Physiology of the Pituitary Gland Flashcards Preview

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Flashcards in Physiology of the Pituitary Gland Deck (122):
1

Where is the supraoptic nucleus located? What is its function?

Anterolaterally above the optic tract

Secretes ADH and Oxytocin

2

Where is the paraventricular nucleus located? What is its function?

Dorsal anterior periventricular area

Regulates appetite and SNS, and
Secretes:
-TRH
-CRH
-ADH
-VIP

3

What is the role of the magnocellular PVN?

Secretes ADH and oxytocin

4

Where is the suprachiasmatic nucleus located? What is its function?

Above the optic chiasm, anteroventral periventricular zone


Secretes:
-GHRH
-GnRH
-Dopamine
-SRIF

5

What part of the brain secretes ADH? Function?

Supraoptic nucleus and PVN

Osmoregulation

6

What part of the brain secretes TRH? Function?

Paraventricular nucleus

regulates thyroid function

7

What part of the brain secretes CRH? Function?

Parvocellular PVN

Regulates adrenocortical function

8

Besides secreting various hormones, what does the paraventricular nucleus play a role in?

regulates the SNS and appetite

9

What part of the brain secretes VIP? Function?

parvocellular PVN
Suprachiasmatic nucleus

10

What part of the brain secretes GHRH? Function?

Arcuate nucleus and ventromedial nucleus

Stimulates growth hormone

11

What part of the brain secretes GnRH? Function?

Arcuate nucleus
Regulation of pituitary gonadotropins

12

What is the function of dopamine secretion in the arcuate nucleus?

Functions as PIH

13

What part of the brain secretes SRIF? Function?

Periventricular and arcuate nuclei

Inhibits GHRH release

14

What is the "satiety" center of the brain?

Ventromedial nucleus

15

Where is the arcuate nucleus located? What is its function (4)?

medial basal hypothalamus; close to the third ventricle

Secretes:
-GHRH
-GnRH
-dopamine
-SRIF

16

Where is the periventricular nucleus located? What is its function?

Anteroventral hypothalamus

Secretes SRIF which inhibits the secretion of growth hormone

17

What is the function of the ventromedial nucleus of the hypothalamus?

Functions as a satiety center, and secretes:
-GHRH
-SRIF

18

What is the function of the dorsomedial nucleus of the hypothalamus?

focal point of information processing

-receives input from the VMN and lateral hypothalamus and projects to the PVN

19

What part of the hypothalamus functions as a hunger center? satiety center?

hunger = lateral hypothalamus
Satiety = Ventromedial

20

What is the function of the lateral hypothalamus?

Hunger center

21

What is the function of the preoptic area?

GnRH

22

What part of the hypothalamus is the "cooling center"?

Anterior hypothalamus

23

What part of the hypothalamus serves as the thirst regulator?

AVOV region

24

What are the two functions of the anterior hypothalamus?

thermoregulation and thirst regulation

25

What part of the hypothalamus serves as the regulator of the circadian rhythm?

Suprachiasmatic nucleus

26

What is the"heating center" of the brain?

Posterior hypothalamus

27

What is the function of the posterior hypothalamus?

heating center

28

What are the four major ways in which cells communicate with one another?

Gap junctions
Synaptic
Paracrine
Endocrine

29

Specificity of gap junctions depends on what? Synapses? Paracrine? Endocrine?

-Gap junctions = anatomic location
-Synaptic = anatomic location and receptors
-Paracrine = receptors
-Endocrine = receptors

30

What is intracrine signalling?

When cells make signals that do not exit the cell

31

What determines the specificity of hormones, generally?

Receptors

32

Water soluble hormones act where? Lipid soluble?

Water soluble = cell membrane

Lipid soluble = intracellularly

33

GTP is bound to which protein subunit in the G-protein coupled receptor? What happens to this, as compared to the others?

Alpha subunit

Moves to activate adenylyl cyclase, whereas the gamma and beta subunit stay put

34

What are the three types of feedback loops that can occur with the endocrine system?

Ultra short
Short
Long

35

Where is the hypothalamus located in the brain?

Floor and lateral walls of the third ventricle

36

Suprachiasmatic nucleus receives fibers from what part of the brain to regulate body rhythms?

Retinohypothalamic

37

What, generally, describes the ultrashort feedback loop in the HPA axis? Short? Long?

Ultrashort = Hypothalamus acting on itself

Short = anterior pituitary feedback onto the hypothalamus

Long = target organ feeding back on the hypothalamus

38

The area of the hypothalamus where the portal vessels arise is what?

