, Question 1
A patient with chronic hypertension develops left ventricular hypertrophy.
Which molecular mechanism best explains the transition from compensated
hypertrophy to heart failure?
A. Upregulation of -adrenergic receptors enhancing contractility
B. Switch from -myosin heavy chain to -myosin heavy chain isoform
C. Increased capillary density matching myocyte growth
D. Downregulation of fetal gene program and decreased fibrosis
Correct Answer: B - Switch from -myosin heavy chain to -myosin
heavy chain isoform
RATIONALE
The fetal gene program reactivation, including a shift from - to
-myosin heavy chain, reduces ATPase activity and contractile
efficiency, contributing to heart failure. Other options are incorrect:
-receptor upregulation is not typical; capillary density does not
increase proportionally; and fetal gene program is upregulated, not
downregulated.
Question 2
In acute respiratory distress syndrome (ARDS), which pathophysiologic
alteration primarily contributes to refractory hypoxemia?
A. Increased alveolar dead space due to pulmonary embolism
B. Intrapulmonary shunt from alveolar flooding and collapse
C. Hypoventilation from respiratory muscle fatigue
D. Diffusion limitation from thickened alveolar membrane alone
Correct Answer: B - Intrapulmonary shunt from alveolar
flooding and collapse
Page 2
, RATIONALE
ARDS causes non-cardiogenic pulmonary edema and alveolar
collapse, leading to intrapulmonary shunting where blood bypasses
ventilated alveoli, causing refractory hypoxemia. While diffusion
limitation and dead space can occur, shunt is the primary mechanism;
hypoventilation is not the main cause.
Question 3
Which renal pathology is most consistent with the following urinalysis: muddy
brown casts, granular casts, and fractional excretion of sodium (FENa) > 2%?
A. Prerenal azotemia from dehydration
B. Acute tubular necrosis (ATN)
C. Acute interstitial nephritis
D. Glomerulonephritis
Correct Answer: B - Acute tubular necrosis (ATN)
RATIONALE
Muddy brown casts and FENa >2% are classic for ATN, indicating
tubular injury and impaired sodium reabsorption. Prerenal azotemia
typically has FENa <1% and hyaline casts; interstitial nephritis shows
white cell casts and eosinophils; glomerulonephritis presents with red
cell casts and proteinuria.
Question 4
A patient with type 1 diabetes presents with ketoacidosis. Which mechanism
explains the hyperglycemia despite insulin deficiency?
A. Increased glucose uptake by insulin-sensitive tissues
B. Enhanced glycogen synthesis in the liver
C. Unrestrained gluconeogenesis and glycogenolysis
D. Decreased glucagon secretion
Correct Answer: C - Unrestrained gluconeogenesis and
glycogenolysis
Page 3
, RATIONALE
Insulin deficiency leads to unopposed glucagon action, promoting
gluconeogenesis and glycogenolysis, causing hyperglycemia. Other
options are incorrect: glucose uptake is decreased, glycogen synthesis
is reduced, and glucagon is elevated, not decreased.
Question 5
Which hematologic finding is most characteristic of disseminated intravascular
coagulation (DIC)?
A. Elevated platelet count and prolonged PT/PTT
B. Decreased D-dimer and normal fibrinogen
C. Thrombocytopenia, elevated D-dimer, and decreased fibrinogen
D. Isolated prolonged bleeding time with normal platelets
Correct Answer: C - Thrombocytopenia, elevated D-dimer, and
decreased fibrinogen
RATIONALE
DIC involves widespread activation of coagulation, leading to
consumption of platelets and clotting factors, resulting in
thrombocytopenia, elevated D-dimer (from fibrinolysis), and low
fibrinogen. Other options do not reflect the consumptive
coagulopathy.
Question 6
In multiple sclerosis, which pathophysiologic process best explains the
characteristic relapsing-remitting course?
A. Continuous viral infection of oligodendrocytes
B. Autoimmune demyelination with remyelination attempts
C. Primary axonal degeneration without inflammation
D. Ischemic infarction of white matter tracts
Correct Answer: B - Autoimmune demyelination with
Page 4
A patient with chronic hypertension develops left ventricular hypertrophy.
