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FA Step 1 2020 > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

Thyroid diverticulum arises from

A

floor of primitive pharynx and descends into neck

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2
Q

“Thyroid diverticulum” (?) is connected to the tongue via

A

thyroglossal duct

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3
Q

Thyroglossal duct normally disappears but may persist as

A

cysts or the pyramidal lobe of thyroid

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4
Q

What is the normal remnant of the thyroglossal duct?

A

Foramen cecum

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5
Q

Most common ectopic thyroid tissue site is

A

tongue (Removal may result in hypothyroidism if it is the only thyroid tissue present)

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6
Q

How does a thyroglossal duct cyst present?

A

an anterior midline neck mass that moves with swallowing or protrusion of the tongue

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7
Q

Thyroglossal duct cyst persistent cervical sinus in presentation

A

Thyroglossal duct cyst presents as an anterior midline neck mass that moves with swallowing or protrusion of the tongue vs persistent cervical sinus leading to pharyngeal cleft cyst in lateral neck.

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8
Q

Thyroid follicular cells derived from

A

endoderm

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9
Q

Hormones secreted by anterior pituitary gland / Adenohypophysis

A

FSH, LH, ACTH, TSH, prolactin, GH, and β-endorphin

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10
Q

Hormones secreted by intermediate lobe of pituitary gland

A

Melanotropin (MSH)

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11
Q

Anterior pituitary gland (interm?) is derived from

A

ectoderm

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12
Q

alfa subunit of anterior pituitary hormones is common to

A

TSH, LH, FSH, and hCG

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13
Q

Which subunit determines hormone specificity of anterior pituitary hormones

A

Beta subunit

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14
Q

Proopiomelanocortin derivatives

A

β-endorphin, ACTH, and MSH

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15
Q

Basophils hormones of the anterior pituitary gland

A

FSH, LH, ACTH, TSH

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16
Q

Acidophils hormones of the anterior pituitary gland

A

PRL, GH

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17
Q

Posterior pituitary (neurohypophysis) —- and —– vasopressin (antidiuretic hormone, or ADH) and oxytocin

A

stores and releases

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18
Q

Both vasopressin (antidiuretic hormone, or ADH) and oxytocin are made in —– and transported to —– via —–

A

made in the hypothalamus (supraoptic and paraventricular nuclei) and transported to posterior pituitary via neurophysins (carrier proteins).

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19
Q

Posterior pituitary (neurohypophysis) is derived from

A

neuroectoderm

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20
Q

Zona glomerulsoa is primarily regulated by

A

Angiotensin II

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21
Q

Zona fasciculata is primarily regulated by

A

ACTH, CRH

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22
Q

Zona reticularis is primarily regulated by

A

ACTH, CRH

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23
Q

The hormone class produced by zona glomerulosa is

A

Mineralocorticoids

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24
Q

The hormone class produced by zona fasciculata is

A

Glucocorticoids

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25
Q

The hormone class produced by zona reticularis is

A

Androgens

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26
Q

The primary hormone produced by zona glomerulosa

A

Aldosterone

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27
Q

The primary hormone produced by zona fasciculata

A

Cortisol

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28
Q

The primary hormone produced by zona reticularis

A

DHEA

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29
Q

Medulla of suprarenal gland is primarily regulated by

A

Preganglionic sympathetic fibers

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30
Q

Medulla of suprarenal gland produces the hormone class

A

Catecholamines

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31
Q

Medulla of suprarenal gland primarily produces the hormone

A

Epi, NE

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32
Q

ADH = antidiuretic hormone = vasopressin function

A

increases water permeability of distal convoluted tubule and collecting duct cells in kidney to increase water
reabsorption

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33
Q

Stimulus for secretion of ADH

A

increased plasma osmolality

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34
Q

Give an exception to the regular ADH stimulus

A

SIADH, in which ADH is elevated despite decreased plasma osmolality

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35
Q

Function of CRH

A

Increases. ACTH, MSH, β-endorphin

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36
Q

Give an example where CRH is decreased

A

Chronic exogenous steroid use

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37
Q

Function of Dopamine

A

Decreases prolactin, TSH

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38
Q

Another name for Dopamine

A

Prolactin-inhibiting factor

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39
Q

Can dopamine antagonists cause galactorrhea

A 
Dopamine antagonists (eg, antipsychotics) can
cause galactorrhea due to hyperprolactinemia
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40
Q

What does GHRH do?