The median eminence

39

What are the two nuclei of the hypothalamus that send their axons down into the posterior pituitary?

Supraoptic
Paraventricular

40

What are the specialized glial cells found in the posterior pituitary?

Pituicytes

41

The posterior pituitary is connected to hypothalamus via what tract?

hypothalamohypophysial tract

42

What is SRIF?

Somatotropin release-inhibiting factor

43

What is PIH?

Prolactin inhibiting hormone

44

What is the hypothalamic nucleus that controls the circadian rhythm? What are the two places this receives input from?

-Suprachiasmatic nucleus

-Lateral geniculate nucleus
-Retinohypothalamic tract

45

The anterior pituitary secretes 6 hormones. 4 of them a tropic hormones. What are these?

-ACTH
-TSH
-FSH
-LH

46

What are tropic hormones?

Hormones that have effects on the morphology and secretory activity of other endocrine glands

47

What subunit of the tropic hormones determines its specificity? Which subunit do they have in common?

-Beta determines specificity
-Alpha they all have in common

48

Adrenocorticotropic hormone is made where?

The corticotroph cells in the anterior pituitary

49

Corticotrophs first synthesize a large precursor protein known as what? What does this turn into?

Proopiomelanocortin (POMC)

Hydrolyzed to ACTH and beta-lipotropin

50

ACTH is released in what sort of pattern? What does this translate to with cortisol release?

Pulsatile

Means that cortisol is released in a pulsatile fashion

51

What is the function of ACTH?

Stimulates the synthesis of Cortisol, androgens, and aldosterone

52

What is the function of effect of ACTH on melanocytes?

Binds to melanotropin-1 receptors to accelerate melanin synthesis

53

Do androgens feedback on ACTH synthesis?

No

54

How can primary adrenal insufficiency cause hyperpigmentation?

The anterior pituitary makes too much ACTH since feedback inhibition does not occur

55

What releasing factor from the hypothalamus causes the release of ACTH?

CRH (corticotropin releasing hormone)

56

What is the function of thyrotropin (TSH)?

Simulates the thyroid to produce T4 and T3

57

Why can Iodine deficiency cause the growth of a goiter?

TSH will be upregulated when it does not sense T3 or T4, which are not produced if there is insufficient Iodine

58

What is the releasing factors for TSH? What else does this stimulate the release of?

Thyroid releasing hormone

Prolactin

59

What causes the release of FSH?

GnRH

60

What is the function of FSH in females? Males?

Females = Growth of ovaries
Males = Sperm maturation

61

What causes the release of LH?

GnRH

62

What is the function of LH in males and females?

Males = stimulation of testosterone synthesis
Females = Stimulation of ovulation, formation of corpus luteum

63

What are the cells that make GH? What is/are the releasing factor(s)?

Somatotropes
GHRH increases release, somatostatin inhibits

64

What is the other name for growth hormone inhibiting hormone?

Somatostatin

65

What are the other names for Growth hormone?

Somatotropic hormone or Somatotropin

66

What are the two forms of growth hormone that are released?

nGH and a splice variant that lacks several amino acids

67

What is the effect of Ghrelin?

a GH secretagogue from the stomach and other places that acts on a difference receptor than GHRH, to stimulate GH secretion

68

What is the basic function of GH?

Stimulates protein synthesis and overall growth of most cells and tissues

Stimulates production of IGF

69

How is GH secreted?

Pulsatile fashion

70

When is GH secretion highest?

Highest = night during deep sleep

Higher in adolescence

71

What cells produce prolactin?

Lactotrophs (mammotrophs)

72

What is Sheehan syndrome?

postpartum hypopituitarism that results from ischemic necrosis of the pituitary

73

True or false: Nipple stimulation in nonpregnant women also increases PRL.

True

74

How is prolactin regulated?

• Release is predominantly under tonic inhibition by the hypothalamic hormone, prolactin-inhibiting hormone (PIH). PIH is the catecholamine dopamine.

75

What is the effect of TSH on prolactin?

Induces its release

76

Which has a stronger effect: the inhibition of prolactin secretion by dopamine (PIH), or increased release of prolactin by TSH

Inhibition by dopamine

77

What happens to prolactin levels if damage occurs to the portal blood circulation which dopamine and TRH use to travel to the anterior pituitary?

increased prolactin levels

78

• If dopamine reaching anterior pituitary decreases then prolactin release (increases/decreases)

Increases

79

Is prolactin related to sleep? Circadian rhythm?

Increased release 60 minutes after sleeping, but is not related to the circadian rhythm

80

What is the effect of prolactin on • If dopamine reaching anterior pituitary decreases then prolactin release increases in females? Male spermatogenesis?

