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S & F 4 Test 2 > McCumbee - Pituitary > Flashcards

McCumbee - Pituitary Flashcards

1
Q

Part of pituitary
Composed of epithelial tissues
Embryologically formed from ectodermal cells from the roof of the embryonic pharynx

A

Adenohypophysis

Anterior pituitary

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2
Q

Part of the pituitary

Composed of neural tissue

From from downward evagination of floor of embyronic brain

A

Neurohypophysis

Posterior pituitary

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3
Q

Hypothalamic hormones can enter the blood directly through the _________

A

Posterior pituitary

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4
Q

The supraoptic nuclei and paraventricular nuclei send unmyelinated magnocellular neurons that pass thru the infundibulum and terminate in close proximity to the capillaries of the posterior pituitary. These release which two hormones?

A

ADH (vasopressin)

Oxytocin

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5
Q

Vasopressin and oxytocin are synthesized as preprohormones containing ____ (x4)

A

Signal peptide

Hormone sequence

Neurophysin domain

Glycopeptide domain (ADH not oxytocin)

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6
Q

Explain the role of neurophysin in ADH and oxytocin release from the posterior pituitary

A

Neurophysin is synthesized as part of the preprohormone.

When the prohormones are packaged at the ER and Golgi, neurophysin is cleaved and then acts as a intraneuronal carrier

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7
Q

Direct hypothalamic control of anterior pituitary secretory function is mediated by neurosecretions called ________

A

Hypophysiotropic hormones

Also called releasing hormones and inhibiting hormones

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8
Q

Growth hormone release hormone _______ somatotropes, which are what release Growth hormone

A

Stimulates

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9
Q

Somatostatin (SS) ________ somatropes which are what release growth hormone (GH)

A

Inhibits

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10
Q

TRH (thyrotropin-releasing hormone) ________ thyrotropes which are what release TSH (thyroid stimulating hormone)

A

Stimulates

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11
Q

TRH (thyrotropin-releasing hormones) _________ lactotropes, which are what release prolactin

A

Stimulates

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12
Q

Dopamine _________ lactotropes which are what release PRL (prolactin)

A

Inhibits

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13
Q

GnRH (Gonadotropin-releasing hormone) ________ gonadotropes, which are what release FSH (follicle stimulating hormone) and LH (luteinizing hormone)

A

Stimulates

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14
Q

CRH (corticotropin-releasing hormone) ________ corticotrope which releases ACTH (adrenocorticotropic hormone) and Beta-LPH (beta-lipotropin)

A

Stimulates

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15
Q

AVP (arginine vasopressin) _____________ corticotrope which releases ACTH (adrenocorticotropic hormone) and Beta-LPH (beta-lipotropin)

A

Stimulates

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16
Q

What are 3 pituitary hormones in the glycoprotein family ?

A

Luteinizing hormone

Follicle stimulating hormone

Thyroid stimulating hormone

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17
Q

What are 4 significant glycoprotein family hormones

A

LH

FSH

TSH

HCG (human chorionic gonadotropin)

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18
Q

Which subunit of the two differs in glycoproteins

A

Beta subunit (this gives specific biological functions)

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19
Q

What pituitary hormones are in the somatomammotropin family ?

A

Growth hormone

Prolactin

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20
Q

Which member of the proopiomelanocortin family is a prominent anterior pituitary player

A

Adrenocorticotropin (ACTH)

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21
Q

ACTH binds to _____ receptors on adrenal gland

A

MC2R

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22
Q

What are the direct actions of GH?

A

Stimulates production and release of IGF-1 and IGF-binding proteins from liver and other target cells

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23
Q

______ is the principle mediator of GH action on skeletal growth

A

IGF-I

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24
Q

What is the indirect action of GH?

A

IGF-I produced, this induces the majority of growth promoting actions of GH.

IGF-I is principle mediator of GH actions on skeletal growth.

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25
Q

GH _____ lipolysis

A

Stimulates

Especially in visceral adipose tissue

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26
Q

GH actions ______ the actions of insulin on glucose and lipid metabolism

A

Oppose

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27
Q

GH ______ insulin-stimulated glucose uptake and oxidation

A

suppresses

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28
Q

GH _______ gluconeogenesis and glycogenloysis

A

Stimulates

29
Q

GH _______ whole body protein synthesis

A

Increases

30
Q

GH _______ proteolysis

A

Inhibits

31
Q

How is IGF-1 typically transported in circulation?

A

In large MW complex w/

IGF

IGFBP-3

ALS (acid-labile subunit)

32
Q

The major source of circulating IGF-1 is the ?

A

Liver

Also locally produced IGF-I by target cells is very important.

33
Q

________ in the epiphyseal growth plate express receptors for both GH and IGF-1

A

Chondrocytes

34
Q

GH target cells in epiphyseal growth plate synth and release ______ in response to GH stimulation

A

IGF-1

35
Q

What are the functions of IGFBP’s

X5

A

Carry IGF’s in circulation

Provide a circulatory reservoir of IGF

Increase circulatory half life of IGF

Modulate IGF bioavailability

Potentiate or inhibit IGF

36
Q

Members of the somatomammotropin family work thru the ______ pathway

A

JAK/STAT

37
Q

Members of the glycoprotein family of hormones work thru the _______ pathway

A

GPCR

Yields cAMP signaling pathway

38
Q

Due to the high degree of homology in their receptors, at high concentrations, IGF-1 will mimic the actions of ________.

