Cell damage

Cell damage (also known as cell injury) is a variety of changes of stress that a cell suffers due to external as well internal environmental changes. Among other causes, this can be due to physical, chemical, infectious, biological, nutritional or immunological factors. Cell damage can be reversible or irreversible. Depending on the extent of injury, the cellular response may be adaptive and where possible, homeostasis is restored. Cell death occurs when the severity of the injury exceeds the cell’s ability to repair itself. Cell death is relative to both the length of exposure to a harmful stimulus and the severity of the damage caused. Cell death may occur by necrosis or apoptosis. Cell damage (also known as cell injury) is a variety of changes of stress that a cell suffers due to external as well internal environmental changes. Among other causes, this can be due to physical, chemical, infectious, biological, nutritional or immunological factors. Cell damage can be reversible or irreversible. Depending on the extent of injury, the cellular response may be adaptive and where possible, homeostasis is restored. Cell death occurs when the severity of the injury exceeds the cell’s ability to repair itself. Cell death is relative to both the length of exposure to a harmful stimulus and the severity of the damage caused. Cell death may occur by necrosis or apoptosis. The most notable components of the cell that are targets of cell damage are the DNA and the cell membrane. Some cell damage can be reversed once the stress is removed or if compensatory cellular changes occur. Full function may return to cells but in some cases a degree of injury will remain. Cellular swelling (or cloudy swelling) may occur due to cellular hypoxia, which damages the sodium-potassium membrane pump; it is reversible when the cause is eliminated.Cellular swelling is the first manifestation of almost all forms of injury to cells. When it affects many cells in an organ, it causes some pallor, increased turgor, and increase in weight of the organ. On microscopic examination, small clear vacuoles may be seen within the cytoplasm; these represent distended and pinched-off segments of the endoplasmic reticulum. This pattern of non-lethal injury is sometimes called hydropic change or vacuolar degeneration. Hydropic degeneration is a severe form of cloudy swelling. It occurs with hypokalemia due to vomiting or diarrhea.