1.Degeneration and Regeneration

2. objective Understand the process of regeneration anddegeneration occurs Able to differentiate between regenerationand degeneration biochemical process. 3. REGENERATIONMaintain proper structure of tissueThe replacement of cell can happen in two ways:by regeneration: the necrotic cells are replaced by the same tissue as was originally there.by repair: injured tissue is replaced with scar tissue.Most organs will heal using a mixture of both mechanism. 4. In order for an injury to be healed byregeneration, the cell type that wasdestroyed must be able to replicate. Most cells have this ability, although it isbelieved that cardiac muscle cells andneurons are two important exceptions. Cells also need a collagen framework alongwhich to grow. 5. Alongside, most cells there is either abasement membrane or a collagenousnetwork made by fibroblasts that will guidethe cells growth. Proliferation of original cell occur from themargin of injury. Since ischaemia and most toxins do notdestroy collagen, it will continue to existeven when the cells around it are dead. 6. Local factors that interfere with thehealing process such as: 1. Presence of inert foreign bodies in thewound 2. Occlusion of blood vessels 3. Malnutrition 7. DEGENERATIONLoss of function of the cell, tissue or organ.Degeneration and infiltration are retrogressive changes in cells and tissues characterized by abnormal structural changes and decreased functions.They are nonspecific responses of cells and tissues following a variety of injuries.Some of these processes may be reversible if the injury is mild. If the injury is severe and persistent, it may progress to the point where the involved cell dies. 8. The distinction between the point wherethe cells would recover and the pointwhere the process is irreversible andleads to cell death is arbitrary. In theory, the difference between the twoprocesses is vague. Most literatures however define thesetwo processes as: Degeneration: the accumulation ofmetabolites or other substances in a celldamaged by preceding injury. 9. Infiltration:the overloading ofpreviously normal cells by materialswhich are abnormal in either type ofquantity. Following these definitions, thechanges in the cells in bothdegeneration and infiltration mayappear similar, and many consider thetwo processes as identical. 10. The patterns of cellular degeneration andinfiltration used by pathologist aregrouped according to the dominantexpression of injury as:1) water overload2) metabolite overload3) Storage overload 11. 1. Water overload cellular swelling. 2. Metabolite overload which involvesexcessive accumulation of normalmetabolic products such as fat, glycogen,or protein (hyaline or proteinaseous). 3. Storage loading which involvesoverloading by non-degradable productssuch as pigments, minerals, andexogenous substances. 12. The causes of impaired energy productionin themechanismof cellulardegeneration are: 1. Hypoglycemia glucose is the mainsubstrate for energy production in mosttissue and sole energy source in braincells. low glucose level = deficient ATPproduction. 2. Hypoxia oxygen carried by blood.Lack of oxygen in the cells may cause =ischemia,anemia,respiratoryobstruction, alteration of hemoglobin. 13. 3. Enzyme inhibition- chemical interferingwith a vital enzyme. Ex= cyanide inhibitcytochrome oxidase final enzyme in therespiratory chain causing acute ATPdeficiency in all cells and cause rapid death. 4. Uncoupling of oxidative phosphorylation -occur either through chemical reactions orthrough physical detachment of enzyme frommitochondrial membrane. Ex= mitochondrialswelling is common changes associated withinjury. 14. Effects of defective energy production Failure of energy production will first affectthose cells with the highest demand for O2 high basal metabolic rate. The earliest clinical sign of hypoxia andhypoglycemia are disturbance of the normalconsciousness such as : A) intracellular accumulation of water andelectrolysis B)changes in organelles C) switch to anaerobic metabolism. 15. Effects of the defective energy production are:i. Intracellular accumulation of water and electrolysisEarliest detachable biochemical evidence- diminished availability of ATP is dysfunction of sodium pump on plasma membraneInflux of water and sodium into cellSwollen and cloudy cellMay lead to enzyme inhibition.Early and reversible effects of cell injury 16. ii. Changes in organelles Endoplasmic reticulum distend Ribosomes detached Interfere protein synthesis Mitochondrial swelling 17. iii. Switch to anaerobic metabolism Production of lactic acid, low theintracellular pH Chromatin to clump in nucleus Lysosomal membrane disrupt leading torelease of enzymes into cytoplasm,damage the vital intracellular molecules. Cellular degeneration becomesirreversible result in necrosis. 18. THANK YOU HAVE A NICE DAY!