Neuroendocrinology Flashcards
(37 cards)
What’s neuroendocrine transmission?
transduction of electrical signal to chemical one
release of hormone –> blood (neurohormone)
What’s paracrine transmission?
release something from a cell that diffuses locally + affects neighbouring cells
What’s autocrine transmission?
when cells release things + what it has released affects its own growth
What’s intracrine transmission?
something that happens entirely within the cell
What are neuroendocrine cells?
release signal molecules (hormones) from their synaptic terminals into blood, controlled via synaptic transmission from presynaptic neurons (neuroendocrine integration)
eg of neuroendocrine cells?
Chromaffin cells of adrenal medulla
Hypothalamic magnocellular neurons
Hypothalamic parvocellular neurons
Describe embryology of pituitary gland
- envagination of 3rd ventricle floor (neural ectoderm)
- forms neural tube
- develops an envagination of oral ectoderm (Rathke’s pouch)
- forms anterior lobe
- Rathke’s pouch pinches off + wraps around neural stalk -forms anterior lobe
- this leaves posterior lobe
Whats the hypothalamus made of?
composed of various nuclei (cell clusters):
magnocellular+parvocellular cells
What are parvocellular nuclei?
neurosecretory cells release hormones to capillaries of median eminence (supplied by superior hypophysial artery); conveyed by portal veins to anterior pituitary
What are magnocellular nuclei?
project to posterior pituitary + release to capillaries supplied by inferior hypophysial artery
Describe structure of posterior pituitary (neurohypophysis)
-Downward extension of hypothalamus
-Magnocellular cells are hypothalamic cells that axons travel down into posterior pituitary + terminate there
-Inferior hypophyseal artery, a capillary bed, inferior
hypophyseal vein in posterior lobe
How are posterior pituitary hormones released?
- hypothalamic hormones (oxytocin +
vasopressin) produced by magnocellular neurones -stored in axon terminal in vesicles - when electrically stimulated released into hypophysial capillaries, inferior hypophysial vein
What’s ADH involved in?
osmoregulation, volume regulation
What’s oxytocin involved in?
utereine contraction during labour, milk release from myoepithelial cells of breast, NT in brain
What are vasopressin + oxytocin structurally?
peptide hormones so small
Describe how ADH released from posterior pituitary
-blood volume decreases
-osmolality increases
-dehydration as there is a loss of water so [Na] rising
-stimulates osmoreceptors in hypothalamus
-signal to magnocellular neurones in hypothalamus to
release ADH
-vasoconstriction, increasing BP, water retention via
the kidney (also increases BP)
Describe how oxytocin released from posterior pituitary
- stretch of cervix
- oxytocin release
- increased contractions of cervix/uterine
- —>more release, positive feedback
- sensory receptors in nipples
- mechanically stimulated
- oxytocin release
- contraction of myoepithelial cells in breast
- lactation
Hormones released from anterior pituitary?
Thyroid Stimulating Hormone (TSH) – Stimulate thyroid
ACTH – Acts on adrenal cortex
FSH and LH – Testes or ovaries
Growth Hormone (GH) – Entire body
Prolactin (PRL) – Mammary gland (in mammals)
[Endorphins]
these are under feedback
Anterior pituitary hormones + their cells?
TSH secreting cells = Thyrotrophs ACTH = Corticotrophs LH/FSH = Gonadotrophs GH = Somatotrophs Prolactin = Lactotrophs
What stimulates adrenocorticotrophic hormone (ACTH)?
CRH (corticotropin releasing hormone)
What stimulates + inhibits thyroid stimulating hormone (TSH)?
Stimulated by TRH, inhibited by somatostatin (growth hormone inhibiting hormone)
What stimulates LH + FSH?
Stimulated by GnRH (gonadotropin releasing hormone)
What inhibits prolactin (PRL)?
Inhibited by dopamine -main control (also stimulated by TRH + others)
What simulates + inhibits growth hormone (GH)?
Stimulated by GHRH,
inhibited by GHIH
