Hypothalamus And Pituitary Flashcards
What hypothalamic nucleus release CRH
PVH
What hypothalamic nuclei release GnRH
Scattered ones
What hypothalamic nuclei release TRH
Periventricular zone
What hypothalamic nuclei releases oxytocin and ADH
PVH
What hormones are produced in the arcuate nucleus
PRH/PIH/Dopamine?GRH/GIH
Neuroendocrine reproductive principles of hypothalamus
- GnRH (LHRH)
- released at median eminence to anterior pituitary
- drives pituitary release of LH and FSH
- GnRH neurons are also diffusely distributed beyond the pre optic area
Reproductive behavior and puberty
- initiated when dormant GnRH neurons become active
- GnRH neurons receive excitator and inhibitory neural input
- timing of puberty can be delayed via inhibitory input
- non-neuroendocrine neurons involved in sexual drive, arousal
- descending projections to spinal cord regulate genital function
The PVH which releases CRH receives ____________ input from many brain regions
Excitatory and inhibitory
Physical stressors that can activate the HPA axis
- hypoglycemia, hypotension, hypovolemia, cold, exercise
- these stimuli activate brainstem system which project to PVH, especially norepi neurons in medulla, which directly project to PVH
Physiological stressors and the HPA axis
- social stress, fear-inducing situations/environments.
- stimulate cortical and limbic regions which activate intermediary brain regions, which then project to the PVN
What brain regions can act to inhibit the PVH
Hippocampus and prefrontal cortex (GABA)
Glucocorticoid receptors in the brain
-widely expressed in the brain and glucocorticoids are known to influence cognitive and emotional function and behavioral regulation
What does cortisol bind to inthe brain
Mineralocorticoid
Pronglonged glucocorticoid receptor activation
Bad
-excessive changes in neuronal excitability, dendritic atrophy, increased vulnerability to hypoxia, stroke, traumatic injury, MDD
Deficient glucocorticoid secretion
Risk factor for psychiatric disorders such as PTSD
Hypothalamic tumor (hamartoma)
- grows into sella turcica and crutches pituitary
- if entire pituitary damaged=pan-hypopituitarism, loss of all hormones
- irritate optic nerves/chiasm/tracts
- abnormal neuronal activity in regions to project to hypothalamus
Pan-hypopituitarism
- deficiency of multiple or all pituitary hormone release
- hamartoma
- pituitary adenoma, non-functioning type
- meningioma, craniopharyngioma
- trauma, infections, autoimmune, pituitary apoplexy
How is pan-hypopituitarism treated
Hormone replacement
Pituitary apoplexy
Hemorrhage of pituitary tumor leading to pan-hypopituitarism
Signs of pituitary apoplexy
Meningeal irritation signs, bilateral cancerous sinus syndrome
Pituitary adenoma-hyper-secretory type
- slow growing, originating from anterior pituitary
- and form from any cell type in ant pituitary
- secrete one or more hormones in excess
- hormone secretion by tumor not controlled by hypothalamus
Pituitary adenoma, non functionin or silent adenoma
Do not secrete hormones, therefore can grow large before symptoms present
Various potential neurological signs of pituitary tumor
- HA
- bitemporal hemianopia
- hydrocephalus
- herniation syndrome