Which molecular mechanism best explains the transition from compensated
hypertrophy to heart failure?
A. Upregulation of -adrenergic receptors enhancing contractility
B. Switch from -myosin heavy chain to -myosin heavy chain isoform
C. Increased capillary density matching myocyte growth
D. Downregulation of fetal gene program and decreased fibrosis
Correct Answer: B - Switch from -myosin heavy chain to -myosin
heavy chain isoform
RATIONALE
The fetal gene program reactivation, including a shift from - to
-myosin heavy chain, reduces ATPase activity and contractile
efficiency, contributing to heart failure. Other options are incorrect:
-receptor upregulation is not typical; capillary density does not
increase proportionally; and fetal gene program is upregulated, not
downregulated.
Question 2
In acute respiratory distress syndrome (ARDS), which pathophysiologic
alteration primarily contributes to refractory hypoxemia?
A. Increased alveolar dead space due to pulmonary embolism
B. Intrapulmonary shunt from alveolar flooding and collapse
C. Hypoventilation from respiratory muscle fatigue
D. Diffusion limitation from thickened alveolar membrane alone
Correct Answer: B - Intrapulmonary shunt from alveolar
flooding and collapse
Page 2
, RATIONALE
ARDS causes non-cardiogenic pulmonary edema and alveolar
collapse, leading to intrapulmonary shunting where blood bypasses
ventilated alveoli, causing refractory hypoxemia. While diffusion
limitation and dead space can occur, shunt is the primary mechanism;
hypoventilation is not the main cause.
Question 3
Which renal pathology is most consistent with the following urinalysis: muddy
brown casts, granular casts, and fractional excretion of sodium (FENa) > 2%?
A. Prerenal azotemia from dehydration
B. Acute tubular necrosis (ATN)
C. Acute interstitial nephritis
D. Glomerulonephritis
Correct Answer: B - Acute tubular necrosis (ATN)
RATIONALE
Muddy brown casts and FENa >2% are classic for ATN, indicating
tubular injury and impaired sodium reabsorption. Prerenal azotemia
typically has FENa <1% and hyaline casts; interstitial nephritis shows
white cell casts and eosinophils; glomerulonephritis presents with red
cell casts and proteinuria.
Question 4
A patient with type 1 diabetes presents with ketoacidosis. Which mechanism
explains the hyperglycemia despite insulin deficiency?
A. Increased glucose uptake by insulin-sensitive tissues
B. Enhanced glycogen synthesis in the liver
C. Unrestrained gluconeogenesis and glycogenolysis
D. Decreased glucagon secretion
Correct Answer: C - Unrestrained gluconeogenesis and
glycogenolysis
Page 3
, RATIONALE
Insulin deficiency leads to unopposed glucagon action, promoting
gluconeogenesis and glycogenolysis, causing hyperglycemia. Other
options are incorrect: glucose uptake is decreased, glycogen synthesis
is reduced, and glucagon is elevated, not decreased.
Question 5
Which hematologic finding is most characteristic of disseminated intravascular
coagulation (DIC)?
A. Elevated platelet count and prolonged PT/PTT
B. Decreased D-dimer and normal fibrinogen
C. Thrombocytopenia, elevated D-dimer, and decreased fibrinogen
D. Isolated prolonged bleeding time with normal platelets
Correct Answer: C - Thrombocytopenia, elevated D-dimer, and
decreased fibrinogen
RATIONALE
DIC involves widespread activation of coagulation, leading to
consumption of platelets and clotting factors, resulting in
thrombocytopenia, elevated D-dimer (from fibrinolysis), and low
fibrinogen. Other options do not reflect the consumptive
coagulopathy.
Question 6
In multiple sclerosis, which pathophysiologic process best explains the
characteristic relapsing-remitting course?
A. Continuous viral infection of oligodendrocytes
B. Autoimmune demyelination with remyelination attempts
C. Primary axonal degeneration without inflammation
D. Ischemic infarction of white matter tracts
Correct Answer: B - Autoimmune demyelination with
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