Thyroid Gland

Question 1

The thyroid gland produces ___ and ___.

Answer 1

T3; T4

Question 2

Parafollicular C cells secrete ____.

Answer 2

calcitonin

Question 3

T3 and T4 are synthesized by the _____ ____ cells.

Answer 3

follicular epitheliall

Question 4

____ is composed of newly synthesized thyroid hormones attached to thyroglobulin.

Answer 4

Colloid

Question 5

Thyroid follicle cells secrete ___ micrograms of new hormone/day.

Answer 5

60

Question 6

__ is the major secretory product of the thyroid gland.

Answer 6

T4

Question 7

Most circulating T3 is due to ____ ____ of T4.

Answer 7

peripheral conversion

Question 8

Fasting, medical and surgical stress, and catabolic diseases causes a ____ in the conversion of T4 to T3.

Answer 8

reduction

Question 9

Mutation in the ___ gene causes defects in iodide transport across the apical membrane. Mutations in this gene also affects the cochlea where it causes sensorineural hearing loss.

Answer 9

Pendrin

Question 10

Patients with Pendred syndrome usually have _____ with goiter.

Answer 10

hypothyroidism

Question 11

Deficiency of ____ mimics dietary iodide deficiency.

Answer 11

deiodinase

Question 12

When the availability of iodide is restricted, the formation of __ is favored.

Answer 12

T3

Question 13

High levels of iodide ___ organification and synthesis of thyroid hormones – the Wolff-Chaikoff effect.

Answer 13

inhibit

Question 14

___ inhibits peroxidase, causing high levels of iodide, inhibiting synthesis of thyroid hormones.

Answer 14

PTU

Question 15

PTU is an effective treatment for ____.

Answer 15

hyperthyroidism

Question 16

Answer 16

Question 17

Do most thyroid hormones circulate in the blood stream bound to plasma proteins or free?

Answer 17

bound to plasma proteins

Question 18

What are the main binding proteins for T3 and T4?

Answer 18

Thyroxine-binding protein (TBG), transthyretin (TTR), and albumin

Question 19

T4’s half life is _ days. T3’s half life is _ days.

Answer 19

6; 1

Question 20

Circulating levels of ___ can be indirectly assessed with T3 resin uptake test.

Answer 20

TBG

Question 21

High TBG results in __ T4 and __ T3 resin uptake.

Answer 21

high; low

Question 22

Low TBG results in __ T4 and __ T3 resin uptake.

Answer 22

low; high

Question 23

Hepatic failure results in __ TBG and __ T3 resin uptake.

Answer 23

low; high

Question 24

Pregnancy results in __ TBG and __ T3 resin uptake.

Answer 24

high; low

Question 25

Pregnancy results in __ TBG levels, __ bound T3 and T4, and ___ free T3 and T4.

Answer 25

high; high; low

Question 26

The high total levels of T3 and T4, but normal levels of free, physiologically active thyroid hormones results in a state where the person is said to be ____ \_\_\_\_.

Answer 26

Clinically euthyroid

Question 27

Hyperthyroidism will have __ T4 and ___ T3 resin uptake.

Answer 27

high; high

Question 28

Hypothyroidism will have __ T4 and __ T3 resin uptake.

Answer 28

low; low

Question 29

Describe the HPT axis.

Answer 29

TRH\>TSH\>T3&T4. T3&T4 inhibit TSH and TRH secretion.

Question 30

\_\_\_ regulates the growth of the thyroid gland (trophic effect) and the secretion of thyroid hormones.

Answer 30

TSH

Question 31

TSH secretion occurs at a ___ rate.

Answer 31

steady

Question 32

\_\_\_ is the second messenger for TSH.

Answer 32

cAMP

Question 33

TSH, thyroid-stimulating immunoglobulins, and increased TBG levels (ie pregnancy) result in ____ of thyroid hormone secretion.

Answer 33

stimulation

Question 34

Iodide deficiency, deiodinase deficiency, excessive iodide intake (Wolff-Chaikoff effect), perchlorate, thiocyanate, PTU, and decreased TBG levels (ie liver disease) cause ____ of thyroid hormone secretion.

Answer 34

inhibition

Question 35

New ____ are synthesized under the direction of thyroid hormones.

Answer 35

proteins

Question 36

In most tissues, synthesis of \_\_-\_\_ ____ is stimulated by thyroid hormones.

Answer 36

Na+-K+ ATPase

Question 37

In the liver and adipose tissue, thyroid hormones induce the synthesis of key _____ \_\_\_\_.

Answer 37

metabolic enzymes

Question 38

Thyroid hormones increase ____ \_\_\_\_ \_\_\_\_.

Answer 38

basal metabolic rate

Question 39

Hyperthyroidism leads to a __ BMR, while hypothyroidism causes a __ BMR.

Answer 39

high; low

Question 40

Thyroid hormones stimulate ____ and ____ metabolism.

