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Endocrine Physiology > Hypothalamus and Pituitary > Flashcards

Hypothalamus and Pituitary Flashcards

1
Q

The posterior pituitary is composed of neural tissue because _______.

A

It is an outgrowth of the hypothalamus. Hypothalamic neurons end is the pos. pituitary. The upper portion is called the median eminence.

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2
Q

Which nuclei secrete into the posterior lobe?

A

Paraventricular and supraoptic (oxytocin and vasopressin)

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3
Q

What does the anterior pituitary produce?

A

FSH, LH, ACTH, TSH, prolactin, GH (flat PG)

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4
Q

Anterior pituitary releasing factors travel to the adenohypophysis via…

A

hypophyseal-portal circulation

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5
Q

CRH…

A

stimulates ACTH

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6
Q

TRH…

A

stimulates TSH and prolactin

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7
Q

GHRH…

A

simulates GH

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8
Q

Somatostatin…

A

inhibits GH

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9
Q

GnRH…

A

stimulates LH and FSH

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10
Q

Prolactin inhibiting hormone (dopamine)…

A

….inhibits PRL (shocker)

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11
Q

Describe GH control (briefly)

A

Stimulated by GHRH and inhibited by somatostatin

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12
Q

What are neurotransmitter systems that stimulate GHRH and/or inhibit somatostatin?

A
  • Catecholamines (alpha2-adrenergic)
  • Dopamine (D1 or D2)
  • Excitatory amino acids (NMDA and non-NMDA receptors)
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13
Q

What neurotransmitter systems inhibit GHRH and stimulate somatostatin?

A

beta-adrenergic

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14
Q

During fasting, GH…

A

antagonizes insulin action, helps mediate glucose-sparing (stimulate gluconeogenesis)

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15
Q

During anabolic or absorptive phase, GH…

A

facilitates insulin action to promote growth

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16
Q

In protein intake:
In carbohydrate intake:
In fasting:

A

GH up and insulin up
GH down and insulin up
GH up and insulin down

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17
Q

What is gigantism?

A 
Excess GH (eosinophilic adenoma of somatotrophs) during early life
- symmetrical enlargement, overgrowth of long bones, connective tissue, visceral organs
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18
Q

What is acromegaly?

A

Excess GH after body growth has stopped

- Overgrowth of cancellous bones, protruding jaw, thickening of phalanges, overgrowth of visceral organs

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19
Q

Proteolytic processing of prepro-opiomelanocortin (POMC) makes…

A

ACTH, beta and gamma lipotropin, beta-endorphin, alpha-melanocyte-stimulating hormone (alpha-MSH)

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20
Q

What can overproduction of ACTH darken the skin?

A

alpha-MSH (a co-product) stimulates melanocytes

Also antipyretic and anti-inflammatory effects (inhibit CRH and LHRH too)

21
Q

ACTH regulates…

A

adrenal cortex and synthesis of adrenocorticosteroids

22
Q

What is Addison’s Disease?

A

Lack cortisol from zona fasciculata; lack negative feedback to suppress ACTH

Skin color will darken

23
Q

What is beta-endorphin?

A

Co-product of ACTH synthesis; binds to opiate receptors; “runner’s high”

24
Q

What stimulates ACTH secretion?

A

CRH, ADH, stress, hypoglycemia

25
Q

Deficiency of ADH (vasopressin, is diabetes insipidus) is accompanied by…

A

decrease in ACTH release

26
Q

ACTH has a ____ pattern of release.

A

circadian; higher in the morning and dependent on sleep-wake cycle

Opposes circadian pattern of GH secretion

27
Q

Lack of cortisol negative feedback leads to high ACTH and other adrenal corticosteroids, such as…

A

adrenal androgens

Adrenogenital Syndrome: masculinization of female fetus

28
Q

What are glycoprotein hormones?

A

LH, FSH, TSH, hCG

all alpha subunits are identical, but their beta subunits offer specificity

29
Q

LH release is stimulated by…

FSH secreted is inhibited by…

A 
GnRH
Inhibin (produced by testes and ovaries)

Pulsatile release of these causes distinct LH and FSH patterns

30
Q

Female LH is _____ and male LH is ______

A

cyclic (surge at ovulation); constant

31
Q

______ disappears in menopause

A

inhibin

32
Q

Testosterone synthesis in the Leydig cells is stimulated by:

A

LH

Feedback inhibits GnRH production in hypothalamus

33
Q

What does progesterone do?

A

Suppresses ovulation (oral contraceptives)

34
Q

What inhibit GnRH release?

A

Dopamine, endorphin, prolactin

35
Q

Overproduction of prolactin can cause…

A

amenorrhea (shuts off GnRH) - treat with bromocryptine, a dopamine agonist, or removal of pituitary tumor

Prolactin inhibition affords post-partum contraceptive effect

36
Q

Estradiol a high plasma concentrations in late follicular phase of ovarian cycle…

A

stimulates GnRH and LH surge to trigger ovulation

37
Q

TSH is synthesized in thyrotrophs of ant. pituitary and is relatively steady. It acts on the thryroid. Negative feedback is accomplished by _____

A

T3

38
Q

What is Grave’s Disease?

A

Hyperthyroidism caused by circulating antibodies to the TSH receptor; mimic action of TSH –> elevated thyroid hormones (goiter)

39
Q

Prolactin is produced by ______

A

lactotrophs

Prolactin required for lactogenesis and breast development; stimulated T cell functions

40
Q

Prolacin is the only anterior pituitary hormone that is _______

A

tonically inhibited (under influence of many factors; balance favors inhibition)

41
Q

Dopamine _____ prolactin

A

inhibits

42
Q

Prolactin releasing hormone is ____

A

TRH

  • also, oxytocin
  • synthesis enhanced by estradiol
43
Q

PRL can be elevated by…

A

lesions that interfere with portal blood flow to anterior pituitary

44
Q

ADH synthesized by:

Oxytocin synthesized by:

A

supraoptic nucleus
paraventricular nucleus

posterior pituitary; as preprohormones; released via an action potential from hypothalamus

45
Q

Oxytocin stimulates _______

A

Myoepithelial contractions (uterus during parturition; mammary gland during lactation)

46
Q

______ is a major stimulus for oxytocin release.

A

Suckling

Sensory receptors in nipple

47
Q

Increased oxytocin in plasma during…

A

ovulation, parturition, coitus

48
Q

Estrogen _____ oxytocin synthesis and ______ threshold for release

A

increases; lowers

Endocrine Physiology (7 decks)

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