hypothalamo-pituitary axis Flashcards
describe the location of the hypothalamic nuclei
top to bottom, front to back
paraventricular
anterior
supraoptic
dorsomedial
ventromedial
arcuate
posterior
mamillary body (brain boob)
what regulates GNRH
kisspeptin
what does gnrh regulate
fsh and lh
what does adh have to do with acth
adh stimulates acth via short portal vessels between posterior and anterior pituitary
50% of pituitary gland cells are
GH cells
what does GH make
IGF-1
what inhibits prolactin
dopamine
what is prolactin stimulated by and when would you see hyperprolactinemia
TRH
hypothyroidism
what stimulated ACTH (2)
CRH, ADH via porrtal system
GH release is what style
pulsatile
what unexpected hormone stimulates GH
ghrelin
child with dwarfism and cretinism probably what mutation
PIT-1
gh released from what sort of cells
somatotroph
McCune Albright syndrome explain pathophysiology
oncogenic mutation in GNAS gene means alpha subunit in the GHRH receptor retains its activation->CAMP downstream function but LOSES its ATPase function so it no longer self-regulates and is always activated
what sort of receptors are endocrine receptors normally
GPCR
why do you only see eg mccune albright in mosaic form
germline mutation would not be compatible with life
how many giants have recognised genetic element
50%
GH receptor is not a GPCR - what is it
dimerised cytokine receptor
IGF is secreted by many tissues but where is the one that can be measured int he blood stream made
liver
what’s the relevance of GPR101
mutation prevalent in gigantism. related to GHRH stimulation but not sure how
how do you recognise Addison’s pt just by looking at them
hyperpigmentation
what is is ACTH made from
POMC
if POMC is high and ACTH is therefore high, what subunit of ACTH will also be high and what will be the result
alpha MSH
hyper pigmenttation( Addison’s disease)
red hair and fair skin
MC-1r variant
cortisol is… in teh morning and …at night
high
undetectable
when Cushing’s disease
pituitary tumour secreting ACTH only
when would you need petrosal sinus/venous sampling
distinguish where excess ACTH is coming from in cushings disease. Eg lung tumour or overactive pituitary
glucocorticoid +++intake leads to
iatrogenic cushings
if you provide steroid tx for a pt, always give them…
steroid card
which four glycoprotein hormones have the same alpha unit but different beta units
LH, FSH, TSH, HCG
how do you stop FSH and LH in the case of breast/prostate cancer
how on earth does it work
give GNRH analogue.
Too much “GNRH” overwhelms the GPCR so it becomes desensitised and stops workign
FSH and LH are released by GNRH from the same cell so how can they be different levels at different times?
pulsatility. If GNRH every hour, LH high, FSH low
If GNRH every three hours, other way round
Kallmann syndrome
can’t smell, don’t go through puberty
what is copeptin
like peptide C of adh precursor. can be measured
what is new name for diabetes insipidus
AVP deficiency
