2. CONTENTS
• DEFINITION.
• MECHANISM OF CELL INJURY.
• PATHOGENESIS OF CELL INJURY.
• PATHOGENESIS OF PHYSICAL INJURY.
• PATHOGENESIS OF CHEMICAL INJURY.
3. • It is defined as a variety of stress a cell encounter as a result of
change in its internal and external environment.
• Stress may be physiologic or pathologic stimuli.
4. MECHANISM OF CELL INJURY
• Cellular response to injury depend on nature,duration and severity of
injury.
• Consequences of injury depend on type,state and adaptability of the
injured cell.
• Cell injury result from different biochemical mechanism acting on
essential cellular components.
• The type or mechanism , extensive cell injury result in death.
• Either by necrosis or apoptosis.
5. • Three major mechanisms are:
• Free radical formation.
• Hypoxia and ATP depletion.
• Disruption of intracellular calcium homeostasis.
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9. PATHOGENESIS OF CELL INJURY
• It may be reversible or irreversible cell injury.
• REVERSIBLE include:
• Decreased generation of cellular ATP.
• Increased glycolysis.
• Damage to plasma membrane.
• Reduced protein synthesis.
10.
11.
12. • IRREVERSIBLE include:
• MEMBRANE DAMAGGE
1. Accelerated degradation of membrane phospholipid.
2. Cytoskeletal damage
3. Reperfusion damage
• HYDROLYTIC ENZYME
• Damage to lysosomal membrane by liberation of
hydrolytic enzymes RNAase,DNAase,glycosidase
which cause enzymetic digestion of cellular component
induce nuclear change and cell death.
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14.
15. PATHOGENESIS OF PHYSICAL INJURY
• Injury is caused by mechanical force but
lead to state of injury ,killing of cell by
ionising radiation direct formation of
hydroxyl radicals damage the cell
membrane and also interact with DNA of
target cell.
16. PATHOGENESIS OF CHEMICAL INJURY
• DIRECT CYTOTOXIC EFFECT , CHEMICAL
COMBINE WITH COMPONENT OF CELL .
• EXAMPLE, mercuric chloride poisoning great damage of cell of
alimentary tract and kidney.
• Cyanide , kill the cell by poisoning mitochondrial cytochrome
oxidase thus blocking oxidative phosphorylation.
