anterior pituitary Flashcards

1
Q

What hormones are produced by the anterior pituitary gland?

A

ACTH, TSH, FSH/LH, PRL

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2
Q

What is the target organ for ACTH?

A

Adrenal Glands

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3
Q

What is the secretory cell type for ACTH?

A

Corticotropic

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4
Q

What is the function of ACTH?

A

increased cortisol, synthesis of adrenal proteins and maintenance of the adrenal gland.

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5
Q

What is the secretary cell type for GH?

A

Somatotropic

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6
Q

What are the two sections of target organs for GH?

A

1- Muscle, bone, and 2- liver

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7
Q

What are the three parts of the adenohypophysis?

A

pars distils, pars tuberalis and pars intermedia

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8
Q

How much of the adenohypophysis does the pars distalis make up?

A

90%

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9
Q

Where is pars tuberalis?

A

wraps around the pituitary stalk

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10
Q

what are the characteristics of pars intermedia?

A

regresses and is absent in adult human cells

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11
Q

What are all endocrine functions in PG regulated by?

A

Hypothalamus and via negative and positive feedback

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12
Q

What type of hormones are most APG hormones?

A

proteins and peptides

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13
Q

What two hormones do NOT act through second messenger systems?

A

GH and PRL

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14
Q

What are the functions of GH in muscle and bone?

A

regulates metabolic processes related to growth and adaption

muscle growth

increased protein synthesis

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15
Q

What are the functions of GH in the liver?

A

increases liver glycigenolysis, induces foration of somatomedins and IGFS

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16
Q

What is the secretory cell type for Prolactin?

A

lactrotropic

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17
Q

What is the target tissue for Prolactin?

A

breasts

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18
Q

What is the secretory cell type for TSH?

A

thyrotropic

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19
Q

what is the target organ for TSH?

A

thyroid gland

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20
Q

What are the functions of TSH?

A

increased secretion/production of TH

Increased iodide uptake

promotion of thyroid gland hypertrophy and hyperplasia

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21
Q

What is the secretory cell type for LH and FSH?

A

Gonadotropic

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22
Q

What are the target organs for LH and FSH?

A

LH and FSH in women: granulosa cells

LH in men: leydig cells

FSH in men: Sertoli cells

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23
Q

What are the functions of LH?

A

ovulation, progesterone production, testicular growth and testosterone production.

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24
Q

What are the functions of FSH?

A

Folicale maturation, estrogen production and spermatogenesis

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25
Q

What does Corticotropes stimulate?

A

Adrenal Cortex

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26
Q

What are Corticotropes AKA?

A

POMC cell

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27
Q

What is the mechanism of action for ACTH?

A

ACTH binds to MC2R which is a GPCR. Activates Gs-cAMP-PKA pathway

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28
Q

What are the three main actions of ACTH?

A

1- increases cortisol and adrenal androgen production

2- increases steroidogenic enzyme production

3- promotes the growth of 2 zones in the adrenal cortex

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29
Q

What is ACTH regulated by?

A

Hypothalamic CRH

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30
Q

Describe the synthesis of ACTH.

A

synthesised in corticotropes by posttranslational cleavage of POMC

31
Q

Describe the pattern of ACTH release.

A

Diurnal (every 24hrs) and peaks early in the morning

32
Q

What are the stimulatory factors of ACTH?

A

Emotional, metabolic and physical stress as well as infection and inflammation

33
Q

What class of hormone is TSH

A

Glycoprotein

34
Q

What are the three glycoprotein hormones?

A

TSH, FSH and LH

35
Q

Describe the heterodimer composition of TSH.

A

heterodimer= protein composed of two polypeptides

a-subunit (common in FSH, and LH as well)

b-subunit - specific and creates its difference

36
Q

Describe the mechanism of action for TSH

A

binds to TSH receptor on thyroid epithelial cells –> linked to GPCR complex –> Gs-cAMP-PKA signal pathway

37
Q

Describe the tropic (affect target cell by stimulating another target cell) effect of TSH.

