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Endo/repro personal > Hypothalamic Pituitary Relationships > Flashcards

Hypothalamic Pituitary Relationships Flashcards

1
Q

The communications between the hypothalamus and ________ _____ are neural and hormonal

A

Anterior pituitary

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2
Q

Hormones of anterior pituitary

A 
ACTH
TSH
FSH
LH
GH
Prolactin
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3
Q

What is a hallmark symptom of pituitary tumors?

A

Vision changes d/t impingement of optic chiasm and optic n

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4
Q

What is the direct route of delivery of hormones from the hypothalamus to the anterior pituitary?

A

Hypothalamic hypophysial portal system

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5
Q

T/F: Hormones from the anterior pituitary appear in high concentrations in systemic circulation

A

False; they have high concentration within the gland itself

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6
Q

The anterior pituitary has neural and hormonal signals with the hypothalamus. The posterior pituitary has ____ signals only

A

Neural

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7
Q

The anterior pituitary is a collection of endocrine cells; the posterior pituitary is a collection of ______ whose cell bodies are located in the hypothalamus

A

Axons

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8
Q

The cell bodies in the hypothalamus that communicate with the posterior pituitary are associated with what 2 nuclei? What neuropeptides do they secrete?

A

Supraoptic nucleus (SON) = secretes ADH

Paraventricular nucleus (PVN) = secretes oxytocin

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9
Q

Compare/contrast primary vs. secondary vs. tertiary endocrine disorders

A

Primary = at the level of peripheral gland

Secondary = problem with pituitary

Tertiary = problem with hypothalamus

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10
Q

Hormone families of the anterior pituitary are organized by structural and functional homology. What are the 3 families of the anterior pituitary?

A

ACTH family = corticotrophs; secrete ACTH

TSH, FSH, LH family = thyrotrophs (secrete TSH); gonadotrophs (secrete FSH and LH)

GH, Prolactin family = somatotrophs (secrete GH), lactotrophs (secrete prolactin)

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11
Q

Match the releasing hormone with its target in anterior pituitary and hormone secreted:

TRH

A

Thyrotrophs —> TSH

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12
Q

Match the releasing hormone with its target in anterior pituitary and hormone secreted:

CRF

A

Corticotrophs —> ACTH

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13
Q

Match the releasing hormone with its target in anterior pituitary and hormone secreted:

GnRH

A

Gonadotrophs —> LH, FSH

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14
Q

Match the releasing hormone with its target in anterior pituitary and hormone secreted:

GHRH vs. somatostatin

A

GHRH —> somatotrophs —> GH

Somatostatin inhibits somatotrophs secretion of GH

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15
Q

PIF (dopamine) from hypothalamus acts on ______ in anterior pituitary to inhibit secretion of _____

A

Lactotrophs; PRL

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16
Q

Activity of endocrine axes are maintained at a set point, often secreting hormones in pulsatile manner and entrained to circadian rhythms. What are the axes associated with the anterior pituitary gland?

A

Hypothalamic-Pituitary-Gonad (HPG)

Hypothalamic-Pituitary-Liver

Hypothalamic-Pituitary-Prolactin

Hypothalamic-Pituitary-testis/ovary

Hypothalamic-Pituitary-thyroid

Hypothalamic-Pituitary-Adrenal

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17
Q

Rare disease characterized by excessive growth of soft tissue, cartilage, and bone in the face, hands, and feet; caused by prolonged and excessive secretion of growth hormone in adult life

A

Acromegaly

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18
Q

Physical findings of acromegaly

A 
Prominent supraorbital ridges
Lower teeth separation
Prominent lower jaw
Cardiomegaly
Organomegaly
Hyperglycemia
Enlarged head circumference
Hypertension
Large hands
Accelerated osteoarthrosis
Increased heel-pad thickness on x-ray
Large feet
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19
Q

Growth hormone is produced by somatotropes

It targets _____ and ______ (organs)

The GH receptor is linked to _______ signaling

A

Liver; bone

Jak-stat

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20
Q

Growth hormone is inhibited by ____ and _____ as part of a negative feedback mechanism

A

Somatostatin (GHIH)

IGF-1

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21
Q

What are the 2 primary stimulators of GH secretion?