A

Increases GH

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41
Q

What can be used to treat HIV-associated lipodystrophy?

A

AN GHRH analog (Tesamorelin)

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42
Q

What does GnRH do?

A

Increases FSH and LH

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43
Q

What does hyperprolactinemia do to GnRH?

A

Suppresses it

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44
Q

How does a tonic GnRH analog work?

A

Tonic GnRH analog (eg, leuprolide) suppresses

hypothalamic–pituitary–gonadal axis.

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45
Q

What does pulsatile GnRH do?

A

Pulsatile GnRH leads to puberty, fertility

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46
Q

What does MSH do?

A

Increases melanogenesis by melanocytes

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47
Q

What causes hyperpigmentation in Cushing disease?

A

MSH causes hyperpigmentation in Cushing disease, as MSH and ACTH share the same precursor molecule, proopiomelanocortin

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48
Q

Functions of Oxytocin

A

Causes uterine contractions during labor.
Responsible for milk letdown reflex in response
to suckling.
Modulates fear, anxiety, social bonding, mood, and depression.

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49
Q

What does prolactin do?

A

Decrreases GnRH

Stimulates lactogenesis.

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50
Q

What does pituitary prolactinoma lead to?

A

Pituitary prolactinoma –> amenorrhea, osteoporosis, hypogonadism, galactorrhea

51
Q

Breastfeeding role in contraception

A

Breastfeeding –> increases prolactin –> increases GnRH –> delayed postpartum ovulation (natural contraception)

52
Q

What does Somatostatin do?

A

Decreases GH, TSH

53
Q

Another name for Somatostatin

A

Also called growth hormone inhibiting hormone (GHIH)

54
Q

Analogs of Somatostatin are used to treat —–

A

Acromegaly

55
Q

What does TRH do?

A

Increases TSH, prolactin

56
Q

TRH role in galactorrhea

A

Increase in TRH (eg, in 1°/2° hypothyroidism) may

increase prolactin secretion –> galactorrhea

57
Q

Another name for GH

A

somatotropin

58
Q

What does GH do?

A
  • Stimulates linear growth and muscle mass through IGF-1 (somatomedin C) secretion by liver.
  • Increases insulin resistance (diabetogenic).
  • Released in pulses in response to growth hormone-releasing hormone (GHRH).
  • Secretion increases during exercise, deep sleep, puberty, hypoglycemia, CKD.
  • Secretion decreases by glucose, somatostatin, somatomedin (regulatory molecule secreted by liver in response to GH acting on target tissues).
  • Excess secretion of GH (eg, pituitary adenoma) may cause acromegaly (adults) or gigantism (children). Treatment: somatostatin analogs (eg, octreotide) or surgery.
59
Q

What does the liver produce in response to GH?

A

IGF-1

60
Q

Another name for IGF-1

A

Somatomedin C

61
Q

GH –> IGF-1 –> bone?

A

Increases

  • Amino acid uptake
  • Protein synthesis
  • DNA and RNA synthesis
  • Chondroitin sulfate
  • Collagen
  • Cell size and number
62
Q

GH –> IGF-1 –> muscle?

A

Increases

  • Amino acid uptake
  • Protein synthesis
63
Q

GH –> fat (?) ?

A

Decreases glucose uptake

Increases lipolysis

64
Q

Another name for antidiuretic hormone

A

Vasopressin

65
Q

Source of ADH

A

Synthesized in hypothalamus (supraoptic and paraventricular nuclei), stored and secreted by posterior pituitary.

66
Q

Function of ADH

A

Regulates blood pressure (V1-receptors) and serum osmolality (V2-receptors). Primary function is serum osmolality regulation (ADH decreases serum osmolality, increases urine osmolality) via regulation of aquaporin channel insertion in principal cells of renal collecting duct.

67
Q

ADH and DI

A

ADH level is decreased in central diabetes insipidus (DI), normal or increased in nephrogenic DI.
Nephrogenic DI can be caused by mutation in V2-receptor.
Desmopressin (ADH analog) is a treatment for central DI and nocturnal enuresis.

68
Q

Name 2 uses of ADH analog

A

central DI and nocturnal enuresis.

69
Q

Regulation of ADH

A

Plasma osmolality (1°); hypovolemia.

70
Q

Prolactin is structurally similar to

A

GH

71
Q

Function of prolactin

A

Stimulates milk production in breast; inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release.

