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Cellular and Tissue Adaptation

Cellular and Tissue Adaptation. Dr. Raid Jastania. Cell Injury. Stress. Response. Cell Death. Adaptation. Injury. Cell Adaptation. Cellular Adaptation in Growth and Differentiation Subcellular Responses to Injury Intracellular Accumulation Pathologic Calcification.

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Cellular and Tissue Adaptation

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  1. Cellular and Tissue Adaptation Dr. Raid Jastania

  2. Cell Injury Stress Response Cell Death Adaptation Injury

  3. Cell Adaptation • Cellular Adaptation in Growth and Differentiation • Subcellular Responses to Injury • Intracellular Accumulation • Pathologic Calcification

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Hypertrophy/Hyperplasia

  9. 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”.

  10. Subcellular Responses to Injury • Lysosomal catabolism: heterophagy, Autophagy • 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. • Mitochondrial Alteration: Example: increase or decrease in the number of mitochondria.

  11. 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).

  12. Intracellular Accumulation: • Fatty Change: Defect in fat metabolism. This commonly occurs in alcoholics due to altered SER function and in toxicity with CCl4. • Cholesterol: is accumulated in histiocytes following ingestion of cellular parts in necrosis • Protein: Example: Mallory bodies in liver cells.

  13. Intracellular Accumulation: 4. Glycogen: Example: diabetes mellitus in liver 5. Pigment: exogenous like carbon, and endogenous like: melanin, lipofuscin, and hemosiderin.

  14. Pathologic Calcification: • Dystrophic calcification: occurs following tissue necrosis (and commonly inflammation). Example: calcification in atheroma. • Metastatic calcification: occurs in normal tissue as a result of high Ca++ level in the blood. Causes: • high PTH, • Renal failure • Bone destruction • Vit D intoxication.

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