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2011-06-12 14:17:13

BRS endocrine
Show Answers:

  1. where are posterior pituitary hormones synthesized?
    in hypothalamic nuclei, then transported down axons to be released into circulation
  2. hormones of the anterior pituitary?
    • -GH
    • -TSH
    • -prolactin
    • -LH
    • -FSH
    • -ACTH
  3. what three anterior pituitary hormones share similary structure?
    TSH, LS, and FSH all have same alpha sub-unit

    GH and prolactin are homologous
  4. Four ways to inhibit Growth hormone.
    • 1. somatostatin from hypothal blocks response of ant. pituitary to GHRH
    • 2. negative feedback from tissues -- release of somatomedins to affect pituitary and hypothal (stim somatostatin)
    • 3. GHRH inhibits itself
    • 4. GH inhibits itself by increasing somatostatin
  5. Two ways to inhibit prolactin.
    • 1. increasing dopamine (prolactin inhibiting factor), which is what prolactin does for negative feedback
    • 2. decreasing thyrotropin releasing hormone (TRH), which is what the hypothal releases
  6. what other hormone does prolactin inhibit, and to what effect?
    inhibits GnRH - to inhibit ovulation and spermatogenesis
  7. Hormones of the posterior lobe?
    oxytocin and ADH -- homologous

    • adh increases aquaporin 2
    • oxytocin causes ejection of milk
  8. where does the organification of I2 occur?
    • (creation of MIT or DIT)
    • -at the junction of follicular cells and lumen
  9. DIT + DIT = ?
    t4 + Thyroglobulin, which is shed to lysosome before t4 enters circulation
  10. Three ways to control cortisol release.
    • 1. Hypothalamic control (CRH) - neg feedback from cortisol
    • 2. Ant. Pituitary control (ACTH) - neg feedback from cortisol
    • -ACTH upregulates it's own receptor
    • 3. cAMP - secondary messeger for both CRH and ACTH, so a phosphodiesterase inhibitor would stimulate
  11. what controls the release of aldosterone?
    • 1. tonic control by ACTH
    • 2. renin-angiotensin system (renal perfusion pressure stim)
    • 3. potassium (so aldosterone increases K secretion)
  12. where is calcitonin made?
    the parafollicular cells of the thyroid
  13. genetic vs gonadal vs phenotypic sex
    • genetic is XX XY
    • gonadal is testes/ovaries
    • phenotypic is internal genital tract and and external genitalia
  14. Two hormones for male differentiation
    • 1. testosterone from leydig cells -- growth and differentiation of wolffian ducts, which develop into male internal genital tract
    • 2. antimullerian hormone from sertoli cells - causes atrophy of muulerian ducts (which would have become femal internal genital tract)
  15. Explain regulation of the testes.
    • 1. Hypothalamic control: GnRH
    • 2. Anterior Pituitary: FSH and LH
    • -FSH acts on sertoli cells to maintain spermatogenesis. Sertoli cells secrete inhibin for negative feedback
    • -LH acts on Leydig cells to promote testosterone synth. Testosterone reinforces effects of FSH on sertoli cells.
    • 3. negative feedback control:
    • -testosterone inhibits both GnRH and LH release
    • -inhibin inhibits FSH release
  16. Puberty initiated by....
    • pulsatile GnRH, which promotes pulsatile LH and FSH
    • -GnRH up-regulates it's own receptor
  17. Estrogen Synthesis in ovaries.
    • 1. LH stimulates Theca cells to produce testosterone
    • 2. FSH stimulates granulosa cells to convert testosterone to estradiol
  18. What rescues the corpus luteum from regression if implantion occurs?
    • HCG, which is produced by placenta
    • -levels peak until weak nine then fade (basically for duration of the first trimester)
  19. What produces estrogen and progesterone during pregnancy?
    • First trimester: corpus luteum
    • 3rd and 2nd trimester: progesterone produced by placent, estrogens by placenta and fetal adrenal gland (which produces DHEA for the placenta to convert)
  20. Human placental lactogen
    HPL: actions similar to GH and prolactin, increases in value throughout pregnancy
  21. Lactation -- during pregnancy
    • -estrogens and progesterone stimulate growth and development of breasts
    • -prolactin levels increase from estrogen stimulation, but both estrogen and progesterone block it's action
  22. Lactation -- after pregnancy
    • -estrogen and prog decrease abruptly, allowing the build up prolactin to act
    • -lactation maintained by suckling, which stimulates both oxytocin and prolactin
  23. Effect of Prolactin on ovulation.
    • prolactin:
    • -inhibits GnRH secretion and action of GnRH on ant. pituitary, so FSH and LH levels decrease
    • -antagonizes the actions of LH and FSH