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31 Cards in this Set
- Front
- Back
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What are estrogens derived from?
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androstenedione or testosterone
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what enzyme converts androstenedione/testosterone into estrogens?
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aromatase complex
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What is the major estrogen of ovarian origin?
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17B-estradiol
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How does pregnancy affect estrogen levels?
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increases the levels of estriol
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Describe the initial steps of estrogen synthesis
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Same as in the adrenals and testis
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What stimulates the initial steps of estrogen synthesis?
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follicle stimulating hormone
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What cells provide the source of androstenedione and testosterone for estrogen synthesis?
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theca cells
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What cells produce estrone and estradiol from the androgens supplied by the theca cells?
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granulosa cells
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What cells produce progesterone?
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cells of the corpus luteum
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What is another way estrogens can be formed other than in the ovary?
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peripheral aromatization of androgens
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How are steroid hormones transported?
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through the blood bound to proteins
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What is corticosteroid-binding alpha2-globulin (CBG)?
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a liver derived glycoprotein
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What is another name for CBG?
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transcortin
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What does CBG transport?
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cortisol
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What form is the greatest concentration of cortisol found in throughout the blood?
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bound to CBG
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If cortisol is not bound to CBG, what is it probably bound to?
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albumin
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If cortisol is not bound to CBG or albumin, how is it likely found?
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free in the blood (5-10% of the time)
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What other steroid hormone binds to CBG?
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aldosterone
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Why might aldosterone have a shorter half-life than cortisol?
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because it binds with less affinity to CBG. If a hormone is bound it's "safer" from degradation and clearance
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What is sex hormone-binding globulin?
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a liver-derived glycoprotein
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What do androgens bind most frequently to?
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sex hormone binding globulin (SHBG)
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If androgens aren't bound to SHBG, what are they bound to?
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albumin and other proteins
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What do estrogens bind to for transport?
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SHBP
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If estrogens are not bound to SHBP, how will they likely be found?
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either bound to albumin or free in the cytoplasm
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What is androgen-binding protein?
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located in the testis, acts as an intracellular binding protein that tries to maintain a high concentration of androgens in the testest. it is NOT for transport
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Where is androgen-binding protein synthesized?
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in the Sertoli cells
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What stimulates the synthesis of androgen binding protein?
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testosterone and FSH
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What is the main site of steroid metabolism?
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liver
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Describe strength of the steroid ring
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cannot be broken (except to form vitamin D)
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How are steroid hormones and their metabolites cleared from the body?
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conjugated in the liver and excreted in the urine
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What are the names of the conjugates steroid hormones frequently bind to before excretion?
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glucuronides and sulfates
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