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( Necrosis)
Necrosis (in Greek ?e???? = "dead") is the name given to unnatural death of cells and living tissue. It begins with cell swelling, chromatin digestion, 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. 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 (e.g. 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. There are seven distinctive morphologic patterns of necrosis
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Necrosis Subcategories
Necrosis Articles
Acute Tubular Necrosis by donald anderson
ATN is a clinicopathologic entity charaterized morphologically by destruction of tubular epithelial cells and clinically by acute suppression of renal function. It is the most common cause of acute renal failure, which signifies acute suppression of ...
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