FPGEE Pathophysiology — Questions and Answers
Question 1: Which pathophysiological mechanism primarily underlies the development of type 2 diabetes mellitus?
- Autoimmune destruction of beta cells
- Insulin resistance combined with progressive beta-cell dysfunction (Correct answer)
- Absolute insulin deficiency due to pancreatectomy
- Excessive glucagon secretion without insulin resistance
Correct answer: Insulin resistance combined with progressive beta-cell dysfunction
Type 2 DM is characterized by peripheral insulin resistance and gradual decline in pancreatic beta-cell secretory capacity, unlike the autoimmune destruction seen in type 1 DM.
Question 2: In heart failure with reduced ejection fraction (HFrEF), which compensatory mechanism initially helps maintain cardiac output but ultimately worsens cardiac remodeling?
- Decreased renin release
- Activation of the renin-angiotensin-aldosterone system (RAAS) (Correct answer)
- Parasympathetic nervous system activation
- Decreased antidiuretic hormone secretion
Correct answer: Activation of the renin-angiotensin-aldosterone system (RAAS)
RAAS activation causes fluid retention and vasoconstriction that initially compensates for low output, but chronic activation promotes maladaptive cardiac hypertrophy and fibrosis.
Question 3: A patient with chronic kidney disease develops anemia. What is the primary pathophysiological reason?
- Iron deficiency due to poor dietary intake
- Decreased erythropoietin production by the diseased kidneys (Correct answer)
- Hemolysis caused by uremic toxins primarily
- Vitamin B12 malabsorption secondary to renal tubular damage
Correct answer: Decreased erythropoietin production by the diseased kidneys
The peritubular interstitial cells of the kidney are the primary source of erythropoietin; CKD destroys these cells, reducing EPO production and thereby red cell production.
Question 4: Which of the following best describes the pathophysiology of asthma?
- Irreversible destruction of alveolar walls leading to air trapping
- Reversible airway inflammation and bronchospasm driven by Th2-mediated hypersensitivity (Correct answer)
- Neutrophilic inflammation causing permanent airway remodeling
- Mucus plug obstruction without underlying inflammation
Correct answer: Reversible airway inflammation and bronchospasm driven by Th2-mediated hypersensitivity
Asthma involves a Th2 lymphocyte-driven inflammatory response with eosinophil recruitment, mast cell degranulation, and reversible bronchoconstriction, distinguishing it from COPD.
Question 5: In atherosclerosis, which event is considered the earliest pathological change in the arterial wall?
- Calcification of the tunica media
- Accumulation of oxidized LDL and foam cell formation in the intima (Correct answer)
- Smooth muscle cell proliferation into the lumen
- Thrombosis over a ruptured plaque
Correct answer: Accumulation of oxidized LDL and foam cell formation in the intima
The fatty streak, formed by oxidized LDL being engulfed by macrophages to form foam cells in the subintimal space, is the earliest lesion in atherosclerosis.
Question 6: A patient presents with polyuria, polydipsia, and hyponatremia. MRI shows a pituitary tumor. Which pathophysiological defect best explains the polyuria?
- Excess ADH production causing water retention and dilutional hyponatremia
- Deficient ADH secretion leading to inability to concentrate urine (Correct answer)
- Primary polydipsia resetting the osmotic threshold
- Aldosterone excess causing potassium wasting and water loss
Correct answer: Deficient ADH secretion leading to inability to concentrate urine
A pituitary lesion can disrupt ADH (vasopressin) synthesis or secretion, causing central diabetes insipidus with hypotonic polyuria and compensatory polydipsia.
Question 7: Which mechanism explains the hypercalcemia seen in primary hyperparathyroidism?
- Decreased calcitonin secretion by thyroid C-cells
- Excess PTH stimulating osteoclast activity, renal calcium reabsorption, and calcitriol synthesis (Correct answer)
- Vitamin D toxicity causing excessive intestinal calcium absorption
- Thiazide diuretic-induced reduction of renal calcium excretion
Correct answer: Excess PTH stimulating osteoclast activity, renal calcium reabsorption, and calcitriol synthesis
Excess PTH acts on bone to release calcium via osteoclasts, on the kidney to reabsorb calcium, and induces 1-alpha hydroxylase to increase calcitriol, collectively raising serum calcium.
