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23 Cards in this Set
- Front
- Back
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What are the 3 chemical classifications of hormones?
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Amino acid derivatives, peptides, steroids
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T/F:
Steroid hormones are stored in the cytoplasm until release. |
False: steroids diffuse freely through the membrane as they are being made
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What are the average half-lives of steroid and peptide hormones? What is the clinical significance?
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Steroids: 4-120 min
Peptides: 4-30 min Impaired clearance can lead to dangerous accumulation |
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What are the 6 major hormones secreted by the anterior pituitary?
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FSH, LH, TSH, ACTH, GH, PRL
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What is the structure of FSH, TSH, and LH?
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They are glycoproteins with identical a-subunits and hormone-specific b-subunits.
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What hormone inhibits the release of GH?
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somatostatin
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What is long loop feedback?
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The hormone released by the target organ inhibits the hypothalamus and anterior pituitary.
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What is short loop feedback?
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The hormone released by the anterior pituitary inhibits the hypothalamus.
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What is the ultrashort feedback loop?
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The hormone released by the hypothalamus inhibits its own further release.
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T/F:
GH is required for normal growth and normal fetal development. |
False: GH is req'd for normal growth but not normal fetal development.
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How does GH normally travel in circulation?
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Bound to GHBP.
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Where is IGF-1 synthesized? What stimulates its expression?
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In the liver.
GH |
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What is the relationship of IGF-1 to insulin?
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Its prescursor resembles proinsulin; there is some cross-binding with insulin receptors, esp. in pts who are insulin resistant.
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What effects of GH are mediated by IGF-1?
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Its growth-promoting effects:
*chondrogenesis in long bones *growth of soft tissues |
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Does IGF-1 circulate free in the plasma or bound to carrier proteins?
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Despite being freely soluble, IGF-1 circulates bound to many different proteins, some of which enhance its action, some of which attenuate its action.
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What are the direct metabolic effects of GH?
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They are "anti-insulin":
*increase lipolysis in adipocytes *increase blood glc thru breakdown of CHO and proteins |
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Describe the release of GH. Is it constant? What stimulates it?
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GH release is stimulated by GHRH and inhibited by SS. The balance between these results in pulsatile synthesis and secretion. Most bursts are nocturnal and occur during REM sleep.
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How are GHRH and SS regulated?
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Circulating GH and IGF-1 inhibits GHRH and stimulates SS.
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What is the result of GH deficiency and how is it treated?
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Pituitary dwarfism; treated with recombinant hGH
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What does excess GH cause?
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Gigantism.
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Describe the average levels of GH over the lifespan.
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Highest level in children, begins to taper after 40, which contributes to body and metabolism changes in middle age.
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What are four benefits to GH replacement tx in older adults?
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1.Increased lean body mass
2.Decreased fat mass 3.Increased SV and cardiac performance 4.Improved mood and vitality |
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What is a risk in GH replacement tx?
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Increased levels of IGF-1 which is a potent mitogen and potential carcinogen.
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