hypothalamic pituitary axis growth hormone Flashcards
what is the hypothalamic pituitary axis
link between endocrine and nervous system
hypothalamus is situated below the thalamus and its role is to monitor the state of the body by integrating sensory pathway
pituitary is below the hypothalamus
what is the exact location of the pituitary gland
beneath the hypothalamus in a socket of bone called the sella turcica
process’ that the hypothalamus and pituitary gland modulate
body growth reproduction adrenal gland function water homeostasis milk secretion lactation thyroid gland function puberty
embryological origin of the posterior pituitary
originates from neuroectoderm - primitive brain tissue. its physically connected to the hypothalamus since during development the hypothalamus drops down though the inufunibulum*? to form the posterior pituitary
embryological origin of the anterior pituitary
arises from evagination of the oral ectoderm (rathkes pouch) - primitive gut tissue
what is the nuerocrine function of the posterior pituitary
connected to hypo via cell axons
oxytocin and ADH produced by neurosecretory cells in supraoptic and paraventricular nuclei of the hypothalamus. these are transported to pos pit via nerve cells. then stored and released into circulation by pospit
anterior pituitary function
hypothalamus releases hormone
travels through portal system
stimulates pituitary to release hormones
what are the posterior pituitary hormones from the hypo
oxytocin - milk and uterus contraction in birth
ADH - regulation of body water vol
tropic hormones of the hypo which travel to the anterior pit and which hormone is released in response
TRH (thyrotropin releasing hormone) - causes release of TSH
PIH (prolactin release inhibiting) - inhibits release of prolactin
CRH - (corticotropin releasing) - causes release of ACTH (adrenal glands)
GnRH - (gonadotropin releasing) - LH(sex hormones) and FSH (eggs and sperm) which stimulate ovaries and testes
GHRH (growth hormone releasing) - GH
GHIH (growth hormone inhibiting) -inhibits GH
these all have direct effect on release of anterior pituitary hormones
how are the release of these tropic and anterior posterior pituitary hormones regulated
by negative feedback. one goes to anterior pituitary and one to hypothalamus to prevent more release if gets too high (cortisol for example)
factors affecting growth
genetics
environment
hormones
nutrition
where is growth hormone produced?
produced in the AP
stimulated by GHRH and inhibitied by somatostatin
its produced in somatotropin cells in anterior pituitary.
response to GH
liver and skeletal muscle secrete IGF’s (insulin like growth factors) which help maintain muscle and bone mass swell as healing and tissue repair
GH stimulate long bone growth
IGF’s promote bone and cartilage growth
control of GH secretion
obvs GHRH and somatostatin
CNS regulates GH secretion
increase in GH secretion ; exercise stress glucose decrease fatty acid decrease fasting
decrease in GH secretion; REM sleep increase in glucose increase in fatty acids obesity
what is the long loop of negative feedback
mediated by IGF’s
they inhibit release of GHRH from hypo and stimulate release of somatostatin. also inhibit GH release from anterior pit
