L71: Posterior Pituitary & Hypothalamic-Pit-Liver (HPL) axis Flashcards
What negatively regulates GH?
IGF-1
GH stimulates what in the liver?
IGF-1
Caveat: GH stimulates IGF1 in the liver, in an ______ dependent manner
Insulin
In what organs does IGF-1 mimic insulin?
Muscle, but not liver and adipose!
Which of the following released from hypothalamus in pulsatile manner? A. GnRH B. GHRH C. GH D. GnRH and GHRH
D. GnRH and GHRH
Where are all the places somatostatin is made?
SS28 - D cells in stomach/duodenum
SS14 - PVN of hypothalamus and pancreatic delta cells
SS14 and SS28 have identical
amino termini
Why does prolactinoma produce reproductive dysfunction?
Too much prolactin release negatively feeds back on hypothalamic GnRH release
Sheehan’s syndrome
prolactin deficiency due to partial pituitary destruction (shock/blood loss)
PVN has 2 cells types
Parvicellular and magnocellular
Cell bodies making AVP are located in
PVN and SON
AVP from parvocellular PVN regulate
mood (anxiety)/stress
AVP from magnocellular SON and PVN regulate
fluid balance
What is neurophysin?
a carrier protein located in the pro hormone for both AVP and OXY
Along with OXY or AVP, what else is in the vesicle?
neurophysin I for OXY
neurophysin II for AVP
What water transporter is on the apical membrane of distal tubule cell? A. AQP2 B. AQP 3 C. AQP 4 D. AQP 3 and 4
A. AQP2
note that AQP3 and 4 are on the basolateral membrane!
AVP defect in what disease?
Diabetes insipidus NOT MELLITUS
OXY is released by _______ neurons located in the ____.
Magnocellular, PVN
Induces skeletal muscle contractions at breast and uterus
OXY. Note: these are both positive control loops.
What’s pitocin?
synthetic oxytocin used to induce labor. Sometimes physicians use this when they want to be home on time for dinner. Tsk tsk tsk.
OXY binds what kind of receptor, to have what effect?
GPCR, increases intracellular Ca++
GH is produced at what hypothalamus nucleus?
TRICK QUESTION. GHRH not GH is released at hypothalamus (Arcuate nucleus).
What is in the GHRH pro hormone?
GHRH + GCTP (c-terminal peptide)
What inhibits GHRH pulse frequency at hypothalamus, and GH and TSH release in pituitary?
SS from PeVN
Bonus detail: what are Furin, PC1, and PC2?
endopeptidases that process somatostatin SS28 and SS14.
Bonus detail: which SS predominates in brain?
SS14
Bonus detail: which SS predominates in intestines?
SS28
What is the primary anabolic goal of GH?
conserve protein
Structurally, GH is in the same family of
prolactin
Downstream GH target organ effects mediated through
IGF-1 (somatomedin)
What’s somatomedin
IGF-1
T/F: GHRH is pulsatile but not GH
F: both are
