Understanding Pathophysiology
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 6-year-old boy presents with recurrent bacterial
infections, delayed wound healing, and poor leukocyte
migration into infected tissues. Flow cytometry demonstrates
absent expression of β2-integrins on neutrophils. The impaired
immune response is most directly attributable to defective
interaction between neutrophils and which cellular structure?
A. Gap junction proteins
B. Extracellular matrix collagen fibers
C. Intercellular adhesion molecules on endothelial cells
D. Cadherin-mediated desmosomes
E. Tight junction occludins
Correct Answer: C
,Rationale:
Clinical Clue:
Recurrent infections with impaired leukocyte migration
suggests leukocyte adhesion deficiency.
Mechanism:
β2-integrins on neutrophils normally bind endothelial
intercellular adhesion molecules (ICAMs), allowing firm
adhesion before transmigration.
Why the Correct Answer Is Right:
ICAM-mediated adhesion is essential for neutrophil
extravasation during inflammation.
Why the Other Options Are Wrong:
A. Gap junctions facilitate intercellular signaling, not leukocyte
adhesion.
B. Collagen provides structural support but is not the primary
adhesion target.
D. Desmosomes provide mechanical stability between epithelial
cells.
E. Tight junctions regulate paracellular permeability.
Exam Trap (common misconception tested):
Confusing leukocyte-endothelial adhesion with general
extracellular matrix attachment.
High-Yield Clinical Correlation:
Defects in integrin-mediated adhesion cause severe bacterial
infections with minimal pus formation.
,Q2. A hepatocyte exposed to cyanide abruptly loses oxidative
phosphorylation capacity. Within minutes, intracellular ATP
levels fall dramatically. Which membrane transport process is
most immediately impaired?
A. Osmosis through aquaporins
B. Facilitated diffusion of glucose
C. Passive diffusion of oxygen
D. Sodium-potassium ATPase activity
E. Chloride ion diffusion through channels
Correct Answer: D
Rationale:
Clinical Clue:
Cyanide inhibits mitochondrial electron transport and ATP
generation.
Mechanism:
The sodium-potassium ATPase requires ATP to maintain
electrochemical gradients.
Why the Correct Answer Is Right:
Loss of ATP rapidly disables active transport, causing sodium
accumulation and cellular swelling.
Why the Other Options Are Wrong:
A. Osmosis is passive.
B. Facilitated diffusion does not directly require ATP.
, C. Oxygen diffusion occurs down concentration gradients.
E. Ion channel diffusion is passive.
Exam Trap (common misconception tested):
Equating all membrane transport processes with ATP
dependence.
High-Yield Clinical Correlation:
Failure of ATP-dependent ion pumps is a major mechanism of
irreversible cell injury.
Q3. A researcher selectively inhibits connexin proteins in
cardiac tissue. The resulting physiologic disturbance would
most likely involve impaired:
A. Mechanical anchoring between cardiomyocytes
B. Protein synthesis within sarcoplasmic reticulum
C. Electrical propagation between adjacent cells
D. Lipid transport across plasma membranes
E. Cellular attachment to basement membrane
Correct Answer: C
Rationale:
Clinical Clue:
Connexins form gap junctions in cardiac tissue.
Mechanism:
Gap junctions permit ion movement between cells, enabling
synchronized depolarization.
8th Edition
Author(s)Sue E. Huether
TEST BANK
Q1. A 6-year-old boy presents with recurrent bacterial
infections, delayed wound healing, and poor leukocyte
migration into infected tissues. Flow cytometry demonstrates
absent expression of β2-integrins on neutrophils. The impaired
immune response is most directly attributable to defective
interaction between neutrophils and which cellular structure?
A. Gap junction proteins
B. Extracellular matrix collagen fibers
C. Intercellular adhesion molecules on endothelial cells
D. Cadherin-mediated desmosomes
E. Tight junction occludins
Correct Answer: C
,Rationale:
Clinical Clue:
Recurrent infections with impaired leukocyte migration
suggests leukocyte adhesion deficiency.
Mechanism:
β2-integrins on neutrophils normally bind endothelial
intercellular adhesion molecules (ICAMs), allowing firm
adhesion before transmigration.
Why the Correct Answer Is Right:
ICAM-mediated adhesion is essential for neutrophil
extravasation during inflammation.
Why the Other Options Are Wrong:
A. Gap junctions facilitate intercellular signaling, not leukocyte
adhesion.
B. Collagen provides structural support but is not the primary
adhesion target.
D. Desmosomes provide mechanical stability between epithelial
cells.
E. Tight junctions regulate paracellular permeability.
Exam Trap (common misconception tested):
Confusing leukocyte-endothelial adhesion with general
extracellular matrix attachment.
High-Yield Clinical Correlation:
Defects in integrin-mediated adhesion cause severe bacterial
infections with minimal pus formation.
,Q2. A hepatocyte exposed to cyanide abruptly loses oxidative
phosphorylation capacity. Within minutes, intracellular ATP
levels fall dramatically. Which membrane transport process is
most immediately impaired?
A. Osmosis through aquaporins
B. Facilitated diffusion of glucose
C. Passive diffusion of oxygen
D. Sodium-potassium ATPase activity
E. Chloride ion diffusion through channels
Correct Answer: D
Rationale:
Clinical Clue:
Cyanide inhibits mitochondrial electron transport and ATP
generation.
Mechanism:
The sodium-potassium ATPase requires ATP to maintain
electrochemical gradients.
Why the Correct Answer Is Right:
Loss of ATP rapidly disables active transport, causing sodium
accumulation and cellular swelling.
Why the Other Options Are Wrong:
A. Osmosis is passive.
B. Facilitated diffusion does not directly require ATP.
, C. Oxygen diffusion occurs down concentration gradients.
E. Ion channel diffusion is passive.
Exam Trap (common misconception tested):
Equating all membrane transport processes with ATP
dependence.
High-Yield Clinical Correlation:
Failure of ATP-dependent ion pumps is a major mechanism of
irreversible cell injury.
Q3. A researcher selectively inhibits connexin proteins in
cardiac tissue. The resulting physiologic disturbance would
most likely involve impaired:
A. Mechanical anchoring between cardiomyocytes
B. Protein synthesis within sarcoplasmic reticulum
C. Electrical propagation between adjacent cells
D. Lipid transport across plasma membranes
E. Cellular attachment to basement membrane
Correct Answer: C
Rationale:
Clinical Clue:
Connexins form gap junctions in cardiac tissue.
Mechanism:
Gap junctions permit ion movement between cells, enabling
synchronized depolarization.
