, Question 1
A patient with severe chronic obstructive pulmonary disease (COPD) exhibits a
flattened diaphragm and increased residual volume. Which of the following
best explains the primary mechanism for their impaired gas exchange?
A. Decreased alveolar surface area due to destruction of alveolar walls.
B. Increased airway resistance leading to air trapping and hyperinflation.
C. Reduced pulmonary capillary blood flow causing ventilation-perfusion
mismatch.
D. Impaired diffusion of oxygen across the thickened alveolar-capillary
membrane.
Correct Answer: B - Increased airway resistance leading to air
trapping and hyperinflation.
RATIONALE
In COPD, increased airway resistance due to inflammation and mucus
leads to air trapping, hyperinflation, and flattened diaphragm, which
impairs ventilation and gas exchange. While alveolar destruction
(emphysema) and V/Q mismatch also occur, the primary mechanism
in this scenario is airway resistance and air trapping.
Question 2
A patient with chronic kidney disease has a glomerular filtration rate (GFR) of
25 mL/min. Which of the following changes in serum electrolyte levels is most
likely to be observed due to impaired renal function?
A. Hyperkalemia and hyperphosphatemia
B. Hypokalemia and hypophosphatemia
C. Hypernatremia and hypocalcemia
D. Hyponatremia and hypercalcemia
Correct Answer: A - Hyperkalemia and hyperphosphatemia
Page 2
, RATIONALE
In CKD, reduced GFR leads to decreased potassium excretion
(hyperkalemia) and decreased phosphate excretion
(hyperphosphatemia). Additionally, decreased activation of vitamin D
leads to hypocalcemia, but hyperkalemia and hyperphosphatemia are
classic.
Question 3
Which of the following statements accurately describes the role of the
sarcoplasmic reticulum in skeletal muscle contraction?
A. It stores acetylcholine and releases it upon stimulation.
B. It sequesters calcium ions and releases them during
excitation-contraction coupling.
C. It generates ATP through oxidative phosphorylation to power
contraction.
D. It provides structural support by anchoring myosin filaments.
Correct Answer: B - It sequesters calcium ions and releases them
during excitation-contraction coupling.
RATIONALE
The sarcoplasmic reticulum stores calcium and releases it in response
to an action potential, triggering muscle contraction. Acetylcholine is
stored in synaptic vesicles, ATP is generated in mitochondria, and
structural support is provided by the cytoskeleton.
Question 4
A patient presents with a tumor in the adrenal medulla causing excessive
secretion of catecholamines. Which of the following cardiovascular changes is
most directly attributable to epinephrine's action on beta-adrenergic receptors?
A. Increased heart rate and contractility
B. Vasoconstriction of skeletal muscle arterioles
C. Decreased cardiac output
Page 3
, D. Bradycardia and hypotension
Correct Answer: A - Increased heart rate and contractility
RATIONALE
Epinephrine binding to beta-1 adrenergic receptors on the heart
increases heart rate and contractility, leading to increased cardiac
output. Alpha-adrenergic receptors mediate vasoconstriction, and
beta-2 receptors cause vasodilation in skeletal muscle.
Question 5
Which of the following best explains why the gastric mucosal barrier is more
susceptible to damage by nonsteroidal anti-inflammatory drugs (NSAIDs)?
A. NSAIDs increase gastric acid secretion by directly stimulating parietal
cells.
B. NSAIDs inhibit cyclooxygenase, reducing prostaglandin synthesis and
mucus/bicarbonate secretion.
C. NSAIDs enhance the secretion of intrinsic factor, which erodes the
mucosa.
D. NSAIDs promote the release of histamine from enterochromaffin-like
cells.
Correct Answer: B - NSAIDs inhibit cyclooxygenase, reducing
prostaglandin synthesis and mucus/bicarbonate secretion.
RATIONALE
NSAIDs inhibit COX enzymes, decreasing prostaglandins that
normally stimulate mucus and bicarbonate secretion and maintain
mucosal blood flow, thus weakening the barrier. They do not directly
stimulate acid secretion or intrinsic factor.
Question 6
A patient with a spinal cord injury at T6 exhibits autonomic dysreflexia. Which
of the following mechanisms best explains the severe hypertension observed?
