1.5necrosis
Post on 05-Apr-2018
218 Views
Preview:
TRANSCRIPT
-
7/31/2019 1.5Necrosis
1/26
2. Necrosis Severe damage
Metabolism stop Structure destroy
Function lose
Classification: necrosis & apoptosis
-
7/31/2019 1.5Necrosis
2/26
(1) Definition: Localized death of cell ortissue occurring in the living body.
-
7/31/2019 1.5Necrosis
3/26
Ultrastructural changes
Margination or progressive loss of
nuclear chromatin Focal rupture of the nuclear membrane
Breakdown of the plasmalemma.
Development of flocculent densities inmitochondria.
(2) Cell death is recognized by:
-
7/31/2019 1.5Necrosis
4/26
Changes in the nucleus.
Pyknosis: condensation of chromatin ofchromatin and shrinkage of the nucleus.
Karyorrhexis: fragmentation of the
nucleus.
Karyolysis: dissolution of the nucleus.
-
7/31/2019 1.5Necrosis
5/26
Normal Pyknosis Karyorrhexis Karyolysis
1979)
-
7/31/2019 1.5Necrosis
6/26
Changes in cytoplasm staining
Positive staining with vital dyes such asTrepan blue which reflects abnormalmembrane permeability.
Opacification: denaturation of proteinslead to aggregation with resultantopacification of the cytoplasm.
Eosino0.philia: exposure of basic aminogroups results in increased affinity foracidic dyes such as eosin.
-
7/31/2019 1.5Necrosis
7/26
Biochemical changes
Release of K+ by dead cells.
Release of enzymes into the blood. e. g.increased plasma levels of creatinekinases, lactic dehydrogenase and
aspartate aminotransferase. Release of protein or protein breakdown
products into the blood.
-
7/31/2019 1.5Necrosis
8/26
Postmortem change: General ofnormal tissues occurring dead body,generally distinguished from necrosis by
being diffuse and not associated withinflammatory response.
Autolysis: Digestion of cell byenzymes released from lysosome;occurs after cell dies.
-
7/31/2019 1.5Necrosis
9/26
(3) Types:
Coagulative necrosis:
Gross features: The necrosis area is swollen,firm and pale.
LM: cell detail is lost, but architecturepreserved. The dead cells retain their outlinebut only indistinctly.
This type of necrosis is frequently caused bylack of blood supply and is exemplified well ininfarcts of solid organs, e. g. heart, spleen,
kidney.
-
7/31/2019 1.5Necrosis
10/26
Coagulative necrosis of kidney
-
7/31/2019 1.5Necrosis
11/26
Coagulative necrosis of the left ventricular wall
From ROBBINS BASIC PATHOLOGY2003
-
7/31/2019 1.5Necrosis
12/26
A. Caseous necrosis:
Gross features: soft, granular, and
friable a cream-cheesy appearance.granular, eosinophilic.
LM: architecture completely destroyed.
i. e. Tuberculosis, syphilis, somesarcoma.
Special types of coagulative necrosis
-
7/31/2019 1.5Necrosis
13/26
From ROBBINS BASIC PATHOLOGY2003
A tuberculous lung with a large area of caseous necrosis
-
7/31/2019 1.5Necrosis
14/26Caseous necrosis
-
7/31/2019 1.5Necrosis
15/26
-
7/31/2019 1.5Necrosis
16/26
a. Dry gangrene:
Conditions: only occurs on the skinsurface following arterial obstruction. It
is particularly liable to affect the limbs,especially the toes.
Character: mummification
Types ofgangrene:
-
7/31/2019 1.5Necrosis
17/26
Dry gangrene
Offered by Prof.Orr
-
7/31/2019 1.5Necrosis
18/26
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.
Types ofgangrene:
-
7/31/2019 1.5Necrosis
19/26
Moist gangrene
-
7/31/2019 1.5Necrosis
20/26
c. Gas gangrene:
Conditions: deep contaminated wounds in
which there is considerable muscle damagedby gas formation bacteria.
Character: swollen obviously, gas bubbles
formation. The infection rapidly spreads andthere is associated severe toxaemia.
Only occasionally in civilian practice but is a
serious complication of war wounds.
Types ofgangrene:
-
7/31/2019 1.5Necrosis
21/26
Liquefactive necrosis:
Soft and liquid grossly. Enzymes digestthe cell and convert it to a formlessproteinaceous mass. Ultimately,discharge of the contents forms a cysticspace. i. e. central nervous system afterischemic injury; abscesses.
-
7/31/2019 1.5Necrosis
22/26
Special type:Fat necrosis:
Grossly: Opaque and chalky
LM: outline of necrotic fat cells filledwith amorphous basophilic material(calcium soaps).
i. e. Digestion of peritoneal fat bypancreatic enzymes in pancreaticinflammation.
-
7/31/2019 1.5Necrosis
23/26
Definition: This is not a truedegeneration but a strongly eosinophilicstain like fibrin.
Location: interstitial collagen and bloodvessels (small artery and arteriole)
Nature: one kind of necrosis.
e. g. in allergic reactive diseases: activerheumatism, polyarteritis nodose.
in non-allergic reactive diseases:malignant hypertension.
Fibrinoid necrosis:
-
7/31/2019 1.5Necrosis
24/26
Fibrinoid change in blood vessel
-
7/31/2019 1.5Necrosis
25/26
(4) Consequences of necrosis
Acute or chronic inflammation
Immunological reactions to subcellular components released by
dead tissue or self-antigens alteredby denaturation.
-
7/31/2019 1.5Necrosis
26/26
lysis and absorption
Isolation and discharge: ulcerationand cavity formation
organization
encapsulation, calcification.
top related