Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 6-year-old boy presents with recurrent bacterial
infections, poor wound healing, and delayed separation of the
umbilical cord after birth. Neutrophil counts are markedly
elevated. Flow cytometry demonstrates absent expression of
CD18 integrins on leukocytes. The patient’s recurrent infections
are most directly explained by failure of which cellular process?
A. Intracellular lysosomal degradation after phagocytosis
B. Selectin-mediated rolling along vascular endothelium
C. Stable leukocyte adhesion and transendothelial migration
D. Chemokine-induced activation of neutrophils in circulation
E. Complement-mediated opsonization of bacteria
Correct Answer: C
,Rationale:
Clinical Clue:
Delayed umbilical cord separation and recurrent bacterial
infections strongly suggest leukocyte adhesion deficiency.
Mechanism:
β2-integrins (CD18) mediate firm leukocyte adhesion to
endothelial ICAM molecules before diapedesis.
Why the Correct Answer Is Right:
Without integrin-mediated adhesion, neutrophils cannot exit
the bloodstream efficiently and migrate into infected tissues
despite marked neutrophilia.
Why the Other Options Are Wrong:
A. Lysosomal degradation occurs after successful migration and
phagocytosis.
B. Rolling is mediated primarily by selectins, not integrins.
D. Chemokine activation remains intact.
E. Complement opsonization is unaffected by CD18 deficiency.
Exam Trap (common misconception tested):
Confusing rolling defects with adhesion defects.
High-Yield Clinical Correlation:
Persistent neutrophilia with impaired tissue migration is
characteristic of adhesion molecule defects.
,Q2. A 58-year-old man develops severe fatigue and exercise
intolerance after exposure to cyanide smoke during an
industrial fire. Venous oxygen saturation is markedly elevated
despite profound lactic acidosis. The cellular abnormality most
directly responsible for this finding involves inhibition of:
A. ATP-dependent sodium-potassium transport
B. Cytochrome oxidase within oxidative phosphorylation
C. Glycolytic conversion of pyruvate to lactate
D. Fatty acid transport into mitochondria
E. Ribosomal peptide elongation
Correct Answer: B
Rationale:
Clinical Clue:
Elevated venous oxygen saturation with lactic acidosis indicates
impaired oxygen utilization rather than impaired oxygen
delivery.
Mechanism:
Cyanide inhibits cytochrome c oxidase (complex IV), halting
electron transport and oxidative phosphorylation.
Why the Correct Answer Is Right:
Cells cannot utilize oxygen for ATP production, forcing
anaerobic metabolism and lactate accumulation.
Why the Other Options Are Wrong:
A. Sodium-potassium pump failure is secondary to ATP
depletion.
, C. Lactate formation increases rather than decreases.
D. Fatty acid transport defects do not explain acute histotoxic
hypoxia.
E. Ribosomal inhibition is unrelated to oxygen utilization failure.
Exam Trap (common misconception tested):
Mistaking tissue hypoxia for impaired oxygen delivery instead
of impaired cellular respiration.
High-Yield Clinical Correlation:
Mitochondrial toxins produce severe lactic acidosis despite
adequate oxygen availability.
Q3. A researcher studies epithelial tissue integrity in patients
with blistering skin disorders. One group demonstrates
separation between adjacent epithelial cells due to
autoimmune destruction of desmosomal proteins. Loss of
which structural feature most directly accounts for the tissue
fragility?
A. Gap junction ion channels
B. Tight junction occlusive proteins
C. Hemidesmosomal basement membrane anchors
D. Intermediate filament-linked intercellular adhesions
E. Microtubule-associated intracellular scaffolding
Correct Answer: D
Rationale:
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 6-year-old boy presents with recurrent bacterial
infections, poor wound healing, and delayed separation of the
umbilical cord after birth. Neutrophil counts are markedly
elevated. Flow cytometry demonstrates absent expression of
CD18 integrins on leukocytes. The patient’s recurrent infections
are most directly explained by failure of which cellular process?
A. Intracellular lysosomal degradation after phagocytosis
B. Selectin-mediated rolling along vascular endothelium
C. Stable leukocyte adhesion and transendothelial migration
D. Chemokine-induced activation of neutrophils in circulation
E. Complement-mediated opsonization of bacteria
Correct Answer: C
,Rationale:
Clinical Clue:
Delayed umbilical cord separation and recurrent bacterial
infections strongly suggest leukocyte adhesion deficiency.
Mechanism:
β2-integrins (CD18) mediate firm leukocyte adhesion to
endothelial ICAM molecules before diapedesis.
Why the Correct Answer Is Right:
Without integrin-mediated adhesion, neutrophils cannot exit
the bloodstream efficiently and migrate into infected tissues
despite marked neutrophilia.
Why the Other Options Are Wrong:
A. Lysosomal degradation occurs after successful migration and
phagocytosis.
B. Rolling is mediated primarily by selectins, not integrins.
D. Chemokine activation remains intact.
E. Complement opsonization is unaffected by CD18 deficiency.
Exam Trap (common misconception tested):
Confusing rolling defects with adhesion defects.
High-Yield Clinical Correlation:
Persistent neutrophilia with impaired tissue migration is
characteristic of adhesion molecule defects.
,Q2. A 58-year-old man develops severe fatigue and exercise
intolerance after exposure to cyanide smoke during an
industrial fire. Venous oxygen saturation is markedly elevated
despite profound lactic acidosis. The cellular abnormality most
directly responsible for this finding involves inhibition of:
A. ATP-dependent sodium-potassium transport
B. Cytochrome oxidase within oxidative phosphorylation
C. Glycolytic conversion of pyruvate to lactate
D. Fatty acid transport into mitochondria
E. Ribosomal peptide elongation
Correct Answer: B
Rationale:
Clinical Clue:
Elevated venous oxygen saturation with lactic acidosis indicates
impaired oxygen utilization rather than impaired oxygen
delivery.
Mechanism:
Cyanide inhibits cytochrome c oxidase (complex IV), halting
electron transport and oxidative phosphorylation.
Why the Correct Answer Is Right:
Cells cannot utilize oxygen for ATP production, forcing
anaerobic metabolism and lactate accumulation.
Why the Other Options Are Wrong:
A. Sodium-potassium pump failure is secondary to ATP
depletion.
, C. Lactate formation increases rather than decreases.
D. Fatty acid transport defects do not explain acute histotoxic
hypoxia.
E. Ribosomal inhibition is unrelated to oxygen utilization failure.
Exam Trap (common misconception tested):
Mistaking tissue hypoxia for impaired oxygen delivery instead
of impaired cellular respiration.
High-Yield Clinical Correlation:
Mitochondrial toxins produce severe lactic acidosis despite
adequate oxygen availability.
Q3. A researcher studies epithelial tissue integrity in patients
with blistering skin disorders. One group demonstrates
separation between adjacent epithelial cells due to
autoimmune destruction of desmosomal proteins. Loss of
which structural feature most directly accounts for the tissue
fragility?
A. Gap junction ion channels
B. Tight junction occlusive proteins
C. Hemidesmosomal basement membrane anchors
D. Intermediate filament-linked intercellular adhesions
E. Microtubule-associated intracellular scaffolding
Correct Answer: D
Rationale:
