Page 251 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

Pathology ` PATHOLOGY—CeLLuLAr InjurY Pathology ` PATHOLOGY—CeLLuLAr InjurY SECtIoN II 207

Cell injury
+
2+
+
Reversible cell injury ƒ  ATP Ž  activity of Ca and Na /K pumps Ž cellular swelling (earliest morphologic
manifestation), mitochondrial swelling
ƒ Ribosomal/polysomal detachment Ž  protein synthesis
ƒ Plasma membrane changes (eg, blebbing)
ƒ Nuclear changes (eg, chromatin clumping)
ƒ Rapid loss of function (eg, myocardial cells are noncontractile after 1-2 minutes of ischemia)
ƒ Myelin figures (aggregation of peroxidized lipids)
Irreversible cell injury ƒ Breakdown of plasma membrane Ž cytosolic enzymes (eg, troponin) leak outside of cell, influx
2+
of Ca Ž activation of degradative enzymes
ƒ Mitochondrial damage/dysfunction Ž loss of electron transport chain Ž  ATP
ƒ Cytoplasmic vacuolization accompanies programmed cell death (apoptosis)
ƒ Rupture of lysosomes Ž autolysis
ƒ Nuclear degradation: pyknosis (nuclear condensation) Ž karyorrhexis (nuclear fragmentation
caused by endonuclease-mediated cleavage) Ž karyolysis (nuclear dissolution)
ƒ Amorphous densities/inclusions in mitochondria

Rupture of
Cellular/ Ribosomal lysosomes Plasma membrane
mitochondrial damage
Normal cell swelling detachment and autolysis

Reversible Irreversible Cell death
injury injury (necrosis)

Membrane blebbing Nuclear mitochondrial
↓
Nuclear chromatin degradation permeability
clumping

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