Thread: Cell Injury and Death

Cell Injury and Death

Cell Injury and Cell Death

• Causes of Cell Injury and Cell Death
• Mechanisms of Injury
• Morphological Changes Associated with Reversible Injury
• Cell Injury Vs Cell death
• Types of Cell Death
• Apoptosis Vs Necrosis

Causes of Cell Injury

• Physical Agents e.g.. trauma, thermal injury
• Chemical Agents e.g. poisons, environmental pollutants and drugs
• Nutritional
• Infectious Diseases caused by protozoa, bacteria, viruses
• Immunological mechanisms
• Inherited diseases- inborn errors of metabolism

Mechanisms of Cell Injury

• Two mechanisms serve as useful models:
• fatty change
• hypoxia
• fatty change is generally a reversible form of sublethal injury whereas the effects of hypoxia depend on the severity, duration
and on the vulnerability of the cell

Mechanisms of Cell Injury

• Fatty Change
• Accumulation of fat in hepatocytes depends on rate of fat synthesis, catabolism
• Malnutrition impairs protein synthesis and therefore reduces lipoprotein synthesis

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Cell Injury and Cell Death
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IRREVERSIBLE CELL INJURY

Definition :

The injury to cells is said to be irreversible if the injury causes the cells to die. The disruption of permeability barrier of the plasma membrane is critical in lethal cell injury. Influx of Ca2+ ions is known to induce loss of mitochondrial function and cause irreversible damage. Cell death is termed NECROSIS Necrosis is the circumscribed death of cells or tissues occurring in the living body. There is associated inflammatory response in the adjacent tissue. in contrast, postmortem change is general autolysis of cells and tissues after death. There is no inflammatory response seen.

Autolysis :

is the digestion of cells by enzymes released from lysosomes after the cell dies. Do you have a relative who is suffering from long standing diabetis ? Has he/she experienced the tip of his/her toe became black ? This is an example of necrosis. The cause of cell death is due to ischaemia.

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