McCance & Huether’s Pathophysiology
The Biologic Basis for Disease in Adults
and Children
9th Edition
Author(s)Julia Rogers
TEST BANK
Q1. A 42-year-old man develops progressive muscle
weakness after exposure to a bacterial toxin that
selectively inhibits mitochondrial oxidative
phosphorylation. Despite adequate oxygen delivery to
, tissues, serum lactate levels rise rapidly. The metabolic
disturbance most directly explains which cellular
consequence?
A. Increased ATP production through the tricarboxylic acid
cycle
B. Failure of sodium-potassium ATPase activity with
cellular swelling
C. Enhanced beta-oxidation leading to intracellular
alkalosis
D. Increased ribosomal protein synthesis due to excess
NADH
Correct Answer: B
Rationale:
• Clinical Clue: Elevated lactate despite normal oxygen
delivery suggests impaired aerobic metabolism.
• Mechanism: Oxidative phosphorylation failure sharply
reduces ATP generation, impairing energy-dependent ion
pumps.
• Why the Correct Answer Is Right: Sodium-potassium
ATPase failure causes intracellular sodium and water
accumulation, producing cellular swelling.
• Why the Other Options Are Wrong:
o A. ATP generation decreases, not increases.
, o C. Beta-oxidation cannot compensate adequately
during severe mitochondrial dysfunction.
o D. Protein synthesis declines during energy depletion.
• Exam Trap: Normal oxygen saturation does not exclude
cellular hypoxia at the mitochondrial level.
• High-Yield Clinical Correlation: Cyanide poisoning and
severe sepsis can produce histotoxic hypoxia with lactic
acidosis.
• Memory Anchor: “No ATP → no pumps → swollen cells.”
Q2. A researcher studying epithelial integrity disrupts
cadherin-mediated junctions in intestinal mucosa. The
resulting defect most likely impairs which physiologic
process?
A. Intercellular electrical coupling
B. Basement membrane synthesis
C. Mechanical adhesion between adjacent cells
D. Endocytosis of extracellular proteins
Correct Answer: C
Rationale:
• Clinical Clue: Cadherins are calcium-dependent adhesion
molecules central to tissue cohesion.
, • Mechanism: Cadherins anchor cells through adherens
junctions and desmosomes.
• Why the Correct Answer Is Right: Loss of cadherin function
weakens mechanical attachment between neighboring
epithelial cells.
• Why the Other Options Are Wrong:
o A. Gap junctions mediate electrical coupling.
o B. Basement membrane is primarily synthesized by
epithelial and connective tissue cells, not cadherins.
o D. Endocytosis depends on membrane transport
systems.
• Exam Trap: Students often confuse tight junctions with
adherens junctions.
• High-Yield Clinical Correlation: E-cadherin loss contributes
to tumor invasion and metastasis.
• Memory Anchor: “Cadherins keep cells clinging together.”
Q3. A newborn is found to have a mutation impairing
lysosomal enzyme targeting due to defective mannose-6-
phosphate tagging. Accumulation of undegraded
intracellular substrates is most likely due to dysfunction of
which organelle?
The Biologic Basis for Disease in Adults
and Children
9th Edition
Author(s)Julia Rogers
TEST BANK
Q1. A 42-year-old man develops progressive muscle
weakness after exposure to a bacterial toxin that
selectively inhibits mitochondrial oxidative
phosphorylation. Despite adequate oxygen delivery to
, tissues, serum lactate levels rise rapidly. The metabolic
disturbance most directly explains which cellular
consequence?
A. Increased ATP production through the tricarboxylic acid
cycle
B. Failure of sodium-potassium ATPase activity with
cellular swelling
C. Enhanced beta-oxidation leading to intracellular
alkalosis
D. Increased ribosomal protein synthesis due to excess
NADH
Correct Answer: B
Rationale:
• Clinical Clue: Elevated lactate despite normal oxygen
delivery suggests impaired aerobic metabolism.
• Mechanism: Oxidative phosphorylation failure sharply
reduces ATP generation, impairing energy-dependent ion
pumps.
• Why the Correct Answer Is Right: Sodium-potassium
ATPase failure causes intracellular sodium and water
accumulation, producing cellular swelling.
• Why the Other Options Are Wrong:
o A. ATP generation decreases, not increases.
, o C. Beta-oxidation cannot compensate adequately
during severe mitochondrial dysfunction.
o D. Protein synthesis declines during energy depletion.
• Exam Trap: Normal oxygen saturation does not exclude
cellular hypoxia at the mitochondrial level.
• High-Yield Clinical Correlation: Cyanide poisoning and
severe sepsis can produce histotoxic hypoxia with lactic
acidosis.
• Memory Anchor: “No ATP → no pumps → swollen cells.”
Q2. A researcher studying epithelial integrity disrupts
cadherin-mediated junctions in intestinal mucosa. The
resulting defect most likely impairs which physiologic
process?
A. Intercellular electrical coupling
B. Basement membrane synthesis
C. Mechanical adhesion between adjacent cells
D. Endocytosis of extracellular proteins
Correct Answer: C
Rationale:
• Clinical Clue: Cadherins are calcium-dependent adhesion
molecules central to tissue cohesion.
, • Mechanism: Cadherins anchor cells through adherens
junctions and desmosomes.
• Why the Correct Answer Is Right: Loss of cadherin function
weakens mechanical attachment between neighboring
epithelial cells.
• Why the Other Options Are Wrong:
o A. Gap junctions mediate electrical coupling.
o B. Basement membrane is primarily synthesized by
epithelial and connective tissue cells, not cadherins.
o D. Endocytosis depends on membrane transport
systems.
• Exam Trap: Students often confuse tight junctions with
adherens junctions.
• High-Yield Clinical Correlation: E-cadherin loss contributes
to tumor invasion and metastasis.
• Memory Anchor: “Cadherins keep cells clinging together.”
Q3. A newborn is found to have a mutation impairing
lysosomal enzyme targeting due to defective mannose-6-
phosphate tagging. Accumulation of undegraded
intracellular substrates is most likely due to dysfunction of
which organelle?