A

Fasting/hunger/starvation

Hypoglycemia

[also puberty hormones, exercise, sleep, and stress]

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22
Q

GH binds directly to target cells in ____ and ____

A

Bones; muscle

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23
Q

GH binds directly to bones and muscle. What effect does it have on growth?

A

Hypertrophy - increase in size/volume of cells (ex: increases bone thickness)

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24
Q

GH binds directly to bones and muscle. What effect does it have on cell reproduction?

A

Hyperplasia = increase number of cells or proliferation rate via mitosis (ex: increase bone length)

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25
Q

GH binds directly to bones and muscle. What effect does it have on metabolism?

A

Increase glycogen and fat breakdown for energy to increase protein synthesis

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26
Q

Another name for growth hormone

A

Somatotropin

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27
Q

Another name for insulin-like growth factor 1 (IGF-1)

A

Somatomedin C

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28
Q

In a normal hypothalamic-pituitary-growth hormone axis, the hypothalamus releases either ______ and ______, or ______, which act at the anterior pituitary which will either be stimulated or inhibited to release growth hormone.

Two of the above will stimulate the release of growth hormone, which proceeds to the ______ which releases _______

A

Ghrelin; GHRH; somatostatin

Liver; IGF-1

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29
Q

Describe a primary GH insensitivity in terms of the HPGh axis

A

The liver is insensitive to GH, so GH levels rise

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30
Q

Describe a secondary GH insensitivity in terms of the HPGh axis

A

Secondary = problem with pituitary

Ghrelin and GHRH or somatostatin are released from hypothalamus, but GH cannot be released from anterior pituitary. IGF-1 does not get stimulated at all. GH levels are LOW

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31
Q

Describe a tertiary GH insensitivity in terms of the HPGh axis

A

Tertiary = problem with hypothalamus

Ghrelin, GHRH, and somatostatin not getting secreted from hypothalamus, no GH being released from anterior pituitary, IGF-1 not stimulated at all. GH levels LOW

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32
Q

Excess growth hormone causes 2 different conditions depending on closure of bone epiphyses (growth plates); what are they?

A

Gigantism if GH excess occurs prior to growth plate closure — due to IGF-1 stimulated long bone growth

Acromegaly if GH excess occurs after growth plate closure due to promotion of growth of deep organs and cartilaginous tissues

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33
Q

Growth promoting factors in the fed state are increased carb intake (leading to increased blood sugar and adequate insulin availability) and increased protein intake (leading to adequate amino acid availability)

These two factors act on the liver to produce IGF-1

What are the 3 anabolic activites encouraged by IGF-1?

A

Mitogenesis

Lipolysis

Differentiation

[increased activity of IGF-1 —> increased osteoblasts, collagen, and bone matrix]

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34
Q

What happens to GH if you have adequate insulin availability but inadequate amino acid availability?

A

GH is inhibited; liver will not produce IGF-1

Net result is weight gain d/t lipogenesis and carb storage

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35
Q

What happens to GH in conditions of adequate amino acid availability and inadequate insulin availability?

A

GH levels increase, liver will produce IGF-1, leading to increased lipolysis, ketogenic metabolism, and diabetogenesis (long term)

36
Q

GH promotes lipolysis, but can also promote _____ insensitivity

A

Insulin

[GH raises BG by decreasing peripheral glucose uptake and stimulating hepatic gluconeogenesis]

37
Q

How are GH abnormalities diagnosed?

A

Elevated serum GH and IGF-1 levels

AND

Failure to suppress GH production in response to an oral load of glucose (very sensitive test for acromegaly)

38
Q

Describe diabetogenic effects of GH

A

Increase in BG concentration causes insulin resistance

Decreased glucose uptake and utilization by target tissues; increased lipolysis in adipose tissue

Results in increased blood insulin levels

39
Q

Increased protein synthesis and organ growth caused by GH leads to increased uptake of amino acids - this stimulates synthesis of DNA, RNA, and protein. It is mediated by ______

A

Somatomedins (IGF-1)

40
Q

GH secretion fluctuates throughout the day but is primarily secreted during _________, so disturbances at this time perturb GH secretion

GH secretion also peaks with ______

A

Sleep; exercise

41
Q

What are different mechanisms of GH deficiency?

