semenar causes of cell injury2

8/3/2019 SEMENAR Causes of Cell Injury2

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Oxygen deprivation

aging

Chemical agents

Infections Physical agents

Immunologic reactions

Genetic defects

Nutritional imbalance


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oxygen deprivation or 'hypoxia' is the lack ofoxygen in the blood.

hypoxia is the comment cause of cell injury.

this is because aerobic respiration isdiminished

hypoxia occurs when there is a reduction in

the blood supply to a tissue or when their is areduction in the oxygen levels of the blood


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hypoxia may also occur when there is ischemia.

Ischemia is the loss of blood supply. it is the mostcommon cause of hypoxia


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Cellular senescence leads to alterationsin replicative and repair abilities ofindividual cells and tissues.


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All of these changes result in a diminishedability to respond to damage and,eventually, the death of cells and of the

organism.


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An enormous number of chemical substances caninjure cells; even innocuous substances such asglucose or salt, if sufficiently concentrated, can so

derange the osmotic environment that cell injuryor death results.


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Oxygen at sufficiently high partial pressures is alsotoxic. Agents commonly known as poisons causesevere damage at the cellular level by altering

membrane permeability, osmotic homeostasis, orthe integrity of an enzyme or cofactor, andexposure to these poisons can culminate in thedeath of the whole organism.


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Other potentially toxic agents are encountereddaily in our environment; these include airpollutants, insecticides, CO, asbestos, and social

"stimuli" such as ethanol. Even therapeutic drugscan cause cell or tissue injury in a susceptiblepatient or if used excessively or inappropriately


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The rang of infectious agents that causeCell and tissue is injury is direct result ofProducts The infectious agent where as in

other much of the injury is a bystanderPhenomenon where the cell gets in theway of the hosts immune response tothe pathogen .


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Mechanical Trauma.

Radiation.

Electric shock.


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Extremes of temperature burns, deep cold& heat.

Sudden change in

atmospheric pressure.


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the immune system is the collection of cells

and molecules that are responsible fordefending us against the countlesspathogenic microbes in our environment.


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Although the immune system defends thebody against pathogenic microbes, immunereactions can also result in cell and tissue injury.

Examples include autoimmune reactionsagainst one's own tissues and allergic reactionsagainst environmental substances in geneticallysusceptible individuals .


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Genetic defects can result in pathologic changes asconspicuous as the congenital malformations

associated with Down syndrome or as subtle as thesingle amino acid substitution in hemoglobin Sgiving rise to sickle cell anemia.


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may cause cell injury because of deficiency offunctional proteins, such as enzymes in inbornerrors of metabolism, or accumulation of damaged

DNA or misfolded proteins, both of which triggercell death when they are beyond repair. Variationsin the genetic makeup can also influence thesusceptibility of cells to injury by chemicals and

other environmental insults


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Even in the current era nutritionaldeficiencies remain a major cause of cell injury

.

Protein-calorie insufficiency amongunderprivileged population is only the most

obvious example .


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Vitamin deficiency are not uncommon even in thedeveloped countries with high standers of living .

Excesses of nutrition are also important cause of

morbidity and mortality . EG:

Obesity diabetes

Animal fat

atherosclerosis


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semenar causes of cell injury2

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