CELL INJURY AND ADAPTATIONS
Introduction to Cell Injury
Cell injury occurs when cells are exposed to a severe stressor, causing them to lose their ability
to maintain homeostasis.
If the injury is mild or reversible, cells can recover. If the injury is severe or persistent, it leads
to irreversible injury and cell death.
Causes of Cell Injury
1. Hypoxia: Oxygen deprivation, leading to ATP depletion. Causes include ischemia, anemia,
carbon monoxide poisoning, and lung diseases.
2. Physical Agents: Trauma, temperature extremes, radiation, electric shock.
3. Chemical Agents and Drugs: Poisons (cyanide), environmental pollutants, alcohol, and
therapeutic drugs.
4. Infectious Agents: Bacteria, viruses, fungi, parasites.
5. Immunologic Reactions: Autoimmune diseases, allergic reactions.
6. Genetic Factors: Genetic mutations, chromosomal abnormalities, inborn errors of
metabolism.
7. Nutritional Imbalances: Deficiency or excess of nutrients (e.g., vitamin deficiencies,
obesity).
Mechanisms of Cell Injury
Key mechanisms involved in cell injury:
A. Depletion of ATP: Due to hypoxia or mitochondrial damage, leading to failure of ATP-
dependent processes. Consequences:
Failure of Na+/K+ pump → Cellular swelling.
Increased anaerobic glycolysis → Lactic acidosis.
Detachment of ribosomes → Decreased protein synthesis.
Introduction to Cell Injury
Cell injury occurs when cells are exposed to a severe stressor, causing them to lose their ability
to maintain homeostasis.
If the injury is mild or reversible, cells can recover. If the injury is severe or persistent, it leads
to irreversible injury and cell death.
Causes of Cell Injury
1. Hypoxia: Oxygen deprivation, leading to ATP depletion. Causes include ischemia, anemia,
carbon monoxide poisoning, and lung diseases.
2. Physical Agents: Trauma, temperature extremes, radiation, electric shock.
3. Chemical Agents and Drugs: Poisons (cyanide), environmental pollutants, alcohol, and
therapeutic drugs.
4. Infectious Agents: Bacteria, viruses, fungi, parasites.
5. Immunologic Reactions: Autoimmune diseases, allergic reactions.
6. Genetic Factors: Genetic mutations, chromosomal abnormalities, inborn errors of
metabolism.
7. Nutritional Imbalances: Deficiency or excess of nutrients (e.g., vitamin deficiencies,
obesity).
Mechanisms of Cell Injury
Key mechanisms involved in cell injury:
A. Depletion of ATP: Due to hypoxia or mitochondrial damage, leading to failure of ATP-
dependent processes. Consequences:
Failure of Na+/K+ pump → Cellular swelling.
Increased anaerobic glycolysis → Lactic acidosis.
Detachment of ribosomes → Decreased protein synthesis.
