Cell Injury and Cellular Responses

Cell Injury: Definition and Causes

• Cell injury refers to the reversible or irreversible damage to cellular structures or functions, leading to cellular dysfunction or death.
• Causes of cell injury:
  • Hypoxia (oxygen deficiency)
  • Infections (bacterial, viral, fungal)
  • Toxins (chemical, environmental)
  • Physical agents (temperature, radiation, mechanical trauma)
  • Nutrient deficiency or excess
  • Genetic defects
  • Immune-mediated injury

Cellular Responses to Injury

• Cellular responses to injury can be:
  • Reversible (cellular adaptation, recovery)
  • Irreversible (cell death, apoptosis, necrosis)
• Cellular responses may involve:
  • Inflammation
  • Oxidative stress
  • Activation of cellular stress responses (e.g., unfolded protein response)
  • Alterations in cellular metabolism and signaling pathways

Types of Cell Death

• Apoptosis (programmed cell death):
  • Regulated process of cellular self-destruction
  • Characterized by cellular shrinkage, chromatin condensation, and fragmentation
  • Important for development, tissue homeostasis, and immune function
• Necrosis:
  • Unprogrammed cell death due to injury or disease
  • Characterized by cellular swelling, rupture, and inflammation
  • Can lead to tissue damage and organ dysfunction

Cellular Changes in Response to Injury

• Cellular changes may include:
  • Mitochondrial dysfunction
  • Endoplasmic reticulum stress
  • Lysosomal dysfunction
  • Cytoskeletal alterations
  • Changes in cellular membrane permeability and transport
• These changes can lead to cellular dysfunction, death, or transformation (e.g., cancer)

Consequences of Cell Injury

• Consequences of cell injury can be:
  • Acute or chronic disease
  • Organ dysfunction or failure
  • Cancer
  • Neurodegenerative disorders
  • Inflammation and tissue repair
• Understanding cell injury is essential for the development of therapeutic strategies for various diseases.