Thyroid Gland - 2/3 Lopez

Question 1

Peripheral conversion of T4 to T3 is done by what enzyme?

Answer 1

Deiodinase

Question 2

What clinical states are associated with a reduction of conversion from T4 to T3?

Answer 2

Fasting
Medical/surgical stress
Catabolic diseases

Question 3

What factors INC conversion of T4 to T3?

Answer 3

Hyperthyroid
Obesity
Cold exposure

HOC

Question 4

What factors DEC conversion of T4 to T3?

Answer 4

Pregnancy 
Fasting
Beta-blockers
Hepatic and renal failure
Aging 
Hypothyroid

ProFootBall HAH

Question 5

What is thyroglobulin synthesized from?

Answer 5

Tyrosine in thyroid follicular cells

Question 6

How is TG packaged and where is TG sent?

Answer 6

Packaged in secretory vesicles and extruded into follicular lumen

Question 7

Where is the iodine pump located?

What does it pump?

Answer 7

Basolateral membrane

2Na and 1 I- INTO the cell

Question 8

What catalyzes the oxidation of I- to I2?

Answer 8

Peroxidase

Question 9

Leftover DIT and MIT are iodinated by what?

Deficiency of this enzyme mimics what?

Answer 9

Thyroid Deiodinase

Dietary I2 deficiency

Question 10

What form is favored when the availability of iodide is restricted?

Answer 10

T3

Question 11

What inhibits the sodium/iodine symporter?

What does this treat?

Answer 11

Perchlorate and thiocynate

Hyperthyroidism

Question 12

What inhibits the peroxidase enzyme?

Answer 12

Propylthiouracil

Question 13

High levels of I- do what?

What is this called?

Answer 13

Inhibit organification and inhibit synthesis of thyroid hormone

Wolff-Chiakoff effect

Question 14

What is the main binding protein of thyroid hormones?

What has a higher affinity for this protein?

Answer 14

TBG

T4

Question 15

What binding protein is in charge of getting thyroid hormones to your brain?

What is the other main binding protein?

Answer 15

Transthyretin (TTR)

Albumin

Question 16

What are TBG, Transient free hormone levels, and T3 resin uptake levels like in hepatic failure?

Answer 16

DEC
INC
INC

Question 17

What are TBG, Transient free hormone, and T3 resin uptake levels like in pregnancy?

Answer 17

INC
DEC
DEC

Question 18

What is TSH regulated by?

Answer 18

TRH

Free T3

Question 19

What enzyme is present in the anterior pituitary that regulates the conversion of T3?

Answer 19

Thyroid deiodinase type 2

Question 20

What is the 2nd messenger for TSH?

Answer 20

cAMP

Question 21

Patients with Graves’ disease have higher or lower than normal levels of TSH? Why?

Answer 21

Lower bc the high levels of circulating thyroid hormones inhibits production of TSH

Question 22

What do T3 and T4 stimulate in cardiac muscle cells?

Answer 22

Myosin
Beta-1-adrenergic receptors
Ca ATPase

Question 23

What nuclear receptor does T3 bind in the nucleus?

Answer 23

Retinoid X receptor

Question 24

What effect does T3 have on growth?

On CNS?

Answer 24

INC growth and bone maturation

Maturation of CNS

Question 25

What effect does T3 have on the heart?

Answer 25

INC CO

Question 26

How does T3/T4 affect BMR?

Answer 26

INC Na-K ATPase INC O2 consumption INC Heat production INC BMR

Question 27

How does T3 affect metabolism?

Answer 27

``` INC glucose absorption INC glycogenolysis INC gluconeogensis INC lipolysis INC protein synthesis ```

Question 28

Patients with hypothyroidism have increased or decreased blood cholesterol levels?

Answer 28

INCREASED [Plasma] of cholesterol and TAGs are inversely correlated with thyroid hormones

Question 29

How does T3 affect tissue thermogenesis? This does what to systemic vascular resistance? what happens next to diastolic BP? Resulting in what in preload and afterload?

Answer 29

INC DEC DEC INC preload, DEC afterload

Question 30

Thyroid hormones stimulate the synthesis of what kind of cardiac receptors?

Answer 30

Beta-1-adrenergic

Question 31

What happens in bone with excess thyroid hormone? Deficiency?

Answer 31

Osteoporosis Stunted growth

Question 32

Excess thyroid hormone in CNS? Deficiency?

Answer 32

Agitation, anxiety, difficulty concentrating Cretinism, impaired memory, DEC mental capacity

Question 33

What is are some causes of primary hypoparathyroidism? Secondary?

Answer 33

Agenesis, Hashimoto's, gland destruction Hypothalamic disease, pituitary disease (Sheehan's syndrome), resistance to thyroid hormones

Question 34

In Hashimoto's disease what is impaired? What does this lead to? What are TSH levels like?

Answer 34

thyroid hormone synthesis by TG or TPO Abs DEC T3 and T4 secretion HIGH

Question 35

What is an example of secondary hyperthyroidism?

Answer 35

TSH-secreting pituitary adenomas

Question 36

What synthesizes thyroid hormones?

Answer 36

Follicular epithelial cells