It is the name given to the unscheduled death of cells and living tissue.
Necrosis is the death of tissues in the body. It can be treated, but the affected tissue cannot be restored to good health.
It is less orderly than apoptosis , which is part of programmed cell death.
Unlike apoptosis, the clearance of cellular debris by phagocytes of the immune system is generally more difficult, since disorderly death generally does not send cellular signals that signal nearby phagocytes to engulf the dying cell .
This lack of signaling makes it more difficult for the immune system to locate and recycle cells that have died from necrosis than in cases where the cell has undergone apoptosis.
Severe damage to an essential system in the cell leads to secondary damage to other systems, a so-called “cascade of effects.”
Necrosis is accompanied by the release of special enzymes, which are stored by lysosomes, which are capable of digesting cellular components or the entire cell.
Lesions received by the cell can compromise the lysosome membrane, or they can initiate a disorganized chain reaction that causes the release of enzymes.
Unlike apoptosis, cells that die from necrosis can release harmful chemicals that damage other cells.
Causes of necrosis
Necrosis is caused by a lack of blood and oxygen in the tissue.
A common type of necrosis is caused by frostbite damage.
During freezing, the tissues are severely damaged by the cold, and if the condition is not treated quickly, the frozen areas turn black and die.
These black areas that are affected by necrosis cannot be cured, so they are usually removed during surgery.
Another type of necrosis occurs when a clot, such as a deep vein thrombosis, forms in a blood vessel and blocks blood vessels to an area of the body.
If blood flow is not quickly restored, the area loses oxygen and eventually dies.
This usually occurs in the legs and can lead to loss of tissue below the site of the blockage if the blood vessel is completely blocked.
It is not always a clot that leads to necrosis, these are just common examples.
Many types of injuries can cause enough damage for necrosis to occur.
The infection can destroy surrounding tissues until they become necrotic, as can trauma such as a car accident or a fall from a ladder.
Any time blood flow to an area is blocked, or an area is so damaged that blood cannot flow to and from it, necrosis may be possible.
It can be caused by other causes such as erosion by chemicals or radiation.
It can also be caused by infections or toxins, cancer, heart attack, and inflammation, or by chronic conditions that alter blood flow.
Necrosis can arise from a lack of proper care at the wound site.
The release of intracellular contents after cell membrane damage is the cause of inflammation in necrosis.
Types of necrosis
In mammalian bodies, cells try to adapt to injury as much as possible. When they can no longer adapt, they degenerate and die.
The exact point at which cell damage becomes irreversible is often difficult to determine.
Often there are no microscopic or ultrastructural indications that this point has been reached.
So it is the degradation that follows cell death that provides many of the characteristics that allow us to determine that a tissue is necrotic and to specify the type of necrosis.
There are many types of necrosis, as it can affect many areas of the body, including bones, skin, organs, and other tissues.
Necrotic tissues vary greatly in appearance, both macroscopically and histologically.
Necrosis is generally divided into basic and distinctive types.
The basic type includes coagulative necrosis and liquefactive necrosis, and the distinctive type includes caseous necrosis, fibrinoid necrosis, gangrenous necrosis, and fat necrosis.
- Coagulative necrosis: This type of necrosis occurs when the enzyme structure and protein undergo primary denaturation leading to increased intracellular acidosis of the cell.
- Liquefactive necrosis : This type of necrosis is caused by highly potent catalytic enzymes that undergo autolysis or heterolysis.
- Caseous necrosis: occurs most prominently in the tuber which is considered a granuloma. In this type of condition, the cellular architecture is completely destroyed and macrophage lysis occurs leading to caseating granulomas.
- Fibrinoid necrosis: In this type of necrosis, the fibrocytes are affected by collagen necrosis and the fibers begin to degenerate, leading to the fragmentation of the collagen fibers.
- Gangrenous necrosis: in this the tissues are affected by the necrosis condition and the condition rises due to the super bacterial addition.
- Fat necrosis: This condition takes place in adipose tissue and is caused by the action of lipase.
Depending on the severity, fat necrosis is divided into two types:
- Acute pancreatic fat necrosis: in this condition, enzymatic necrosis of fat occurs located in the Pancreas and omental tissue.
- Traumatic Fat Necrosis: Traumatic fat necrosis usually takes place in the breast and the necrotic area is surrounded by accumulation of neutrophils, fibroblasts, lipid-laden macrophages, and giant cells.
The degree of preservation of the original cell and tissue architecture is the most important criterion used to differentiate these types.
When living cells or tissues die, the condition is medically called necrosis.
This condition occurs due to external factors and is totally different from apoptosis, which is a condition in which cells die naturally.
Necrosis is considered as the change in the structure of the cell that ultimately leads to its death, and therefore in this situation it is difficult to determine the moment of cell death.
These changes in cells occur due to multiple reasons such as oxygen deprivation, enzymatic dissolution, various types of trauma affecting cells, and infections.
The process begins when cells are deprived of oxygen until their final death.
This process of cell death or necrosis progresses as follows:
When cells are deprived of oxygen, their mitochondria switch to anaerobic respiration producing lactic acid.
The amount of lactic acid begins to increase in the cells because its pH factor decreases making them acidic.
The presence of acidic nature within cells stimulates the release of lysosomes, which are a type of enzymes.
Lysosomes further degrade cells due to which the cell membrane loses its control over the normal functioning of the cells and the cellular components within the cell begin to make room for external fluid to enter the cell.
Because of this, the mitochondrion is completely damaged and what remains of the cell becomes inactive. Leftover proteins are denatured.
The nucleus within this cell changes and the DNA as well as other structures located within the nucleus are damaged.
In the end, the cytoplasm is invaded by external fluids that cause the cell walls to swell.
Ultimately, the cell membrane bursts and leads to cell death.
The enzymes and other substances produced during the cell death process can kill other healthy cells thus spreading the necrotic condition.
It also causes inflammation to nearby healthy tissues.
When a large mass of tissue is affected by necrosis, it is called gangrene.
In case of gangrene, the affected part must be cut since there is no other solution for it.
The symptoms will depend on the place where it occurs, the tissues turn black, with defined limits, with the presence of exudate with pus or blood.
You can also have fever, pain, redness and swelling, these symptoms will depend on the part of the body affected.
Diagnosis of necrosis
The patient’s medical history, diseases associated with necrosis, other systemic symptoms, and data revealed in the laboratory should be reviewed.
Imaging tests can also help identify the cause of pain, when it occurs.
Treatment may include surgery to restore blood flow or to remove damaged tissues, antibiotics to prevent or treat an infection, or to treat the burn or some other problem that caused the initial damage.