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12 Cards in this Set
- Front
- Back
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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) |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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) |
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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 |
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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 |