72
Q

How does prolactin inhibit ovulation in females and spermatogenesis in males

A

by inhibiting GnRH synthesis and release

73
Q

Excessive amounts of prolactin associated with

A

decreased libido

74
Q

Why does 1° or 2° hypothyroidism increase prolactin?

A

Because it increases TRH which increases prolactin

75
Q

Regulation of prolactin

A

Prolactin secretion from anterior pituitary
is tonically inhibited by dopamine from tuberoinfundibular pathway of hypothalamus. Prolactin in turn inhibits its own secretion bydopamine synthesis and secretion from hypothalamus. TRHprolactin secretion (eg, in 1° or 2° hypothyroidism).

76
Q

Do we use dopamine agonists or antagonists in treatment of hyperprolactinoma

A

Dopamine agonists (eg, bromocriptine) inhibit prolactin secretion and can be used in treatment of prolactinoma.

77
Q

Name 2 medications that stimulate prolactin secretion

A

Dopamine antagonists (eg, most antipsychotics, metoclopramide) and estrogens (eg, OCPs, pregnancy) stimulate prolactin secretion.

78
Q

Name 3 factors that can inhibit Dopamine

A

Medications
Chest wall injury (via ANS)
Nipple stimulation

79
Q

What are thyroid hormones?

A

Thyroid produces triiodothyronine (T3) and thyroxine (T4), iodine-containing hormones that
control the body’s metabolic rate.

80
Q

What is the source of thyroid hormones?

A

Follicles of thyroid

81
Q

What the major thyroid product?

A

T4

82
Q

How and where is T4 converted to T3?

A

5′-deiodinase converts T4 (the major thyroid product) to T3 in peripheral tissue (5, 4, 3)

83
Q

What inhibits the peripheral conversion from T4 to T3?

A

1- glucocorticoids
2- β-blockers
3- propylthiouracil (PTU)

84
Q

What is Reverse T3?

A

Reverse T3 (rT3) is a metabolically inactive byproduct of the peripheral conversion of T4

85
Q

What increases reverse T3 production?

A

1- growth hormone

2- glucocorticoids

86
Q

Functions of thyroid peroxidase include

A

1- oxidation
2- organification of iodine
3- coupling of monoiodotyrosine (MIT) and diiodotyrosine (DIT)

87
Q

What inhibits thyroid peroxidase

A

1- PTU

2- Methimazole

88
Q

DIT + DIT =

A

T4

89
Q

DIT + MIT =

A

T3

90
Q

What is Wolff-Chaikoff effect?

A

Excess iodine temporarily turns off thyroid peroxidaseŽT3/T4 production (protective autoregulatory effect).

91
Q

What thyroid hormone is active?

A

Only free hormone is active.

92
Q

T? binds nuclear receptor with greater affinity than T?

A

T3 binds nuclear receptor with greater affinity than T4

93
Q

T3 functions —7 B’s:

A

ƒ Brain maturation
ƒ Bone growth (synergism with GH)
ƒ β-adrenergic effects.β1 receptors in heartŽCO, HR, SV, contractility; β-blockers alleviate adrenergic symptoms in thyrotoxicosis
ƒ Basal metabolic rate(via Na+/K+-ATPase activityŽO2 consumption, RR, body temperature)
ƒ Blood sugar ( glycogenolysis, gluconeogenesis)
ƒ Break down lipids ( lipolysis)
ƒ Stimulates surfactant synthesis in Babies

94
Q

Regulation of thyroid hormone production through follicular cells

A

TRH ⊕ TSH releaseŽ⊕ follicular cells. Thyroid-stimulating immunoglobulin (TSI) may ⊕ follicular cells in Graves disease.

95
Q

Negative feedback in thyroid hormone regulation

A

Negative feedback primarily by free T3/T4:

  • Anterior pituitaryŽsensitivity to TRH
  • HypothalamusŽTRH secretion
96
Q

Role of thyroxine-binding globulin in regulation of thyroid hormone production

A

Thyroxine-binding globulin (TBG) binds most T3/T4 in blood. Bound T3/T4 = inactive.

