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− | {{review}}
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− | |linkpage =General Pathology
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− | |linktext =General Pathology
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− | |maplink = General Pathology (Content Map)
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− | |pagetype =Pathology
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− | <br>
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| ==Introduction== | | ==Introduction== |
| * '''Necrosis''' means the death of cells within the living body. | | * '''Necrosis''' means the death of cells within the living body. |
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| ===Loss of Blood Supply=== | | ===Loss of Blood Supply=== |
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− | * Necrosis due to interuption of blood supply to a portion of tissue is known as '''ischaemic necrosis''', or [[Ischaemia and Infarction - Pathology#Infarction|'''infarction''']]. | + | * Necrosis due to interuption of blood supply to a portion of tissue is known as '''ischaemic necrosis''', or [[Infarction|'''infarction''']]. |
− | * The effects of [[Ischaemia and Infarction - Pathology#Ischaemia|ischaemia]] on a tissue vary according to: | + | * The effects of [[Ischaemia|ischaemia]] on a tissue vary according to: |
| ** The tissue affected. | | ** The tissue affected. |
| *** Some tissues are more susceptible than others. | | *** Some tissues are more susceptible than others. |
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− | * Tissue [[Ischaemia and Infarction - Pathology#Ischaemia|ischamia]] can be brought about in three ways: | + | * Tissue [[Ischaemia|ischamia]] can be brought about in three ways: |
| ** Compression of the blood vessel. | | ** Compression of the blood vessel. |
| ** Narrowing of the lumen. | | ** Narrowing of the lumen. |
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| ====Blocking of the Lumen==== | | ====Blocking of the Lumen==== |
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− | * Important causes are [[Thrombosis - Pathology#Introduction|thrombi]] and [[Thrombosis - Pathology#Embolism|emboli]]. | + | * Important causes are [[Thrombosis#Introduction|thrombi]] and [[Embolism|emboli]]. |
| * Renal vessels are commonly affected. | | * Renal vessels are commonly affected. |
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| ** Also contains the remnants of the necrotic tissue cells. | | ** Also contains the remnants of the necrotic tissue cells. |
| * Although in favourable cases the [[Neutrophils|neutrophils]] may eventually kill the organisms, in most cases the organisms persist, producing more pus. | | * Although in favourable cases the [[Neutrophils|neutrophils]] may eventually kill the organisms, in most cases the organisms persist, producing more pus. |
− | ** Produces an expanding sphere of pus known as an [[Acute Inflammation - Pathology#Purulent|'''abscess''']]. | + | ** Produces an expanding sphere of pus known as an [[Purulent Inflammation|'''abscess''']]. |
| *** If the abscess is near to the skin and pressure becomes sufficient after build up, it will burst. | | *** If the abscess is near to the skin and pressure becomes sufficient after build up, it will burst. |
| **** Pus is discharged, hopefully along with the organisms responsible. | | **** Pus is discharged, hopefully along with the organisms responsible. |
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| ** E.g. tuberculosis in the ox, pig and sheep. | | ** E.g. tuberculosis in the ox, pig and sheep. |
| ** Necrotic tissue is not derived from the organ in which it occurs. | | ** Necrotic tissue is not derived from the organ in which it occurs. |
− | *** Formed from [[Macrophages - WikiBlood|Macrophages]] sent into the tissue in large numbers to engulf the causative organism. | + | *** Formed from [[Macrophages|Macrophages]] sent into the tissue in large numbers to engulf the causative organism. |
− | ** The organism has defences against the enzymes of the [[Macrophages - WikiBlood|Macrophages]]. | + | ** The organism has defences against the enzymes of the [[Macrophages|Macrophages]]. |
| *** Is able to grow and multiply within these macrophages and eventually causes their death. | | *** Is able to grow and multiply within these macrophages and eventually causes their death. |
| ** In some granulomas, the macrophages will combine together and form giant cells. | | ** In some granulomas, the macrophages will combine together and form giant cells. |
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| * The zone of inflammation between the dead putrefying tissue and living tissue is indistinct. | | * The zone of inflammation between the dead putrefying tissue and living tissue is indistinct. |
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− | =====Gas Gangrene===== | + | =====[[Gas Gangrene]]===== |
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− | * A variation of wet gangrene.
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− | * Produced by [[:Category:Clostridium species|''Clostridia'']] organisms such as [[:Category:Clostridium species|''Clostridium chauvei'']] and ''[[Clostridium septicum]]''.
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− | ** Organisms also form gas.
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− | * E.g. in Blackleg, and [[:Category:Clostridium species|''Clostridia'']] contamination of wounds.
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| ====Dry Gangrene==== | | ====Dry Gangrene==== |
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| *** Commonly seen following a septicaemic condition when an embolus blocks the blood supply. | | *** Commonly seen following a septicaemic condition when an embolus blocks the blood supply. |
| **** When seen in calves, the possibility of [[Salmonellosis|salmonellosis]] must be kept in mind. | | **** When seen in calves, the possibility of [[Salmonellosis|salmonellosis]] must be kept in mind. |
− | *** Other causes are frostbite and [[Skin Environmental - Pathology#Ergot poisoning|ergot poisoning]]. | + | *** Other causes are frostbite and [[Ergot Poisoning|ergot poisoning]]. |
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| ==Calcification== | | ==Calcification== |
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| * The colour is usually chalk-white. | | * The colour is usually chalk-white. |
| ** There may be a yellowish-green tinge if the inciting cause is a parasite. | | ** There may be a yellowish-green tinge if the inciting cause is a parasite. |
− | *** Due to attraction of a large number of [[Eosinophils - WikiBlood|eosinophils]]. | + | *** Due to attraction of a large number of [[Eosinophils|eosinophils]]. |
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| ===Histological Appearance=== | | ===Histological Appearance=== |
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| ** The cell breaks up into fragments that are engulfed by neighbouring cells or local macrophages. | | ** The cell breaks up into fragments that are engulfed by neighbouring cells or local macrophages. |
| *** Their remnants can be seen in the neighbouring cells’ cytoplasm. | | *** Their remnants can be seen in the neighbouring cells’ cytoplasm. |
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| + | [[Category:General Pathology]] |