73 - HPA Axis Flashcards
Where is the median eminence (ME), w/r/t the hypothalamus?
What’s important about it?
- Floor of the hypothalamus
- Convergence point for axons
What hypothalamic nucleus is important for sleep?
SCN (suprachiasmatic nucleus)
What hypothalamic nucleus is important for feeding behavior/satiety?
ARC (arcuate nucleus)
What hypothalamic nucleus is important for thirst?
PVN (paraventricular nucleus)
What hypothalamic nucleus is important for reproduction?
POA (preoptic nucleus)
What hypothalamic nucleus is important for circadian rhythms?
SCN
What hypothalamic nucleus is important for mood/emotions/stress?
PVN/ARC
What hypothalamic nucleus is important for body temp?
POA
What hypothalamic nucleus is important for BP?
PVN
Name the major hypothalamic-releasing factors/hormones (7)
GnRH, GnIH, CRH, TRH, GHRH, SS, Dopamine.
What hypothalamic nucleus releases GnRH/GnIH?
Scattered; POA has majority
What hypothalamic nucleus releases CRH?
PVN (parvocellular)
What hypothalamic nucleus releases TRH?
PVN
What hypothalamic nucleus releases GHRH?
ARC
What hypothalamic nucleus releases Somatostatin (SS)?
What is the function of SS?
Periventricular Nucleus (PeVN) - GHRH inhibitor
What hypothalamic nucleus releases dopamine?
ARC
What type of hormones are most of the hypothalamic releasing hormones?
What are the exceptions?
Peptides
- Dopamine (Amine)
What cells are the pituitary targets of GnRH/GnIH?
What do these cells synthesize?
- Gonadotrophs
- FSH/LH
What cells are the pituitary targets of CRH?
What do these cells synthesize?
- Corticotrophs
- ACTH
What cells are the pituitary targets of TRH?
What do these cells synthesize?
- Thyrotrophs
- TSH
What cells are the pituitary targets of GHRH/SS?
What do these cells synthesize?
- Somatotrophs
- GH
What cells are the pituitary targets of dopamine?
What do these cells synthesize?
- Lactotrophs
- PRL
What is the common target of all hypothalamic-releasing hormones?
They all target the anterior pituitary
Explain where you’d find cell bodies for GnRH. Which nucleus has most of them?
- Scattered throughout the forebrain
- Largest concentration in POA
There are relatively few cell bodies that have GnRH (~1500-2000). Why are they scattered throughout the forebrain?
Redundant for species survival (need to be able to have offspring even if part of the hypothalamus is damaged)
How many AA’s long is GnRH?
10 AAs (decapeptide)