Question 8: In rheumatoid arthritis, the chronic joint destruction is primarily mediated by:
- Uric acid crystal deposition activating neutrophils in synovial fluid
- Pannus formation driven by synovial fibroblasts and macrophages secreting destructive cytokines (Correct answer)
- Cartilage wear from mechanical overload in weight-bearing joints
- Anti-dsDNA antibodies depositing immune complexes in the joint space
Correct answer: Pannus formation driven by synovial fibroblasts and macrophages secreting destructive cytokines
RA pannus is a hyperplastic synovial tissue containing activated fibroblasts and macrophages that secrete TNF-α, IL-1, IL-6, and metalloproteinases that erode cartilage and bone.
Question 9: A patient with acute pancreatitis develops hypocalcemia. Which mechanism is most responsible?
- Increased renal calcium excretion due to loop diuretic therapy
- Saponification of peripancreatic fat by lipases binding calcium (Correct answer)
- Hypoparathyroidism triggered by pancreatic enzyme activation
- Vitamin D deficiency from pancreatic exocrine insufficiency
Correct answer: Saponification of peripancreatic fat by lipases binding calcium
Released pancreatic lipases cleave peripancreatic fat into fatty acids, which bind calcium ions to form calcium soaps (saponification), sequestering calcium and lowering serum levels.
Question 10: Which pathophysiological event triggers the cascade of cellular injury in ischemia-reperfusion injury?
- Sustained ATP depletion preventing membrane pump recovery
- Rapid restoration of oxygen leading to reactive oxygen species generation and cellular damage (Correct answer)
- Persistent vasoconstriction after reperfusion preventing oxygen delivery
- Inflammatory cytokine release during ischemia before reperfusion
Correct answer: Rapid restoration of oxygen leading to reactive oxygen species generation and cellular damage
Paradoxically, reoxygenation after ischemia produces a burst of ROS from xanthine oxidase and mitochondria, activating proteases and causing endothelial and parenchymal cell damage.
Question 11: In nephrotic syndrome, the edema forms primarily because:
- Increased ADH secretion causes water retention in the collecting duct
- Massive proteinuria lowers plasma oncotic pressure, allowing fluid to shift into interstitial spaces (Correct answer)
- Aldosterone excess causes renal sodium retention as the primary event
- Lymphatic obstruction prevents protein return to the circulation
Correct answer: Massive proteinuria lowers plasma oncotic pressure, allowing fluid to shift into interstitial spaces
Heavy urinary protein loss (>3.5 g/day) depletes albumin, reducing intravascular oncotic pressure and allowing Starling forces to drive fluid out of capillaries into the interstitium.
Question 12: Pernicious anemia is caused by:
- Dietary deficiency of cobalamin due to strict veganism
- Autoimmune destruction of gastric parietal cells impairing intrinsic factor production (Correct answer)
- Ileal Crohn's disease preventing cobalamin absorption
- Metformin therapy blocking intestinal cobalamin uptake receptors
Correct answer: Autoimmune destruction of gastric parietal cells impairing intrinsic factor production
Pernicious anemia is an autoimmune condition with antibodies against parietal cells and/or intrinsic factor, leading to loss of IF and inability to absorb dietary vitamin B12 in the terminal ileum.
Question 13: Which pathophysiological mechanism explains the Somogyi effect in diabetes management?
- Insufficient insulin at bedtime causing morning hyperglycemia
- Nocturnal hypoglycemia triggering counter-regulatory hormone release causing rebound morning hyperglycemia (Correct answer)
- Dawn phenomenon from growth hormone surges at 4–8 AM independent of prior hypoglycemia
- Post-meal insulin resistance causing persistent overnight hyperglycemia
Correct answer: Nocturnal hypoglycemia triggering counter-regulatory hormone release causing rebound morning hyperglycemia
The Somogyi effect involves nocturnal hypoglycemia that triggers glucagon, epinephrine, cortisol, and growth hormone release, causing liver glycogenolysis and rebound morning hyperglycemia.
Question 14: In systemic lupus erythematosus (SLE), glomerulonephritis is primarily caused by:
- T-cell mediated cytotoxic attack on podocytes
- Deposition of anti-dsDNA immune complexes in the glomerular basement membrane activating complement (Correct answer)
- Eosinophilic infiltration of the mesangium from type I hypersensitivity
- Direct binding of antinuclear antibodies to glomerular type IV collagen
Correct answer: Deposition of anti-dsDNA immune complexes in the glomerular basement membrane activating complement
SLE nephritis results from type III hypersensitivity: circulating anti-dsDNA immune complexes deposit in the glomerulus and activate complement (C3, MAC), causing inflammation and structural damage.
