B6-060 Thyroid Gland Physiology (used Ninja Nerd instead of awful lecture) Flashcards

1
Q

synthesis of thyroid hormone begins when the paraventricular nuclei in the hypothalmus secrete […]

A

tryrotrophin-releasing hormone (TRH)

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2
Q

TRH travels through the vascular connection between the hypothalmus and anterior pituitary, called the [….]

A

hypophyseal portal system

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3
Q

TRH stimulates pituitary to secrete […] into the blood stream

A

thyroid stimulating hormone (TSH)

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4
Q

TSH binds to the receptors on the follicles of the thyroid and stimulate it to produce […]

A

thyroglobulin (basic unit of thyroid hormone)

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5
Q

[…] needs to be ingested to produce thyroid hormone

A

iodide

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6
Q

how is iodide brought from the lumen into the thyrocyte?

A

via Na/I symport

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7
Q

enzyme in the luminal space that performs iodine oxidation, iodination, and coupling

A

thyroid peroxidase

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8
Q

3 functions of thyroid peroxidase

A
  1. iodine oxidation
  2. iodination
  3. coupling
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9
Q

converts iodide to iodine

A

iodine oxidation (thyroid peroxidase)

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10
Q

process that attaches one or two iodine molecules to thyroglobulin to create MIT or DIT

A

iodination (thyroid peroxidase)

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11
Q

couples the iodinated tyrosine amino acids into T3 and T4

A

coupling (thyroid oxidase)

DIT+DIT= T4
DIT+MIT= T3

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12
Q

T3 and T4 are collectively known as

A

thyroid hormone

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13
Q

once iodinated, the thyroglobulin enters the thyrocyte via

A

pinocytosis –> vesicles

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14
Q

the vesicles containing thyroglobulin fuse with lysosomes, resulting in

A

isolated T3 and T4

**vesicles containing isolated T3 and T4 fuse with the membrane and are released into the bloodstream

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15
Q

in the blood, T3 and T4 bind to the transport protein […]

A

thyroxine binding globulin (TBG)

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16
Q

TBG is synthesized by the

A

liver

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17
Q

summarize the steps of thyroid hormone synthesis

A

.

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18
Q

what is the structural unit of the thyroid gland?

A

follicles

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19
Q

what hormone is produced by the anterior pituitary gland?

A

TSH

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20
Q

which cells are stimulated by TRH?

A

follicular cells (thyrocytes)

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21
Q

what does TSH activate?

A

Gs protein

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22
Q

what is the main amino acid of thyroglobulin?

A

tyrosine

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23
Q

what is added to thyroidglobulin during iodation?

A

Iodine

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24
Q

what binds TH in the bloodstream?

A

TBG

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25
Q

enzyme that removes iodine from thyroxine

A

5’ deiodinase

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26
Q

enzyme that converts T4 to T3 (active)

A

5’ deiodinase

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27
Q

enzyme that converts T4 reverse T3 (inactive)

A

5-deiodinase

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28
Q

T3 and retinoic acid bind to the transcription factor to move into the nucleus and stimulate synthesis of

A

NaKATPase

**leading to production of more sodium-potassium pumps, requiring more energy=catabolic state

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29
Q

TH effects on liver [3]

A

glycogenolysis
gluconeogenesis
increase LDL receptors

**increases blood glucose level and uptake of bad cholesterol

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30
Q

effects of TH on heart

A

stimulates beta 1 receptors to increase contractility, SV, and BP

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31
Q

effects of TH on CNS

A

increases dendrite formation
increases myelination
increases number of synapses

**as a result, hyperparathyroidism can cause irritability

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32
Q

TH regulates bone […]

A

remodeling

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33
Q

cells responsible for bone deposition

A

osteoblasts

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34
Q

cells responsible for bone resorption

A

osteoclasts

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35
Q

how does TH affect chondrocytes in the epiphyseal plates?

A

stimulates proliferation, hypertrophy, and ossification

**causes bones to lengthen

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36
Q

TH stimulates endochondral

A

ossification

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37
Q

TH effects on adipose

A

stimulates lipolysis

**excess glycerol converted to glucose, increases blood glucose

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38
Q

TH regulates both catabolism and anabolism.
Hyperthyroidism causes the balance to shift to […]

A

catabolism

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39
Q

how does hyperthyroidism effect muscles?

A

catabolism causes weak, atrophied muscles/movements

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40
Q

how does TH affect the skin?

A

increased body temperature causes vessels to dilate it to try to cool –> skin flushed, radiates heat

increases sweat production

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41
Q

brittle nails, thin hair [hypo or hyperthyroidism]

A

hypothyroidism

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42
Q

thick hair [hypo or hyperthyroidism]

A

hyperthyroidism

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43
Q

how does TH affect the GI system?

A

stimulates secretion and enhances motility

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44
Q

diarrhea [hypo or hyperthyroidism]

A

hyperthyroidism

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45
Q

constipation [hypo or hyperthyroidism]

A

hypothyroidism

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46
Q

what substance is required for T3 to exert its effects?

