Cell Injury and Disease

Cell Injury and Death

• A cell can undergo reversible or irreversible cell injury, leading to recovery or cell death
• Reversible cell injury: cellular swelling, ER and mitochondrial swelling, no change in nucleus
• Irreversible cell injury: cell death, membrane rupture, cytoplasmic lysosomal rupture, nuclear pyknosis, karyolysis, and karyorrhexis, mitochondrial damage

Cell Death

• Necrosis: pathological cell death, death of a group of cells in a living organism
• Apoptosis: programmed cell death

Types of Necrosis

• Coagulative necrosis: in solid organs, tissue outlines preserved, denaturation of protein, pale and well-demarcated
• Colliquative necrosis: in wet organs, loss of cell outline, enzymatic degradation
• Caseous necrosis: subtype of coagulative necrosis, seen in chronic infections like TB
• Fat necrosis: seen in breast and omentum

Mechanism of Apoptosis

• Activation of caspase enzymes
• Interaction between FAS receptors and ligand
• Withdrawal of growth factors
• Involvement of Bcl-2 proteins
• Up-regulation of P53 gene

Pathology

• Pathogenesis: mechanism of disease
• Pathology: structural changes
• Clinical features: signs and symptoms
• Diagnosis: lab investigations
• Management and prevention
• Prognosis: outcome

Lab Methods in Pathology

• Routine investigations: hematological, biochemical, serological
• Fine-needle aspiration: cytology
• Biopsy: histopathology
• Immunohistochemistry: phenotyping
• Molecular biology: PCR