VIEWS: 9 PAGES: 21 POSTED ON: 5/28/2012
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.
Pages to are hidden for
"Cellular and Tissue Adaptation"Please download to view full document