WGU D236 Pathophysiology OA Actual Exam
2026/2027 | Questions with Verified Answers |
100% Correct | Pass Guaranteed
SECTION 1: Cellular Biology & Foundations
Q1: A patient presents with severe diarrhea. Arterial blood gas reveals: pH 7.28, PaCO₂
38 mm Hg, HCO₃⁻ 16 mEq/L. What is the primary pathophysiological process?
A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis
Correct Answer: C
Rationale: Disease/Process: Metabolic acidosis due to bicarbonate loss.
Pathophysiological Sequence: Severe diarrhea (etiology) causes excessive loss of
bicarbonate-rich intestinal fluids (pathogenesis). This depletes the body's base buffer
(HCO₃⁻), leading to an increase in H⁺ concentration and a low pH with a correspondingly
low HCO₃⁻ (clinical manifestation/ABG finding). The normal PaCO₂ indicates the lungs
are not compensating yet. Distractor Analysis: A & B are incorrect because the primary
disturbance is metabolic (abnormal HCO₃⁻), not respiratory (PaCO₂ is normal). D is
incorrect because diarrhea causes acid gain/base loss, not alkali gain.
,Q2: A patient with SIADH develops confusion. Serum Na⁺ is 118 mEq/L. Which
mechanism is primarily responsible for the neurological symptoms?
A. Osmotic demyelination from rapid sodium shifts
B. Water movement into brain cells causing cerebral edema
C. Neuronal dehydration and shrinkage
D. Hypoxic injury due to vascular collapse
Correct Answer: B
Rationale: Disease/Process: Hyponatremia due to SIADH. Pathophysiological Sequence:
SIADH (etiology) causes excessive water retention (pathogenesis), diluting serum
sodium. The resulting hypotonicity drives water movement from the extracellular space
into the intracellular space along an osmotic gradient, causing cerebral edema
(pathogenesis), which manifests as confusion and can progress to seizures/coma
(clinical manifestations). Distractor Analysis: A occurs during rapid correction, not the
primary hyponatremia. C is opposite (hypernatremia). D is unrelated; hyponatremia does
not cause hypoxia.
Q3: A genetic defect results in a faulty sodium-potassium pump (Na⁺/K⁺ ATPase).
Which cellular event is most likely to occur?
A. Increased intracellular potassium and cell shrinkage
B. Cellular swelling due to accumulation of sodium and water
C. Decreased intracellular sodium and apoptosis
D. No change in cell volume due to compensatory mechanisms
,Correct Answer: B
Rationale: Disease/Process: Cellular swelling due to pump failure. Pathophysiological
Sequence: The Na⁺/K⁺ ATPase (etiology defect) normally pumps 3 Na⁺ out and 2 K⁺ in,
maintaining osmotic balance. Failure (pathogenesis) causes intracellular Na⁺
accumulation, creating an osmotic gradient that draws water into the cell
(pathogenesis), leading to cellular swelling (clinical manifestation). Distractor Analysis:
A is opposite; K⁺ would leak out. C is incorrect; Na⁺ would accumulate. D is incorrect;
pump failure overwhelms compensation.
Q4: A patient with chronic kidney disease develops hyperphosphatemia. Which
compensatory mechanism is activated to lower serum phosphate?
A. Increased renal phosphate reabsorption
B. Increased secretion of FGF-23 from bone
C. Decreased parathyroid hormone release
D. Increased activation of vitamin D
Correct Answer: B
Rationale: Disease/Process: CKD-mineral bone disorder. Pathophysiological Sequence:
Hyperphosphatemia (etiology) stimulates osteocytes to secrete fibroblast growth
factor-23 (FGF-23) (pathogenesis), which inhibits renal phosphate reabsorption
(pathogenesis) and suppresses vitamin D activation (pathogenesis), attempting to
lower serum phosphate (clinical goal). Distractor Analysis: A is opposite; reabsorption
would worsen hyperphosphatemia. C is incorrect; PTH would increase. D is incorrect;
FGF-23 suppresses 1-α-hydroxylase, decreasing active vitamin D.
, Q5: A patient with heatstroke develops rhabdomyolysis. Which pathophysiological
process is primarily responsible for acute kidney injury?
A. Myoglobin precipitation in renal tubules causing obstruction and oxidative damage
B. Hypovolemia leading to cortical necrosis
C. Immune complex deposition in glomeruli
D. Decreased ADH secretion
Correct Answer: A
Rationale: Disease/Process: Rhabdomyolysis-induced AKI. Pathophysiological
Sequence: Heatstroke (etiology) causes muscle breakdown (pathogenesis), releasing
myoglobin into the bloodstream. In acidic urine, myoglobin precipitates in the renal
tubules (pathogenesis), causing obstruction and releasing free iron, which generates
reactive oxygen species and tubular injury (pathogenesis), manifesting as AKI (clinical
manifestation). Distractor Analysis: B contributes but is not primary. C is unrelated. D is
incorrect; ADH is not involved.
Q6: A patient with diabetic ketoacidosis receives excessive insulin and develops
hypokalemia. Which ECG change is most characteristic?
