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12 Cards in this Set

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development of the pituitary gland

-neurohypophysis is derived from the infundibulum; the distal part is the posterior pituitary aka pars nervosa


-epithelial part is derived from rathke's pouch and is called the adenohypophysis; makes up the anterior pituitary (most of which is the pars distalis)

structure of the pituitary gland

-at the base of the dienchephalon, just below the hypothalamus in the sella turcica (sphenoid)


-composed of neural tissue and epithelial tissue

neurohypohysis

-composed of the distal pars nervosa (aka posterior pituitary), infundibular stalk, and the median eminance (swelling at the beginning of the infundibulum)


-is a neuronal track from the supraoptic and paraventricular nuclei through the infundibulum to the posterior pituitary (magnocellular neuroendocrine neurons)


-synthesize either ADH or oxytocin

ADH

-9 AA peptide synthesized by magnocellular neuroendocrine neurons of the neurohypophysis


-preprovasophysin is packaged into SVs with prohormone convertases


-release is stimulated by increased Posm or ECV depletion


-promotes water retention via V2 at the collecting duct

hypothalamus-pituitary-endocrine gland axes

-exist to the thyroid gland, adrenal cortex, liver, testes, and ovaries


-composed of a specific hypothalamic nucleus (parvicellular neuroendocrine neurons) that secrete releasing hormones into the portal system, anterior pituitary cells that produce tropic hormones, and a specific peripheral endocrine gland that produces the effector hormones


-the effector provides negative feedback to pituitary and hypothalamus

releasing hormones

-parvicellular neuroendocrine neurons of a hypothalamic nuclei secrete RH at median eminence


-enters the primary capillary plexus of the hypothalamo-hypophyseal portal system


-portal vessels deliver the RH to the anterior pituitary and exit via the secondary capillary plexus


-binds the receptors on specific anterior pituitary endocrine cells causing tropic hormone release

hypothalamus-pituitary-adrenal axis

-involves corticotrophin-RH, adrenocorticotrophic hormone (ACTH), and cortisol and adrenal androgens


-POMC is ACTH prohormone


-regulated by stress, diurnal signals from the suprachiasmatic nucleus, and negative feedback by cortisol


-ACTH acts through MC2R, which is Gs coupled, though at high levels it can cross react with MC1R on skin melanocytes


-activity increases during sleep

hypothalamus-pituitary-thyroid axis

-involves thyrotropin-RH, thyroid-stimulating hormone, and T4 (pro) and T3 from thyroid


-TSH is a glycoprotein composed of common alpha and specific beta subunits; carbs extend the half-life and increase the specificity


-TSH-R is Gs linked and induces hypertrophy and hyperplasia


-regulated by T3 (neg. feedback), infection, starvation and dopaminergic, and diurnal rhythm

hyptothalamus-pitutiary-gonadal axis

-involves gonadotropinRH, follicle stimulating and lutenizing hormone, and wither testosteron and dihydrotestosterone from the testes and peripheral converion or estradiol and progesterone from the ovaries


-inhibited by CNS during childhood, inhibin (released by gonads for negative feedback of FSH), emotional stress, low energy, weight, and SSRIs


-FSH and LH are glycoprotein hormones and have non-endocrine impact on gonads


-GnRH is released in pulses; more frequent pulses = LH, less frequent = FSH


-in females estradiol switches to positive feedback on LH and FSH mid-mentrual cycle

GH

-produced by AP somatotropes


-forms an axis with the liver, which produces the hormone insulin-like growth factor (IGF-1)


-also has direct metabolic actions (anti-insulin with respect to glucose and lipid, pro-insulin with respect to proteins)

prolactin

-does not function in an axis (is the effector)


-under inhibitory regulation from the hypothalamus by dopamine, stimulated by estrogen during pregnancy and suckling at the nipple

oxytocin

-9 AA peptide synthesized by magnocellular neuroendocrine neurons of the neurohypophysis


-preprooxyphysin is packaged into SVs with prohormone convertases


-release is stimulated by stimulation at the nipple and psychogenic stimuli


-induces contraction of myoepithelial cells in the breast and contraction of the uterine myometrium during parturition