Thyroid - Exam 3

Question 1

follicles

Answer 1

circular pattern of epithelial cells

Question 2

colloid

Answer 2

within follicles, viscous protein rich fluid, main storage form of thyroid hormones

Question 3

parafolicullar cell “c cell”

Answer 3

located outside of the follicles, secretes calcitonin, regulate calcium metabolism

Question 4

thyroid hormone production

Answer 4

tyrosine: thyroglobulin, formed within the follicle cell & secreted into the colloid where it is stored until needed

Question 5

iodine

Answer 5

comes from the diet, converted to iodide in intestinal tract, follicle cell traps, active transport process

Question 6

step 1

Answer 6

oxidation of iodide to iodine via TPO thyroid peroxidase

Question 7

step 2

Answer 7

binding of iodide with thyroglobulin molecule “organification”

Question 8

step 3

Answer 8

TPO catalyzes coupling of 2 of these iodinated thyrosines

Question 9

1 DIT + 1 DIT =

Answer 9

T4 (thyroxine); most abundant

Question 10

1 MIT + 1 DIT =

Answer 10

T3 (triiodothyronine)

Question 11

increase of thyroxine =

Answer 11

decrease of TSH

Question 12

secretion of thyroid hormone

Answer 12

endocytosis via lysosomal enzymes, T3 and T4 freely pass through membrane, MIT and DIT recycled to form new hormones

Question 13

thyroid gland regulation

Answer 13

secreted after stimulation by TSH which is released from adenohypophysis, TRH released from hypothalamus, transported in plasma attached to proteins (TBG & albumin)