Pituitary and Hypothalamus Flashcards
(42 cards)
What is autoimmune hypophysitis? How can you tell it apart from Sheehan’s?
- Autoimmune hypophysitis causes hypopit in a mother that just delivered.
- You can tell it apart from Sheehan’s as Sheehan’s is accompanied by significant blood loss during delivery.
What is the cause of congenital isolated ACTH deficiency?
AR mutation in TBX19
Summarize the embryological origin of the hypothalamus. Which nuclei signal to the pituitary?
- Hypothalamus is derived from the neuroectoderm.
- Anterior pituitary: Parvocellular neurons from the arcuate nucleus stop at top of ant pit then send communication through blood supply to ant pit.
- Posterior pituitary: Magnocellular neurons from the supraoptic and PVN nuclei extend DIRECTLY into post pit.
Summarize the embryology of the pituitary gland.
- Both structures are from the ectoderm.
- The anterior pituitary comes from Rathke’s pouch.
- The posterior pituitary comes from the ventral hypothalamus and 3rd ventricle.
What are the 3 parts of the anterior pituitary gland and their corresponding functions? What is the 1 part of posterior pituitary?
- Pars tuberalis: Part of stalk and secretes FSH and LH.
- Pars distalis: The body of the ant pit. Secretes everything else.
- Pars intermedia: No function, gone by adulthood.
- Posterior pituitary: Pars nervosa.
What are thyrotrophs, somatotrophs, and lactotrophs?
- Thyrotrophs make TSH
- Somatotrophs make GH
- Lactotrophs make prolactin
What is the timing of development of the different hormones in the anterior pituitary?
Rathke’s pouch makes progenitor cells, which then give rise to:
- Corticotrophs (ACTH) @ 6-8 wks gestation
- Somatotrophs (GH) @ 8 wks
- Gonadotrophs (LH, FSH) @ 12 wks
- Thyrotrophs (TSH) @ 12 wks
- Lactotrophs (prolactin) @ 24 wks
Which genes cause the ectoderm to turn into Rathke’s pouch?
- BMP4
- *HESX1
- PITX1/2
- LHFX3,4
What is TBX19?
Gene that makes the protein TPIT, which causes a progenitor cell in the ant pituitary gland to turn into corticotrophs, which make ACTH.
What is PROP1?
Gene that causes differentiation of progenitor cells in the ant pituitary to pretty much all downstream hormones we know of.
Which genes cause differentiation of anterior pituitary progenitor cells to turn into gonadotropins?
- GATA2
- SF1
What is PIT1 (AKA POUF1)?
A gene that causes differentiation of anterior pituitary progenitor cells to turn into TSH, GH, and prolactin.
What is GATA2?
A gene that causes differentiation of progenitor cells in the ant pit to become LH, FSH, and TSH.
What genes cause differentiation of anterior pituitary progenitor cells into prolactin?
- ER
- BMP4
What does TRH stimulate production of?
- TSH
- Prolactin
Which hormones causes the release of prolactin?
- Oxytocin
- TRH
Which hormones stimulate release of ACTH?
- CRH
- AVP (ADH)
What does somatostatin (SRIF) inhibit?
TAG
- TSH
- ACTH
- GH
What is the relationship between dopamine and prolactin?
Dopamine inhibits prolactin release
How is GHBP made?
- It is actually the cleaved extracellular end of the growth hormone receptor (JAK2/STAT5).
- As such, GHBP has a very high affinity for GH.
How big is GH?
22kd
When does endogenous GH pulsatility occur?
- 2/3 (67%) occurs during night during slow-wave sleep, which is stages 3 and 4 of non-rapid eye movement sleep
- During the day, there are 10 pulses
What hormones stimulate the release of GH?
- GHRH
- Ghrelin
- Thyroid hormone
- Insulin
- Glucagon
- Arginine
- Clonidine
- Propanolol
How does ghrelin cause GH release?
- On somatotrophs (the cells that release GH), ghrelin beinds something called the growth hormone secretagogue receptor (GHSR).
- GHSR –> G-alpha-Q –> GHSR –> IP3 –> calcium –> GH release
