CELL INJURY Cell Injury: As the effect of various stresses d
Cell Injury: As the effect of various stresses due to etiological agents a cell results in change
in internal and external environment. It is reversible when stress is mild to moderate and
irreversible when it is severe
Causes: Hypoxia (by blood loss), Physical agents (trauma, radiation etc), chemical agents
and drugs, infectious agents, immunological reactions, Genetic, Nutritional imbalance.
Types: Reversible (Recovery of cell damage once stress removed) and Irreversible (No
recovery / Cell death)
• Reversible: Occurred mainly due to Alteration in plasma membrane (i.e. Bleb
formation, loosening of intracellular attachment and steatosis: means fat
accumulation within cell), Change in mitochondria (Swelling or hydropic,
rarefaction, phospholipids amorphous densities), Nuclear change (Disaggregation of
granular and fibrillar element) and ER changes (Dilatation, detachment and
• Irreversible: Mainly occurred as the result of Swelling of ER, Lysosomes rupture,
nuclear condensation, nuclear lysis, Membrane blebs, and swollen mitochondria
with amorphous densities.
The irreversible is mainly of two types Necrosis and Apoptosis
NECROSIS: It is death of localized area of tissue followed latter by degradation of
tissue by lysosomal enzyme mainly occur in inflammation and in hypoxia.
APOPTOSIS: also known as coordinated and programmed death of cell occurred
mainly in pathological condition but not in inflammation
Changes after cell death:
• Gangrene: Putrefaction of necrosis, two types dry gangrene e.g. Buerger’s
disease, Raynaud’s disease and wet gangrene e.g. Bed sore, diabetic foot
• Pathological Calcification: Deposition of calcium salt in tissues other than
enamel of tooth occur both in dead tissue and degenerated tissue