Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 6-year-old child develops recurrent respiratory infections
and chronic sinusitis. Bronchial biopsy demonstrates immotile
cilia with ultrastructural abnormalities involving dynein arms.
The child also has situs inversus. Which pathophysiologic defect
most directly explains this presentation?
A. Impaired microtubule-mediated intracellular trafficking
B. Defective actin filament polymerization at the plasma
membrane
C. Abnormal ATP-dependent movement of ciliary microtubules
D. Disruption of intermediate filament structural integrity
E. Excessive lysosomal degradation of cytoskeletal proteins
,Correct Answer: C
Rationale:
Clinical Clue: Chronic respiratory infections with situs inversus
suggests dysfunctional motile cilia.
Mechanism: Dynein proteins generate ATP-dependent sliding
of microtubules within cilia. Defective dynein arms impair
coordinated ciliary motion and embryologic left-right
patterning.
Why the Correct Answer Is Right: Loss of ATP-driven ciliary
beating causes mucus retention and abnormal organ
positioning.
Why the Other Options Are Wrong:
A. Intracellular trafficking defects impair vesicle movement but
do not explain situs inversus.
B. Actin dysfunction affects motility and shape, not ciliary
motion.
D. Intermediate filaments provide tensile support.
E. Lysosomal degradation abnormalities do not explain ciliary
immobility.
Exam Trap (common misconception tested): Confusing
microtubules used for intracellular transport with ciliary
dynein-dependent movement.
High-Yield Clinical Correlation: Defective ciliary motility
predisposes to recurrent pulmonary infections and infertility.
,Q2. During severe hypoxia following hemorrhagic shock, a
patient’s cells begin swelling despite intact plasma membranes.
The earliest intracellular event best accounting for this finding
is:
A. Increased lysosomal rupture
B. Failure of ATP-dependent sodium-potassium transport
C. Excessive intracellular calcium sequestration
D. Accelerated mitochondrial oxidative phosphorylation
E. Increased membrane cholesterol synthesis
Correct Answer: B
Rationale:
Clinical Clue: Acute hypoxia with early reversible cellular injury.
Mechanism: ATP depletion disables Na⁺/K⁺-ATPase function,
allowing sodium and water influx into cells.
Why the Correct Answer Is Right: Cellular swelling is an early
hallmark of reversible hypoxic injury caused by ion transport
failure.
Why the Other Options Are Wrong:
A. Lysosomal rupture is a later, irreversible injury event.
C. Calcium sequestration decreases injury. Cytosolic calcium
overload worsens damage.
D. Oxidative phosphorylation decreases during hypoxia.
E. Cholesterol synthesis is not the primary determinant of acute
swelling.
Exam Trap (common misconception tested): Assuming
membrane rupture causes early swelling.
, High-Yield Clinical Correlation: Reversible ischemic injury is
characterized by cell swelling before necrosis develops.
Q3. A researcher inhibits tight junction proteins in intestinal
epithelial tissue. Which physiologic consequence is most likely?
A. Reduced mechanical anchoring between adjacent cells
B. Increased uncontrolled paracellular diffusion
C. Loss of electrical communication through ion exchange
D. Reduced basement membrane attachment
E. Failure of leukocyte migration
Correct Answer: B
Rationale:
Clinical Clue: Tight junction disruption affects epithelial barrier
integrity.
Mechanism: Tight junctions regulate selective permeability
between adjacent epithelial cells.
Why the Correct Answer Is Right: Loss permits leakage of
luminal contents through paracellular pathways.
Why the Other Options Are Wrong:
A. Desmosomes mediate anchoring.
C. Gap junctions allow ion transfer.
D. Hemidesmosomes anchor to basement membrane.
E. Leukocyte migration involves adhesion molecules, not tight
junctions.
Exam Trap (common misconception tested): Confusing
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 6-year-old child develops recurrent respiratory infections
and chronic sinusitis. Bronchial biopsy demonstrates immotile
cilia with ultrastructural abnormalities involving dynein arms.
The child also has situs inversus. Which pathophysiologic defect
most directly explains this presentation?
A. Impaired microtubule-mediated intracellular trafficking
B. Defective actin filament polymerization at the plasma
membrane
C. Abnormal ATP-dependent movement of ciliary microtubules
D. Disruption of intermediate filament structural integrity
E. Excessive lysosomal degradation of cytoskeletal proteins
,Correct Answer: C
Rationale:
Clinical Clue: Chronic respiratory infections with situs inversus
suggests dysfunctional motile cilia.
Mechanism: Dynein proteins generate ATP-dependent sliding
of microtubules within cilia. Defective dynein arms impair
coordinated ciliary motion and embryologic left-right
patterning.
Why the Correct Answer Is Right: Loss of ATP-driven ciliary
beating causes mucus retention and abnormal organ
positioning.
Why the Other Options Are Wrong:
A. Intracellular trafficking defects impair vesicle movement but
do not explain situs inversus.
B. Actin dysfunction affects motility and shape, not ciliary
motion.
D. Intermediate filaments provide tensile support.
E. Lysosomal degradation abnormalities do not explain ciliary
immobility.
Exam Trap (common misconception tested): Confusing
microtubules used for intracellular transport with ciliary
dynein-dependent movement.
High-Yield Clinical Correlation: Defective ciliary motility
predisposes to recurrent pulmonary infections and infertility.
,Q2. During severe hypoxia following hemorrhagic shock, a
patient’s cells begin swelling despite intact plasma membranes.
The earliest intracellular event best accounting for this finding
is:
A. Increased lysosomal rupture
B. Failure of ATP-dependent sodium-potassium transport
C. Excessive intracellular calcium sequestration
D. Accelerated mitochondrial oxidative phosphorylation
E. Increased membrane cholesterol synthesis
Correct Answer: B
Rationale:
Clinical Clue: Acute hypoxia with early reversible cellular injury.
Mechanism: ATP depletion disables Na⁺/K⁺-ATPase function,
allowing sodium and water influx into cells.
Why the Correct Answer Is Right: Cellular swelling is an early
hallmark of reversible hypoxic injury caused by ion transport
failure.
Why the Other Options Are Wrong:
A. Lysosomal rupture is a later, irreversible injury event.
C. Calcium sequestration decreases injury. Cytosolic calcium
overload worsens damage.
D. Oxidative phosphorylation decreases during hypoxia.
E. Cholesterol synthesis is not the primary determinant of acute
swelling.
Exam Trap (common misconception tested): Assuming
membrane rupture causes early swelling.
, High-Yield Clinical Correlation: Reversible ischemic injury is
characterized by cell swelling before necrosis develops.
Q3. A researcher inhibits tight junction proteins in intestinal
epithelial tissue. Which physiologic consequence is most likely?
A. Reduced mechanical anchoring between adjacent cells
B. Increased uncontrolled paracellular diffusion
C. Loss of electrical communication through ion exchange
D. Reduced basement membrane attachment
E. Failure of leukocyte migration
Correct Answer: B
Rationale:
Clinical Clue: Tight junction disruption affects epithelial barrier
integrity.
Mechanism: Tight junctions regulate selective permeability
between adjacent epithelial cells.
Why the Correct Answer Is Right: Loss permits leakage of
luminal contents through paracellular pathways.
Why the Other Options Are Wrong:
A. Desmosomes mediate anchoring.
C. Gap junctions allow ion transfer.
D. Hemidesmosomes anchor to basement membrane.
E. Leukocyte migration involves adhesion molecules, not tight
junctions.
Exam Trap (common misconception tested): Confusing