A

Decreased secretion of GHRH

Decreased secretion of GH itself

Failure to generate somatomedins

GH or somatomedin resistance (deficiency of receptors)

42
Q

Describe diagnosis of acromegaly using GH and the oral glucose tolerance test

A

Diagnosis of acromegaly requires:

  1. Increased serum IGF-1
  2. Failure to suppress serum GH
  3. Pituitary enlargement on MRI
43
Q

T/F: GH levels fluctuate throughout the day, whereas IGF-1 levels remain constant

A

True

44
Q

Prolactin (PRL) is synthesized by _______, with an increase in secretion beginning around 5th week of pregnancy. Secretion is pulsatile.

PRL is under tonic inhibition by hypothalamic _________

Its primary action is to stimulate and maintain _______

A

Lactotropes

Dopamine

Lactation

45
Q

Prolactin suppresses _____ (thus inhibiting LH and FSH), decreasing reproductive function and suppressing sexual drive

A

GnRH

46
Q

Major stimulatory factors affecting PRL secretion

A 
Pregnancy (estrogen)
Breastfeeding
Sleep
Stress
TRH
47
Q

Major inhibitory factors affecting PRL secretion

A

Dopamine
Dopamine agonists
Somatostatin
Prolactin via negative feedback

48
Q

A normal menstrual cycle in females depends on what 2 hormones?

A

LH; FSH

49
Q

FSH and LH are secreted by _______

They promote _____ and ____ secretion in females and ______ production in males

A

Gonadotropes

Estrogen; progesterone; testosterone

50
Q

FSH and LH are regulated by hypothalamic GnRH

What types of things can inhibit GnRH function?

A

Extreme energy deficits (anorexia nervosa or starvation), extreme exercise, and depression

51
Q

What effect does hyperprolactinemia have on FSH and LH secretion?

A

Suppression

52
Q

Why are the major symptoms of excess PRL galactorrhea (abnormal milk production) and infertility?

A

PRL suppresses GnRH

53
Q

Pulsatile GnRH stimulates LH/FSH secretion from AP, while ______ GnRH secretion inhibits LH/FSH

A

Continuous

54
Q

Ovaries may also secrete ___ and ____ that alter release of FSH in the feedback control mechanism

A

Inhibin; activin

55
Q

Hyperpituitarism affecting corticotrophs leads to which of the following?

A. Cushing’s disease
B. TSH-secreting Adenoma
C. Acromegaly; gigantism
D. Prolactinoma
E. Non-functioning adenoma
A

A. Cushing’s disease

56
Q

Hyperpituitarism affecting gonadotrophs leads to which of the following?

A. Cushing’s disease
B. TSH-secreting Adenoma
C. Acromegaly; gigantism
D. Prolactinoma
E. Non-functioning adenoma
A

E. Non-functioning adenoma

57
Q

Hyperpituitarism affecting lactotrophs leads to which of the following?

A. Cushing’s disease
B. TSH-secreting Adenoma
C. Acromegaly; gigantism
D. Prolactinoma
E. Non-functioning adenoma
A

D. Prolactinoma

58
Q

Hyperpituitarism affecting somatotrophs leads to which of the following?

A. Cushing’s disease
B. TSH-secreting Adenoma
C. Acromegaly; gigantism
D. Prolactinoma
E. Non-functioning adenoma
A

C. Acromegaly; gigantism

59
Q

Hyperpituitarism affecting thyrotrophs leads to which of the following?

A. Cushing’s disease
B. TSH-secreting Adenoma
C. Acromegaly; gigantism
D. Prolactinoma
E. Non-functioning adenoma
A

B. TSH-secreting adenoma

60
Q

How does hypopituitarism manifest in terms of GH?

A

Children have short stature

Adults = no effect

61
Q

How does hypopituitarism manifest in terms of FSH/LH?

A

Infertility, hypogonadism

Males: reduced sperm count

Females: menstrual irregularity

62
Q

How does hypopituitarism manifest in terms of TSH?

A

Hypothyroidism

63
Q

How does hypopituitarism manifest in terms of ACTH?