Page 4
A patient with severe chronic obstructive pulmonary disease (COPD) exhibits a
flattened diaphragm and increased residual volume. Which of the following
best explains the primary mechanism for their impaired gas exchange?
A. Decreased alveolar surface area due to destruction of alveolar walls.
B. Increased airway resistance leading to air trapping and hyperinflation.
C. Reduced pulmonary capillary blood flow causing ventilation-perfusion
mismatch.
D. Impaired diffusion of oxygen across the thickened alveolar-capillary
membrane.
Correct Answer: B - Increased airway resistance leading to air
trapping and hyperinflation.
RATIONALE
In COPD, increased airway resistance due to inflammation and mucus
leads to air trapping, hyperinflation, and flattened diaphragm, which
impairs ventilation and gas exchange. While alveolar destruction
(emphysema) and V/Q mismatch also occur, the primary mechanism
in this scenario is airway resistance and air trapping.
Question 2
A patient with chronic kidney disease has a glomerular filtration rate (GFR) of
25 mL/min. Which of the following changes in serum electrolyte levels is most
likely to be observed due to impaired renal function?
A. Hyperkalemia and hyperphosphatemia
B. Hypokalemia and hypophosphatemia
C. Hypernatremia and hypocalcemia
D. Hyponatremia and hypercalcemia
Correct Answer: A - Hyperkalemia and hyperphosphatemia
Page 2
, RATIONALE
In CKD, reduced GFR leads to decreased potassium excretion
(hyperkalemia) and decreased phosphate excretion
(hyperphosphatemia). Additionally, decreased activation of vitamin D
leads to hypocalcemia, but hyperkalemia and hyperphosphatemia are
classic.
Question 3
Which of the following statements accurately describes the role of the
sarcoplasmic reticulum in skeletal muscle contraction?
A. It stores acetylcholine and releases it upon stimulation.
B. It sequesters calcium ions and releases them during
excitation-contraction coupling.
C. It generates ATP through oxidative phosphorylation to power
contraction.
D. It provides structural support by anchoring myosin filaments.
Correct Answer: B - It sequesters calcium ions and releases them
during excitation-contraction coupling.
RATIONALE
The sarcoplasmic reticulum stores calcium and releases it in response
to an action potential, triggering muscle contraction. Acetylcholine is
stored in synaptic vesicles, ATP is generated in mitochondria, and
structural support is provided by the cytoskeleton.
Question 4
A patient presents with a tumor in the adrenal medulla causing excessive
secretion of catecholamines. Which of the following cardiovascular changes is
most directly attributable to epinephrine's action on beta-adrenergic receptors?
A. Increased heart rate and contractility
B. Vasoconstriction of skeletal muscle arterioles
C. Decreased cardiac output
Page 3
, D. Bradycardia and hypotension
Correct Answer: A - Increased heart rate and contractility
RATIONALE
Epinephrine binding to beta-1 adrenergic receptors on the heart
increases heart rate and contractility, leading to increased cardiac
output. Alpha-adrenergic receptors mediate vasoconstriction, and
beta-2 receptors cause vasodilation in skeletal muscle.
Question 5
Which of the following best explains why the gastric mucosal barrier is more
susceptible to damage by nonsteroidal anti-inflammatory drugs (NSAIDs)?
A. NSAIDs increase gastric acid secretion by directly stimulating parietal
cells.
B. NSAIDs inhibit cyclooxygenase, reducing prostaglandin synthesis and
mucus/bicarbonate secretion.
C. NSAIDs enhance the secretion of intrinsic factor, which erodes the
mucosa.
D. NSAIDs promote the release of histamine from enterochromaffin-like
cells.
Correct Answer: B - NSAIDs inhibit cyclooxygenase, reducing
prostaglandin synthesis and mucus/bicarbonate secretion.
RATIONALE
NSAIDs inhibit COX enzymes, decreasing prostaglandins that
normally stimulate mucus and bicarbonate secretion and maintain
mucosal blood flow, thus weakening the barrier. They do not directly
stimulate acid secretion or intrinsic factor.
Question 6
A patient with a spinal cord injury at T6 exhibits autonomic dysreflexia. Which
of the following mechanisms best explains the severe hypertension observed?
Page 4
