USMLE ACTUAL TEST PAPER COMPLETE QUESTIONS AND ANSWERS FULL SOLUTION

USMLE ACTUAL TEST PAPER COMPLETE
QUESTIONS AND ANSWERS FULL
SOLUTION

●● what are the two extrinsic apoptosis pathways?
Answer: ligand receptor interactions
immune cell (T cell release of perforin and granzyme)


●● ligand receptor interactions involved in extrinsic apoptosis pathway
Answer: FasL binding to Fas (CD95)
TNF-a binding TNF


●● action of Bcl-2
Answer: prevents cytochrome c release by binding and inhibiting APAF-
1, which normally induces activation of caspase 9


●● what apoptotic process is required for thymus medullary negative
selection?
Answer: FasL-Fas interactions


●● irreversible cell injury associations
Answer: mitochondrial permeability/vacuolization

,nuclear pyknosis
plasma membrane damage
lysosomal rupture


●● neurons most vulnerable to ischemia
Answer: parking cells of cerebellum
pyramidal cells of hippocampus


●● region of heart most vulnerable to ischemia
Answer: subendocardium (LV)


●● region of kidney most vulnerable to ischemia
Answer: proximal tubule and thick ascending limb (in medulla)


●● region of liver most vulnerable to ischemia
Answer: central vein (zone III)


●● region of colon most vulnerable to ischemia
Answer: splenic flexure
rectum


●● tissues subject to red infarct

, Answer: tissues with multiple blood supplies
-liver
-testes
-intestine
-lung


●● tissues subject to white infarct
Answer: solid organs with single blood supply
-heart
-kidneys
-spleen


●● chromatolysis
Answer: reaction of neuronal body to axonal injury
-round cellular swelling
-dispersion of nil substance throughout cytoplasm
-displacement of the nucleus to the periphery


●● dystrophic calcification
Answer: -Ca deposition in abnormal tissue
-secondary to injury or necrosis
-patients are normocalcemia