Hypothalamus-Pituitary hormones Flashcards
(26 cards)
Where is prolactin secreted from?
anterior pituitary
What is the function of prolactin?
Stimulates milk production in the breast, inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release.
What inhibits prolactin release?
- Dopamine from hypothalamus.
- Prolactin self-inhibits by increasing dopamine synthesis in hypoT.
- Dopamine agonists inhibit prolactin secretion
What stimulates prolactin release?
TRH increases prolactin secretion. Dopamine antagonists (eg most antipsychotics) and estrogens (OCPs, pregnancy) increase prolactin secretion.
Where is growth hormone secreted from?
released in pulses from anterior pituitary
What stimulates secretion of growth hormone? When does this typically happen?
GHRH. GHRH is secreted during exercise, sleep, hypoglycemia states.
Ghrelin also stimulates GH release via GH secretagog receptor.
What inhibits secretion of GH?
- Somatostatin inhibits GH
- GH itself provides negative inhibition on hypothalamus, decreased GHRH.
- IGF-1 inbhits both GH and GHRH
What is the function of GH?
Stimulates linear growth and muscle mass through IGF-1 secretion.
Increases insulin-resistance (diabetogenic).
Why is serum GH not a good measurement?
Half life is 6-20 mins. IGF-1 is better to measure.
What does CRH do? Where is it secreted from?
Stimulates ACTH, MSH, and Beta-endorphin. Hypothalamus.
What does Dopamine do?
decrease prolactin secretion
What does GHRH do?
Increase GH
What does GnRH do?
Increase FSH and LH when pulsatile, suppress when tonic
What hormone does prolactin suppress secretion of?
GnRH
What does somatostatin do at the pituitary level?
Decrease GH, and TSH.
What does somatostatin do at the pancreas?
Inhibit glucagon and insulin
Where else are somatostatin receptors found?
GI tract
What does TRH do?
Increases TSH secretion, increases prolactin secretion
Where is ADH synthesized and secreted?
Synthesized in hypothalamus (supraoptic nuclei), released by posterior pituitary.
What two receptors does ADH interact w/?
V1 and V2
What does stimulation of V1 receptors by ADH do?
Increase blood pressure.
What does stimulation of V2 receptors by ADH do?
Regulates serum osmolarity; ADH decreases serum osmolarity and decreases urine osmolarity.
How do V2 receptors/ADH decrease serum osmolarity?
Increase expression of aquaporin channels in principal cells of renal collecting duct –> bring in more water.
What is the defect in central diabetes insipidus?
Decreased ADH level.