A

Loss of pigmentation

Hypoadrenalism

64
Q

How does hypopituitarism manifest in terms of ADH

A

Diabetes insipidus

65
Q

2 primary causes of hypopituitarism

A

Brain damage (TBI, subarachnoid hemorrhage, irradiation, stroke)

Pituitary tumors (adenoma)

[other causes include non-pituitary tumors, infections like meningitis/encephalitis/hypophysitis, infarction, autoimmune disorder, pituitary hypoplasia or aplasia, genetic disorder]

66
Q

What is the most common non-pituitary tumor affecting the HP axis in children?

A

Craniopharyngioma

67
Q

____ syndrome = pituitary in pregnancy is enlarged and more vulnerable to infarction

A

Sheehan syndrome

68
Q

Diabetes insipidus is due to a lack of an effect of _____ on the renal collecting duct, resulting in polyuria, polydipsia, and polyphagia

A

ADH

69
Q

What is the difference between central vs. nephrogenic diabetes insipidus?

A

Central = deficient secretion of ADH from hypothalamus or pituitary

Nephrogenic = renal insensitivity to ADH

70
Q

How does the ADH test distinguish between central and nephrogenic diabetes insipidus?

A

After exogenous ADH (desmopressin) administration:

Central DI = kidneys respond by concentrating urine

Nephrogenic DI = no change; kidneys cannot concentrate urine

71
Q

In contrast to central DI, nephrogenic DI involves the kidneys unresponsiveness to ADH, resulting in ________ plasma [ADH] levels, chronic kidney disease, and _____ toxicity

A

Increased; lithium

72
Q

What condition is characterized by excessive secretion of ADH leading to excessive water retention?

A

SIADH

[hyposmolarity fails to inhibit ADH release]

73
Q

What is the common electrolyte imbalance that occurs with acute SIADH? What occurs with chronic SIADH?

A

Acute = hyponatremia d/t water retention

Ongoing volume expansion due to SIADH activates secondary natriuretic mechanisms, resulting in sodium and water loss. The net effet in chronic SIADH is sodium loss that is more prominent than water retention

74
Q

What fluid/solute mechanisms are involved with euvolemic hyponatremia in terms of EC sodium and TBW?

A

EC sodium is normal

TBW slightly increased

[possible underlying causes = SIADH, COPD, malignancy]

75
Q

What fluid/solute mechanisms are involved with hypervolemic hyponatremia in terms of EC sodium and TBW?

A

EC sodium increased

TBW greatly increased

[possible causes = CHF, renal impairment, cirrhosis]

76
Q

Increased or decreased: SIADH

Urinary output
ADH levels
Plasma Na
Hydration status
Thirst
TBW
A 
Urinary output decreased
ADH levels increased
Plasma Na decreased
Hydration status increased
Thirst increased
TBW normal or slightly increased
77
Q

Increased or decreased: DI

Urinary output
ADH levels
Plasma Na
Hydration status
Thirst
TBW
A 
Urinary output increased
ADH levels decreased (central)
Plasma Na increased
Hydration status decreased
Thirst increased
TBW decreased
78
Q

2 primary actions of oxytocin

A

Milk ejection (stimulates contraction of myoepithelial cells lining milk ducts)

Uterine contraction (stimulated by dilation of the cervix or orgasm)

79
Q

Exogenous form of oxytocin used to induce labor

A

Pitocin

80
Q

Hormone from hypothalamus: CRH

Function on anterior pituitary?

A

Stimulates ACTH, MSH

81
Q

Hormone from hypothalamus: dopamine

Function on anterior pituitary?

A

Inhibits prolactin

82
Q

Hormone from hypothalamus: GHRH

Function on anterior pituitary?

A

Stimulates GH release

83
Q

Hormone from hypothalamus: GnRH

Function on anterior pituitary?

A

Stimulates FSH, LH release

84
Q

Hormone from hypothalamus: somatostatin

Function on anterior pituitary?

A

Inhibits GH, TSH

85
Q

Hormone from hypothalamus: TRH

Function on anterior pituitary?

A

Stimulates TSH, prolactin release

Endo/repro personal (18 decks)

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