Cellular and Tissue Adaptation by malj

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									Cellular and Tissue Adaptation

         Dr. Raid Jastania
Stress   Cell      Response
         Injury




         Cell     Adaptation
Injury   Death
          Cell Adaptation
• Cellular Adaptation in Growth and
  Differentiation
• Subcellular Responses to Injury
• Intracellular Accumulation
• Pathologic Calcification
   Cellular Adaptation in
 Growth and Differentiation
• Atrophy:
• Atrophy is shrinkage in the size of cells
  (and the organ) due to loss of cell
  substance.
• apoptosis.
• Causes: decrease in work load,
  immobilization, loss of innervation,
  diminished blood supply, nutrients, or
  loss of endocrine stimulation and aging.
                Atrophy
• Atrophy may occurs in any organ or
  tissue.
• Example: muscle atrophy due to paralysis
  or immobilization.
• Atrophy results when the production of
  cellular substance is less than the
  degradation. Degradation can occur in
  lysosomes or in ubiquitin-proteasome
  system.
• Hypertrophy:
• Hypertrophy is the increase in the size of
  cells (and organs)
• caused by increased functional demand.
• Example: Left ventricular hypertrophy due
  to hypertension. Hypertrophy can result
  from mechanical stress or hormonal
  stimulation.
• Hyperplasia:
• Hyperplasia is increase in the number of
  cells in an organ.
• It can be physiological. Example: hormonal
  hyperplasia of breast during lactation.
• It can be pathological. Example: Hormone
  imbalance and endometrial hyperplasia.
Hypertrophy/Hyperplasia
• Metaplasia:
• Metaplasia is a reversible change of one adult cell
  type to another adult cell type.
• Example: change of the respiratory mucosa in the
  respiratory tract from the ciliated culomnar
  epithelium to squamous epithelium due to
  smoking.
• This change results from “genetic
  reprogramming”.
  Subcellular Responses to
            Injury
1. Lysosomal catabolism: heterophagy, Autophagy
2. Hypertrophy of Smooth Endoplasmic
   Reticulum: increase in the ability of the cell to
   metabolize substance. This results in “drug
   tolerance”. Example: tolerance to Barbiturates,
   and Alcohol.
3. Mitochondrial Alteration: Example: increase or
   decrease in the number of mitochondria.
  Subcellular Responses to
            Injury
4. Cytoskeletal Abnormalities: Occur in
    hypertrophy and atrophy of the cells.
5. Heat Shock Proteins: HSP are proteins
    involved in protein folding, disaggregation
    and transport. The production of HSP is
    increased in stress situations (injury).
 Intracellular Accumulation:
1. Fatty Change: Defect in fat metabolism. This
   commonly occurs in alcoholics due to altered
   SER function and in toxicity with CCl4.
2. Cholesterol: is accumulated in histiocytes
   following ingestion of cellular parts in necrosis
3. Protein: Example: Mallory bodies in liver cells.
 Intracellular Accumulation:
4. Glycogen: Example: diabetes mellitus in
  liver
5. Pigment: exogenous like carbon, and
  endogenous like: melanin, lipofuscin, and
  hemosiderin.
   Pathologic Calcification:
1. Dystrophic calcification: occurs following tissue
   necrosis (and commonly inflammation).
   Example: calcification in atheroma.
2. Metastatic calcification: occurs in normal tissue
   as a result of high Ca++ level in the blood.
   Causes:
   1.   high PTH,
   2.   Renal failure
   3.   Bone destruction
   4.   Vit D intoxication.

								
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