Injurious Agents

Nota:

• Hypoxia : Lack of Oxygen to any tissues such as carbon monoxide poisoning. Chemical and Drug: Such as alcohol or nicotine, could be recreational drugs too. Physical agents: Blunt trauma, thermal or electrical burns Infective agents: bacteria/fungi Nutritional: Food disorder/deficit Immunological abnormalities: Cancer/Aids? Genetic abnormalities: Hereditary.

1. Effects

   Nota:

   • Biochemical Lesion initially it will lead to functional abnomality and also cause a morphological change in the injury site. On a much longer time scale: It changes protein in terms of structural changes and enzyme function, it may lead to impaired synthesis. WHile DNA needs to undergo synthesis and repair.
2. Biochemical Targets

   Nota:

   • Changes in Aerobic Respiration of cells: Depletion of ATP (change to anaerobic and hence fall in pH. Enzymic Activation and lowering of entry of calcium ions. Changes in membrane integrity: Loss of phospholipids Lipid Peroxidation Mitochondrial or cytoskeletal damage. Proteins: Altered structural proteins, enzyme function, impaired synthesis. DNA: Altered synthesis and repair.
3. Altered Growth or Differentiation
   1. Adaptive

      Nota:

      • Changes in cellular physiology due to injury. Possible cellular responses are Hypertrophy: Increase in cellular size. Hyperplasia: Increase in cellular number Metaplasia: substitution of one type of cellular type with another. Atrophy: Decrease in cellular tissue size, problem arise either due to decrease in cellular size or number
   2. Pathological

      Nota:

      • Dysplasia: Atypical Cellular differentiation Dysplasia may lead to neoplasia which is an abnormal growth of tissue.
4. Inflammation

   Nota:

   • Process of repair by the immune system. It could lead to either acute or chronic inflammation whereby acute inflammation can improve to chronic and both of them can lead to repair of the cellular tissue. Acute inflammation could also lead to resolution.