  • TBG in pregnancy, OCP use (estrogen –> TBG)Žtotal T3/T4
  • TBG in steroid use, nephrotic syndrome
97
Q

Source of parathyroid hormone

A

Chief cells of parathyroid

98
Q

Primary function of PTH

A

Increases free calcium in the blood

99
Q

Functions of PTH

A

Primary function: increases free calcium in the blood

GI: inc ca and phos absorption
bone: inc ca and phos from bone resorption
kidneys: ins ca reabsorption from DCT - dec phos reasorption in PCT - inc 1,25-(OH)2D3 (calcitriol) production by
activating 1α-hydroxylase in PCT

Tri to make D3 in the PCT

All in all, PTH

  • inc serum ca
  • dec serum phos
  • inc urine phos
  • inc urine cAMP

inc RANK-L (receptor activator of NF-κB ligand) secreted by osteoblasts and osteocytes; binds RANK (receptor) on osteoclasts and their precursors to stimulate osteoclasts and inc Ca2+ –> bone resorption (intermittent PTH release can also stimulate bone formation)

100
Q

PTH is phosphate—–hormone

A

PTH = Phosphate-Trashing Hormone

101
Q

What does PTH-related peptide (PTHrP) do?

A

Functions like PTH and is commonly increased in malignancies (eg, squamous cell carcinoma of the lung, renal cell carcinoma)

102
Q

Regulation of PTH

A

The following increase PTH secretion

  • decreased serum Ca2+
  • increased serum PO4 3−
  • decreased serum Mg2+

But very decreased Mg2+ decreases PTH secretion

103
Q

Common causes of decreased Mg2+ include

A

diarrhea,

aminoglycosides, diuretics, alcohol abuse

104
Q

All in all, what does PTH result in?

A
  • inc serum ca
  • dec serum phos
  • inc urine phos
  • inc urine cAMP
105
Q

Action of PTH on

  • GI
  • Bone
  • Kidneys
A

GI: inc ca and phos absorption

Bone: inc ca and phos from bone resorption

Kidneys: inc ca reabsorption from DCT - dec phos reasorption in PCT - inc 1,25-(OH)2D3 (calcitriol) production by
activating 1α-hydroxylase in PCT

106
Q

Action of PTH on

GI

A

inc ca and phos absorption

107
Q

Action of PTH on

bone

A

inc ca and phos from bone resorption

108
Q

Action of PTH on

kidneys

A
  • inc ca reabsorption from DCT
  • dec phos reabsorption in PCT
  • inc 1,25-(OH)2D3 (calcitriol) production by
    activating 1α-hydroxylase in PCT
109
Q

Name 2 things that activate/stimulate 1α-hydroxylase

A
  • PTH

- Decreased PO4 3−

110
Q

Name 2 things that increase calcium and decrease PO4 3− release from bone

A
  • PTH

- 1,25-(OH)2D3

111
Q

Plasma Ca2+ exists in three forms

A
  • Ionized/free (~ 45%, active form)
  • Bound to albumin (∼ 40%)
  • Bound to anions (∼ 15%)
112
Q

Which pH increases PTH secretion?

A

Increased pH (basic)

113
Q

How is albumin binding to Ca2+ affected by pH?

A

Proportional

Increased pH (less H+) --> Increased albumin binds more
Ca2+ --> Decreased ionized Ca2+ (eg, cramps, pain, paresthesias, carpopedal spasm) --> Increased PTH

Decreased pH (more H+) –> Decreased albumin binds less Ca2+ –> Increased ionized Ca2+ –> Decreased PTH

114
Q

What is the primary regulator of PTH?

A

Ionized/free Ca2+

115
Q

Do changes in pH alter PTH secretion?

A

Yes

116
Q

Do changes in albumin alter PTH secretion?

A

No

117
Q

What is the source of Calcitonin?

A

Parafollicular cells (C cells) of thyroid.

118
Q

What is the function of Calcitonin?

A

Decreases bone resorption of Ca2+.

119
Q

How is

Calcitonin secretion regulated?

A

Increased serum Ca2+ –> Increased calcitonin secretion.

120
Q

How is Calcitonin function different from PTH function?

A

Calcitonin opposes actions of PTH. Not important in normal Ca2+ homeostasis
Calcitonin tones down serum Ca2+ levels and keeps it in bones

121
Q

What is the source of Glucagon?

A

Made by α cells of pancreas.

122
Q

What is the function of Glucagon?

A 
Promotes
1- glycogenolysis,
2- gluconeogenesis,
3- lipolysis,
4- ketogenesis.

Elevates blood sugar levels to maintain homeostasis when bloodstream glucose levels fall too low (ie, fasting state).

123
Q

Glucagon is secreted in response to

A

hypoglycemia

124
Q

Glucagon is inhibited by

A

1- insulin,
2- hyperglycemia,
3- somatostatin.

FA Step 1 2020 (1 decks)

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