Lecture 6- Thyroid Gland Flashcards

1
Q

What are the functional units of the thyroid gland called?

A

Follicles

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2
Q

What cells are dispersed between the follicles?

A

C cells (parafollicular cells)

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3
Q

What do c cells secrete?

A

Calcitonin

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4
Q

What do the central cavities of the follicles contain?

A

Colloid

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5
Q

What is the major constituent of colloid?

A

Thyroglobulin

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6
Q

What hormone are follicular cells dependent on?

A

Thyroid stimulating hormone

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7
Q

What 2 molecules are required for thyroid hormone synthesis?

A

Iodine and tyrosine

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8
Q

Which cells produce thyroglobulin?

A

Follicular cells

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9
Q

How is thyroglobulin moved into the follicle lumen?

A

Exocytosis

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10
Q

Where do follicular cells take up iodide from?

A

The blood

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11
Q

Where does oxidation of iodide to molecular iodine?

A

Follicular cells

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12
Q

Where does iodine attach to thyroglobulin?

A

Tyrosine residues

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13
Q

Where does iodine-tyrosine attachment take place?

A

Colloid

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14
Q

What 2 molecules are formed from iodine-tyrosine attachment?

A

Monoiodotyrosine and diiodotyrosine

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15
Q

What 2 molecules are formed from coupling of monoiodotyrosine and diiodotyrosine?

A

T3 and T4

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16
Q

How does secretion of T3 and T4 to the follicular cell occur?

A

Endocytosis

17
Q

Once T3 and T4 enter the follicular cells, what do they fuse with?

18
Q

How do T3 and T4 enter the bloodstream from the follicular cells?

19
Q

Which hormone, T3 or T4 is secreted in greater proportions?

20
Q

Which molecule, T3 or T4, is more potent?

21
Q

Which 2 organs convert T4 into T3?

A

Liver and kidneys

22
Q

What regulatory effect do thyroid hormones have?

A

Negative feedback to both anterior pituitary and hypothalamus, inhibiting thyroid stimulating hormone and thyrotropin releasing hormone release

23
Q

What kind of receptors are thyroid stimulating hormone receptors?

A

G protein coupled receptors

24
Q

What hormone do thyroid hormones stimulate the release of?

A

Human growth hormone

25
What are the effects of thyroid hormones on metabolism?
Increased metabolic activities
26
What is the effect of thyroid hormones on oxygen consumption?
Oxygen consumption increases to most metabolically active tissues
27
What is the effect of thyroid hormones on basal metabolic rate?
Increased by up to 60-100%
28
What is the effect of thyroid hormones on body temperature?
Heat is released during metabolic reactions, increasing body heat
29
What are the effects of thyroid hormones on catecholamine receptors?
Increased production of receptors so cells are more responsive (upregulation)
30
What are the cardiovascular effects of thyroid hormones?
Increased heart rate, force of contractions and cardiac output