Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Chapter 1: Cellular Biology
Q1. A 6-year-old boy presents with recurrent respiratory
infections, chronic otitis media, and poor mucociliary clearance.
Electron microscopy of respiratory epithelium demonstrates
immotile cilia with absent dynein arms. The impaired
movement of these cellular structures most directly reflects
dysfunction of which process?
A. ATP-dependent interaction between microtubules within the
axoneme
B. Actin polymerization at the leading edge of the plasma
membrane
C. Intermediate filament stabilization of epithelial junctions
,D. Ligand-gated calcium influx across the apical membrane
E. Integrin-mediated attachment to the extracellular matrix
Correct Answer: A
Rationale:
Clinical Clue:
Chronic sinopulmonary infections with immotile cilia indicate
defective ciliary motility.
Mechanism:
Ciliary movement depends on dynein-mediated sliding of
microtubules within the 9+2 axonemal structure.
Why the Correct Answer Is Right:
Dynein arms hydrolyze ATP to generate microtubule sliding,
producing coordinated ciliary beating necessary for mucociliary
clearance.
Why the Other Options Are Wrong:
B. Actin polymerization drives cell migration, not ciliary motion.
C. Intermediate filaments provide structural integrity but do
not generate movement.
D. Calcium influx may regulate signaling but is not the primary
motor mechanism.
E. Integrins mediate adhesion to extracellular matrix
components rather than ciliary propulsion.
Exam Trap (common misconception tested):
Confusing actin-based motility with microtubule-based ciliary
movement.
,High-Yield Clinical Correlation:
Primary ciliary dyskinesia commonly produces recurrent
respiratory infections, infertility, and situs abnormalities.
Q2. A researcher exposes hepatocytes to cyanide, resulting in
abrupt cessation of oxidative phosphorylation. Within minutes,
the cells develop swelling and membrane blebbing. The earliest
intracellular change responsible for this injury is most likely:
A. Activation of lysosomal hydrolases
B. Failure of ATP-dependent sodium-potassium transport
C. Irreversible fragmentation of nuclear DNA
D. Calcium-mediated degradation of membrane phospholipids
E. Mitochondrial release of cytochrome c
Correct Answer: B
Rationale:
Clinical Clue:
Acute ATP depletion causes rapid reversible cellular swelling.
Mechanism:
Loss of ATP disables sodium-potassium ATPase activity, causing
intracellular sodium and water accumulation.
Why the Correct Answer Is Right:
The sodium-potassium pump is highly ATP dependent. Early
pump failure produces osmotic swelling before irreversible
membrane or nuclear injury develops.
, Why the Other Options Are Wrong:
A. Lysosomal rupture occurs later in severe injury.
C. DNA fragmentation reflects irreversible cell death.
D. Phospholipid degradation is a later calcium-mediated event.
E. Cytochrome c release is associated with apoptosis rather
than early reversible swelling.
Exam Trap (common misconception tested):
Assuming mitochondrial dysfunction immediately causes
irreversible necrosis.
High-Yield Clinical Correlation:
Hydropic swelling is a classic early manifestation of ischemic or
toxic cellular injury.
Q3. A patient with metastatic carcinoma is treated with a
monoclonal antibody that blocks epidermal growth factor
receptor signaling. Tumor growth slows because the drug most
directly inhibits which intracellular event?
A. Translation of mitochondrial messenger RNA
B. Ligand-induced activation of intracellular kinase cascades
C. Hydrolysis of lysosomal membrane proteins
D. Diffusion of steroid hormones across the membrane
E. Covalent cross-linking of cytoskeletal microfilaments
Correct Answer: B
Rationale:
8th Edition
Author(s)Sue E. Huether
TEST BANK
Chapter 1: Cellular Biology
Q1. A 6-year-old boy presents with recurrent respiratory
infections, chronic otitis media, and poor mucociliary clearance.
Electron microscopy of respiratory epithelium demonstrates
immotile cilia with absent dynein arms. The impaired
movement of these cellular structures most directly reflects
dysfunction of which process?
A. ATP-dependent interaction between microtubules within the
axoneme
B. Actin polymerization at the leading edge of the plasma
membrane
C. Intermediate filament stabilization of epithelial junctions
,D. Ligand-gated calcium influx across the apical membrane
E. Integrin-mediated attachment to the extracellular matrix
Correct Answer: A
Rationale:
Clinical Clue:
Chronic sinopulmonary infections with immotile cilia indicate
defective ciliary motility.
Mechanism:
Ciliary movement depends on dynein-mediated sliding of
microtubules within the 9+2 axonemal structure.
Why the Correct Answer Is Right:
Dynein arms hydrolyze ATP to generate microtubule sliding,
producing coordinated ciliary beating necessary for mucociliary
clearance.
Why the Other Options Are Wrong:
B. Actin polymerization drives cell migration, not ciliary motion.
C. Intermediate filaments provide structural integrity but do
not generate movement.
D. Calcium influx may regulate signaling but is not the primary
motor mechanism.
E. Integrins mediate adhesion to extracellular matrix
components rather than ciliary propulsion.
Exam Trap (common misconception tested):
Confusing actin-based motility with microtubule-based ciliary
movement.
,High-Yield Clinical Correlation:
Primary ciliary dyskinesia commonly produces recurrent
respiratory infections, infertility, and situs abnormalities.
Q2. A researcher exposes hepatocytes to cyanide, resulting in
abrupt cessation of oxidative phosphorylation. Within minutes,
the cells develop swelling and membrane blebbing. The earliest
intracellular change responsible for this injury is most likely:
A. Activation of lysosomal hydrolases
B. Failure of ATP-dependent sodium-potassium transport
C. Irreversible fragmentation of nuclear DNA
D. Calcium-mediated degradation of membrane phospholipids
E. Mitochondrial release of cytochrome c
Correct Answer: B
Rationale:
Clinical Clue:
Acute ATP depletion causes rapid reversible cellular swelling.
Mechanism:
Loss of ATP disables sodium-potassium ATPase activity, causing
intracellular sodium and water accumulation.
Why the Correct Answer Is Right:
The sodium-potassium pump is highly ATP dependent. Early
pump failure produces osmotic swelling before irreversible
membrane or nuclear injury develops.
, Why the Other Options Are Wrong:
A. Lysosomal rupture occurs later in severe injury.
C. DNA fragmentation reflects irreversible cell death.
D. Phospholipid degradation is a later calcium-mediated event.
E. Cytochrome c release is associated with apoptosis rather
than early reversible swelling.
Exam Trap (common misconception tested):
Assuming mitochondrial dysfunction immediately causes
irreversible necrosis.
High-Yield Clinical Correlation:
Hydropic swelling is a classic early manifestation of ischemic or
toxic cellular injury.
Q3. A patient with metastatic carcinoma is treated with a
monoclonal antibody that blocks epidermal growth factor
receptor signaling. Tumor growth slows because the drug most
directly inhibits which intracellular event?
A. Translation of mitochondrial messenger RNA
B. Ligand-induced activation of intracellular kinase cascades
C. Hydrolysis of lysosomal membrane proteins
D. Diffusion of steroid hormones across the membrane
E. Covalent cross-linking of cytoskeletal microfilaments
Correct Answer: B
Rationale:
