Cell Injury:
Cell injury is defined as the effects of a variety of stresses due to etiologic agents a cell encounters
resulting in changes in it's internal and external environment.
The cellular response to stress may vary and depends upon the following two variables:
1. Host Factors i.e., the type of cell and tissue involved.
2. Factors pertaining to injurious agents i.e., extent and type of cell injury.
Various forms of cellular responses to cell injury may be as follows:
Normal cell
Altered functional demand mild to
The residual effects of reversible cell injury may persist in the cell as evidence of cell injury at subcellular
level [ subcellular changes] or metabolites may accumulate within the cell [ Intercellular accumulations].
Etiology of cell injury:
A. Acquired causes
B. Genetic causes
A. Acquired causes:
Based on underlying agent, the acquired causes of cell injury can be further categorised as under,
1. Hypoxia and Ischemia
, 2. Physical agents
3. Chemical agents and drugs
4. Microbial agents
5. Immunologic agents
6. Nutriotional derangements
7. Ageing
8. Psychogenic diseases
9. Iatrogenic diseases
10. Idiopathic diseases
1. Hypoxia and Ischemia:
Hypoxia: Reduced oxygen supply.
Ischemia: Reduced blood supply.
Cells of different tissues essentially requires oxygen to generate energy and perform metabolic
functions.
Deficiency of oxygen or hypoxia results in failure to carry out these activities by the cells.
Hypoxia may result from the following 2 ways:
1.The most common mechanism of hypoxic cell injury is by reduced supply of blood to the cells due to
interruption. I.e., Ischemia.
2. Hypoxia may also result from impaired blood supply from causes other than interruption.
Examples: Disorders of oxygen carrying RBCs [Anemia, CO poisoning], heart diseases, lung diseases and
increased demand of tissues.
2. Physical agents:
Physical agents in causation of disease are as under,
a. Mechanical trauma [ Ex: Road accidents]
b. Thermal trauma [ Ex: By heat and cold]
c. Electricity
Cell injury is defined as the effects of a variety of stresses due to etiologic agents a cell encounters
resulting in changes in it's internal and external environment.
The cellular response to stress may vary and depends upon the following two variables:
1. Host Factors i.e., the type of cell and tissue involved.
2. Factors pertaining to injurious agents i.e., extent and type of cell injury.
Various forms of cellular responses to cell injury may be as follows:
Normal cell
Altered functional demand mild to
The residual effects of reversible cell injury may persist in the cell as evidence of cell injury at subcellular
level [ subcellular changes] or metabolites may accumulate within the cell [ Intercellular accumulations].
Etiology of cell injury:
A. Acquired causes
B. Genetic causes
A. Acquired causes:
Based on underlying agent, the acquired causes of cell injury can be further categorised as under,
1. Hypoxia and Ischemia
, 2. Physical agents
3. Chemical agents and drugs
4. Microbial agents
5. Immunologic agents
6. Nutriotional derangements
7. Ageing
8. Psychogenic diseases
9. Iatrogenic diseases
10. Idiopathic diseases
1. Hypoxia and Ischemia:
Hypoxia: Reduced oxygen supply.
Ischemia: Reduced blood supply.
Cells of different tissues essentially requires oxygen to generate energy and perform metabolic
functions.
Deficiency of oxygen or hypoxia results in failure to carry out these activities by the cells.
Hypoxia may result from the following 2 ways:
1.The most common mechanism of hypoxic cell injury is by reduced supply of blood to the cells due to
interruption. I.e., Ischemia.
2. Hypoxia may also result from impaired blood supply from causes other than interruption.
Examples: Disorders of oxygen carrying RBCs [Anemia, CO poisoning], heart diseases, lung diseases and
increased demand of tissues.
2. Physical agents:
Physical agents in causation of disease are as under,
a. Mechanical trauma [ Ex: Road accidents]
b. Thermal trauma [ Ex: By heat and cold]
c. Electricity
