Pituitary Gland

Question 1

Anterior pituitary lobe

Answer 1

Adenohypophysis

Question 2

Posterior pituitary lobe

Answer 2

Neurohypophysis

Question 3

3 Pathways that regulate pituitary gland

Answer 3

1. Hypothalamic inputs
2. Feedback effects of circulating hormones
3. Paracrine/autocrine secretions of circulating hormones

Question 4

CRH axis

Answer 4

CRH –> ACTH –> adrenal

Question 5

GnRH axis

Answer 5

GnRH –> FSH/LH –> gonads

Question 6

TRH axis

Answer 6

TRH –> TSH –> thyroid

Question 7

GHRH axis

Answer 7

GHRH –> GH –> liver +

Question 8

Dopamine axis

Answer 8

Dopamine –> PRL –> breast

Question 9

How are hormones transported from Hypothalamus to anterior pituitary?

Answer 9

median eminence –> Portal blood of portal stalk

Question 10

Hypothalamic releasing hormones

Answer 10

Stim release of stored pituitary hormones
Stim synth of pituitary hormones
Tiny
Short plasma half lives

Question 11

Corticotropin Releasing Hormone (CRH)

Answer 11

Stim synth & release of ACTH (corticotropin) from corticotroph cells (and POMC)
Half life 6-10 min and 40-50 min (biphasic)
Effects on ACTH potentiated by ADH & Angiotensin II

Question 12

Gonadotropin Releasing Hormone (GnRH)

Answer 12

Stim synth & release of LH & FSH from gonadotroph cells
Half life 2-4 min

Question 13

Dopamine

Answer 13

Inhibitory fx to dec prolactin synth & release from lactotroph cells

Question 14

Thyrotropin Releasing Hormone (TRH)

Answer 14

Stim synth & release of TSH from thyrotroph cells
Half life 6 min
Also stim prolactin release at high []

Question 15

Somatostatin (STT)

Answer 15

Inhib of GH synth & release from somatotroph cells
Also inhib TSH
Half life 2-3 min

Question 16

Growth Hormone Releasing Hormone (GHRH)

Answer 16

Stim secretion & release of growth hormone from somatotroph cells
Half life 3-7 min

Question 17

Ant Pituitary hormone general facts

Answer 17

Larger molecules
Made in troph cells
Systemic release

Question 18

Which of the main ant pituitary hormones does not stim peripheral hormone secretion?

Answer 18

PRL

Question 19

Dopamine

Answer 19

(-) by Dopamine

(+) by estrogen & TRH

Question 20

Hyperprolactinemia

Answer 20

Inhib gonadotropin secretion
Causes galatorrheaC
Can be caused by psych meds, nipple stim, prolactinomas, idiopathic

Question 21

GH regulation

Answer 21

GHRH (+)
SST (-)

Ghrelin (+)
B-ad antag (+)
A-ad ag (+)

Question 22

Insulin-like Growth Factor-1 (IGF-1)

Answer 22

Synth/secreted by liver (& others) in response to GH
Mediates many GH effects
Binds to IGF-1R & insulin-R to stim mitogenic & growth effects

Question 23

Where does IGF-1 exert endocrine effects

Answer 23

Bone
Cartilage
Muscle

Question 24

SST secretion stim by:

Answer 24

GH (+)

IGF-1 (+)

Question 25

How does SST (-) on GH?

Answer 25

SST-R are Gi coupled on GPCR --> dec cAMP

Question 26

Ghrelin

Answer 26

Stim GH secretion directly & in synergy w GHRH | Fasting (+)

Question 27

What feedback loops monitor ghrelin?

Answer 27

Hypothalamus Stomach Liver

Question 28

GH secretion pattern

Answer 28

Pulsatile GH levels difficult to interpret 2/3 of production during slow wave sleep (diurnal rhythm)

Question 29

GH effects on plasma glucose

Answer 29

- Dec glucose uptake - Inc hep gluconeogenesis - Inc hep glycogenolysis - Dec insulin sensitivity

Question 30

GH effects on plasma FA

Answer 30

- Inc adipose lipolysis | - Inc muscle B-ox of FA in muscle

Question 31

How does GH affect muscle and organs?

Answer 31

Promotes growth - Inc prot synth - Dec prot breakdown

Question 32

Mitogenic effects of GH & IGF-1 on SKM

Answer 32

GH (via IGF-!): Inc prot synth from bone cells Inc bone length (children) Inc bone width

Question 33

Miscellaneous mitogenic effects of GH & IGF-1

Answer 33

Growth of visceral organs | Skin thickening

Question 34

Miscellaneous mitogenic effects of GH

Answer 34

Sweat gland hyperplasia Hair growth Plasma calcitriol

Question 35

Miscellaneous mitogenic effects of IGF-1

Answer 35

Hemoglobin/hematocrit action on bone marrow | Inc GFR

Question 36

Symtoms of GH Deficiency

Answer 36

``` Ateleotic dwarf Dec muscle mass Thin hair Thin skin Dec counter regulatory to hypo-g ```

Question 37

Symptoms of GH excess

Answer 37

``` Gigantism Joint problems Enlarged jaw/brow/handsds/feet Hepatomegaly Splenomegaly ```