A

Insulin

39
Q

What is the action of IGFBP proteases?

A

At baseline IGF has a higher affinity for IGFBP than it does for IGF-receptors.

IGFBP proteases break down these IGFBP’s and allow IGF’s to bind to their target cells more readily.

(Some cancers increase the amount of IGFBP proteases)

40
Q

What are the 5 target cells of IGF?

A

Fibroblasts

Chondrocytes

Osteoblasts

Adipocytes

Muscle cells

41
Q

What are specific effects of IGF (x3)

A

Stimulate RNA and DNA, increasing protein synthesis

Cell proliferation

Small insulin like effect on muscle cells and adipose tissue

42
Q

The actions of GHRH on GH release are enhanced by ?

A

Ghrelin

43
Q

What does GHRH do at the cell membrane to increase exocytosis of GH?

A

It stimulates influx of calcium thru calcium channels, depolarizing membrane.

44
Q

What does somatostatin do at the cell membrane to inhibit the release of GH?

A

It increases K+ influx into the cell.

45
Q

Negative feedback inhibition of GH secretion is exerted primarily by the actions of IGF-1 on the ____- and _____

A

Pituitary and hypothalamus

46
Q

Conditions that inhibit GH secretion ? X2

A

Hyperglycemia

Elevated levels of FFA

47
Q

During starvation and protein-calorie malnutrition, circulating GH levels are _______

A

Elevated

48
Q

During starvation and protein-calorie malnutrition, circulating IGF-1 levels are ______

A

Decreased

49
Q

GH is released in a circadian pattern characterized by a large burst of secretory activity occurring approximately 1-2 hours after ?

A

The onset of deep sleep.

50
Q

What are 6 physiological stimuli that stimulate GH secretion?

A

Exercise

Stress

Ghrelin

Sex hormones

Protein infusion. (Arginine for stimulation test)

Postprandial hypoglycemia

51
Q

Fetal growth is affected by (x6)

A

Maternal genome

Maternal environment (cigs, etoh, hypoxia, etc)

Hormones produced by placenta

Uterine blood flow

Maternal diet and metabolism

Adequate invasion of endometrium by trophoblast (and subsequent development of uteroplacental circulation)

Maternal genome

52
Q

Uteroplacental bloodflow is ________ substantially in women w/ preeclampsia

A

Reduced

53
Q

What are 3 big hormones and GFs that affect fetal growth?

A

IGF/IGFBP’s

Glucocorticoids

Insulin

54
Q

High levels of insulin are associated with what type of birth weights?

A

Higher birth weights

55
Q

Women w/ diabetes tend to have babies with _______ birth weight

A

High

56
Q

What do glucocorticoids do to developing fetus?

A

Play role in promoting development and maturation of various organs

57
Q

What is the principle extrinsic regulator of growth?

A

Adequate nutrition

58
Q

What types of nutrition are of significant importance in growth regulation?

A

Protein, minerals, vitamins, adequate caloric intake

59
Q

_____ is the single most important hormone involved in promoting postnatal growth

A

Growth hormone

60
Q

Explain thyroid hormones role in postnatal growth?

A

Thyroid hormone promotes linear growth by increasing growth hormone.

Thyroid hormone won’t promote growth in absence of GH.

61
Q

Explain growth in hypothyroid patients

A

Circulating levels of GH and IGF are low. GH secretion in response to provocative stimuli is diminished.
Kid will be undersized.
Treating kid w/ thyroxine restores plasma GH levels (and IGF), kid will have rapid catch-up in growth and an increase in skeletal muscle following treatment.

62
Q

What happens in the growth spurt of puberty?

A

Sex hormones (principally estradiol) cause the increase of linear growth and the fusion of the epiphyseal growth plates (estradiol E2), principally by causing the increase in growth hormone

63
Q

Enzyme that converts androgens to estrogens

A

Aromatase

64
Q

Insulin promotes protein ______ and inhibits protein _______

A

Anabolism

Catabolism

65
Q

__________ has a negative effect on growth

A

Glucocorticoids

66
Q

What are the three main causes of GH deficient state

A

Hypothalamus (fail to produce GHRH)

Pituitary (tumor destroys somatotropes, GH defective, or decrease quant GH)

Target tissue (GH receptor, or problem producing IGF)

67
Q

Why do GH deficient people have tendencies for hypoglycemia?

A

GH is a counterregulatory molecule for insulin, meaning it helps to prevent insulin induced hypoglycemia (along w/ epinephrine, glucagon, and cortisol)

68
Q

What are typical consequences for pt’s with GH deficiency? (X4)

A

Short stature

Delayed bone maturation

Tendency for hypoglycemia

Mild obesity

69
Q

Explain laron dwarfism

A

Laron dwarfism is cause by deletions or mutations in GH receptors. (Type 1, receptors and high GH but no IGF production.
Type 2 - GH receptor defects for binding)

Short stature
Mild obesity
Bone delayed maturity
Prone to hypoglycemia

S & F 4 Test 2 (15 decks)

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