Causes, mechanisms and health consequences of reversible and irreversible cell and tissue injury

Causes, mechanisms and health consequences of reversible and irreversible cell and

tissue injury

Causes of Cell and Tissue Injury

  • Cell and tissue injuries can be caused by a variety of factors, including physical agents (temperature extremes, radiation), chemical injury (toxins, poisons), biological agents (viruses, parasites, bacteria), nutritional imbalance, and insufficiency of oxygen (ischemia).
  • Genetic defects can also lead to cell and tissue injury, as they can result in abnormal protein synthesis and function.
  • Aging is another significant cause, resulting in generalised cell and tissue deterioration over time.

Mechanisms of Cell and Tissue Injury

  • Reversible cell injury, such as cellular swelling or fatty change, is characterised by adaptation or distress. It often precedes irreversible cell injury, which involves substantial structural changes and inevitably leads to cell death.
  • Oxygen deprivation, or ischemia, is a particularly severe stressor that hinders ATP production. This, in turn, can lead to reduced function of both active transport systems and cellular sodium-potassium pumps, causing loss of ionic homeostasis and cellular swelling.
  • Free radicals and reactive oxygen species (ROS) can cause cell injury through oxidative stress, resulting in lipid peroxidation, protein modification, and DNA damage.

Health Consequences of Cell and Tissue Injury

  • The health consequences of cell and tissue injury depend on the extent and site of damage, whether the injury is reversible or irreversible, and the capacity of the affected tissues for regeneration.
  • Acute cell injury often leads to inflammation and the release of enzymes and other biomarkers detectable in laboratory tests.
  • If the cell injury is chronic or repeated, it can lead to pathologic adaptations such as atrophy (reduced cell size and number), hypertrophy (increased cell size), metaplasia (change in cell type), or dysplasia (abnormal cell growth).
  • Irreversible injury, if extensive, can lead to cell death and necrosis, triggering inflammatory responses that can further damage surrounding tissues.
  • Ultimately, perennial cell and tissue injury can contribute to the development and progression of various diseases, including cancer, cardiovascular disease, and neurodegenerative conditions.