A

Strong- stimulates hypertropy, hyperplasia and suvical of thyroid epithelial cells

38
Q

When areTSH levels elevated?

A

low iodide availability = negative feedback

39
Q

What is the thyrotrope stimulated by?

A

TRH

40
Q

Describe the negative feedback of T3 on thyrotropes and TRH neurons.

A

T3 inhibits TRH and repesses b-TSH expression

41
Q

What cell-secreting types is a dual hormone producer What two hormones doe they secrete?

A

Gonadotropes- FSH and LH

42
Q

What do the gonadotropes regulate?

A

function of gonads in both sexes

43
Q

Describe the mechanism of action for FSH and LH.

A

Bind ro respective receptors which are both part of GPCR –> cAMP-PKA pathway

44
Q

What regulates FSH and LH?

A

GnRH

45
Q

In what manner is FSH released?

A

In a pulsatile manner

46
Q

What negatively feedback in men (Gn)

A

testosterone and estrogen

47
Q

What negatively feedbacks in FSH secretion for men and women

A

Inhibin

48
Q

At a low dose: estrogen

A

causes negative feedback on FSH and LH secretion

49
Q

At a high dose: estrogen (what does it cause, when and what type of feedback)

A

causes surge of LH (ovulation = postive feedback)

50
Q

What predominantly stimulates GH secretion and via what hormone

A

Hypothalamus via GHRH

51
Q

What is an inhibitor of GH?

A

Somatostatin

52
Q

What is a stimulator of GH?

A

GHRH

53
Q

What does PRL act on (different from all other APG hormones)

A

non-endocrine cells to create a physiologcal change

54
Q

What controls the production and secretion of PRL?

A

inhibitory conrtol via dopamine

55
Q

What stimulates PRL and what Inhibits it?

A

S= TRH I=Dopamine

56
Q

What does the disruption of the pituitary stalk and hypophyseal portal vessels result in? why?

A

INCREASE in PRL levels and DECREASE in ACTH, TSH, LH and GH? The sceretion of all others in prevented but as no dopamine, the PRL will secrete.

57
Q

What is the mechanism of action for PRL?

A

JAK-STAT signalling pathway

PRL binds to receptor in mammory glands –> Tyrosine Kinase Activation occurs –> transcriptioal regulation –> synthesis of milk

58
Q

What is the main action of PRL

A

Breast development and milk production

59
Q

What is the effect of PRL during puberty?

A

stimulates growth of alveolar component of breast tissue

60
Q

What is the effect of PRL during pregnancy?

A

final alveolar and ductal development of breasts

61
Q

What are high prolactin levels in prganancy promoted by?

A

estrogen

62
Q

What is the effect of PRL after birth?

A

Suckling promotes its synthesis and release

63
Q

What happnes to GnRH is PRL is increased

A

it decreases

64
Q

What are the stimulatory factors of PRL?

A

Pregnancy, breast feeding, sleep, stress. TRH and dopamine antagonist

65
Q

What are the inhibitory factors of PRL?

A

Dopamine, Bromocripine (dopamine agonist), somatotatsin and PRL (negative feedback loop)

66
Q

What are the two main Anteriror piturtary disorders

A

Hyper and hypo secretion

67
Q

What are the visual field defects for APG disorders, How are they invetsigated?

A

unexplained visual feild, consider due o pituitray or hypothalamic disorder until proven not and use opthalamolgical evaltions, neuro radiological studies and prolactin measurements.

68
Q

What might hyperpituitarsm be due to?

A

over activity of gland or a adenoma

69
Q

what is the most common cause of hypopituitarism?

A

compression of PG by non-secretory P macroadenoma

70
Q

What is the neumonic for the sequnce pf hormone oss for hypopituritarsim?

A

Go Look For The Aderonoma

71
Q

What are the two pituitary adenomas?

A

Macro and Micro

72
Q

What is Panhyopopituitarsim

A

complete abesne of P hormones

73
Q

What APG hormones do basophils secrete?

A

TSH, FSH, LH and ACTH

74
Q
A