21.3 Thyroid hormones Flashcards Preview

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Flashcards in 21.3 Thyroid hormones Deck (41):
1

What type of pump is the iodide pump?

2:1 sodium:iodide symporter.
-sodium potassium ATPase pump

2

Where is iodide more highly concentrated?

in the cell (colloid gland). 30-250x that in the plasma

3

What is used to transport the iodide across the apical membrane?

pendrin: choride-iodide counter transporter

4

How does the thyroid hormone form?

1. thyroglobulin from the thyroid binds up 70 Tyr with iodine to form thyroid hormones

5

Which form of iodide is able to bind with tyrosine directly?

nascent form binds directly (oxidized form)

6

What is the major hormonal product of teh thyroid?

thyroxine

7

What combinations will produce thyroxine?

1. 2 diiodotyrosine joining
2. monoiodotyrosine and dioodotyrosine to form triiodothyronine (T3)

8

Explain the process of how thyroid hormones are released.

1.apical surface pinches off to form the pinocytosic vesicles
2. lysosome fuse with vesicels, digest thyroblogulin molecules, releases thyroxine and triiodothyronine
3. thyroid diffuse into blood

9

What is the majority of thyroid hormone that is released?

1. thyroxine, which slowly deiodinated to form triiodothyronine

10

What is the purpose of the deiodinase enzyme?

1. helps to recycle the majority of iodinated tyrosine in the thyroglobulin during a recycling process

11

What plasma component has a high affinity for the thyroid hormones?

plasma proteins which maintains a high level in the blood and slow diffusion into tissues

12

How does thyroid hormone affect the cardiovascular system?

1. increase blood flow and cardiac output
2. increase heart rate
3. normal arterial pressure (no change)
4. increased respiration

13

How does thyroid hormone affect the nervous and muscular systems?

1. increases excitation of CNS leading to muscle tremors

14

Does thyroid hormone affect the GI?

1. yes, it will lead to increased GI motility

15

How will thyroid affect the metabolic system?

1. initiate carbohydrate metabolism
2. initiate fat metabolism
3. requires increased vitamin in take
4. increase BMR and decrease body weight

16

What type of signaling molecule is thyroid hormone?

1. intracellular; lipophilic signaling. Both T3,T4 can cross membrane. T4 requires iodinase to enter into the nucleus

17

What compounds regulate thyroid secretions?

TSH, cAMP, TRH, cold(immune response), Thyroid hormone feedback

18

Causes of hyperthyroidism?

1. Grave's disease
2. Adenoma (benign glandular tumor)

19

What are common effects of hyperthyroidism?

1. fatigue
2. inability to sleep
3. tremors
4. exopthalmos (anterior bulging of the eye)
5. psychic disorder

20

What are common causes of hypothyroidism?

1. Hasimoto disease (autoimmune)
2. Endemic goiter
3. Cretinism
Cause: myxedema, atherosclerosis

21

What does thiocyanate ions Rx do?

inhibit iodine uptake by blocking the I, Na cotransporter

22

What is used to block the I, Na cotransporter system?

thiocyanate ion

23

What drug is used to inhibit peroxidase?

propylthiouracil

24

What is the effect of propylthiouracil?

inhibiting peroxidase uptake

25

What can low levels of deiodinase enzyme simulate or mimic?

similar to iodine deficiency

26

What effects will thyroid hormones have on teh cardiovascular system?

1. increase cardiac output
2. increase HR
3. no effect on arterial pressure
4. increase respirations

27

What will growth hormone do to the GI motility?

increase motility

28

What will growth hormone do to muscles and nerves?

1. increase muscle function
2. increase CNS excitation

29

How will TSH (thyrotropin) affect thyroid hormone secretion?

1. increase thyroid hormone secretion

30

How will cAMP affect thyroid hormone secretion?

1. increase thyroid hormone secretions and prolong growth of thyroid glandular tissue

31

How will TRH affect thyroid hormone secretion?

1.Secreted from the hypothatlamus to stimulate secretion of TSH. which will increase thyroid hormone release

32

What affect do cold and neurogenic stimuli have on thyroid hormone release?

1. cold/parasympathetic stimulation leads to increased TSH.
2. Sympathetic stimulation leads to decreases the TSH release

33

What does the thyroid hormone feedback system do to regulate the thyroid secretions?

1. causes inhibition when circulating concentrations reach 1.75 times normal. inhibit TSH

34

What can cause hyperthyroidism?

1. grave's disease
2. adenoma

35

What are common symptoms of hyperthyroidism?

1. highly excitable
2. heat intolerant
3. increased sweating
4. weight loss
5. diarrhea
6. weakness

36

How is yperthyroidism treated?

1. removal of thyroid gland or treat with radioactive iodine

37

What are commons causes of hypothyroidism?

1. autoimmune (hashimoto) disease
2. endemic goiter
3. crteinism

38

Can myxedema and atherosclerosis be symptoms of hypothyroidism?

yes, corrected with supplemental thyroid

39

What is the effect of thiocyanate?

inhibits uptake of iodine, reducing thyroid T3,T4 production

40

What is the effect of propylthiouracil?

inhibition of peroxidases

41

What can iodides do in high concentrations?

decrease thyroid activity