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HOS Exam 4 > Thyroid Hormones > Flashcards

Thyroid Hormones Flashcards

1
Q

Within the thyroid gland, thyroid hormone is produced by _ cells, and stored bound to _

A

Follicle cells

Thyroglobulin

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2
Q

Parafollicular cells produce _

A

Calcitonin

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3
Q

Within the thyroid, DIT and MIT are used to make _ (3)

A

T3, T4 and reverse T3

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4
Q

Iodine trapping within the thyroid require wha transport protein?

A

Na/I symporter

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5
Q

Iodide ions are converted to iodine by _

A

Thyroid peroxidase

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6
Q

What is the organification step of thyroid synthesis?

A

Oxidized iodine binds tyrosine AA residues on thyroglobulin to make DIT or MIT

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7
Q

What is stored as colloid in the follicle lumen?

A

Iodinated thyroglobulin, NOT T3 or T4

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8
Q

Free MIT and DIT are deiodinated by _, freeing iodine for reuse

A

Deiodinase enzyme

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9
Q

T3 and T4 are transported in the blood stream bound to _. How are they delived to the CNS? Majority of thyroid hormone released is _? Why?

A

Thyroxine binding globulin
Transthyretin
T4 - longer plasma half life

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10
Q

Where are thyroid receptors located?

A

Nuclear receptor

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11
Q

The major regulator of thyroid release is _. What are the effects of somatostatin and dopamine?

A

TSH

Both inhibit TSH release

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12
Q

increased thyroglobulin proteolysis, increased Iodide pump activity, increased organisfication, increase size, activity and number of thyroid cells are mediated by _

A

TSH

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13
Q

If a patient has low TSH, what would you expect upon inspection of the thyroid cells?

A

Low TSH - High amounts of colloid (b/c not released), flat follicular cells

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14
Q

An iodine deficiency can lead to _.

A

Goiter. Thyroid cell proliferation

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15
Q

The first effect of TSH on the thyroid cells is _

A

Binding surface GPCR

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16
Q

Increased cold and increased caloric intake lead to _

A

Increased TSH release

17
Q

A diet high in iodide lead to _

A

High blood iodide levels, reduced trapping of iodide by thyroid, decreased size and decreased blood supply

18
Q

The active form of the thyroid hormone is _. How does it bind DNA?

A

T3

As a T3-RXR heterodimer (vs. steroid hormones homodimerize)

19
Q

Know that T3 is able to bind ribosomes, mitochon, plasma mem. to mediate non-genomic responses

A

done

20
Q

T4 is converted to T3 by _

A

Mono-deiodinase

21
Q

In the absence of T3 binding, what is the action of the T3 receptor?

A

It is able to bind DNA and repres gene transcription, unlike the steroid hormone sequestered by HSP90

22
Q

The major effect of thyroid hormone is _

A

Increase in metabolic rate

23
Q

How does thyroid hormone affect proteins?

A

Increases protein catabolism, too much can lead to muscle breakdown / weakness

24
Q

Regarding linear growth, fetal brain development and tooth/hair development, what is the role of thyroid hormone?

A

Required for all.
Reduced fetal thyroid = poor outcome for fetus
Low thyroid post birth = dry brittle hair

25
Q

What are the effects of thyroid hormone on carbohydrates and fat?

A

Increase carb metabolism

Increase lipid mobilization (GH like) and secretion

26
Q

What are the effect if thyroid hormone on cardiac function?

A

Increases heart rate, blood flow, CO, tachycardia

27
Q

How does thyroid hormone affect CNS function?

A

Hyper-secretion can lead to anxiety and nervousness

28
Q

In males, too little thyroid hormone leads to_, while too much leads to _

A

Reduced libido

Impotence

29
Q

In females, too little thyroid hormone leads to_ (3), while too much leads to _

A

Menorrhagia, polymenorrhea, reduced libido

Oligomenorrhea

30
Q

2 causes of hyperthyroidism mentioned are _

A

Graves disease

Thyroid adenoma

31
Q

Graves disease is caused by _

A

Thyroid stimulating antibodies

32
Q

heat intolerance, diarrhea, muscle weakness, tremor, osteoporosis (long term) are all symptoms of _

A

Graves disease

33
Q

Graves disease can be treated by _ (2)

A

Surgery to remove most of gland

Radioactive iodine

34
Q

Thiouracil drugs treat hyperthyroidism by O

A

Inhibiting thyroid peroxidase activity

35
Q

Thyroid storm is _

A

Life threatening result of hyperthyroidism

36
Q

Myxedema is _. Major symptom is _

A

Hypothyroidism in adults

Bagginess under eyes

37
Q

Myxedema coma is _

A

Rare, in elderly adult who fail to take thyroid medications

38
Q

Cretinism is _

A

Hypothyroidism in infants. Mental retardation, stunted skeletons, soft tissue enlargement

39
Q

The most common time of endocrine cancers are _. They are treated by _ (2)

A

Thyroid cancers

Thyroidectomy or radioactive iodine

HOS Exam 4 (7 decks)

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