Cell Injury and Death Pathology

Cell Injury, Death, and Adaptation

Necrosis

• Definition: Unprogrammed cell death, often resulting from severe injury or inflammation
• Causes: Ischemia, infection, toxins, trauma, metabolic disorders
• Characteristics:
  • Cellular swelling
  • Plasma membrane rupture
  • Release of cellular contents
  • Inflammation
  • Tissue damage
• Consequences: Can lead to further tissue damage and organ dysfunction

Cellular Stress Responses

• Definition: Mechanisms that help cells cope with stress or injury
• Types:
  1. Cellular repair: Reversible changes to restore cellular function
  2. Cellular adaptation: Permanent changes to maintain cellular function
  3. Cell death: Irreversible changes leading to cell death
• Examples:
  • Heat shock proteins (HSPs)
  • Oxidative stress response
  • Unfolded protein response (UPR)
  • Autophagy

Apoptosis

• Definition: Programmed cell death, a controlled process of cellular self-destruction
• Causes: Genetic damage, DNA damage, growth factor withdrawal, immune response
• Characteristics:
  • Cellular shrinkage
  • Chromatin condensation
  • Nuclear fragmentation
  • Membrane blebbing
  • Phagocytic removal of apoptotic cells
• Functions:
  • Eliminate damaged or unwanted cells
  • Maintain tissue homeostasis
  • Regulate immune responses
  • Prevent cancer development

Cell Injury and Death

• Necrosis: Unprogrammed cell death resulting from severe injury or inflammation, characterized by cellular swelling, plasma membrane rupture, and release of cellular contents, leading to inflammation and tissue damage.
• Causes of Necrosis: Ischemia, infection, toxins, trauma, and metabolic disorders.

Cellular Stress Responses

• Definition: Mechanisms that help cells cope with stress or injury, including cellular repair, cellular adaptation, and cell death.
• Types of Cellular Stress Responses:
  • Cellular Repair: Reversible changes to restore cellular function.
  • Cellular Adaptation: Permanent changes to maintain cellular function.
  • Cell Death: Irreversible changes leading to cell death.
• Examples of Cellular Stress Responses:
  • Heat Shock Proteins (HSPs): Protective proteins that help maintain protein function during stress.
  • Oxidative Stress Response: Mechanisms that counteract oxidative damage to cells.
  • Unfolded Protein Response (UPR): Response to misfolded proteins, helping to restore protein function.
  • Autophagy: Process by which cells recycle damaged or dysfunctional components.

Apoptosis

• Definition: Programmed cell death, a controlled process of cellular self-destruction, characterized by cellular shrinkage, chromatin condensation, and nuclear fragmentation.
• Causes of Apoptosis: Genetic damage, DNA damage, growth factor withdrawal, and immune response.
• Functions of Apoptosis:
  • Eliminate Damaged or Unwanted Cells: Remove cells that are damaged or no longer needed.
  • Maintain Tissue Homeostasis: Regulate cell numbers to maintain tissue health.
  • Regulate Immune Responses: Involved in immune response and prevention of autoimmune diseases.
  • Prevent Cancer Development: Eliminate cells that could become cancerous.