Cellular Injury

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Cellular Injury Ageing

• Dr. Venkatesh M. Shashidhar
• Senior Lecturer in Pathology
• Fiji School of Medicine

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Objectives

• Disease
• terminology, classification, etiology
• Cellular Injury
• Etiology, types, features.
• Ageing
• Etiology, Features, theories.

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Cellular Injury Adaptation

• Normal cell is in a steady state Homeostasis
• Homeostasis Sum of all chemical reactions
• Injury is any stimulus bringing changes in cell
  physiology and or anatomy Internal/External
  
• Injury can be Reversible / Irreversible
• Adaptation is the changes in a cell due to
  reversible Injury
  
• cell death / autolysis

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Causes of cell Injury

• Reduced oxygen - Ishemia, infarction
• Physical agents
• Chemical
• Toxins
• Biological agents - Viruses, Bacteria etc.
• Immune reaction - Hypersensitivity
• Nutritional deficiencies.
• Genetic abnormalitiy - Sickle, Hemophilia

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Terminology

• Hydropic swelling water collection within cell
• Fatty change accumulation of fat
• Necrosis morphologic changes seen in dead cells
  within living tissue.
  
• Autolysis dissolution of dead cells by the cells
  own digestive enzymes. (Not seen)
  
• Apoptosis programmed cell death. Physiological,
  cell regulation.
  

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Targets of cell Injury

• Respiration Poisoning, ischemia
• Integrity of cell membrane Toxins, bacteria
• synthesis of proteins Alcohol
• integrity of genetic apparatus. - Radiation
• Injury at one locus results in wide ranging
  secondary effects.

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General Considerations

• Morphology becomes apparent late in cell injury.
• Reaction of cell to injury depends on type of
  injury, duration and severity.
  
• Reaction of cell to injury also depends on the
  type, state adaptability of the cell.

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Response to Injury

• Adaptations (reversible)
• Hydropic degeneration
• Hypertrophy, Hyperplasia, Atrophy
• Accumulations - hyaline, fat, etc.
• Cell death / Necrosis (irreversible)
• Coagulative Infarction - Heart
• Liquifactive - Brain, abscess
• Caseous - Tuberculosis
• Gangrene - With infection limbs.

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LVH - Heart in Hypertension
Left Ventricular Hypertrophy
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Goitre Iodine Deficiency
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Renal Artery stenosis - Atrophy
Nephrosclerosis Atrophic Kidney
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Cerebral Infarction (Stroke)
Haemorrhagic Necrosis
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Normal Ischemic - kidney tubule
Microvilli
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Renal Infarction - Coagulative
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Infarct Adrenal gland
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Caseous necrosisTuberculosishilar lymphnode
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Extensive Caseous necrosisTuberculosis
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Muscle - ischemic atrophy
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Splenic Infarction - Coagulative necrosis
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Stroke- Liquifactive necrosis
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Liver abscess Liquifactive necrosis
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Gangrene Intestine - Thrombosis.
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Gangrene - Diabetic foot
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Gangrene - Amputated Diabetic foot
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Ageing
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Ageing

• Progressive time related loss of structural and
  functional capacity of cells leading to death
  
• Senescence, Senility, Senile changes.
• Ageing of a person is intimately related to
  cellular ageing.
  
• Countdown starts with birth!

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Factors affecting Ageing

• Genetic Clock genes, (fibroblasts)
• Diet malnutrition, obesity etc.
• Social conditions -
• Diseases Atherosclerosis, diabetes etc.
• Genetic disease - Werners syndrome.

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Cellular mechanisms of ageing
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Telomerase in ageing
Germ Cells Somatic Cells
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Cellular ageing mechanisms

• Nuclear
• Reduced synthesis of nucleic acids
• Telomere shortening
• Clock genes
• Metabolic
• Reduced Mitochondrial oxidative reactions
• Reduced protein synthesis, Protein cross
  linking.
  
• Decreased cell receptors, transcription factors.
• Oxidative peroxidation of organelles.

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Ageing Morphologic changes

• Loss of skin elasticity
• Easy bruising fragile capillaries.
• Glycosylation of lens proteins
• Accumulation of Lipofuscin pigment Brown
  atrophy.
  

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Normal Brain surface
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Cerebral atrophy - Alzheimers
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Elastosis of skin
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Pathology of Ageing
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Conclusions

• Cellular Injury - Various causes
• Reversible Injury - Adaptations
• Hypertrophy, Hyperplasia, Atrophy
• Accumulations - Hydropic, hyaline, fat..
• Irreversible Injury - Necrosis
• Coagulative, Liquifactive, Caseous, fat
• Ageing Physiological pathological.
• Time related, several theories.

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Thank You

• Dr. Venkatesh M. Shashidhar
• Senior Lecturer in Pathology
• Fiji School of Medicine