What is the process of Necrosis?

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When the living cells or tissues die the condition is medically termed as necrosis. This condition occurs owing to unnatural and external factors and is totally different from apoptosis which is a condition in which cells die naturally. Necrosis is considered as the shift in the structure of cell that ultimately leads to their death and hence in this situation it is difficult to ascertain the time of the death of cells. These changes in the cells occur due to multiple reasons like deprivation of oxygen, enzymatic dissolution, various type of trauma affecting cells and infections.

 

How does the Death of a cell Occur?

 

There are many reasons which lead to cell death but the process starts from the cells getting deprived off oxygen to their ultimate death. This process of cell death or necrosis progresses as follows:

  • When the cells are deprived of oxygen their mitochondria shifts to anaerobic respiration thereby producing lactic acid
  • The amount of lactic acid starts increasing in the cells due to which their pH factor drops down making them acidic
  • The presence of acidic nature inside the cells stimulates the release of lysosomes, which are a type of enzymes
  • Lysosomes further break down the cells owing to which the cell membrane looses its control over the normal functioning of cells and the cell components within the cell start making space for the outer fluid to come inside the cell
  • Due to this the mitochondria gets completely damaged making what is remaining of the cell inactive. The leftover proteins are denatured.
  • Nucleus inside this cell changes and the DNA as well as other structures located inside the nucleus gets damaged.
  • At the end cytoplasm gets overrun by external fluids making the cell walls swell. Ultimately, the cell membrane bursts leading to the death of the cell.

 

How does Necrosis Spread?

The enzymes and the other substances produced during the process of cell death can further kill other healthy cells thereby spreading the necrosis condition. It also causes inflammation to the nearby healthy tissues. When a large mass of tissue gets affected by necrosis, it is termed as gangrene. In case of gangrene, the part affected has to be cut off as there is no other solution for it.

 

What are the Different Types of Necrosis?

Necrosis broadly is 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.

  • Cogulative necrosis: This type of necrosis occurs when the structure and enzymic protein undergo primary denaturation leading to increase in the intracellular acidosis of the cell.
  • Liquefactive necrosis or Colliquative necrosis: This type of necrosis is caused by highly powerful catalytic enzymes which undergo autolysis or heterolysis.
  • Caseous necrosis: It most prominently occurs in the tubercle which is considered a granuloma. In this type of condition, the cell architecture is completely destroyed and lysis of macrophages occurs leading to caseating granulomas.
  • Fibrinoid necrosis: In this type of necrosis fibrocytes are affected by collagen necrosis and the fibers start degenerating leading to fragmentation of collagen fibers!
  •  Gangrenous necrosis: In this the tissues are affected by the necrosis condition and the condition gets elevated due to bacterial super addition.

 

What are the Two types of Fat Necrosis?

 This condition takes place in the adipose tissue and is caused by the lipase action. Depending upon the severity Fat necrosis  is divided into two types:

  • Acute pancreatic fat necrosis: In this condition enzymatic necrosis of fat located in the Pancreas and the omental tissue occurs.
  • Traumatic fat necrosis: Traumatic fat necrosis usually takes place in the breast and the necrosed area gets surrounded with neutrophils accumulation, fibroblasts, lipid loaded macrophages and giant cells.
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