07 Thyroid and Parathyroid Anatomy

Question 1

What is the embryologic origin of thyroid

Answer 1

Median downgrowth of the 1st and 2nd pharyngeal pouches in the area of the foramen cecum

Question 2

What is the embryologic origin of PT glands

Answer 2

Superior from 4th pharyngeal POUCH; inferior from 3rd pharyngeal POUCH

Question 3

What is the predominant glycoprotein found in colloid?

Answer 3

Thyroglobulin

Question 4

What is the function of pendrin

Answer 4

Mediates exchange of iodide from the thyrocyte to the colloid, which is one of the first steps of thyroid hormone synthesis

Question 5

What is the NIS

Answer 5

A Na+/I- symporter that serves to concentrate I- into cells. It is found in the thyroid gland, salivary glands, gastric mucosa, placenta, ciliary body of the eye, choroid plexus, mammary glands, and certain cancers. Except for the thyroid gland, the NIS in these tissues does not respond to TSH

Question 6

What are 3 plasma proteins that bind thyroid hormones

Answer 6

albumin, transthyretin, and throxine-binding globulin (TBG)

Question 7

What percent of population has more than 4 PT glands

Answer 7

10%

Question 8

What percent of population has 3 PT glands

Answer 8

3%

Question 9

What percent of PT glands are in the mediastinum

Answer 9

2%

Question 10

Where are the inferior PT glands typically located

Answer 10

Inferior and anterior to the inferior thyroid arter

Question 11

Where are the superior PT glands typically located

Answer 11

Superior and posterior to the inferior thyroid artery

Question 12

What types of cells are in PT glands

Answer 12

chief cells, clear cells, oxyphil cells

Question 13

Which terminal of PTH is active

Answer 13

N-terminal