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26 Cards in this Set
- Front
- Back
What do the testes of gonadal males secrete? |
Antimullerian hormone |
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What is the function of testosterone in sexual differentiation? |
Testosterone stimulates the growth and differentiation of the wolffian ducts, which develop into the male internal genital tract. |
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Where is testosterone produced? |
Leydig cells. |
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Besides ACTH acting in the adrenal cortex, what hormone increases testosterone synthesis? How? |
LH increases testosterone synthesis by stimulating cholesterol desmolase. |
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Which enzyme converts testosterone to its more active form, dihydrotestosterone? |
5α-reductase. |
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Where does FSH act? What is its function? |
FSH acts on the Sertoli cells to maintain spermatogenesis. |
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Where does LH act? What is its function? |
LH acts on the Leydig cells to promote testosterone synthesis. |
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What are the feedback controls? |
Testosterone inhibits the secretion of LH by inhibiting the release of GnRH and by directly inhibiting the release of LH from the anterior pituitary. |
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What is the function of testosterone? |
a) Differentiation of epididymis, vas deferens, and seminal vesicles |
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What is the function of dihydrotestosterone? |
a) Differentiation of penis, prostate, and scrotum |
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How do the hormone levels change over life? |
In childhood, hormone levels are lowest and FSH>LH. |
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In female reproduction, what is the pathway to estradiol? |
Theca cells produce testosterone (stimulated by LH). Testosterone diffuses to the nearby granulosa cells, which contain aromatase and convert testosterone to 17β-estradiol (stimulated by FSH). |
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What is the function of estrogen? |
a) Has both negative and positive feedback effects on FSH and LH. |
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When does progesterone have negative feedback on FSH and LH? |
Progesterone has negative feedback effects on FSH and LH secretion during the luteal phase (Day 14-28; ovulation to menses). |
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What is the order of the stages in the menstrual cycle? |
Follicular phase (days 0-14) |
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What occurs in the follicular phase? |
A primordial follicle develops to the graafian stage, with atresia of neighboring follicles. |
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What is characteristic of ovulation? |
It occurs 14 days before menses, regardless of cycle length. |
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If a menstrual cycle lasts 35 days, how long is each of the stages? |
Follicular phase (days 0-22) |
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What occurs in the luteal phase? |
The corpus luteum begins to develop, and it synthesizes estrogen and progesterone. |
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What happens if fertilization does not occur? |
The corpus luteum regresses at the end of the luteal phase. As a result, estradiol and progesterone levels decrease abruptly. |
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When do progesterone levels rise? |
In the luteal phase, after ovulation. |
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What characterizes pregnancy? |
Steadily increasing levels of estrogen and progesterone, which maintain the endometrium for the fetus, suppress ovarian follicular function (by inhibiting FSH and LH secretion), and stimulate development of the breasts. |
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During the first trimester, what produces progesterone? Second trimester? |
In the first trimester, the corpus luteum (stimulated by hCG) is responsible for the production of both estradiol and progesterone. |
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How is estrogen produced in the second trimester? |
Estrogens are produced by the interplay of the fetal adrenal gland and the placenta. The fetal adrenal gland synthesizes DHEA-S, which is then hydroxylated in the fetal liver. These intermediates are transferred to the placenta, where enzymes remove sulfat and aromatize to estrogens. |
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What is the major placental estrogen? |
Estriol. |
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What effects does prolactin have? |
a) Inhibits hypothalamic GnRH secretion |