Regulation of Thyroid Secretion

20 questions • 1 test • tap a section to begin

Welcome! 5.2 Regulation of Thyroid Secretion — 20 questions, CSIR-NET style.

What this test covers

  • TRH → TSH → T3/T4 (cAMP at the gland)
  • T3 negative feedback on the pituitary
  • Thyroid-stimulating immunoglobulins (Graves)
  • TSH effects on gland growth

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5.2 Regulation of Thyroid Secretion — Test 1
Q1. TSH increases thyroid hormone synthesis and secretion by acting through:✓ The adenylate cyclase-cAMP mechanism
Q2. TRH from the hypothalamus stimulates the anterior pituitary to secrete:✓ TSH (and prolactin)
Q3. T3 inhibits TSH secretion mainly by:✓ Downregulating TRH receptors on the anterior pituitary
Q4. In Graves disease, the thyroid is overstimulated by:✓ Thyroid-stimulating immunoglobulins (antibodies to the TSH receptor)
Q5. In Graves disease, the serum TSH level is:✓ Decreased (feedback from high thyroid hormone)
Q6. Chronic elevation of TSH (e.g. in iodine deficiency) causes:✓ Hypertrophy/enlargement of the thyroid gland (goitre)
Q7. Match each component with its role in the thyroid axis and choose the correct option.✓ A-iii, B-ii, C-i
Q8. In primary hypothyroidism (gland failure), the laboratory pattern is:✓ High TSH with low T4
Q9. Thyroid-stimulating immunoglobulins belong to which class of plasma proteins?✓ IgG
Q10. A patient with low TSH AND low free T4 most likely has:✓ Central (secondary) hypothyroidism
Q11. Each step of thyroid hormone synthesis (trapping, organification, release) is stimulated by:✓ TSH
Q12. Why is TSH low in Graves disease despite an overactive thyroid?✓ High circulating thyroid hormone suppresses the pituitary by feedback
Q13. TSH-receptor stimulating antibodies that cross the placenta can cause:✓ Transient neonatal hyperthyroidism
Q14. The trophic (growth) effect of TSH on the thyroid is mediated by:✓ cAMP signalling driving gland hypertrophy
Q15. In a person taking excess thyroxine, the expected feedback effect is:✓ Suppressed TSH and reduced endogenous thyroid output
Q16. The hypothalamic-pituitary-thyroid axis is an example of:✓ A negative-feedback hormonal axis
Q17. Subclinical hypothyroidism is characterised by:✓ Raised TSH with normal free T4
Q18. In Graves disease, why does the thyroid gland enlarge (goitre)?✓ Stimulating antibodies act like TSH, driving growth
Q19. The second messenger used by TSH at the thyroid follicular cell is:✓ cAMP
Q20. A TSH-secreting pituitary adenoma would show:✓ High TSH with high free T4 (no feedback suppression)