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Endo by Minnie: AH Version > 172b/173b/175b - Hypothalamus/Pituitary Basics, Histo, Path, Pathophys > Flashcards

172b/173b/175b - Hypothalamus/Pituitary Basics, Histo, Path, Pathophys Flashcards

1
Q

Which nuclei of the hypothalamus secrete TRH and GnRH? (3

A

Paraventricular

Ventromedial

Dorsal nucleus

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2
Q

What substances are secreted by the arcuate nucleus of the hypothalamus? (3)

A

GHRH

Dopamine

GnRH

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3
Q

What causes Laron’s syndrome?

What is the treatment?

A

Defective growth hormone receptor -> GH insensitivity

-> Cannot generate IGF-1 in response

Treatement: Give IGF-1 analog (mecasermin)

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4
Q

What is the difference between Cushing Syndrome and Cushing Disease?

A
  • Cushing Syndrome
    • Hypercortisolism of any etiology
  • Cushing Disease
    • Hypercortisolism due to ATCH pituitary adenoma
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5
Q

What is the embryonic tissue of origin for the anterior pituitary?

Posterior pituitary?

A

Anterior: Oral cavity ectoderm (Rathke pouch)

Posterior: Neuroectoderm (diencephalon)

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6
Q

List the 4 sites of action of Growth Hormone (GH)

(general)

A
  • Linear growth (epiphyseal plate via IGF-1 modulation)
  • Bone
  • Muscle
  • Adipose tissue
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7
Q

The biopsy of this sellar lesion from a 35-year-old postpartum woman is most consistent with which of the following statements?

  1. This was a normal change
  2. This was caused by hypertension, and elevated intracranial pressure
  3. The portal venous circulation from hypothalamus was compromised
  4. The small arteriole branches from the posterior pituitary were compromised
A

c. The portal venous circulation from hypothalamus was compromised

  • Sheehan syndrome
    • Postpartum bleeding
  • > hypotension
  • > infarct of the anterior pituitary
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8
Q

What substances are secreted by the dorsal nucleus of the hypothalamus? (2)

A

TRH

GnRH

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9
Q

Which two pituitary hormones are negatively regulated by somatostatin?

A

Growth hormone (GH)

Thyroid stimulating hormone (TSH)

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10
Q

Which portion of the pituitary contains axons?

Where do they originate?

A

Posterior pituitary

Axons originate in neurons in the supraoptic (ADH) and paraventricular (oxytocin) nuclei of the hypothalamus

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11
Q

What class of receptor is the vasopressin receptor?

A

GPCR

  • V1 = Gq
  • V2 = Gs
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12
Q

What is the most common sellar mass?

A

Craniopharyngioma

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13
Q

Which pituitary adenoma is most likely to present as a microadenoma?

A

ACTH-producing

Often symptomatic, presents when small

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14
Q

How do you expect the following to change as plasma vasopressin levels increase?

  • Urine output:
  • Urine osmolarity:
A
  • Urine output: Decreases
  • Urine osmolarity: Increases
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15
Q

What hypothalamic hormone inhibits the release of growth hormone?

Where is it released?

A

Somatostatin

Paraventricular nucelus

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16
Q

What are the two receptors for vasopressin (ADH)?

What happens when they are activated?

A
  • V1 in vascular endothelium and smooth muscle
    • Increases smooth muscle contraction
  • > Increased BP
  • V2 in the basolateral membrane of collecting tubules
    • Insertion of AQP2 into the luminal membrane
  • > Reduce urinary water excretion
  • V2 outside of the kidney
    • Increases release of Factor VIII and vWF
  • > platelet aggregation
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17
Q

What is the treatment for prolactinoma?

A

Bromocriptine

Cabergoline

(Dopamine receptor agonists)

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18
Q

How are GPCRs desensitized and downregulated?

A
  • Phosphorylation
  • Endocytosis
    • Degradation -> permanent signal termination
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19
Q

A 27 year old woman who had been previously well has developed amenorrhea (loss of menses) and galactorrhea. Which one of the following hormones might you expect to be elevated?

a. Growth hormone
b. Vasopressin
c. Prolactin
d. ACTH
e. Luteinizing Hormone

A

c. Prolactin

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20
Q

Which drug is a growth hormone receptor antagonist?

A

Pegvisomant

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21
Q

What are the two major stimuli for oxytocin release?

A
  • Suckling (breast feeding)
  • Cervical stretch (during labor)

-> Oxytcin release from posterior pituitary

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22
Q

Which pituitary hormone is tonically suppressed by the hypothalamus?

What is the mechanism of suppresion?

A

Prolactin is tonically suppressed by dopamine

  • All other pituitary hormones are stimulated by the hypothalamus
    • => If the pituitary stalk is severed, prolactin levels will increase and all other hormone levels will decrease
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23
Q

What is the most common cause of SIADH?

A

Neoplasm - small cell carcinomas of the lung

24
Q

Which part of the pituitary is most likely to be affected by CNS sarcoidosis?

A

Strictures in the suprasellar region

25
Q

What is the most common cause of hyperpituitarism?

A

Pituitary adenoma

26
Q

Which pituitary pathology?

What will the presentation look like?

A

Lymphocytic hypophysitis

  • Lymphocytic infiltration
  • Symmetrical enlargement of the pituitary + anterior pituitary insufficiency
  • Often in a pregnant or post-partum woman
27
Q

Damage to the _____ hypothalamus results in anorexia and weight loss

Damage to the _____ hypothalamus results in obesity

A

Damage to the lateral hypothalamus results in anorexia and weight loss

Damage to the ventromedial hypothalamus results in obesity

28
Q

Which nucleus of the hypothalamus releases oxytocin?

