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Cell Biology > L27 Thyroid > Flashcards

L27 Thyroid Flashcards

1
Q

The thyroid is the largest of the…

A

True endocrine glands

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2
Q

The thyroid regulates…

A

Metabolism and body weight

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3
Q

The thyroid has wide ranging effects on a variety of tissues. It is often involved in…

A

Synergistic effects

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4
Q

The thyroid effects(4)…

A
  1. Cardiovascular
  2. Metabolic
  3. Neurological
  4. Growth and development
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5
Q

The thyroid is linked with foetal…

A

Neural development

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6
Q

The thyroid is linked with bone growth…

A

After birth

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7
Q

3 products of the thyroid…

A
  1. Tetraiodothyronine (thyroxine / T4)
  2. Triiodothyronine T3
  3. Calcitonin
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8
Q

Calcitonin regulates…

A

Calcium homeostasis

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9
Q

T4 thyroxine is the most produced, however T3 thyroxine is…

A

The most physiologically active

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10
Q

In the thyroid gland, in health, is (palpable / not palpable)…

A

Not palpable

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11
Q

The thyroid gland has a…

A

Rich blood supply

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12
Q

On the posterior surface of the thyroid, there are 2 to 4 pairs of a distinct tissue, known as the…

A

Parathyroid

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13
Q

The functional units of the thyroid are the…

A

Follicles

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14
Q

The structure of thyroid follicles is a ring of follicular cells interior…

A

Colloid

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15
Q

The colloid functions to…

A

Produce and store thyroid hormone

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16
Q

Follicles ( can b cannot ) change size…

A

Can

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17
Q

Among follicles are distributed C-cells which are…

A

Bigger and secrete calcitonin

18
Q

In the colloid tyrosine in thyroglobulin is converted to thyroid hormone precursors by…

A

Iodination by thyroperoxidase

19
Q

Thyroid hormone precursors are….

A

T1 and T2 (mono and diodotyrosine)

20
Q

In coupling, thyroid hormone precursors…

A

Are joined together to form T3 and T4 (again by thyroperoxidase)

21
Q

Iodine moves from the blood into thyroid follicular cells by…

A

Active transport

22
Q

Which of the following is true:

a) T3 can be converted to T4
b) T4 can be converted to T3
c) T1 can be converted to T2
d) T2 can be converted to T1
e) All of the above

A

b) T4 can be converted to T3

23
Q

Due to its convertibility and longer half life, T4…

A

Acts as a reservoir for T3

24
Q

Thyroid hormones require…

A

Transport proteins

25
Q

3 thyroid hormone transport proteins…

A
  1. Thyroxine binding protein
  2. Thyroxine binding pre-albumin
  3. Albumin
26
Q

Albumin is a major source of free hormones because…

A

It dissociates rapidly

27
Q

Thyroxine binding protein binds to what percentage of T4?

A

70%

28
Q

Thyroxine binding pre-albumin binds what proportion of T4?

A

10%

29
Q

Thyroxine binding pre-albumin has…

a) 100x higher affinity for T3 than T4
b) 10x higher affinity for T4 than T3
c) 100x lower affinity for T3 than T4
d) Equal affinity for T3 and T4

A

b) 10x higher affinity for T4 than T3

30
Q

15% of circulating T3 and T4 is found bound to…

A

Albumin

31
Q

TRH is released by the…

A

Hypothalamus

32
Q

TRH acts on the…

A

Anterior pituitary gland, causing it to release TSH

33
Q

TSH acts on the thyroid gland, leading to (5)…

A 
Increases in thyroglobulin  synthesis
Increase in iodination of thyroglobulin
Increase in pinocytosis
Increase in lysosomal activity
Increase in size of thyroidal cells
34
Q

When thyroidal cells increase in size, their shape changes from…

A

Cuboidal to columnar

35
Q

Most plasma T3 is derived from the…

A

Peripheral metabolism of T4

36
Q

Quantity of T3 is regulated by…

A

Step up/ step down regulation

37
Q

Step up regulation (converting T4 to T3) involves the enzymes (2)…

A

1 & 2 5’-deiodinase

38
Q

Step down regulation (converting T4 to inactive form (rT3) involves…

A

3 5’-deiodinase

39
Q

Thyroid hormone receptor alpha 2:

a) Binds T3
b) Binds T3 and T4
c) Binds T4
d) None of the above

A

c) Binds T4

Thyroid hormone receptor alpha 2 does not bind T3

40
Q

TR-α 1 and TR-β 1 & 2 have a higher…

A

Affinity for T3 than TR-α 2

41
Q

Key targets of thyroid hormone are…

A

Uncoupling proteins in the mitochondria

which affects heat release

42
Q

T3 effects gene…

A

Transcription

Cell Biology (21 decks)

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