A

retinoic acid

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47
Q

T3 [increases or decreases] the available ATP in the cell

A

decreases

**NaKATPases constantly using ATP

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48
Q

irritability [hypo or hyperthyroidism]

A

hyperthyroidism

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49
Q

paraventricular neurons in the hypothalmus release

A

thyrotropin releasing hormone (TRH)

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50
Q

TRH goes through the […] to the pituitary

A

hypophyseal portal system

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51
Q

TRH stimulates anterior pituitary to release

A

TSH

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52
Q

TH is transported through the blood via

A

TBG

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53
Q

high levels of TH exert a negative feedback mechanism that

A

inhibits paraventricular nucleus from making TRH
-decreases TSH production
-decreases T3 and T4 production

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54
Q

low levels of TH exert a negative feedback mechanism that

A

stimulate the paraventricular nucleus to release excessive TRH
-increases TSH production
-increases T3 and T4 production

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55
Q

TH increases the basal metabolic rate by

A

increasing the number of NaKATPases

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56
Q

TH aims to increase blood glucose by stimulating [3]

A

lipolysis
glycolysis
gluconeogenesis

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57
Q

TH increases the uptake of […] lipoproteins in liver

A

LDL (bad cholesterol)

58
Q

TH promotes normal nerve development via [3]

A

increasing number of synapses
increasing myelination
increasing number of dendrites

59
Q

triiodothyronine

A

T3

60
Q

thyroxine

A

T4

61
Q

converts T4 to T3 in the peripheral tissues

A

5’ deiodinase

**5, 4, 3

62
Q

peripheral conversion of T4 to T3 is inhibited by [3]

A

glucocorticoids
beta blockers
propylthiouracil (PTU)

63
Q

proplythiouracil inhibits [2]

A

thyroid peroxidase
5-deiodinase- conversion of T4 to T3 in peripheral tissues

64
Q

metabolically inactive byproduct of the peripheral conversion of T4

A

rT3

65
Q

rT3 production is increased by [2]

A

growth hormone
glucocorticoids

66
Q

functions of thyroid peroxidase [3]

A

oxidation
iodination
coupling of MIT and DIT

67
Q

DIT + DIT =

A

T4

68
Q

DIT + MIT =

A

T3

69
Q

Wolff-Chaikoff effect

A

sudden exposure to iodine temporarily turns off thyroid peroxidase, decreasing T3/T4 production

70
Q

[…] binds nuclear receptors with greater affinity than […]

A

T3 binds nuclear receptors with greater affinity than T4

71
Q

T3 functions:

**Seven Bs

A

Brain maturation
Bone growth
B-adrenergic effects
Basal metabolic rate (increase)
Blood sugar (increase)
Break down lipids
stimulate surfactant production in Babies

72
Q

describe negative feedback of TH production

A
  1. too much free T3/T4
  2. anterior pituitary decreases sensitivity to TRH
  3. hypothalamus decreases TRH secretion
73
Q

binds most T3/T4 in the blood

A

TBG

74
Q

bound T3/T4 is [active/inactive]

A

inactive

75
Q

what conditions upregulate TBG? [2]

A

pregnancy
OCP use (estrogen)

76
Q

what conditions downregulate TBG? [6]

A

androgens (anabolic steroids)
large doses of glucocorticoids
chronic liver disease
severe systemic illness
active acromegaly
kidney disease with proteinuria

77
Q

iodide is transported into the thyrocyte via

A

Na/I active symport

78
Q

where does organification/coupling occur?

A

in the lumen

TG then brought back into cell via endocytosis

79
Q

once TG has been brought back into the cell via endocytosis, […] in the lysosome convert it to free T3/T4

A

proteases

80
Q

[hypo or hyper]
cold intolerance
hypohidrosis
weight gain

A

hypothyroidism

**due to decreased BMR, decreased calorigenesis, and hyponatremia

81
Q

[hypo or hyper]
heat intolerance
hyperhidrosis
weight loss

A

hyper

**due to increased NaKATPase increasing BMR, increased calorigenesis

82
Q

[hypo or hyper]
dry cool skin

A

hypo

**due to decreased bood flow

83
Q

[hypo or hyper]
coarse brittle hair
alopecia
brittle nails
puffy facies
nonpitting edema

A

hypo

**due to increased GAGs in interstitial spaces increased the osmotic pressure –> water retention

84
Q

[hypo or hyper]
periorbital edema

A

hypo

85
Q

[hypo or hyper]
constipation
low appetite

A

hypo

**due to decreased GI motility

86
Q

[hypo or hyper]
proximal weakness with increased CK

A

hypo

**hypothyroid myopathy

87
Q

[hypo or hyper]
carpal tunnel syndrome

A

hypo

88
Q

[hypo or hyper]
myoedema

A

hypo

**small lump rising on surface of muscle when struck with reflex hammer

89
Q

[hypo or hyper]
abnormal uterine bleeding
decreased libido
infertility

A

hypo

90
Q

[hypo or hyper]
lethargy
fatigue
weakness
depressed mood
slow reflexes

A

hypo

91
Q

[hypo or hyper]
bradycardia
dyspnea on exertion

A

hypo

**due to decreased cardiac output

92
Q

expected labs for hypothyroidism [3]

