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What is Necrosis? Cell, Tissue Death Process

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Necrosis is the medical term for the death of living cells or tissue. Necrosis occurs due to unnatural factors, as a consequence of external factors. Necrosis should not be confused with apoptosis which is natural cell death.

The exact time of cell death cannot be ascertained, therefore necrosis is technically the structural changes that occur within the cell as a result of death. Necrotic tissue undergoes these changes for a number of reasons – either due to oxygen deprivation, enzymatic dissolution, infection and other forms of trauma to the cell.

Process of Cell Death

Cell death may occur due to a number of reasons. However, the changes that occur from an interrupted oxygen supply  to a cell may progress as follows :

  • The cell’s mitochondria (energy factories) switch to anaerobic respiration due to the lack of oxygen and lactic acid is produced.
  • This lactic acid builds up in the cell and drops the pH (making it acidic) within the cell.
  • This acidic environment within the cell triggers the release of enzymes known as lysosomes.
  • These lysosomes begin the cellular breakdown.
  • The cell membrane cannot maintain its normal function and cellular products escape the cell, while other compounds from the surrounding tissue fluid enters the cell.
  • This then permanently damages the mitochondria, rendering them inactive, while any proteins within the cells are denatured.
  • The nucleus of the cell then undergoes changes leading to the damage of the DNA and other structures within the nucleus.
  • The cytoplasm of the cell becomes flooded and the cell swells.
  • The cell membrane ruptures and adjacent cell remnants fuse into a mass.

The enzymes and other substances released from a ruptured cell can also kill healthy cells lying adjacent to it, thereby perpetuating the spread of necrosis. Alternatively it may cause inflammation of the surrounding healthy tissue. A large mass of necrotic tissue is known as gangrene.

Article reviewed by Dr. Greg. Last updated on May 14, 2010