AskDefine | Define necrosis

Dictionary Definition

necrosis n : the localized death of living cells (as from infection or the interruption of blood supply) [syn: mortification, gangrene, sphacelus]

User Contributed Dictionary

English

Noun

  1. The localized death of cells or tissues through injury or disease.

Derived terms

Related terms

Translations

localized death of cells or tissue
  • Dutch: necrose, afsterving
  • Finnish: nekroosi
  • French: nécrose

Extensive Definition

Necrosis (in Greek Νεκρός = Dead) is the name given to accidental death of cells and living tissue. It begins with cell swelling, chromatin digestion, and disruption of the plasma membrane and organelle membranes. Late necrosis is characterized by extensive DNA hydrolysis, vacuolation of the endoplasmic reticulum, organelle breakdown, and cell lysis. The release of intracellular content after plasma membrane rupture is the cause of inflammation in necrosis.
In contrast to apoptosis, cleanup of cell debris by phagocytes of the immune system is generally more difficult, as the disorderly death generally does not send cell signals which tell nearby phagocytes to engulf the dying cell. This lack of signaling makes it harder for the immune system to locate and recycle dead cells which have died through necrosis than if the cell had undergone apoptosis.

Causes

There are many causes of necrosis including prolonged exposure to injury, infection, cancer, infarction, poisons, and inflammation. Severe damage to one essential system in the cell leads to secondary damage to other systems, a so-called "cascade of effects". Necrosis can arise from lack of proper care to a wound site. Necrosis is accompanied by the release of special enzymes, that are stored by lysosomes, which are capable of digesting cell components or the entire cell itself. The injuries received by the cell may compromise the lysosome membrane, or may initiate a disorganised chain reaction which causes the release in enzymes. Unlike apoptosis, cells that die by necrosis may release harmful chemicals that damage other cells. In biopsy, necrosis is halted by fixation or freezing. Many species of viper (eg rattlesnakes or Bothrops) produce venom which causes severe necrosis in snake-bite victims. Additionally, some spiders (eg the Brown Recluse) contain venom which may cause significant cutaneous injuries with tissue loss and necrosis.

Morphologic patterns

There are seven distinctive morphologic patterns of necrosis:

Arachnogenic necrosis

Spider bites are cited as causing necrosis in some areas. These claims are widely disputed. In the US at least, only the bites of spiders in the genus Loxosceles or brown recluse have been proven to consistently cause necrosis. Many other spider species are claimed to cause necrosis but in most cases firm evidence is lacking. Partially this is because the early bite is often painless and the spider species cannot be identified.
Several species of spiders possess toxins proven to cause necrosis: Spiders suspected of, but not shown to cause necrosis:

Footnotes

necrosis in Bulgarian: Некроза
necrosis in Czech: Nekróza
necrosis in Danish: Nekrose
necrosis in German: Nekrose
necrosis in Estonian: Nekroos
necrosis in Spanish: Necrosis
necrosis in French: Nécrose
necrosis in Ido: Nekroso
necrosis in Italian: Necrosi
necrosis in Hebrew: נקרוזה
necrosis in Lithuanian: Nekrozė
necrosis in Hungarian: Nekrózis
necrosis in Dutch: Necrose
necrosis in Japanese: 壊死
necrosis in Polish: Martwica
necrosis in Portuguese: Necrose
necrosis in Russian: Некроз
necrosis in Slovak: Nekróza
necrosis in Finnish: Nekroosi
necrosis in Swedish: Nekros
necrosis in Turkish: Nekroz
necrosis in Ukrainian: Некроз

Synonyms, Antonyms and Related Words

Privacy Policy, About Us, Terms and Conditions, Contact Us
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2
Material from Wikipedia, Wiktionary, Dict
Valid HTML 4.01 Strict, Valid CSS Level 2.1