Thyroid Hormone

Dr. Sadaf Mumtaz25/02/11

Microscopic appearance of thyroid gland

Thyroid cellular mechanisms

Regulation of thyroid secretion

Effect of cold and other neurogenic stimuli on TRH and TSH secretion

Effects of TSH on thyroid functions

• Increased proteolysis of the thyroglobulin• Increased activity of iodide pump• Increased iodination of tyrosine• Increased size and secretory activity of thyroid

cells• Increased number of thyroid cells

MCQ’s• The metabolic effect is least affected by an increase in the plasma level

of

a) TSH

b) TRH

c) TBG

d) Free T4

e) Free T3

• Which of the following is not essential for normal biosynthesis of thyroid hormones?

a) Iodine

b) Ferritin

c) Thyroglobulin

d) Protein synthesis

e) TSH

• Which of the following would be least affected by injections of TSH?a) Thyroidal uptake of iodineb) Synthesis of thyroglobulinc) cAMP in thyroid cellsd) cGMP in thyroid cellse) Size of thyroid

• Increasing intracellular Iodine due to the action of NIS is an example of a) Endocytosisb) Passive diffusionc) Na and K cotransportd) Primary active transporte) Secondary active transport

• Thyroid hormone receptor bind to DNA in which of the following forms?a) A heterodimer with prolactin receptorb) A heterodimer with GH receptorc) A heterodimer with retinoid X receptord) A heterodimer with insulin receptore) A heterodimer with progesterone receptor

ThanksGrasmere 20-03-10