Answer 40

lipid; carbohydrate

Question 41

Thyroid hormones stimulate the synthesis of cardiac \_\_-\_\_\_\_\_ receptors and is more sensitive to stimulation by the sympathetic nervous system.

Answer 41

B1-adrenergic

Question 42

Thyroid hormones work synergistically with GH and somatomedins to promote ___ \_\_\_\_.

Answer 42

bone formation

Question 43

Thyroid hormones are important for CNS \_\_\_\_\_.

Answer 43

maturation

Question 44

Neural changes induced by thyroid hormone deficiency during the perinatal period are irreversible and lead to _____ unless replacement therapy is started soon after birth.

Answer 44

cretinism

Question 45

What is the effect of changes in thyroid hormones on metabolism?

Answer 45

Excess: heat intolerance, weight loss, and increased BMR Deficiency: cold intolerance, weight gain, and decreased BMR

Question 46

What is the effect of changes in thyroid hormones on bone?

Answer 46

Excess: osteoporosis Deficiency: stunted growth

Question 47

What is the effect of changes in thyroid hormones on CNS?

Answer 47

Excess: agitation, anxiety, difficulty concentrating, hyperreflexia Deficiency: cretinism (congenital); listlessness, slowed movement, somnolence, impared memory, decreased mental capacity

Question 48

What is the effect of changes in thyroid hormones on the skin?

Answer 48

Excess: sweating Deficiency: dry; myxedema

Question 49

What is the effect of changes in thyroid hormones on the CV system?

Answer 49

Excess: tachycardia, AFIB, palpitations, high-output heart failure Deficiency: bradycardia, decreased contractility, decreased cardiac output, heart failure

Question 50

What is the effect of changes in thyroid hormones on the intestines?

Answer 50

Excess: diarrhea Deficiency: constipation

Question 51

Grave's disease is ____ hyperthyroidism that results in overproduction of T3 and T4 due to thyroid-stimulating immunoglobulins.

Answer 51

primary

Question 52

\_\_\_\_\_ hyperthyroidism is due to a TSH-secreting pituitary tumor.

Answer 52

Secondary

Question 53

TSH levels are ___ in primary hyperthyroidism.

Answer 53

low

Question 54

TSH levels are ___ in secondary hyperthyroidism.

Answer 54

high

Question 55

Major clinical signs of Grave's disease are _____ and _____ \_\_\_\_.

Answer 55

exophthalmos; periorbital edema

Question 56

\_\_\_\_ _____ can be due to gland destruction, Hashimoto's thyroiditis, inhibition of thyroid hormone synthesis and release, and agenesis of thyroid.

Answer 56

Primary hypothyroidism

Question 57

\_\_\_\_\_ syndrome can cause postpartum hypothyroidism due to the necrosis of the pituitary gland.

Answer 57

Sheehan

Question 58

Hypothyroidism due to an iodine deficiency leads to transient ___ in the synthesis of thyroid hormones. TSH levels are \_\_\_\_\_. Patients present with \_\_\_\_.

Answer 58

decrease; elevated; goiters

Question 59

Untreated congenital hypothyroidism results in \_\_\_\_.

Answer 59

cretinism

Question 60

Hashimoto's thyroiditis has ____ T3 and T4 secretion and ___ levels of TSH which cause a goiter.

Answer 60

low; high

Question 61

Hypothyroidism is treated by replacement doses of \_\_.

Answer 61

T4

Question 62

\_\_\_\_\_ increases the speed of bodily functions and leads to weight loss, sweating, rapid heart rate, and high blood pressure.

Answer 62

Hyperthyroidism

Question 63

\_\_\_\_\_\_\_ decreases the speed of bodily functions and leads to fatigue, weight gain, and cold intolerance.

Answer 63

Hypothyroidism

Question 64

Grave's disease results in ___ TSH, ___ T3/T4, ___ TSI, and ____ radioactive iodine uptake test.

Answer 64

low; high; positive; high

Question 65

Thyroiditis with hyperthyroidism results in ___ TSH, ___ T3/T4, ___ TSI, and ____ radioactive iodine uptake test.

Answer 65

low; high; negative; low

Question 66

Thyroid nodules (hot or toxic) results in ___ TSH, ___ T3/T4, ___ TSI, and ____ radioactive iodine uptake test.

Answer 66

low; high; negative; high or normal

Question 67

Hashimoto's disease (thyroditis, early stage) results in ___ TSH, ___ T3/T4, and ____ antithyroid antibody.

Answer 67

high; low or normal; positive

Question 68

Hashimoto's disease (thyroditis, late stage) results in ___ TSH, ___ T3/T4, and ____ antithyroid antibody.

Answer 68

high; low; positive

Question 69

Pituitary abnormality results in ___ TSH, ___ T3/T4, and ____ antithyroid antibody.

Answer 69

low; low; negative