Necrosis

Necrosis is the death of cells within living tissue as a result of damage, such as a cut-off blood supply, infection, burns, toxins or physical injury. It is often called accidental cell death, to set it apart from apoptosis, the orderly, programmed self-destruction the body uses to remove cells it no longer needs.

In necrosis, injured cells lose control over their membranes, swell and finally burst, spilling their contents into the surrounding tissue. These released contents act as alarm signals that set off inflammation, drawing in white blood cells to clear away the debris, which can harm nearby healthy tissue too. Apoptosis, by contrast, dismantles the dying cell neatly so it can be removed without triggering inflammation.

Necrosis is a central idea in pathology. An infarct, such as the patch of dead heart muscle left by a heart attack, is an area of necrosis caused by ischemia, a lack of blood flow. Gangrene is necrosis of a larger body part, often a toe, foot or limb, after its blood supply fails or it becomes badly infected, and it is more likely in people with diabetes or diseased blood vessels.