Docstoc

Necrosis Tissue and Cellular Injury gangrene

Document Sample
Necrosis Tissue and Cellular Injury gangrene Powered By Docstoc
					          2. Necrosis
   Severe damage
   Metabolism stop
   Structure destroy
   Function lose

Classification: necrosis & apoptosis
(1) Definition: Localized death of cell or
  tissue occurring in the living body.
(2) Cell death is recognized by:

① Ultrastructural changes

   Margination or progressive    loss   of
    nuclear chromatin
   Focal rupture of the nuclear membrane
   Breakdown of the plasmalemma.
   Development of flocculent densities in
    mitochondria.
② Changes in the nucleus.

   Pyknosis: condensation of chromatin of
    chromatin and shrinkage of the nucleus.
   Karyorrhexis:   fragmentation    of   the
    nucleus.

   Karyolysis: dissolution of the nucleus.
 Normal    Pyknosis   Karyorrhexis   Karyolysis


(参照武忠弼 病理学规划教材第一版 人民卫生出版社1979,修改)
③ Changes in cytoplasm staining
   Positive staining with vital dyes such as
    Trepan blue which reflects abnormal
    membrane permeability.
   Opacification: denaturation of proteins
    lead to aggregation with resultant
    opacification of the cytoplasm.
   Eosino0.philia: exposure of basic amino
    groups results in increased affinity for
    acidic dyes such as eosin.
④ Biochemical changes

   Release of K+ by dead cells.
   Release of enzymes into the blood. e. g.
    increased plasma levels of creatine
    kinases, lactic dehydrogenase and
    aspartate aminotransferase.
   Release of protein or protein breakdown
    products into the blood.
⑤ Postmortem change: General of
 normal tissues occurring dead body,
 generally distinguished from necrosis by
 being diffuse and not associated with
 inflammatory response.

⑥Autolysis: Digestion of cell by
 enzymes released from lysosome;
 occurs after cell dies.
(3) Types:
① Coagulative necrosis:

 Gross features: The necrosis area is swollen,
  firm and pale.
  LM: cell detail is lost, but architecture
  preserved. The dead cells retain their outline
  but only indistinctly.
  This type of necrosis is frequently caused by
  lack of blood supply and is exemplified well in
  infarcts of solid organs, e. g. heart, spleen,
  kidney.
Coagulative necrosis of kidney
Coagulative necrosis of the left ventricular wall

  (From ROBBINS BASIC PATHOLOGY,2003)
Special types of coagulative necrosis

A. Caseous necrosis:
 Gross features: soft, granular, and
 friable a cream-cheesy appearance.
 granular, eosinophilic.
 LM: architecture completely destroyed.
 i. e. Tuberculosis, syphilis, some
 sarcoma.
A tuberculous lung with a large area of caseous necrosis
  From ROBBINS BASIC PATHOLOGY,2003)
Caseous necrosis
   Special types of coagulative necrosis

B. Gangrene
  Definition: necrosis of big tissue with
  superadded putrefaction, black, fou-smelling
  appearance.

Necrosis of big tissue   putrefactive    black, green

  Or organ or limb     organisms infection appearance
  (black or green due to breakdown of haemoglobin)
   Types of gangrene :

a. Dry gangrene:

 Conditions: only occurs on the skin
 surface following arterial obstruction. It
 is particularly liable to affect the limbs,
 especially the toes.
 Character: mummification
 Dry gangrene

Offered by Prof.Orr
  Types of gangrene :
b. Wet gangrene:

Conditions: Both arterial and venous
obstruction; wet in environment;
Character: wet swollen, foul-smelling,
black or green.

Commonly in small intestine, appendix,
lung, and uterus, also in limbs.
Moist gangrene
  Types of gangrene :
c.    Gas gangrene:
Conditions: deep contaminated wounds in
which there is considerable muscle damaged
by gas formation bacteria.
Character: swollen obviously, gas bubbles
formation. The infection rapidly spreads and
there is associated severe toxaemia.
Only occasionally in civilian practice but is a
serious complication of war wounds.
② Liquefactive necrosis:

Soft and liquid grossly. Enzymes digest
the cell and convert it to a formless
proteinaceous mass. Ultimately,
discharge of the contents forms a cystic
space. i. e. central nervous system after
ischemic injury; abscesses.
Special type:
 Fat necrosis:
 Grossly: Opaque and chalky
 LM: outline of necrotic fat cells filled
 with amorphous basophilic material
 (calcium soaps).
 i. e. Digestion of peritoneal fat by
 pancreatic enzymes in pancreatic
 inflammation.
     Fibrinoid necrosis:
 Definition: This is not a true
  degeneration but a strongly eosinophilic
  stain like fibrin.
 Location: interstitial collagen and blood
  vessels (small artery and arteriole)
 Nature: one kind of necrosis.
 e. g. in allergic reactive diseases: active
  rheumatism, polyarteritis nodose.
 in    non-allergic reactive diseases:
  malignant hypertension.
Fibrinoid change in blood vessel
(4) Consequences of necrosis

① Acute or chronic inflammation

② Immunological reactions to sub
 cellular components released by
 dead tissue or self-antigens altered
 by denaturation.
③ lysis and absorption

④ Isolation and discharge: ulceration
 and cavity formation
⑤ organization

⑥ encapsulation, calcification.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:211
posted:1/26/2011
language:English
pages:26