necrosis
Meaning of necrosis: Cells dying by accident spill their contents and inflame the area around them, unlike the body's orderly disposal of unwanted cells.
Definition of necrosis
Necrosis is the death of cells or tissue within a living body, occurring when injury is severe enough that cells can no longer maintain their structure and function. Loss of blood supply, infection, physical or chemical injury and extremes of temperature are typical causes. The dying cells swell and rupture, spilling their contents and provoking inflammation around them.
How necrosis is built
- necr/o Combining form · Greek death of tissue
- -osis Suffix · Greek abnormal condition, increase
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
How does it differ from apoptosis?
| Necrosis | Apoptosis | |
|---|---|---|
| Trigger | Injury the cell cannot survive | A controlled internal signal |
| What the cell does | Swells and bursts | Shrinks and breaks into packaged fragments |
| Contents released | Yes, into the surrounding tissue | No, they stay wrapped in membrane |
| Inflammation | Marked | Little or none |
| Scale | Groups of neighboring cells | Single cells, scattered |
Apoptosis is how the body removes cells it no longer needs, and it proceeds constantly without leaving any sign. Necrosis is failure rather than housekeeping, and the contents released from ruptured cells are what recruit immune cells and produce redness, swelling, pain and heat around the dead area. That inflammatory reaction is often what brings the problem to attention, rather than the cell death itself.
What patterns does necrosis take?
Pathologists describe several appearances, and each points toward a cause. Coagulative necrosis preserves the outline of the tissue for a time and is typical of an area cut off from its blood supply, as in a heart attack. Liquefactive necrosis dissolves the tissue into a soft or fluid mass, characteristic of bacterial infection and of the brain after a stroke. Caseous necrosis leaves crumbly, cheese-like material and is associated with tuberculosis. Fat necrosis follows the breakdown of fat by trauma or by released digestive enzymes, leaving firm areas that can be mistaken for a tumor on examination or on a scan. Gangrene is not a separate mechanism but a word for necrosis of a whole limb or organ, described as dry when blood supply alone has failed and wet when infection is added.
What happens to the dead tissue?
Small areas are cleared by immune cells and replaced with scar tissue, since most adult tissue cannot regrow what was lost. Larger areas may liquefy into an abscess, become walled off, or persist as dead material the body cannot remove on its own. Dead tissue also offers a surface on which bacteria grow readily, because blood carrying immune cells and antibiotics no longer reaches it. Necrosis appearing inside a tumor is a separate situation, reflecting growth that has outstripped its blood supply, and it can also follow effective treatment, as in radiation necrosis, where dead tissue at a treated site may resemble persistent tumor on imaging.
Used in a sentence
Imaging revealed an area of necrosis within the tumor following treatment.
Good to know
Necrosis describes uncontrolled cell death caused by injury or loss of blood supply, a distinct process from apoptosis, the body's normal programmed method of removing individual cells.
Word origin
Where “necrosis” comes from
From Greek nekrosis, meaning a state of death, from nekros, meaning corpse.