Pituitary Physiology Flashcards
T/F anterior pituitary has a direct connection to the hypothalamus
false. it only has vascular connection. it is not nervously connected
the ___ ___ artery supplies the outer 2/3 of the antierior pituitary, and the __ ___ supplies the inner 1/3
the LONG PORTAL artery supplies the outer 2/3 of the antierior pituitary, and the SHORT PORTAL supplies the inner 1/3
two hormones that are released by the posterior pituitary
ADH and oxytocin releeased
the ___ sinus drains lateral to the pituitary and houses the ___ nerves
cavernous sinus. houses cranial nerves. impingement can lead to cranial nerve malfunction and double vision (diplopia)
___ immunostain can detect ___, __ ,___ hormone cells, and ____ immunostain can detect ___/___ lineage cells.
___ immunostain can detect ACTH cells
- *Pit-1 f**or GH, Prl, TSH lineage cells,
- *SF-1** (steroidgenic factor-1) for LH/FSH lineage cells,
- *TPit** for ACTH lineage cells
pituitary adenomas are common and are one of the most common causes of acromegaly. what three hormones are most commonly secreted in the case of a seceting pituitary adenoma (benign)
prolactin, growht homrone, ACTH
- size matters!! the larger the tumor, the more secretion ability
growth in the __- direction will cause it to push on the chiasm
superior
Craniopharygiomas are epithelial tumours arising along the path of the craniopharyngeal duct (remnant of Rathke’s pouch). What does this cause?
this is an epithelial tumor. not a glandular secreting tumor. if it pushes onto normal glandular tissue it can cause a DEFECIT of pituitary hormone, depending on the type of cell being occluded. Usually it causes a GH deficiency
post partum hemorhhage can cause a pituitary infarction. this is called ___
sheehans syndome. causes hypopituiarism
role of dopamine in the prolactin pathway
DA inhibits prolactin
best test to see thyroid function
pitatuiary TSH
outline the gonadotropic axis
hypothalamus produces GnRH
GnRH stimulates pituatry to release FSH and LH.
FASH and LH act on gondads to produce estrogen or testosterone
WHy does DEFICIENT cortisol also lead to hyperpigmentation?
the creation of ACTH also creates Kpeptide, involved in melatnin production. NoT enough cortisol production from the adrenal gets picked up by the pituitary, which secretes more ACTH (and Kpeptide) to try and elecate cortisol levels
when does cortisol peak
morning. increased cortisol is needed in certain times of day for metabolic and hemodynamic reasons
tests to diagnose hyposecretion of ACTH (the cortisol axis)
- baseline serum cortisol IN THE MORNING (normal is >350. if less than 100, you’re in trouble)
- if cortisol is LOW, do a serum ACTH– will separate central (low) from adrenal dysfunction (high). – baseline serum ACTH by itself is not useful– must measure target organ function responsivenetess.
- if yu cannot establish then you need a stimulation test; failure to stimulate indicates hyposecretion
as plasma glucose lowers , cortisol should___
should increase.
you can do an insulin stimulation test to see if ACH hyposecretion is an issue.
- when you administer insulin, glucose will go down. you should see an increase in cortisol and GH. if you do not see an increase, you willk now that ACTH hyposecretion is a factor
ACTH participates in the upregulation of its own receptor. in Chronic ACTH insufficeincy, you will see __ ___ ___.
adrenal cortical atrophy. an injection of ACTH results in a poor increase of serum cortisol. Normal repsonse to ACTH is to increase serum cortisol. BUT if the adrenal gland is atrophic because it isn’t stimulated enough, the adrenal gland becomes less reponseive to stimulation (ex/ Adddisons)
Tf unlike GH which you need to be cognizant when you’re measuring it, you can measure prolactin any time
true.
most common hormoen to be secreted by pitiotary adenomas
prolacting
when does GH peak
it often peaks at night, and then lowers in the day. That’s why kids need sleep to grow
