Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 7-year-old child is diagnosed with a congenital defect
affecting lysosomal enzyme activity. Over time,
hepatosplenomegaly, developmental delay, and progressive
neurologic dysfunction develop. The accumulation of
undegraded macromolecules is most directly explained by
failure of which intracellular process?
A. ATP synthesis through oxidative phosphorylation
B. Protein translation at rough endoplasmic reticulum
C. Hydrolytic degradation of endocytosed substrates
D. Calcium sequestration within smooth endoplasmic reticulum
E. DNA proofreading during replication
Correct Answer: C
,Rationale:
Clinical Clue: Progressive storage disease with organomegaly
and neurologic decline suggests lysosomal dysfunction.
Mechanism: Lysosomes contain acid hydrolases responsible for
degradation of engulfed macromolecules.
Why the Correct Answer Is Right: Defective lysosomal enzymes
prevent intracellular digestion of substrates, causing
accumulation.
Why the Other Options Are Wrong:
A. Mitochondrial ATP production defects cause energy failure,
not storage accumulation.
B. Rough ER defects impair protein synthesis.
D. Smooth ER regulates lipid synthesis and calcium storage.
E. DNA proofreading errors cause mutation accumulation.
Exam Trap (common misconception tested): Confusing
lysosomes with proteasomes or mitochondria.
High-Yield Clinical Correlation: Lysosomal dysfunction
underlies many inherited metabolic disorders with multisystem
manifestations.
Q2. A patient with severe hypoxia after carbon monoxide
poisoning develops rapid confusion, tachycardia, and elevated
serum lactate. The increased lactate most directly reflects
which metabolic adaptation?
A. Increased beta-oxidation of fatty acids
B. Shift from aerobic metabolism to anaerobic glycolysis
,C. Enhanced gluconeogenesis by hepatocytes
D. Increased urea cycle activity
E. Activation of pentose phosphate pathway
Correct Answer: B
Rationale:
Clinical Clue: Hypoxia plus lactate elevation indicates impaired
oxidative phosphorylation.
Mechanism: Reduced oxygen availability prevents
mitochondrial electron transport, forcing ATP generation
through anaerobic glycolysis.
Why the Correct Answer Is Right: Pyruvate is converted to
lactate to regenerate NAD+, sustaining glycolysis.
Why the Other Options Are Wrong:
A. Beta-oxidation requires mitochondrial oxidative metabolism.
C. Gluconeogenesis consumes ATP.
D. Urea cycle is unrelated to acute lactate generation.
E. Pentose phosphate pathway primarily generates NADPH.
Exam Trap: Assuming lactate comes directly from
mitochondrial dysfunction rather than compensatory glycolysis.
High-Yield Clinical Correlation: Elevated lactate is a marker of
tissue hypoperfusion or hypoxia.
Q3. A researcher inhibits Na+/K+-ATPase in cultured skeletal
muscle cells. Which immediate physiologic consequence is
most likely?
, A. Hyperpolarization of cell membrane
B. Cellular shrinkage from osmotic water loss
C. Membrane depolarization with intracellular sodium
accumulation
D. Accelerated DNA replication
E. Increased calcium export from cell
Correct Answer: C
Rationale:
Clinical Clue: Na+/K+ pump maintains ionic gradients.
Mechanism: ATPase failure increases intracellular sodium and
reduces potassium uptake.
Why the Correct Answer Is Right: Loss of gradient leads to
depolarization and osmotic swelling.
Why the Other Options Are Wrong:
A. Membrane depolarizes, not hyperpolarizes.
B. Water enters rather than exits.
D. No direct link to replication.
E. Calcium export is secondary and impaired as sodium gradient
collapses.
Exam Trap: Confusing ion pump inhibition with channel
blockade.
High-Yield Clinical Correlation: Digitalis partly acts through
Na+/K+-ATPase inhibition.
Q4. A mutation disrupts cadherin-mediated cell adhesion in
epithelial tissue. Which pathophysiologic change is most likely?
