Neuroendocrinology Flashcards
(18 cards)
how are neuroendocrine cells controlled
via synaptic transmission from presynaptic neurons (neuroendocrine integration)
Embryology of pituitary (3)
- Evagination of floor of 3rd ventricle (neural ectoderm)
- Evagination of oral ectoderm (Rathke’s pouch)
- Rathke’s pouch pinched off
What is the hypothalamus composed of
various nuclei
What do the neurosecretory cells of the parvocellular nuclei do
release hormones to capillaries of median eminence (supplied by superior hypophysial artery); conveyed by portal veins to anterior pituitary
What do the magnocellular nuclei do
project to posterior pituitary and release to capillaries supplied by inferior hypophysial artery
what are the posterior pituitary hormones
oxytocin and vasopressin (ADH)
how is water retention increased
increased osmolality/decreased blood volume >
osmoreceptors & volume receptors >
hypothalamus >
posterior pituitary releases ADH >
1) Kidney (V2R) > Aquaporins - increased retention
2) Smooth muscle (V1aR/V1R) > Vasoconstriction
how does oxytocin cause uterine contractions
sensory receptors in cervix, uterus >
hypothalamus >
post. pituitary releases oxytocin>
uterus
how does oxytocin cause milk to be let down
sensory receptors in nipples > hypothalamus > post. pituitary releases oxytocin > myoepithelial cells of breast > milk let down
Which 3 compounds are involved in control of growth hormone secretion
Growth hormone releasing hormone (GHRH), somatostatin, ghrelin produced by the stomach
How does long feedback regulate GH secretion
insulin-like growth factor (IGF-1) secreted by liver in response to GH
What’s the predominant hypothalamic influence on GH secretion
GHRH
Stimulatory factors controlling GH secretion
GHRH, ghrelin, hypoglycaemia, decreased FA, starvation, exercise, sleep, stress
Inhibitory factors controlling GH secretion
Somatostatin (GHIH), GH, hyperglycaemia, increased FA, IGFs
Action of GH (6)
- Liver - stimulates IGF-1 production
- increased lipolysis -FFA
- increased gluconeogenesis - Blood sugar
- Increased AA intake in muscle
- stimulates chrondrocytes - linear growth
- stimulates somatic growth: increased organ/tissue size
What is acromegaly
Excess GH
Most common cause of acromegaly
pituitary adenoma - increase in GH secreting somatotrophs
Less common cause of acromegaly
tumour not on pituitary secretes GHRH