Inhibits ovulation
Inhibits spermatogenesis

81

What is the most predominant cell type of the anterior pituitary gland?

Somatotropes

82

What are the two breakdown products of POMC?

ACTH and beta-LPH

83

What is aldosterone regulated by?

Angiotensin II and [K]

84

What are the short and long feedback mechanisms for cortisol?

ACTH feedback on hypothalamus = short

Cortisol feedback on hypothalamus = long

85

true or false: the cholesterol based hormones do not really feedback onto the corticotropin releasing pathway

True

86

What is the active hormone: T3 or T4? Which is released in larger amounts?

T3 is active, T4 released in larger amounts

87

What is T3 and T4 bound to in the serum?

Thyroid binding globulin

88

Thyroxin = (T3 or T4)?

T4

89

What happens in the ovarian cycle just prior to the FSH/LH spike?

Spike in estradiol

90

Where does GH go to? What does this cause?

Liver to cause the release of somatomedins (IGFs)

91

Can IGF feedback to the pituitary?

Yes

92

What are the effects of growth hormone on adipose tissue?

Increased lipolysis
Decreased glucose uptake

93

What are the effects of GH on muscle cells?

Increased protein synthesis
Decreased glucose uptake

94

What is the effect of IGF-1 on somatostatin neurons?

Increases somatostatin release

95

What happens to GH release with aging in adults?

Decreases

96

What is the general effect of prolactin?

Increased breast tissue differentiation to produce milk

97

Where in the hypothalamus are vasopressin and oxytocin synthesized?

Magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus

98

Where does the processing of the prepro-hormones of ADH and oxytocin take place?

Hormone processing occurs as the neurosecretory vesicles are transported down the hypothalamic-hypophysial tract.

99

Where are ADH and oxytocin stored?

At the end of the neuronal neurons (Herring bodies)

100

What is the cause of neurogenic diabetes insipidus?

Some lesion in the hypothalamus, pituitary, or the connection between

101

What is the cause of nephrogenic diabetes insipidus?

Mutation that affects the production and insertion of the aquaporins

102

What is psychogenic diabetes insipidus?

Increased intake of water causes polyuria

103

What is SIADH?

Producing concentrated urine when not needed or wanted

104

Is the hyponatremia in SIADH true or pseudohyponatremia? Why or why note?

This is not pseudohyponatremia since plasma sodium concentration is low and plasma osmolarity is also low.

105

What is the main stimulus for the secretion of ADH?

Increased osmotic pressure

106

Where does Li act to cause diabetes insipidus (kidney or the brain)?

Kidney

107

The release of oxytocin is stimulated when?

During breastfeeding and childbirth.

108

What causes the milk-let down reflex?

Afferent signals from the nipples of the mother’s breast when an infant suckles result in the release of oxytocin which then causes the milk let-down reflex

109

What role does oxytocin play in the birthing process?

By term of pregnancy the mother’s uterus has experienced an up- regulation in the number of oxytocin receptors. Distension of the cervix and contraction of the uterus stimulate the release of oxytocin which results in positive feedback and the release of more oxytocin which further increases the contractility of the uterus. This aids in the delivery of the baby and the involution of the uterus after childbirth.

110

What is the role of oxytocin in the hypothalamus?

oxytocin is released in the hypothalamus (in the supraoptic and paraventricular nuclei) where it acts in an autocrine fashion. Oxytocin in the hypothalamus acts via positive feedback to increase the release of oxytocin from the posterior pituitary.

111

Which does milk production and which does milk ejection?

Production = Prolactin
Expulsion = oxytocin

112

What is the effect of GH on the breakdown of protein?

Decreases

113

What is the effect of GH on the release of fat?

Increases

114

What is the effect of GH on the glucose uptake?

Decreases

115

What is the effect of GH on the glucose synthesis by the liver?

Increases

116

What is the effect of GH on the insulin secretion?

Increase

117

What is the effect of GH on long bones?

Stimulates osteoblasts to increase bone length and density

118

What are the hormones that GH induces the liver to release?

IGF (somatomedins)

119

How is GH secreted? How is this modified?

Pulsatile
Strenuous exercise increases, and starvation

120

What is panhypopituitarism?

Congenital defect (or tumor destroying) leading to a loss of all of the pituitary hormones

121

What are the causes of dwarfism?

Inability to form somatomedin C (IGF-1) or too little GH

122

What is acromegaly?

Enlargement of the hands and feet, protruding jaw, swelling of organs d/t GH secretion

(this occurs after epiphyseal plates have closed, so no increase in height)