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 7-year-old child is diagnosed with a congenital defect
affecting lysosomal enzyme activity. Over time,
hepatosplenomegaly, developmental delay, and progressive
neurologic dysfunction develop. The accumulation of
undegraded macromolecules is most directly explained by
failure of which intracellular process?
A. ATP synthesis through oxidative phosphorylation
B. Protein translation at rough endoplasmic reticulum
C. Hydrolytic degradation of endocytosed substrates
D. Calcium sequestration within smooth endoplasmic reticulum
E. DNA proofreading during replication
Correct Answer: C
,Rationale:
Clinical Clue: Progressive storage disease with organomegaly
and neurologic decline suggests lysosomal dysfunction.
Mechanism: Lysosomes contain acid hydrolases responsible for
degradation of engulfed macromolecules.
Why the Correct Answer Is Right: Defective lysosomal enzymes
prevent intracellular digestion of substrates, causing
accumulation.
Why the Other Options Are Wrong:
A. Mitochondrial ATP production defects cause energy failure,
not storage accumulation.
B. Rough ER defects impair protein synthesis.
D. Smooth ER regulates lipid synthesis and calcium storage.
E. DNA proofreading errors cause mutation accumulation.
Exam Trap (common misconception tested): Confusing
lysosomes with proteasomes or mitochondria.
High-Yield Clinical Correlation: Lysosomal dysfunction
underlies many inherited metabolic disorders with multisystem
manifestations.
Q2. A patient with severe hypoxia after carbon monoxide
poisoning develops rapid confusion, tachycardia, and elevated
serum lactate. The increased lactate most directly reflects
which metabolic adaptation?
A. Increased beta-oxidation of fatty acids
B. Shift from aerobic metabolism to anaerobic glycolysis
,C. Enhanced gluconeogenesis by hepatocytes
D. Increased urea cycle activity
E. Activation of pentose phosphate pathway
Correct Answer: B
Rationale:
Clinical Clue: Hypoxia plus lactate elevation indicates impaired
oxidative phosphorylation.
Mechanism: Reduced oxygen availability prevents
mitochondrial electron transport, forcing ATP generation
through anaerobic glycolysis.
Why the Correct Answer Is Right: Pyruvate is converted to
lactate to regenerate NAD+, sustaining glycolysis.
Why the Other Options Are Wrong:
A. Beta-oxidation requires mitochondrial oxidative metabolism.
C. Gluconeogenesis consumes ATP.
D. Urea cycle is unrelated to acute lactate generation.
E. Pentose phosphate pathway primarily generates NADPH.
Exam Trap: Assuming lactate comes directly from
mitochondrial dysfunction rather than compensatory glycolysis.
High-Yield Clinical Correlation: Elevated lactate is a marker of
tissue hypoperfusion or hypoxia.
Q3. A researcher inhibits Na+/K+-ATPase in cultured skeletal
muscle cells. Which immediate physiologic consequence is
most likely?
, A. Hyperpolarization of cell membrane
B. Cellular shrinkage from osmotic water loss
C. Membrane depolarization with intracellular sodium
accumulation
D. Accelerated DNA replication
E. Increased calcium export from cell
Correct Answer: C
Rationale:
Clinical Clue: Na+/K+ pump maintains ionic gradients.
Mechanism: ATPase failure increases intracellular sodium and
reduces potassium uptake.
Why the Correct Answer Is Right: Loss of gradient leads to
depolarization and osmotic swelling.
Why the Other Options Are Wrong:
A. Membrane depolarizes, not hyperpolarizes.
B. Water enters rather than exits.
D. No direct link to replication.
E. Calcium export is secondary and impaired as sodium gradient
collapses.
Exam Trap: Confusing ion pump inhibition with channel
blockade.
High-Yield Clinical Correlation: Digitalis partly acts through
Na+/K+-ATPase inhibition.
Q4. A mutation disrupts cadherin-mediated cell adhesion in
epithelial tissue. Which pathophysiologic change is most likely?
