Thyroid Physiology Terms

Question 1

total T4 (TT4)

Answer 1

concentration of free T4 plus protein-bound T4

Question 2

total T3 (TT3)

Answer 2

concentration of free T3 plus protein-bound T3

Question 3

free T4 (FT4)

Answer 3

concentration of free T4

Question 4

free T3 (FT3)

Answer 4

concentration of free T3

Question 5

thyroid stimulating hormone (TSH)

Answer 5

helpful in differentiating the causes of hypothyroidism

Question 6

T4 autoantibodies (T4AA)

Answer 6

antibodies, produced by lymphocytes/plasma cells, directed against T4; indicative of thyroid gland inflammation

Question 7

T3 autoantibodies (T3AA)

Answer 7

antibodies, produced by lymphocytes/plasma cells, directed against T3; indicative of thyroid gland inflammation

Question 8

thyroglobulin autoantibodies (TgAA)

Answer 8

antibodies, produced by lymphocytes/plasma cells, directed against thyroglobulin; indicative of thyroid gland inflammation

Question 9

cathepsins

Answer 9

lysosomal enzymes that catalyze the hydrolysis of peptide bonds; in the thyroid follicuar cell, cathepsins hydrolyze thyroglobulin, liberating T3 and T4

Question 10

Na+/I- symporters (NIS)

Answer 10

an integral (transmembrane) protein located within the basolateral membrane of thyroid follicular epithelial cells; the NIS simulstaneously transports sodium cations and iodide anions into the follicular epithelial cell; NIS-mediated uptake of iodide into the follicular epithelial cells that is the first step in the syntheis of thyroid hormones

Question 11

pendrin

Answer 11

an integral (transmembrane) protein located within the apical (luminal) membrane of thyroid follicular cells; it transports iodide into the follicular lumen

Question 12

goiter

Answer 12

any abnormal enlargement of the thyroid gland; an animal with a goiter may be hypothyroid, hyperthyroid, or euthyroid (meaning no specific function is pathogonomic of goiter)