irreversible cell injury
TRANSCRIPT
Reversible If stressor removed, and
If cell damage mild: cells survive
Irreversible --> cell death. Types:Apoptosis: normal (leaves falling) as in
menses, aging PROGRAMMED
Necrosis: patho-logical...
Autolysis: after death of entire organism (dissolution of dead
cells by its own digestive enzymes)
The first is the inability to
reverse mitochondrial dysfunction (lack
of oxidative phosphorylation and ATP
generation) even after resolution of the original
injury.
The second is the development of profound
disturbances in membrane function.
DEFINITION:
Death of a group of contiguous
cells within a living tissue or organ
Affect both nucleus and cytoplasm
Unregulated cell death with
inflammation
Cytoplasmic
Nuclear
Cytoplasmic changes :
Cytoplasmic eosinophilia due to loss of normal basophilia& increased binding of eosin to denaturatedproteins
(Granular or homogenous glassy)
Nuclear changes:
Pyknosis: shrinkage-increased staining with haematoxylin
Karyorrhexis: fragmentation
Karyolysis: total disappearance
Coagulative
Liquefactive
Caseation
Fat
In: infarcts of kidney, heart, spleen
Gross: pale , yellow, opaque, firm
Mic.: All cellular details are lost but general
architecture of the tissue is preserved
Surrounding tissue----acute inflammation
Ex: Infarction - heart
Infarction - kidney
In: centers of pyogenic abscess
amoebiasis
infarcts of C.N.S.
Necrotic tissue---completely liquified---turbid
fluid----absorbed----space
Ex: Brain - infarction
Amoebiasis ---liver
In: Tuberculosis
Necrotic tissue is partially liquefied---cheesy
material (caseation)
Mic: Both cellular details & general architecture of
dead tissue are lost---structureless eosinophilic
material
Traumatic: in female breast
Enzymatic: in acute hemorrhagic
pancreatitis
Gross: opaque & white
fat cells appear cloudy, surrounded by
chronic inflammatory
cells, histiocytes, foreign body giant cells
(programmed cell death)
Definition: death of individual cells
surrounded by viable cells
when a cell dies through activation of an
internally suicide program
It is an active process—energy dependent
Does not elicit inflammatory response
May be physiologic or pathologic
PHYSIOLOGIC
During embryogenesis e.g. removal of
interdigital webs during embryonic development
of toes and fingers
Hormone-dependent e.g. endometrial cellloss in
menstruation
PATHOLOGIC
Irradiated tissues
Cell death induced by cytotoxic T-lymphocytes
Viral infections e.g. viral hepatitis
Cell death in tumours
Necrosis
Death of groups of cells
A passive process—not energy-dependent
Elicits inflammatory response
Always pathologic
Apoptosis
Death of individual cells
Active process—energy-dependent
Does not elicit inflammatory response
May be pathologic or physiologic
Definition:
-abnormal accumulation of triglycerides within parenchymal cells
Sites:
Liver (the most common)
Others, heart, kidney,--
Pathogenesis:
Excessive accumulation of triglycerides within the liver may result from defects in any one of the events in the sequence from fatty acid entry to lipoprotein exit
Congestive heart failure
Diabetes mellitus
Severe anaemia
Ischaemia
Septicaemia
Poisons
malnutrition
In all organs, fatty change appears as clear
vacuoles within parenchymal cells
Due to fat solvents used in paraffin
embedding
To identify fat, frozen tissue sections are
stained with Sudan IV or Oil Red-O---orange-
red colour
When mild - - - no effects on cell function
Severe - - - - - -impair cell function