Thyroid

Question 1

master gland of metabolism

Answer 1

thyroid gland

Question 2

The ___ is the largest endocrine gland in the
body

Answer 2

thyroid gland

Question 3

thyroid gland weight influenced by (4)

Answer 3

greater in men than women

increased with age

increases with body weight increase

increases as dietary iodine intake decreases

Question 4

the thyroid gland is extremely well ____

Answer 4

vascularized

Question 5

Increasing/decreasing thyroid hormone release can change ___ and ____ to regulate body temperature in
homeostatic fashion

Answer 5

basal metabolic rates & heat production

Question 6

Question 7

Question 8

the feedback loop of HPT (hypothalamic-pituitary-thyroid)

Answer 8

Question 9

inactive thyroid gland vs active thyroid gland

Answer 9

Question 10

Thyroid gland serves as huge reservoir of both T4 (and T3) in _______, the protein in which the hormones are assembled & stored.

Answer 10

thyroglobulin (TGB)

Question 11

Question 12

endocrine functions of the thyroid gland (2)

Answer 12

secretion of thyroxine (T4) and triiodothyrine (t3)

secretion of calcitonin

Question 13

2 biologically active forms of thyroid hormones from thyroglobulin:

Answer 13

thyroxine (T4) (moderately active)

triiodothyronine (T3) (most active form)

Question 14

calcitonin secreted by the parafollicular cells (a.k.a., C-cells) of the thyroid gland in
response to _____

Answer 14

high blood Ca2+

Question 15

calcitonin decreases the release of Ca2+ from bone by decreasing the activity of
____, which break bone down.

Answer 15

osteoclasts

Question 16

Question 17

Answer 17

Question 18

Answer 18

Question 19

Thyroxine (T4) is synthesized from ___ & ___

Answer 19

iodine & tyrosine

Question 20

T4 is made exclusively in the ____
T3 is made extrathyroidally from ___

Answer 20

thyroid
T4 (in liver and intestines)

Question 21

______ is the protein in which
T4 and T3 are assembled and stored.

Answer 21

Thyroglobulin (Tg)

Question 22

Almost all T4 produced is quickly converted to T3 peripherally (most in liver) once released from ____ stores

Answer 22

thyroglobulin

Question 23

T3 is ~__x more potent than T4.
rT3 is ____form made mostly
in liver

Answer 23

~4x

inactive

Question 24

Answer 24

Question 25

Answer 25

Question 26

Many chronic stress-like conditions lead to ____

Answer 26

hypothyroidism

Question 27

During chronic stress, chronic iron deficiency, chronic iodine deficiency (etc.), the body converts ______to more_______ to conserve its
energy (with less T3, the cells of the body slow down).

Answer 27

T4 to more rT3

Question 28

In the case of iodine deficiency, one may also develop a ____

Answer 28

goiter

Question 29

Without Iodine, thyroid hormones are not released from thyroglobulin, so ___ builds up.

Answer 29

TSH

*goiter

Question 30

iodine deficiency causes excess TSH -> oxidative stress -> which leads to ___

Answer 30

thyroid hyperplasia (goiter)

Question 31

Thyroid cells are the only cells in the body that can absorb ___

Answer 31

iodine

Question 32

____ is essential for normal thyroid function

Question 33

Iodine deficiency is defined as
urine iodine excretion of ____
of dietary iodine intake

Answer 33

> 70%

Question 34

Goiter result from excessive tissue growth when thyroid cells are exposed chronically to too much ____ or too much human
____

Answer 34

thyroidstimulating hormone (TSH)
chorionic gonadotropin (HCG)

Question 35

what is the most common cause of goiter?

Answer 35

iodine deficiency

Question 36

Goiter due to iodine deficiency is most commonly observed in

Answer 36

underdeveloped areas with poor nutrition
*Iodine supplementation in salt prevents most iodine deficiency in USA

Question 37

medications that may promote goiter (5)

Answer 37

• Hyperthyroid medications (i.e., propylthiouracil)
• Sulfonamide antimicrobials (i.e., sulfamethoxazole component of
  SMX-TMP (Bactrim))
• Amiodarone: anti-arrhythmic agent
• Lithium: for bipolar disorders, anxiety, cluster headaches & migraines
• Salofalk: contains the active ingredient, mesalazine, a type of aminosalicylate is used for the treatment of ulcerative colitis

Question 38

Environmental compounds may also promote goiter: (3)

Answer 38

• Mercury, Arsenic & some other heavy metals
• Nitrates
• Pesticide compounds

Question 39

iodine deficiency disorder

Answer 39

hypothyroidism and goiter or diffuse thyroid enlargement

Question 40

Congenital Hypothyroidism (Cretinism)

Answer 40

Cretinism is the most extreme
manifestation of severe IDD

due to a deficiency of iodine in
the mother’s diet during pregnancy
resulting in congenital hypothyroidism
(from birth)

Question 41

Too much or too little thyroid hormone can lead to ___

Answer 41

enlarged thyroid (goiter)

Question 42

Hashimoto’s disease

Answer 42

autoimmune hypothyroidism

Question 43

Grave’s disease

Answer 43

autoimmune hyperthyroidism caused by thyroid-stimulating immunoglobulins
(TSIs) to the TSH receptor (TSHR).

Question 44

The main complications of patients with
hyperthyroidism and hypothyroidism are associated with ___ ___ since either condition can cause life-threatening cardiac events.

Answer 44

cardiac comorbidity

Question 45

The amount of T4 produced and released by the thyroid gland is controlled directly by TSH released by the ___________?

Answer 45

Anterior Pituitary

Question 46

What is the best known stimuli for increasing the rate of thyroid stimulating hormone (TSH) secretion by the anterior pituitary?

Answer 46

Exposure to Cold

Thyroid Hormones are “Calorigenic”
* Cause cells to consume more
energy and produce heat as a
byproduct.