Necrosis
- Abnormal tissue death during life
- Energy independent
- Occurs as a result of factors outside the cell
- Associated with inflammatory changes
Classification
- Coagulative
- Tissue architecture preserved - kidney, heart, spleen
- Proteins coagulate rapidly from heat
- Colliquative
- Tissues rich in lipid, lysosomal enzymes denature fats and cause liquifaction - brain
- Caseous
- Unstructured
- Impossible to identify tissue affected by necrosis as architecture is destroyed - classical of TB
Fat Necrosis
Gangrene
- Dry: mummification of tissue without infection
- Wet: Necrosis with putrefaction caused by infection (anaerobic streptococci, bacteroides)
Autolysis
- Degradation of a cell by activation of enzymes presnet in the affected cell (self-digestion)
- May occur in necrosis or apoptosis
Heterolysis
- Degradation of a cell by activation of enzymes present in cells other than the affected cell