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Unformatted text preview: Regeneration and Repair Introduction: Tissues are restored (to structural and functional integrity) via: Removal of exudate; Removal of cellular and tissue debris; Replacement of cells and tissues lost *stable= only divide if killed/damaged Replacement of Cells and Tissues: A) regeneration: if the cells (or tissue) replacing those lost in inflammation are identical or very similar (physiological or pathological) B) repair: a broader term; it includes the process of replacement by cells and tissues, either of the same kind as those lost or of a different and often simpler type; pathological Cells of the body are divided into 3 groups on the basis of their regeneration capacity: Labile: continue to proliferate throughout life (epitheliumskin, bronchial epi, bone marrow epi, blood cells, endometrial cells); follow cell cycle from one mitosis to the next; these tissues can readily regenerate after injury as long as the pool of stem cells is preserved; contain stem cells that differentiate and replenish lost cells and maintain tissue homeostasis Stable: low normal level of replication but able to divide in response to stimuli (parenchymal cells of glandular organs , mesenchymal cells, endothelial cells, fibroblasts and smooth muscle cells etc); considered to be on G0 but recruited to G1; minimal replicative activity in their normal state; ex renal tubular cells, liver cells Permanent: cannot divide in postnatal life (neurons of CNS and cardiac muscle cells); have left the cell cycle; considered to be terminally differentiated and nonproliferative in post natal life; cannot be replaced themselves **most common= regeneration and repair combo; identical cells and granulation tissue Regeneration Much better developed in lower animals, and in protozoa and metazoan represent the major feature of reaction to injury Physiological regeneration (replacement) in man: Epidermis, blood, uterine mucosa, glandular epithelium Great variation in the ability of different kinds of cells and tissues to regenerate : Supporting tissue regenerates best (fibrous, osseous, cartilage, blood vessels, epithelium, epidermis, renal tubular, glandular, intestinal, uterine) Other cells lose their ability to regenerate in postnatal life (cardiac muscle, nerve); require replacement by simpler tissue Atypical regeneration of an organ- dont arrange properly but are capable of dividing In an organ, restoration depends not only upon the parenchymatous tissues ability to regenerate, but also whether or not the framework was destroyed ( eg in the skin: no sweat + sebaceous glands or hair; in liver: when architectural skeleton destroyed: regeneration is irregular producing an afunctional tissue: cirrhosis ); occurs when support frame is destroyed; lots of cells but no communication; function is impaired; ex hepatisis: kills liver cells by destroying framework; hepatocytes are stable and therefore replace themselves but dont arrange properly, therefore not a functional liver...
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This note was uploaded on 02/08/2012 for the course PATHOLOGY 3245 taught by Professor X during the Spring '11 term at UWO.
- Spring '11