A

Paraventricular

29
Q

What causes Kallmann’s Syndrome?

What are the manifestations?

A

Mutation in the protein that facilitates migration of GnRH and olfactory neurons from the olfactory placode to the anterior septal region of the hypothalamus

  • -> Insufficient growth
    • Hypogonadotropic hypogonadism
  • -> Possibly cannot smell properly
30
Q

Embryonic origin of:

  • Anterior pituitary:
  • Posterior pituitary:
A
  • Anterior pituitary: Oral ectoderm - Rathke’s pouch
    • ​Note: contact between Rathke pouch and developing hypothalamus is important for signaling!
  • Posterior pituitary: Neuroectoderm - ventral outgrowth of hypothalamic floor
31
Q

Describe the blood supply to the anterior pituitary

A

Portal venous circulation - low pressure

  • Susceptible to ischemic injury during elevated ICP
32
Q

What is the difference between Sheehan’s syndrome and pituitary apoplexy?

A
  • Sheehan’s syndrome = infarct
    • Post-partum
  • Pituiatry apoplexy = hemorrhage
    • Often in the setting of a pituitary adenoma
    • This is an emergency!

Both result in hypopituitarism

33
Q

In which part of the pituitary is a Rathke’s cleft cyst most likey to arise?

A

Pars intermedia

34
Q

Which histologic feature of the posterior pituitary represents axonal expansions from the hypothalamus?

A

Herring bodies

(Finely granular, round/ellipsoidal)

35
Q

Enlargement of an ACTH adenoma after removal of both adrenal glands is called:

A

Nelson Syndrome

36
Q

How does hyperprolactinemia cause hypogonadism?

A

Disrupts GnRH pulsations

  • -> Disrupts FSH, LH pulsations
  • Also interferes with feedback
37
Q

List 2 neoplasmic causes of central diabetes insipidus

A
  • Craniopharyngeaoma
    • Adamantinomatous or papillary
  • Germ cell tumor (germinoma)
38
Q

What class of receptor is the insulin receptor?

A

Tyrosine kinase

39
Q

What causes Sheehan’s syndrome?

A

Post-partum infarct of the pituitary gland

  • > ischemia
  • > necrosis
  • > hypopituitarism
40
Q

Which part of the pituitary gland contains pituicytes?

A

Posterior pituitary

Pituicytes = special astrocytes for the posterior pituitary

41
Q

Which nucleus of the hypothalamus secretes GHRH, dopamine, and GnRH?

A

Arcuate nucelus

42
Q

Which pituitary pathology?

A

Pituitary adenoma

  • Cells look alike (no nests)
  • Loss of reticulin between nests
43
Q

What substances are secreted by the ventromedial nucleus of the hypothalamus? (2)

A

TRH

GnRH

44
Q

Which pituitary hormone has the strongest diurnal rhythm?

A

ACTH

  • Results in strong diurnal rhythm for cortisol
  • Lowest levesl 12am-8am
45
Q

What pituitary pathology is shown?

A

Rathke’s cleft cyst

  • Lined by ciliated cuboidal epithelium
  • Most likely in pars intermedia
  • NOT a neoplasm
46
Q

Which nucleus of the hypothalamus releases vasopressin (ADH)?

A

Supraoptic

47
Q

List 3 ligands that bind JAK receptors

A
  • Growth hormone
  • Prolactin
  • Leptin
48
Q

A 16 year old boy is brought in by his parents because he has not yet started puberty. On examination he is found to be prepubertal. On your examination of him, which of the following senses might be expected to be abnormal?

a. Vision
b. Hearing
c. Smell
d. Touch
e. Pain

A

c. Smell

49
Q

What substances are secreted by the paraventricular nucleus of the hypothalamus? (4)

A

TRH

CRH

GnRH

Somatostatin

50
Q

How does a craniopharyngioma cause hyperprolactinemia and diabetes insipidus?

A

Craniopharyngioma is a cyst

-> Mass effect

  • Diabtes insipidus due to blockage of signals to secrete ADH
  • Hyperprolactinemia due to blockage of dopamine signals that suppress prolactin
51
Q

Which nucleus of the hypothalamus secretes TRH, CRH, GnRH and somatostatin?

A

Paraventricular nucelus

52
Q

Which part of the pituitary is most likely to be affectec by lymphocytic hypophysitis?

In what settings is it common?

A

Anterior pituitary

Most common in pregnancy or post-partum

53
Q

Which pituitary pathology?

How do you know?

A

CNS sarcoidosis

  • Non-caseating granulomatous inflammation
  • Multinucleated giant cells (Langhans’ cells)
54
Q

Which image represents normal pituitary histology?

What abnormality is pictured in the other image?

A
  • Pituitary adenoma
    • Loss of nest pattern - all cells look alike
  • Normal pituitary
    • Nests of different kinds of cells (multi-colored)
55
Q

What is the most common pituitary adenoma?

A

Prolactin-producing pituitary adenoma

56
Q

What is the treatment for acromegaly?

A
  • Surgery is first line
  • Medical therapy if incomplete/failed response to surgery
    • Dopamine agonists (cabergoline)
    • Somatostatin analog (octreotide)
    • GH receptor antagonist (pegvisomant)

Endo by Minnie: AH Version (19 decks)

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