Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 4-year-old boy develops progressive muscle weakness
and cardiomyopathy. Skeletal muscle biopsy demonstrates
markedly enlarged mitochondria with disrupted cristae. Serum
lactate is persistently elevated despite adequate oxygenation.
The patient’s exercise intolerance is most directly explained by
failure of which cellular process?
A. Ribosomal peptide elongation
B. Oxidative phosphorylation within the inner mitochondrial
membrane
,C. Lysosomal degradation of glycogen
D. Peroxisomal beta-oxidation of very-long-chain fatty acids
E. Golgi-mediated protein packaging
Correct Answer: B
Rationale:
Clinical Clue:
Exercise intolerance with lactic acidosis and abnormal
mitochondria indicates impaired aerobic ATP generation.
Mechanism:
The electron transport chain located along the inner
mitochondrial membrane generates ATP through oxidative
phosphorylation.
Why the Correct Answer Is Right:
Failure of oxidative phosphorylation reduces ATP production,
forcing cells into anaerobic glycolysis and lactate accumulation,
particularly affecting high-energy tissues like muscle and
myocardium.
Why the Other Options Are Wrong:
A. Ribosomal dysfunction impairs protein synthesis but does
not primarily cause lactic acidosis.
C. Lysosomal glycogen disorders produce glycogen
accumulation rather than defective aerobic respiration.
D. Peroxisomal oxidation defects primarily impair lipid
metabolism and neurologic development.
,E. Golgi dysfunction affects protein trafficking, not ATP
generation.
Exam Trap (common misconception tested):
Confusing mitochondrial energy failure with generalized
metabolic disorders.
High-Yield Clinical Correlation:
Mitochondrial dysfunction preferentially affects tissues with
high ATP demand: brain, muscle, myocardium, and renal
tubules.
Q2. A hospitalized patient with severe burns develops
generalized edema despite normal cardiac function.
Microscopy reveals disruption of endothelial tight junctions.
The edema most directly results from loss of which cellular
function?
A. ATP-dependent vesicular transport
B. Structural cytoskeletal contraction
C. Selective paracellular barrier regulation
D. Receptor-mediated endocytosis
E. Intracellular signal amplification
Correct Answer: C
Rationale:
, Clinical Clue:
Burn injury increases vascular permeability through disruption
of intercellular junctions.
Mechanism:
Tight junctions regulate paracellular movement of water and
solutes between adjacent cells.
Why the Correct Answer Is Right:
Loss of tight junction integrity permits leakage of plasma
proteins and fluid into interstitial spaces, producing edema.
Why the Other Options Are Wrong:
A. Vesicular transport involves transcellular trafficking, not
junctional permeability.
B. Cytoskeletal contraction contributes indirectly but is not the
primary barrier defect.
D. Endocytosis concerns cellular uptake of ligands.
E. Signal amplification does not directly regulate permeability
barriers.
Exam Trap (common misconception tested):
Assuming edema is always due to hydrostatic pressure
abnormalities.
High-Yield Clinical Correlation:
Endothelial junction integrity is central to capillary permeability
regulation in burns, sepsis, and inflammatory states.
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 4-year-old boy develops progressive muscle weakness
and cardiomyopathy. Skeletal muscle biopsy demonstrates
markedly enlarged mitochondria with disrupted cristae. Serum
lactate is persistently elevated despite adequate oxygenation.
The patient’s exercise intolerance is most directly explained by
failure of which cellular process?
A. Ribosomal peptide elongation
B. Oxidative phosphorylation within the inner mitochondrial
membrane
,C. Lysosomal degradation of glycogen
D. Peroxisomal beta-oxidation of very-long-chain fatty acids
E. Golgi-mediated protein packaging
Correct Answer: B
Rationale:
Clinical Clue:
Exercise intolerance with lactic acidosis and abnormal
mitochondria indicates impaired aerobic ATP generation.
Mechanism:
The electron transport chain located along the inner
mitochondrial membrane generates ATP through oxidative
phosphorylation.
Why the Correct Answer Is Right:
Failure of oxidative phosphorylation reduces ATP production,
forcing cells into anaerobic glycolysis and lactate accumulation,
particularly affecting high-energy tissues like muscle and
myocardium.
Why the Other Options Are Wrong:
A. Ribosomal dysfunction impairs protein synthesis but does
not primarily cause lactic acidosis.
C. Lysosomal glycogen disorders produce glycogen
accumulation rather than defective aerobic respiration.
D. Peroxisomal oxidation defects primarily impair lipid
metabolism and neurologic development.
,E. Golgi dysfunction affects protein trafficking, not ATP
generation.
Exam Trap (common misconception tested):
Confusing mitochondrial energy failure with generalized
metabolic disorders.
High-Yield Clinical Correlation:
Mitochondrial dysfunction preferentially affects tissues with
high ATP demand: brain, muscle, myocardium, and renal
tubules.
Q2. A hospitalized patient with severe burns develops
generalized edema despite normal cardiac function.
Microscopy reveals disruption of endothelial tight junctions.
The edema most directly results from loss of which cellular
function?
A. ATP-dependent vesicular transport
B. Structural cytoskeletal contraction
C. Selective paracellular barrier regulation
D. Receptor-mediated endocytosis
E. Intracellular signal amplification
Correct Answer: C
Rationale:
, Clinical Clue:
Burn injury increases vascular permeability through disruption
of intercellular junctions.
Mechanism:
Tight junctions regulate paracellular movement of water and
solutes between adjacent cells.
Why the Correct Answer Is Right:
Loss of tight junction integrity permits leakage of plasma
proteins and fluid into interstitial spaces, producing edema.
Why the Other Options Are Wrong:
A. Vesicular transport involves transcellular trafficking, not
junctional permeability.
B. Cytoskeletal contraction contributes indirectly but is not the
primary barrier defect.
D. Endocytosis concerns cellular uptake of ligands.
E. Signal amplification does not directly regulate permeability
barriers.
Exam Trap (common misconception tested):
Assuming edema is always due to hydrostatic pressure
abnormalities.
High-Yield Clinical Correlation:
Endothelial junction integrity is central to capillary permeability
regulation in burns, sepsis, and inflammatory states.
