Part 5 Flashcards

0
Q

What do selenodeiodinases do?

A

They catalyze the conversion of T4 to T3 and T4 to reverse T3

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1
Q

What is more powerful, T3 or T4?

A

T3 is four times more powerful

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2
Q

True or False. The body only has thyroid receptors for T3

A

True

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3
Q

True or false. T3 is better at crossing the blood brain barrier

A

False. T4 is better at crossing the blood brain barrier

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4
Q

What are 10 things that can decrease the conversion of T4 to T3?

A

Beta blockers, lithium, anticonvulsants, amiodarone (but can also cause hyperthyroidism), inflammation and infections, smoking, physical and mental stress, dieting, radiation and cancer

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5
Q

Deficiency of what 2 nutrients can result in decreased thyroid activity?

A

Selenium and iodine

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6
Q

One grain of desiccated thyroid (60 mg) has what in it?

A
  • 38 mcg T4
  • 9 mcg T3
  • Trace T1 and T2
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7
Q

What is the half-life of T4?

A

Six days

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8
Q

What is the half-life of T3?

A

18 hours

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9
Q

True or false. Both thyroid deficiency and severe excess can inhibit thyroid hormone production

A

True

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10
Q

Low free T3 is a strong predictor of what?

A

Death in cardiovascular patients

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11
Q

What is the most common cause of hypothyroidism globally?

A

Iodine deficiency

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12
Q

What causes hypothyroidism most often in the industrialized world?

A

Autoimmune disease

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13
Q

T3 and T4 are what percentage iodine by weight?

A
T3 = 59% iodine by weight
T4 = 65% iodine by weight
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14
Q

Growth hormone stimulates the production of what in the liver?

A

IGF-1

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15
Q

Growth hormone stimulates production of what binding protein?

A

IGF binding protein – 3 which is associated with decreased cancer risk

16
Q

True or false. Growth hormone worsens carotid atherosclerosis

A

Faults. It inhibits carotid atherosclerosis

17
Q

True or false. Growth hormone deficiency is associated with increased cardiovascular mortality

A

True

18
Q

IGF-1 has what effect on the nerves in the brain?

A

It has cytoprotective effects against beta-amyloid plaque formation and it increases dendritic formation of cortical neurons

19
Q

What is the best serum marker of growth hormone levels?

A

IGF – 1

20
Q

How is testosterone associated with memory and dementia?

A

Low levels are associated with impaired memory and an increased risk for dementia

21
Q

True or false. Men with low testosterone die 88% later then men with high testosterone

A

False. Men with low testosterone die 88% sooner than men with high testosterone

22
Q

True or false. The lower the free testosterone the more likely coronary artery disease will be present

A

True

23
Q

Name three things that testosterone replacement will do to improve cardiac function

A

1) it improves ST depression
2) it dilates coronary arteries
3) it increases cardiac output

24
Q

Female:Male Testosterone levels

A

1:10

25
Q

Why is testosterone therapy anti-inflammatory?

A

It prevents cytokine production and prevents the formation of VCAMS

26
Q

What does testosterone therapy do to the skeletal system?

A

It prevents bone loss

27
Q

How does testosterone replacement therapy help a person to feel better?

A

It improves sense of emotional well-being, self confidence and motivation

28
Q

Two routes of aromatization via aromatase (CYP 19)

A

Androstenedione to estrone

Testosterone to estradiol

29
Q

What 6 things increase aromatization?

A

Obesity, alcohol and decreased zinc

Stress, inflammation and insulin resistance

30
Q

What four things decrease aromatization?

A

Zinc supplementation, weight-loss, chrysin and anastrozole

31
Q

Does chrysin decrease aromatization in vivo?

A

No, only in Vitro

32
Q

What is another name for anastrozole?

A

Arimidex

33
Q

Gonadotropin Releasing Hormone stimulates what and releases what?

A

It stimulates the anterior pituitary and releases FSH and LH

34
Q

FSH stimulates and produces what?

A

It stimulates the Sertoli cells and produces sperm

35
Q

LH stimulates what produces what?

A

It stimulates the Leydig cells produces testosterone