A. Peaked T waves
B. U waves and flattened T waves
C. Widened QRS complexes
D. Shortened QT interval
Correct Answer: B
2026/2027 | Questions with Verified Answers |
100% Correct | Pass Guaranteed
SECTION 1: Cellular Biology & Foundations
Q1: A patient presents with severe diarrhea. Arterial blood gas reveals: pH 7.28, PaCO₂
38 mm Hg, HCO₃⁻ 16 mEq/L. What is the primary pathophysiological process?
A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis
Correct Answer: C
Rationale: Disease/Process: Metabolic acidosis due to bicarbonate loss.
Pathophysiological Sequence: Severe diarrhea (etiology) causes excessive loss of
bicarbonate-rich intestinal fluids (pathogenesis). This depletes the body's base buffer
(HCO₃⁻), leading to an increase in H⁺ concentration and a low pH with a correspondingly
low HCO₃⁻ (clinical manifestation/ABG finding). The normal PaCO₂ indicates the lungs
are not compensating yet. Distractor Analysis: A & B are incorrect because the primary
disturbance is metabolic (abnormal HCO₃⁻), not respiratory (PaCO₂ is normal). D is
incorrect because diarrhea causes acid gain/base loss, not alkali gain.
,Q2: A patient with SIADH develops confusion. Serum Na⁺ is 118 mEq/L. Which
mechanism is primarily responsible for the neurological symptoms?
A. Osmotic demyelination from rapid sodium shifts
B. Water movement into brain cells causing cerebral edema
C. Neuronal dehydration and shrinkage
D. Hypoxic injury due to vascular collapse
Correct Answer: B
Rationale: Disease/Process: Hyponatremia due to SIADH. Pathophysiological Sequence:
SIADH (etiology) causes excessive water retention (pathogenesis), diluting serum
sodium. The resulting hypotonicity drives water movement from the extracellular space
into the intracellular space along an osmotic gradient, causing cerebral edema
(pathogenesis), which manifests as confusion and can progress to seizures/coma
(clinical manifestations). Distractor Analysis: A occurs during rapid correction, not the
primary hyponatremia. C is opposite (hypernatremia). D is unrelated; hyponatremia does
not cause hypoxia.
Q3: A genetic defect results in a faulty sodium-potassium pump (Na⁺/K⁺ ATPase).
Which cellular event is most likely to occur?
A. Increased intracellular potassium and cell shrinkage
B. Cellular swelling due to accumulation of sodium and water
C. Decreased intracellular sodium and apoptosis
D. No change in cell volume due to compensatory mechanisms
,Correct Answer: B
Rationale: Disease/Process: Cellular swelling due to pump failure. Pathophysiological
Sequence: The Na⁺/K⁺ ATPase (etiology defect) normally pumps 3 Na⁺ out and 2 K⁺ in,
maintaining osmotic balance. Failure (pathogenesis) causes intracellular Na⁺
accumulation, creating an osmotic gradient that draws water into the cell
(pathogenesis), leading to cellular swelling (clinical manifestation). Distractor Analysis:
A is opposite; K⁺ would leak out. C is incorrect; Na⁺ would accumulate. D is incorrect;
pump failure overwhelms compensation.
Q4: A patient with chronic kidney disease develops hyperphosphatemia. Which
compensatory mechanism is activated to lower serum phosphate?
A. Increased renal phosphate reabsorption
B. Increased secretion of FGF-23 from bone
C. Decreased parathyroid hormone release
D. Increased activation of vitamin D
Correct Answer: B
Rationale: Disease/Process: CKD-mineral bone disorder. Pathophysiological Sequence:
Hyperphosphatemia (etiology) stimulates osteocytes to secrete fibroblast growth
factor-23 (FGF-23) (pathogenesis), which inhibits renal phosphate reabsorption
(pathogenesis) and suppresses vitamin D activation (pathogenesis), attempting to
lower serum phosphate (clinical goal). Distractor Analysis: A is opposite; reabsorption
would worsen hyperphosphatemia. C is incorrect; PTH would increase. D is incorrect;
FGF-23 suppresses 1-α-hydroxylase, decreasing active vitamin D.
, Q5: A patient with heatstroke develops rhabdomyolysis. Which pathophysiological
process is primarily responsible for acute kidney injury?
A. Myoglobin precipitation in renal tubules causing obstruction and oxidative damage
B. Hypovolemia leading to cortical necrosis
C. Immune complex deposition in glomeruli
D. Decreased ADH secretion
Correct Answer: A
Rationale: Disease/Process: Rhabdomyolysis-induced AKI. Pathophysiological
Sequence: Heatstroke (etiology) causes muscle breakdown (pathogenesis), releasing
myoglobin into the bloodstream. In acidic urine, myoglobin precipitates in the renal
tubules (pathogenesis), causing obstruction and releasing free iron, which generates
reactive oxygen species and tubular injury (pathogenesis), manifesting as AKI (clinical
manifestation). Distractor Analysis: B contributes but is not primary. C is unrelated. D is
incorrect; ADH is not involved.
Q6: A patient with diabetic ketoacidosis receives excessive insulin and develops
hypokalemia. Which ECG change is most characteristic?
A. Peaked T waves
B. U waves and flattened T waves
C. Widened QRS complexes
D. Shortened QT interval
Correct Answer: B
