Thyroid Hormones (Lec 16)

Question 1

___ mg of Iodine are required each year

Answer 1

50

Question 2

Iodine is absorbed from gut tract in same manner as what?

Answer 2

chlorides

Question 3

What symporter is in the basal membrane of thyroid cell?

Answer 3

sodium-iodide

Question 4

Where does energy for sodium-iodide pump come from?

Answer 4

sodium-potassium ATPase pump

Question 5

Iodide can be concentrated inside the cell ____ X plasma concentration

Answer 5

30-250

Question 6

Iodide is transported across apical membrane of cell into follicle via what?

Answer 6

chloride-iodide counter-transporter = pendrin

Question 7

Thyroid cells secrete ___ into follicle

Answer 7

thyroglobulin

Question 8

Each thyroglobulin molecule has about ___ tyrosine amino acids which bind iodine to form thyroid hormones

Answer 8

70

Question 9

Iodide ions are converted to what?

Answer 9

an oxidized form of iodine: either nascent iodine or I3-

note: these can bind directly to tyrosine

Question 10

The major hormonal product of iodine metabolism is what?

Answer 10

thyroxine (T4)

Question 11

How is thyroxine formed?

Answer 11

when two molecules of diiodotyrosine are joined together or one monoiodotyrosine may combine with one diiodotyrosine to form triiodothyronine (T3)

Question 12

Each thyroglobulin contains about ___ molecules of thyroxine

Answer 12

30

Question 13

The thyroid can store several months supply of what?

Answer 13

thyroid hormones

Question 14

In regards to the release of thyroid hormones, the apical surface of thyroid cells pinch off small portions of the ___ ___ to form pinocytic vesicles

Answer 14

follicular colloid

Question 15

In regards to the release of thyroid hormones, lysosomes fuse with vesicles and digest thyroglobulin molecules to release what?

Answer 15

thyroxine and triodothyronine (thyroid hormones)

Question 16

In regards to the release of thyroid hormones, they diffuse where?

Answer 16

into blood

Question 17

In regards to the release of thyroid hormones, most of the iodinated tyrosine in the thyroglobulin does not become thyroid hormones but is recycled using what?

Answer 17

a deiodinase enzyme

Question 18

In regards to the release of thyroid hormones, most of released thyroid hormone is thyroxine which then is slowly deiodinated to from what?

Answer 18

triiodothyronine

Question 19

In regards to the release of thyroid hormones, most thyroid hormones entering blood are immediately bound to plasma proteins synthesized where?

Answer 19

in the liver

Question 20

True or false?
In regards to the release of thyroid hormones, plasma proteins have a high affinity for thyroid hormones so the hormones are released rapidly to tissue cells

Answer 20

false; slowly to tissue cells

Question 21

Increased transcription of a large number of genes, increased cellular metabolic activity, effect on growth, effects on specific bodily mechanisms are all physiological functions caused by what?

Answer 21

thyroid hormones

Question 22

List some of the specific bodily mechanisms thyroid hormones provoke

Answer 22

stimulation of carbohydrate metabolism, stimulation of fat metabolism, effect on plasma and liver fats, increased requirement for vitamins, increased BMR, decreased body weight

Question 23

What are thyroid hormone’s effects on the cardiovascular system?

Answer 23

increased blood flow and cardiac output, increased heart rate, normal arterial pressure, increased respiration

Question 24

What do thyroid hormones do to the GI system?

Answer 24

increase GI motility

Question 25

What are thyroid hormone's effects on CNS

Answer 25

excitatory

Question 26

True or false? | Thryoid hormones can cause muscle tremor

Answer 26

true

Question 27

In regards to sleep, endocrine, glands, and sexual function; do thyroid hormones have a positive or negative effect on these three things?

Answer 27

negative

Question 28

TSH has what effect on thyroid hormone?

Answer 28

increases release of thyroid hormone

Question 29

TRH has what effect on on thyroid hormone secretion?

Answer 29

stimulates release of TSH

Question 30

Grave's disease and Adenoma are two causes of what?

Answer 30

hyperthyroidism

Question 31

What are the symptoms of hyperthyroidism?

Answer 31

high state of excitability, intolerance to heat, increased sweating, mild to extreme weight loss, varying degrees of diarrhea, muscle weakness, nervousness, extreme fatigue, inability to sleep, tremor in hands, exophthalmos (eyes bulging out)

Question 32

How is hyperthyroidism treated?

Answer 32

surgical removal of most of thyroid gland; treatment with radioactive iodine

Question 33

what is the major issue with removal of thyroid gland?

Answer 33

removal of parathyroid glands = death

Question 34

What are the causes of hypothyroidism?

Answer 34

hashimoto disease (autoimmunity), endemic goiter, cretinism

Question 35

Myexdema and atherosclerosis are symptoms of what?

Answer 35

hypothyroidism

Question 36

How is hypothyroidism treated?

Answer 36

oral medication

Question 37

In regards to antithyroid drugs, what do thiocyanate ions do?

Answer 37

inhibit iodine uptake

Question 38

In regards to antithyroid drugs, what does propylthiouracil do?

Answer 38

inhibits peroxidase

Question 39

In regards to antithyroid drugs, what do iodides do?

Answer 39

decrease thyroid activity when present in very high concentrations