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43 Cards in this Set

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  • Back
How are hormones transported from the hypothalamus to the a/p?
hormones are synthesized in hypothalamic cell bodies, released in median eminence, diffues into capillary plexus of hypophysial portal vessels, which deliver hormone directly to a/p
How are hormones transported from teh hypothalamus to the p/p?
synthesized in cell bodies in supraoptic (ADH) and paraventricular (oxytocin) nuclei of hypothal, transported down axons in neurosecretory vessels, released into p/p by action potential, diffuse into venous capillary plexus
From what primitive structure is the a/p derived?
primative foregut
From what primitive tissue is the p/p derived?
neural tissue
What are the properties of the TSH, FSH, LH family?
glycoproteins; identical alpha subunits and different beta subunits
What hormones are included in the ACTH family?
ACTH, MSH, beta-lipotropin, beta-endorphin
What is the common precursor for the hormones of the ACTH family?
POMC (pro-opiomelanocortin)
What factors increase s/c of growth hormone?
sleep, stress, puberty, starvation, exercise, hypoglycemia
What factors decrease s/c of growth hormone?
somatostatin, somatomedins, obesity, hyperglycemia, pregnancy
What is the action of GHRH?
stimulate s/c of growth hormone from a/p
What is the action of somatostatin (SRIF)?
inhibit s/c of growth hormone from a/p
What 3 factors/hormones provide negative feedback for the production of growth hormone?
1. somatomedians
2. growth hormone
What is the mechanism of negative feedback by somatomedians (i.e. insulin-like growth factors (IRF))?
somatomedians directly inhibit release of GH from a/p, and stimulate s/c of somatostatin (SRIF) from hypothalamus
How does growth hormone feed back upon itself?
GH stimulates somatostatin (SRIF), which inhibits release of GH from a/p
What is the feedback mechanism of GHRH?
GHRH directly inhibits its own release from the hypothalamus (ultrashort-loop feedback)
Where is growth hormone synthesized, and by what type of cells?
by somatotrophs in the a/p
What are the direct effects of growth hormone?
diabetogenic effect (dec gluc uptake), inc lipolysis, inc protein synth in musc & inc in lean body mass, inc production of IGF (insulin-like growth factors)
What are the main indirect effects of growth hormone?
growth-promoting effects: proliferation of chondrocytes, inc linear growth, inc musc size, body mass, & organ size
What factor mediates the indirect effects of growth hormone? Where in the body is this factor produced?
IGF (insulin-like growth factors), aka somatomedians; produced in liver
What are some possible causes of growth hormone deficiency?
a/p deficiency (no GH), GH receptor deficiency, hypothalamic deficiency (no GHRH), failure to generate IGF in liver
What is used to treat growth hormone excess?
somatostatin analogs (octreotide)
What results from hypersecretion of growth hormone before puberty? After puberty?
before puberty: inc linear growth (gigantism)

after puberty: inc periosteal bone growth, inc organ size, glucose intolerance
What results from growth hormone deficiency?
failure to grow, short stature, mild obesity, delayed puberty
What are the major actions of prolactin?
stimulate milk production (lactogenesis) and breast development (and inhibits ovulation)
What is the hypothalamic releasing factor for prolactin?
TRH (thyrotropin releasing factor) (by altering transcription of prolactin gene)
What is the hypothalamic inhibitory factor for prolactin?
PIF (prolactin inhibiting factor), aka dopamine

*prolactin s/c is tonically inhibited by PIF, thus interruption of hypothal-pit tract causes prolactin s/c*
What is the major negative feedback mechanism for prolactin?
prolactin stimulates DA s/c
What are the most important stimuli for prolactin secretion?
pregnancy and breast-feeding (suckling)
Via what mechanism does prolactin inhibit ovulation?
it inhibits the synthesis and release of GnRH (accounts for decreased fertility during breast-feeding)

note: inc prolactin in males inhibits spermatogenesis and causes infertility
What could cause prolactin deficiency? What would the result be?
destruction of lactotrophs or entire a/p; failure to lactate
What could cause prolactin excess?
destruction of hypothalamus, interruption of hypothalamic-hypophysial tract (results in loss of tonic inhibition by DA), or prolactinomas
What are the major sx of prolactin excess?
galactorrhea (excessive lactation), dec libido, failure to ovulate, amenorrhea (due to inhibitory effect on GnRH)
What could be used to treat prolactin excess?
DA agonist (e.g. bromocriptine)
What 2 hormones are secreted by the p/p, and where are they synthesized?
ADH, oxytocin; supraoptic and paraventricular nuclei (respectively)
What are the major actions of ADH (aka vasopressin)?
Inc water permeability of pricipal cells of late distal tubule and collecting ducts (via V2 receptor - cAMP mech)

constricts vascular smooth muscle (via V1 receptor - IP3/Ca mech)
What are some factors that increase ADH secretion?
inc serum osmolarity, volume contraction, pain, nausea, hypoglycemia, nicotine, opiates
What are some factors that decrease ADH secretion?
dec serum osmolarity, etoh, alpha agonists, ANP
What type of receptor senses hypovolemia?
baroreceptors in the left atrium, aortic arch, and carotid artery
Pt with large volumes of dilute urine, high serum osmolarity, and low ADH. Disease? Tx?
Central diabetes insipidus; failure of p/p to s/c ADH, collecting ducts impermeable to water; treat w/ADH analogue (dDAVP)
Pt with large volumes of dilute urine, high serum osmolarity, and high ADH. Disease? Tx?
Nephrogenic diabetes insipidus; principal cells of collecting ducts are unresponsive to ADH (defect in V2 receptor, G-protein, or AC), w/inc ADH due to neg feedback; treat w/ thiazide diuretics (interferes w/dilution of urine)
Pt w/inappropriately concentrated urine (relative to the decreased serum osmolarity). Dx? Tx?
SIADH (syndrome of inappropriate ADH); ADH is secreted from autonomous site (e.g. oat cell carcinoma of lung); treat w/ADH antagonist (demeclocycline) or water restriction
What are the major actions of oxytocin?
milk ejection, contraction of uterine smooth muscle (used to induce labor and reduce postpartum bleeding)
What are the major stimulatory factors for oxytocin?
suckling, sight/sound of infant, dilation of cervix, orgasm