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26 Cards in this Set
- Front
- Back
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What do the testes of gonadal males secrete?
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Antimullerian hormone
Testosterone |
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What is the function of testosterone in sexual differentiation?
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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?
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Leydig cells.
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Besides ACTH acting in the adrenal cortex, what hormone increases testosterone synthesis? How?
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LH increases testosterone synthesis by stimulating cholesterol desmolase.
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Which enzyme converts testosterone to its more active form, dihydrotestosterone?
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5α-reductase.
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Where does FSH act? What is its function?
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FSH acts on the Sertoli cells to maintain spermatogenesis.
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Where does LH act? What is its function?
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LH acts on the Leydig cells to promote testosterone synthesis.
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What are the feedback controls?
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Testosterone inhibits the secretion of LH by inhibiting the release of GnRH and by directly inhibiting the release of LH from the anterior pituitary.
Inhibin (produced at the Sertoli cells) inhibits the secretion of FSH from the anterior pituitary. |
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What is the function of testosterone?
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a) Differentiation of epididymis, vas deferens, and seminal vesicles
b) Pubertal growth spurt c) Cessation of pubertal growth spurt (epiphyseal closure) d) Libido e) Spermatogenesis in Sertoli cells f) Deepening of voice g) Increased muscle mass h) Growth of penis and seminal vesicles i) Negative feedback on the anterior pituitary |
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What is the function of dihydrotestosterone?
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a) Differentiation of penis, prostate, and scrotum
b) Male hair pattern c) Male pattern baldness d) Sebaceous gland activity e) Growth of prostate |
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How do the hormone levels change over life?
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In childhood, hormone levels are lowest and FSH>LH.
At puberty and during reproductive years, hormone levels increase and LH>FSH. In senescence, hormone levels are highest and FSH>LH. |
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In female reproduction, what is the pathway to estradiol?
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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?
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a) Has both negative and positive feedback effects on FSH and LH.
b) Causes maturation and maintenance of the fallopian tubes, uterus, cervix, and vagina. c) Causes the development of female secondary sex characteristics at puberty. d) Causes the development of the breasts e) Up-regulates estrogen, LH, and progesterone receptors. f) Causes proliferation and development of the ovarian granulosa cells. g) Maintains pregnancy h) Lowers the uterine threshold to contractile stimuli during pregnancy i) Stimulates prolactin secretion (but then blocks its action on the breast). |
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When does progesterone have negative feedback on FSH and LH?
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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?
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Follicular phase (days 0-14)
Ovulation (day 14) Luteal phase (days 14-28) Menses (days 0-4) |
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What occurs in the follicular phase?
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A primordial follicle develops to the graafian stage, with atresia of neighboring follicles.
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What is characteristic of ovulation?
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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?
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Follicular phase (days 0-22)
Ovulation (day 22) Luteal phase (days 22-35) Menses |
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What occurs in the luteal phase?
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The corpus luteum begins to develop, and it synthesizes estrogen and progesterone.
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What happens if fertilization does not occur?
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The corpus luteum regresses at the end of the luteal phase. As a result, estradiol and progesterone levels decrease abruptly.
The endometrium is sloughed because of this abrupt decrease in estradiol and progesterone. |
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When do progesterone levels rise?
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In the luteal phase, after ovulation.
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What characterizes pregnancy?
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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?
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In the first trimester, the corpus luteum (stimulated by hCG) is responsible for the production of both estradiol and progesterone.
In the second trimester (and third), progesterone is produced by the placenta. |
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How is estrogen produced in the second trimester?
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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?
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Estriol.
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What effects does prolactin have?
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a) Inhibits hypothalamic GnRH secretion
b) Inhibits the action of GnRH on the anterior pituitary, and consequently inhibits LH and FSH secretion c) Antagonizes the action of LH and FSH on the ovaries |
