Pituitary Physiology

Question 1

Pituitary sits in the _____

Answer 1

sella tursica

Question 2

Adenohypophysis

Answer 2

anterior pituitary

Question 3

Neurohypophysis

Answer 3

posterior pituitary

Question 4

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

Answer 4

Prop1 or Pit1

Question 5

Somatotrope secretes ____

Answer 5

growth hormone

Question 6

Thyrotrope secretes ____

Answer 6

thyrotropin/TSH

Question 7

Lactotrope secretes ____

Answer 7

prolactin

Question 8

Gonadotrope secretes ____

Answer 8

LH/FSH

Question 9

Corticotropesecretes ____

Answer 9

ACTH

Question 10

Glycoprotein AP hormones

Answer 10

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

Question 11

ACTH is derived from ____

Answer 11

POMC

Question 12

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

Answer 12

T –> structural homology

Question 13

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

Answer 13

GH

Question 14

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

Answer 14

TSH

Question 15

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

Answer 15

ACTH

Question 16

Which hormone? Stimulates milk production.

Answer 16

Prolactin

Question 17

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

Answer 17

LH

Question 18

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

Answer 18

FSH

Question 19

Which hormones share the same alpha subunit in their structure?

Answer 19

TSH/LH/FSH

Question 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.

Answer 20

feedback inhibition –> hypersecretion and hyperplasia

Question 21

Ultradian rhythm

Answer 21

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

Question 22

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

Answer 22

Anterior pituitary

Question 23

Hypothalamic-Pituitary-Adrenal Axis

Answer 23

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

Question 24

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

Answer 24

T –> cleaved from POMC (pro-opiomelanocortin)

Question 25

Stimuli for CRH secretion

Answer 25

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

Question 26

Inhibitor of ACTH

Answer 26

cortisol

Question 27

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

Answer 27

High cortisol, low ACTH

Question 28

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

Answer 28

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

Question 29

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

Answer 29

low ACTH, low cortisol

Question 30

Hypothalamic-Pituitary-Growth Hormone axis

Answer 30

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

Question 31

Stimulators of GHRH

Answer 31

hypoglycemia, dietary protein, exercise

Question 32

GHRH is inhibited by ____

Answer 32

IGF1 and GH

Question 33

T/F SST are present in many tissues

Answer 33

T --> hypothalamus, GI tract, pancreas

Question 34

Somatostatin inhibits:

Answer 34

TSH, PRL, glucagon, insulin, and GH release

Question 35

Growth hormone

Answer 35

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

Question 36

GH half life

Answer 36

6-20 minutes

Question 37

What is the measure of GH production?

Answer 37

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

Question 38

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

Answer 38

reduction in GHRH, increase in somatostatin, increase in IGF1

Question 39

Prolactin axis

Answer 39

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

Question 40

Inhibitory feedback in prolactin axis

Answer 40

Milk does not feedback!

Question 41

prolactin is inhibited by

Answer 41

dopamine

Question 42

prolactin negatively regulates ______ via hypothalamus GnRH

Answer 42

FSH/LH

Question 43

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

Answer 43

T

Question 44

Why do we treat hyperprolactinemia in men?

Answer 44

to treat hypogonadism (via GnRH)

Question 45

HPG axis

Answer 45

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

Question 46

Effect of constant GnRH infusion

Answer 46

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

Question 47

LH effect in males

Answer 47

stimulates androgen synthesis

Question 48

LH effect in females

Answer 48

ovulation, progesterone synthesis

Question 49

FSH effect in males

Answer 49

spermatogenesis

Question 50

FSH effect in females

Answer 50

follicle growth, estrogen synthesis

Question 51

Which laboratory picture is characteristic of physiologic menopause?

Answer 51

low estrogen, high fsh, high lh

Question 52

hypothalamic-pituitary-thyroid axis

Answer 52

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

Question 53

TRH

Answer 53

sitmulates TSH and prolactin

Question 54

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

Answer 54

low and decreases

Question 55

Inhibitory hypothalamic factors

Answer 55

somatostatin and dopamine