A

increased TSH (if primary)
decreased free T3/T4
hypercholesterolemia

93
Q

[hypo or hyper]
warm, moist skin
fine hair
onycholysis

A

hyper

**due to increased vasodilation

94
Q

[hypo or hyper]
pretibial myxedema

A

hyper

Grave’s disease

95
Q

[hypo or hyper]
diarrhea
increased appetite

A

hyper

**increased GI motility

96
Q

[hypo or hyper]
proximal weakness with normal CK

A

hyper

**thyrotoxic myopathy

97
Q

[hypo or hyper]
osteoporosis
increased fracture risk

A

hyper

**T3 directly stimulates bone reabsorption

98
Q

[hypo or hyper]
abnormal uterine bleeding
gynecomastia
decreased libido
infertility

A

hyper

99
Q

[hypo or hyper]
restlessness
anxiety
insomnia
tremors
brisk reflexes

A

hyper

**due to increased b-adrenergic activity

100
Q

[hypo or hyper]
tachycardia
palpitations
dyspnea
arrhythmias
chest pain
systolic HTN

A

hyper

**due to increased b-adrenergic receptors, increased expression of NaKATPase on cardia sarcolemma

101
Q

expected labs for hyperthyroidism

A

decreased TSH (if primary)
increased free T3/T4
hypocholesterolemia

102
Q

most common cause of hypothyroidism worldwide
often presents with goiters

A

iodide deficiency

103
Q

commonly caused by thyroid dysgenesis or dyshormonogenesis in utero

A

congenital hypothyroidism

104
Q

pot-bellied
pale
puffy-face child
protruding umbilicus
protuberant tongue
poor brain development

A

6 Ps of congenital hypothyroidism

105
Q

caused by a shift in conversion of T4 from T3 to rT3 (inactive)

A

non-thyroidal illness

106
Q

decreased T3 with normal or low T4/TSH in a critically ill patient

A

non-thyroidal illness

107
Q

self limited disease preceded by viral illness

A

subacute granulomatous thyroiditis (de Quervains)

108
Q

thyroid replaced by fibrous tissue and inflammatory infiltrate

A

Riedel

109
Q

autoimmune disease that attacks/destroys the thyroid gland

A

Hashimoto’s

110
Q

rare but occurs due to sporadic mutation in thyroglobulin or TPO

A

sporadic goiter

111
Q

treatment for hypothyroid disorders

A

exogenous L4 (levothyroxine)

112
Q

autoimmune disease that destroys TSH-R preventing negative feedback onto TSH production

A

Graves

113
Q

most prevalent autoimmune disorder in the US

A

Graves

114
Q

occurs in 50% of Graves patients

A

ophthalmopathy

115
Q

excessive quantities of TH

A

thyrotoxicosis

116
Q

adenomas of the thyroid gland cause […] hyperthyroidism

A

primary

117
Q

pituitary adenomas cause […] hyperthyroidism

A

secondary

**due to excessive TSH secretion

118
Q

PTU inhibits [2]

A

type 1 5’deiodinase
TPO

119
Q

carbimazole/methimazole inhibit

A

TPO

120
Q

treatment for hyperthyroidism [4]

A

radioactive iodine
thyroidectomy
drugs -PTU, carbimazole/methimazole
beta blockers for heart effects

121
Q

[hot or cold nodule]
take up radiotracer

A

hot

122
Q

[hot or cold nodule]
secreted thyroid hormone

A

hot

123
Q

[hot or cold nodule]
ablate with radiotracer

A

hot

124
Q

[hot or cold nodule]
nonfuctional-do not take up tracer

A

cold

125
Q

[hot or cold nodule]
non-secretory

A

cold

126
Q

[hot or cold nodule]
increased association with malignancy

A

cold

127
Q

[hot or cold nodule]
require FNA cytology

A

cold

128
Q

younger patients with thyroid deficiency secondary to lack of iodine present with [2]

A

growth delay
neurologic impairment

129
Q

pretibial myxedema
exophthalmos

A

Graves disease

130
Q

in Graves, radionucleotide scan will display

A

increase in tracer uptake

131
Q

after thyroidectomy, patients must be treated with levothyroxine to prevent

A

symptoms of hypothyroidism

132
Q

anti-thyroglobulin and anti-thyroid peroxidase are associated with

A

Hashimoto

133
Q

lymphocytic infiltration with well-developed germinal centers and Hurthle cells

A

Hashimoto

134
Q

which drug used to treat hyperthyroidism is safe in pregnancy?

A

PTU

135
Q

definitive treatment of hyperthyroidism is accomplished with [2]

A

surgical thyroidectomy
radioactive iodine ablation

136
Q

medications for initial treatment of hyperthyroidism [2]

A

methimazole
PTU

137
Q

mental retardation
protruding tongue
slow movements
coarse facial features

A

congenital hypothyroidism

138
Q

congenital hypothyroidism is caused by

A

impaired production of T4

**causes increased production of TSH

139
Q

rare but severe side effect of PTU

A

agranulocytosis

140
Q

MOA of PTU

A

inhibits peripheral conversion of T4 to T3