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6.2 Glucocorticoid Regulation — Test 1
Q1. The hypothalamic hormone that drives the cortisol axis is:✓ CRH (corticotropin-releasing hormone)
Q2. ACTH increases steroid synthesis in the adrenal by stimulating:✓ Cholesterol desmolase (cholesterol -> pregnenolone)
Q3. Cortisol secretion shows a circadian rhythm with levels highest:✓ Just before waking (early morning)
Q4. Cortisol exerts negative feedback by inhibiting:✓ CRH (hypothalamus) and ACTH (pituitary)
Q5. The dexamethasone suppression test is based on the fact that dexamethasone:✓ Inhibits ACTH secretion (suppressing cortisol) in normal individuals
Q6. The second messenger for both CRH (at the pituitary) and ACTH (at the adrenal) is:✓ cAMP
Q7. Match each component with its action and choose the correct option.✓ A-iii, B-ii, C-i
Q8. In a patient with an ACTH-secreting pituitary tumour (Cushing disease), high-dose dexamethasone typically:✓ Partially suppresses cortisol (tumour retains some feedback)
Q9. Stress increases cortisol mainly by increasing the amplitude of:✓ CRH secretory pulses
Q10. Chronically increased ACTH causes the adrenal cortex to:✓ Hypertrophy (enlarge)
Q11. In a patient on long-term exogenous glucocorticoids, endogenous ACTH and the adrenal cortex are:✓ Suppressed and atrophic
Q12. The 'internal clock' that drives the cortisol rhythm is abolished by:✓ Coma or constant light/dark exposure
Q13. Why does a single random cortisol level poorly diagnose adrenal disorders?✓ Cortisol varies with circadian rhythm and stress
Q14. Low-dose dexamethasone failing to suppress cortisol is an early sign of:✓ Cushing syndrome (cortisol excess)
Q15. The diurnal rhythm of cortisol is ultimately directed by:✓ Higher CNS centres driving CRH
Q16. ACTH also upregulates its own receptor, which:✓ Increases adrenal sensitivity to ACTH
Q17. In primary adrenal failure (Addison), ACTH is high because:✓ Low cortisol removes negative feedback
Q18. The cortisol response to surgical stress is mediated by:✓ Increased CRH/ACTH drive
Q19. A patient with an adrenal cortisol-secreting adenoma will have ACTH that is:✓ Low (suppressed by high cortisol)
Q20. The cortisol axis is regulated chiefly by:✓ Negative feedback (cortisol on CRH/ACTH)