Pituitary Physiology Flashcards Preview

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Flashcards in Pituitary Physiology Deck (55):
1

Pituitary sits in the _____

sella tursica

2

Adenohypophysis

anterior pituitary

3

Neurohypophysis

posterior pituitary

4

Deficiency in ____ or ____ transcription factors will result in panhypopituitary.

Prop1 or Pit1

5

Somatotrope secretes ____

growth hormone

6

Thyrotrope secretes ____

thyrotropin/TSH

7

Lactotrope secretes ____

prolactin

8

Gonadotrope secretes ____

LH/FSH

9

Corticotropesecretes ____

ACTH

10

Glycoprotein AP hormones

TSH/LH/FSH: same alpha subunit, different beta subunit

11

ACTH is derived from ____

POMC

12

T/F Both GH and prolactin can activate the prolactin receptor

T --> structural homology

13

Which hormone? Stimulates secretion of IGF1 from liver and stimulates lipid and CHO metabolism.

GH

14

Which hormone? Stimulates synthesis and secretion of thyroid hormones and regulates thyroid cell proliferation and survival.

TSH

15

Which hormone? Stimulates synthesis and secreetion of adrenal cortex steroids and proliferation and survival of adrenal cortex cells.

ACTH

16

Which hormone? Stimulates milk production.

Prolactin

17

Which hormone? Stimulates ovulation and progesterone synthesis. Gametogenesis in males and synthesis/secretion of testosterone.

LH

18

Which hormone? Stimulates estrogen synthesis and follicular growth. Spermatogenesis in males.

FSH

19

Which hormones share the same alpha subunit in their structure?

TSH/LH/FSH

20

Loss of ______ by target hormones results in pituitary trophic hormone hypo/hypersecretion and hypo/hyperplasia of pituitary cells as seen in severe hypothyroidism or hypoadrenalism.

feedback inhibition --> hypersecretion and hyperplasia

21

Ultradian rhythm

burst/spike of hormon secretion that can be superimposed on circadian rhythm--> important for things like reproduction

22

Hypothyroidism caused by thyroid gland destruction can lead to hypertrophy of which gland?

Anterior pituitary

23

Hypothalamic-Pituitary-Adrenal Axis

Hypothalamic CRH (stimulatory trophic factor) --> AP ACTH --> Adrenal Cortex cortisol --> feedback to hypothalamus and pituitary

24

T/F melanotropin and ACTH are derived from the same molecule

T --> cleaved from POMC (pro-opiomelanocortin)

25

Stimuli for CRH secretion

stress, hypoglycemia, anxiety, depression, alpha/beta adrengergic agonists --> peaks before waking

26

Inhibitor of ACTH

cortisol

27

What laboratory picture is expected in a patient with excessive cortisol production by an adrenal tumor?

High cortisol, low ACTH

28

Student is studying for at test at 1 am. What is his cortisol profile?

high ACTH, high cortisol --> stress can overcome circadian rhythm

29

Student is asleep at 1 am. What is his cortisol profile?

low ACTH, low cortisol

30

Hypothalamic-Pituitary-Growth Hormone axis

hypothalamic ghrh -->pituitary GH -->liver IGF1--> with negative feedback from hypothalamic somatostatin, liver IGF1 and pituitary GH

31

Stimulators of GHRH

hypoglycemia, dietary protein, exercise

32

GHRH is inhibited by ____

IGF1 and GH

33

T/F SST are present in many tissues

T --> hypothalamus, GI tract, pancreas

34

Somatostatin inhibits:

TSH, PRL, glucagon, insulin, and GH release

35

Growth hormone

stimulates post natal growth indirectly via IGF1--> declines from puberty onward, pulsatile secretion

36

GH half life

6-20 minutes

37

What is the measure of GH production?

IGF1 --> cannot get accurate GH measurement because of short half life and b/c amplitude and frequency of pulses are affected by many variables

38

Which physiologic process will lead to a decrease in GH production?

reduction in GHRH, increase in somatostatin, increase in IGF1

39

Prolactin axis

breast neural stimulus -->hypothalamic PRF --> pituitary prolactin --> mammary gland //hypothalamic dopamine inhibits the pituitary, pituitary prolactin inhibits hypothalamic GnRH, and ovarian E2 stimulates the pituitary

40

Inhibitory feedback in prolactin axis

Milk does not feedback!

41

prolactin is inhibited by

dopamine

42

prolactin negatively regulates ______ via hypothalamus GnRH

FSH/LH

43

T/F high prolactin negatively regulates HPG axis and can explain amenorrhea in a nursing woman

T

44

Why do we treat hyperprolactinemia in men?

to treat hypogonadism (via GnRH)

45

HPG axis

hypothalmic GnRH --> pituitary FSH/LH --> positive/negative feedback from ovary/testis estrogens (on both hypothalamus and pituitary), negative feedback from inhibin (on pituitary), negative testosterone/progesterone feedback on hypothalamus

46

Effect of constant GnRH infusion

inhibition of LH/FSH --> which normally are pulsatile

47

LH effect in males

stimulates androgen synthesis

48

LH effect in females

ovulation, progesterone synthesis

49

FSH effect in males

spermatogenesis

50

FSH effect in females

follicle growth, estrogen synthesis

51

Which laboratory picture is characteristic of physiologic menopause?

low estrogen, high fsh, high lh

52

hypothalamic-pituitary-thyroid axis

Hypothalamic TRH --> Pituitary TSH --> Thyroid T3/T4- -> negative feedback on hyptothalamus and pituitary // hypothalamic somatostatin also opposes TRH

53

TRH

sitmulates TSH and prolactin

54

When T3 is high/low, TRH receptors decrease and thus response of thyrotrope to TRH decreases and thus TSH increases/decreases

low and decreases

55

Inhibitory hypothalamic factors

somatostatin and dopamine