Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 24-year-old man develops profound muscle weakness
and dark urine 2 days after completing an ultramarathon in
extreme heat. Laboratory studies reveal markedly elevated
creatine kinase and hyperkalemia. Skeletal muscle biopsy
demonstrates widespread loss of plasma membrane integrity
with uncontrolled ion flux. Failure of which cellular process
most directly initiated this injury?
A. ATP-dependent maintenance of transmembrane ionic
gradients
B. Increased ribosomal synthesis of contractile proteins
C. Activation of lysosomal phospholipases
,D. Enhanced mitochondrial β-oxidation
E. Accelerated nuclear transcription of stress proteins
Correct Answer: A
Rationale:
Clinical Clue:
Exertional rhabdomyolysis with hyperkalemia indicates
membrane failure and necrotic myocyte injury.
Mechanism:
ATP depletion disables Na+/K+-ATPase activity, causing
intracellular sodium and calcium accumulation, osmotic
swelling, and membrane disruption.
Why the Correct Answer Is Right:
Loss of ATP-driven ion transport is an early irreversible step in
severe ischemic or metabolic cellular injury.
Why the Other Options Are Wrong:
B. Protein synthesis declines during injury rather than initiating
necrosis.
C. Lysosomal enzymes contribute later after membrane
destabilization.
D. β-oxidation impairment may worsen energy failure but is not
the direct initiating mechanism here.
E. Stress protein synthesis is adaptive rather than destructive.
Exam Trap (common misconception tested):
Confusing secondary lysosomal damage with the primary
energy-dependent mechanism of membrane failure.
,High-Yield Clinical Correlation:
ATP depletion is a unifying mechanism in ischemia, shock,
severe hypoxia, and toxin-mediated necrosis.
Q2. A researcher cultures epithelial cells and selectively
disrupts cadherin-mediated junctions. The cells remain viable
but lose organized polarity and detach from neighboring cells
under mechanical stress. This finding most strongly reflects
dysfunction of which structure?
A. Tight junctions
B. Gap junctions
C. Desmosomes
D. Hemidesmosomes
E. Microtubules
Correct Answer: C
Rationale:
Clinical Clue:
Loss of mechanical cohesion between adjacent epithelial cells
indicates impaired structural adhesion.
Mechanism:
Desmosomes use cadherin-family proteins linked to
intermediate filaments to resist shearing stress.
, Why the Correct Answer Is Right:
Desmosomal disruption causes weakened intercellular
attachment and tissue fragility.
Why the Other Options Are Wrong:
A. Tight junctions regulate permeability barriers, not primary
mechanical stability.
B. Gap junctions mediate communication through ion transfer.
D. Hemidesmosomes anchor cells to basement membrane
rather than to each other.
E. Microtubules support intracellular transport, not cell-cell
adhesion.
Exam Trap (common misconception tested):
Mixing up desmosomes with tight junctions in epithelial
organization.
High-Yield Clinical Correlation:
Autoimmune disruption of desmosomes causes blistering
disorders such as pemphigus vulgaris.
Q3. A patient with septic shock develops progressive lactic
acidosis despite adequate oxygen delivery. Mitochondrial
dysfunction is suspected. Which cellular process is most directly
impaired?
A. Anaerobic glycolysis
B. Oxidative phosphorylation
C. Cytoplasmic protein translation
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 24-year-old man develops profound muscle weakness
and dark urine 2 days after completing an ultramarathon in
extreme heat. Laboratory studies reveal markedly elevated
creatine kinase and hyperkalemia. Skeletal muscle biopsy
demonstrates widespread loss of plasma membrane integrity
with uncontrolled ion flux. Failure of which cellular process
most directly initiated this injury?
A. ATP-dependent maintenance of transmembrane ionic
gradients
B. Increased ribosomal synthesis of contractile proteins
C. Activation of lysosomal phospholipases
,D. Enhanced mitochondrial β-oxidation
E. Accelerated nuclear transcription of stress proteins
Correct Answer: A
Rationale:
Clinical Clue:
Exertional rhabdomyolysis with hyperkalemia indicates
membrane failure and necrotic myocyte injury.
Mechanism:
ATP depletion disables Na+/K+-ATPase activity, causing
intracellular sodium and calcium accumulation, osmotic
swelling, and membrane disruption.
Why the Correct Answer Is Right:
Loss of ATP-driven ion transport is an early irreversible step in
severe ischemic or metabolic cellular injury.
Why the Other Options Are Wrong:
B. Protein synthesis declines during injury rather than initiating
necrosis.
C. Lysosomal enzymes contribute later after membrane
destabilization.
D. β-oxidation impairment may worsen energy failure but is not
the direct initiating mechanism here.
E. Stress protein synthesis is adaptive rather than destructive.
Exam Trap (common misconception tested):
Confusing secondary lysosomal damage with the primary
energy-dependent mechanism of membrane failure.
,High-Yield Clinical Correlation:
ATP depletion is a unifying mechanism in ischemia, shock,
severe hypoxia, and toxin-mediated necrosis.
Q2. A researcher cultures epithelial cells and selectively
disrupts cadherin-mediated junctions. The cells remain viable
but lose organized polarity and detach from neighboring cells
under mechanical stress. This finding most strongly reflects
dysfunction of which structure?
A. Tight junctions
B. Gap junctions
C. Desmosomes
D. Hemidesmosomes
E. Microtubules
Correct Answer: C
Rationale:
Clinical Clue:
Loss of mechanical cohesion between adjacent epithelial cells
indicates impaired structural adhesion.
Mechanism:
Desmosomes use cadherin-family proteins linked to
intermediate filaments to resist shearing stress.
, Why the Correct Answer Is Right:
Desmosomal disruption causes weakened intercellular
attachment and tissue fragility.
Why the Other Options Are Wrong:
A. Tight junctions regulate permeability barriers, not primary
mechanical stability.
B. Gap junctions mediate communication through ion transfer.
D. Hemidesmosomes anchor cells to basement membrane
rather than to each other.
E. Microtubules support intracellular transport, not cell-cell
adhesion.
Exam Trap (common misconception tested):
Mixing up desmosomes with tight junctions in epithelial
organization.
High-Yield Clinical Correlation:
Autoimmune disruption of desmosomes causes blistering
disorders such as pemphigus vulgaris.
Q3. A patient with septic shock develops progressive lactic
acidosis despite adequate oxygen delivery. Mitochondrial
dysfunction is suspected. Which cellular process is most directly
impaired?
A. Anaerobic glycolysis
B. Oxidative phosphorylation
C. Cytoplasmic protein translation
