Necrosis is a type of cell death that occurs when cells are subjected to extreme or irreversible damage, such as from toxins, trauma, or ischemia (lack of blood flow). Unlike apoptosis, which is a highly regulated and programmed process, necrosis is an uncontrolled and pathological process that triggers a cascade of cellular and biochemical events leading to the breakdown of cellular components and the release of intracellular contents into the extracellular space.
During necrosis, the cell swells and its membrane becomes disrupted, leading to the leakage of intracellular contents into the surrounding tissue. This can trigger inflammation and the activation of the immune system, which can further damage the surrounding tissue. In contrast to apoptosis, necrosis does not produce apoptotic bodies, and the cell debris is usually cleared by phagocytes.
Necrosis can occur in various tissues and organs, including the heart, liver, kidneys, and brain, and is often associated with diseases such as heart attack, stroke, and sepsis. The severity of necrosis depends on the duration and extent of the damage, and can range from reversible damage to complete tissue destruction.