Thyroid Gland and Thyroid Hormones

Question 1

What is Grave’s Disease?

Answer 1

Enlargement of the the Thyroid Gland as a result of hyperthroidism:
Increased sweating
Increased metabolism
Bradycardia

Question 2

Region of the remenant thyroglossal duct is normally a result of what embryonic structure?

Answer 2

Foramen Cecum

nb: located at the back of the sulcus terminalis

Question 3

What is the major protein that transports thyroglobulin into colloid space in the thyroid?

Answer 3

Pendrin

Question 4

Role of Thyroid Peroxidase

Answer 4

Puts I- onto tyrosine residue

Question 5

Role of Dual Oxidase

Answer 5

Preps Iodine for addition to tyrosine

Question 6

Major Amino Acid on naive thyroid globulin?

Answer 6

Tyrosine

Question 7

Relationship between TSH and Free T4

Answer 7

High Free T4 results in low TSH

Low Free T4 results in high TSH

Question 8

TSH binding to receptor has the following effects within the cell

Answer 8

1. Increases endocytosis of thyroglobulin
2. Increases production of thyroid peroxidase
3. Increases Na/I symporter

Question 9

TSH binding to receptor has the following synthesis effects within the cell

Answer 9

1. Increased Na/I (NIS) Symporter
2. Increases Gs/Gq on plasma membrane
3. Increased Dual oxidase and Thyroid Peroxidase

Question 10

Reason why high levels of Iodine inhibit Thyroid Hormone Production?

Answer 10

I occupies both active sites of thyroid peroxidase

Question 11

Mechanism of Amidarone

Answer 11

Inhibits deiodinase from changing T4 to T3

Question 12

Which deiodinase is found in the liver and kidney and provides the majority of serum T3?

Answer 12

D1

Question 13

Which deiodinase is capable of inactivating T4 and T3?

Answer 13

D3
T4 (3,5,3’,5’) to rT3 (3,5’,3’)
T3 (3,5,3’) to T2 (3,3’)

Question 14

T3 effects on metabolism?

Answer 14

Increases ATP
Decreases efficiency of ATP use (generate Heat)
Decrease efficiency of ATP synthesis (generates heat)
Increase glucose, FFA and protein utilization
Promotes futile cycles