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Zach's Physiology Card > 21.3 Thyroid hormones > Flashcards

21.3 Thyroid hormones Flashcards

1
Q

What type of pump is the iodide pump?

A

2: 1 sodium:iodide symporter.

- sodium potassium ATPase pump

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2
Q

Where is iodide more highly concentrated?

A

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

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3
Q

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

A

pendrin: choride-iodide counter transporter

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4
Q

How does the thyroid hormone form?

A
  1. thyroglobulin from the thyroid binds up 70 Tyr with iodine to form thyroid hormones
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5
Q

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

A

nascent form binds directly (oxidized form)

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6
Q

What is the major hormonal product of teh thyroid?

A

thyroxine

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7
Q

What combinations will produce thyroxine?

A
  1. 2 diiodotyrosine joining

2. monoiodotyrosine and dioodotyrosine to form triiodothyronine (T3)

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8
Q

Explain the process of how thyroid hormones are released.

A
  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
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9
Q

What is the majority of thyroid hormone that is released?

A
  1. thyroxine, which slowly deiodinated to form triiodothyronine
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10
Q

What is the purpose of the deiodinase enzyme?

A
  1. helps to recycle the majority of iodinated tyrosine in the thyroglobulin during a recycling process
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11
Q

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

A

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

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12
Q

How does thyroid hormone affect the cardiovascular system?

A
  1. increase blood flow and cardiac output
  2. increase heart rate
  3. normal arterial pressure (no change)
  4. increased respiration
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13
Q

How does thyroid hormone affect the nervous and muscular systems?

A
  1. increases excitation of CNS leading to muscle tremors
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14
Q

Does thyroid hormone affect the GI?

A
  1. yes, it will lead to increased GI motility
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15
Q

How will thyroid affect the metabolic system?

A
  1. initiate carbohydrate metabolism
  2. initiate fat metabolism
  3. requires increased vitamin in take
  4. increase BMR and decrease body weight
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16
Q

What type of signaling molecule is thyroid hormone?

A
  1. intracellular; lipophilic signaling. Both T3,T4 can cross membrane. T4 requires iodinase to enter into the nucleus
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17
Q

What compounds regulate thyroid secretions?

A

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

18
Q

Causes of hyperthyroidism?

A
  1. Grave’s disease

2. Adenoma (benign glandular tumor)

19
Q

What are common effects of hyperthyroidism?

A
  1. fatigue
  2. inability to sleep
  3. tremors
  4. exopthalmos (anterior bulging of the eye)
  5. psychic disorder
20
Q

What are common causes of hypothyroidism?

A
  1. Hasimoto disease (autoimmune)
  2. Endemic goiter
  3. Cretinism
    Cause: myxedema, atherosclerosis
21
Q

What does thiocyanate ions Rx do?

A

inhibit iodine uptake by blocking the I, Na cotransporter

22
Q

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

A

thiocyanate ion

23
Q

What drug is used to inhibit peroxidase?

A

propylthiouracil

24
Q

What is the effect of propylthiouracil?

A

inhibiting peroxidase uptake

25
Q

What can low levels of deiodinase enzyme simulate or mimic?

A

similar to iodine deficiency

26
Q

What effects will thyroid hormones have on teh cardiovascular system?

A
  1. increase cardiac output
  2. increase HR
  3. no effect on arterial pressure
  4. increase respirations
27
Q

What will growth hormone do to the GI motility?

A

increase motility

28
Q

What will growth hormone do to muscles and nerves?

A
  1. increase muscle function

2. increase CNS excitation

29
Q

How will TSH (thyrotropin) affect thyroid hormone secretion?

A
  1. increase thyroid hormone secretion
30
Q

How will cAMP affect thyroid hormone secretion?

A
  1. increase thyroid hormone secretions and prolong growth of thyroid glandular tissue
31
Q

How will TRH affect thyroid hormone secretion?

A

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

32
Q

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

A
  1. cold/parasympathetic stimulation leads to increased TSH.

2. Sympathetic stimulation leads to decreases the TSH release

33
Q

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

A
  1. causes inhibition when circulating concentrations reach 1.75 times normal. inhibit TSH
34
Q

What can cause hyperthyroidism?

A
  1. grave’s disease

2. adenoma

35
Q

What are common symptoms of hyperthyroidism?

A
  1. highly excitable
  2. heat intolerant
  3. increased sweating
  4. weight loss
  5. diarrhea
  6. weakness
36
Q

How is yperthyroidism treated?

A
  1. removal of thyroid gland or treat with radioactive iodine
37
Q

What are commons causes of hypothyroidism?

A
  1. autoimmune (hashimoto) disease
  2. endemic goiter
  3. crteinism
38
Q

Can myxedema and atherosclerosis be symptoms of hypothyroidism?

A

yes, corrected with supplemental thyroid

39
Q

What is the effect of thiocyanate?

A

inhibits uptake of iodine, reducing thyroid T3,T4 production

40
Q

What is the effect of propylthiouracil?

A

inhibition of peroxidases

41
Q

What can iodides do in high concentrations?

A

decrease thyroid activity

Zach's Physiology Card (25 decks)

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