Accidental Cell death Necrosis It is a local death of cells or tissue in the living body. The necrosis is caused by the progressive degradative action of enzymes on the injured cells. After a cell die, lysosomes rupture and their hydrolytic enzymes are released. The release and activation of these enzymes are responsible for cell necrosis. NB: Necrotic cells are dead cells; but dead cells are not necessarily necrotic.
Causes of Cell Injury and Necrosis: 1-Hypoxia or Ischemia (Hypoxic Cell Injury): Hypoxia rapidly leads to i-Decrease of ATP ii-Increase of Cytosolic Ca++. iii-Free radical formation. All of which cause cellular membrane injury.
i-Decrease of ATP leads to: A-lose of most energy dependent processes as; -Protein synthesis -DNA replication