherapy.
Avascular necrosis of the hallucal sesamoids update with reference to two case-reports.
He also suffers from avascular necrosis of the left hip and staphlecoccal septicaemia.
In addition to synovial chondromatosis, the differential diagnosis of loose joint bodies in the TMJ includes osteochondral fracture fragments, condylar fracture, rheumatoid arthritis, degenerative arthritis, and avascular necrosis.
Some of the more common kinds of bone disease include: Osteoporosis which makes your bones weak and easily breakable; Avascular necrosis through which blood vessels in the bone are damaged and there is a lack of blood supply to the bone, and degenerative joint disease which is an advanced form of arthritis.
Iwasaki, UCLA's trainer who worked closely with both players, said the key to Carter's recovery was preventing avascular necrosis, or the decaying of the joint.
In people with HIV, however, we sometimes see a serious condition that presents as hip pain and goes by the name of avascular necrosis (AVN).