59 Questions
What is the mechanism by which LH stimulates progesterone secretion in the corpus luteum?
Activation of adenylyl cyclase and subsequent protein synthesis
What is the effect of progesterone on the myometrial cells?
Decreases their excitability and sensitivity to oxytocin
What is the effect of progesterone on estrogen receptors in the endometrium?
Decreases their number and activity
What is the role of progesterone in the breast during lactation?
Induces differentiation of estrogen-prepared ductal tissue
What is the effect of large doses of progesterone on LH secretion?
Inhibits LH secretion
What is the physiological effect of progesterone in terms of body temperature?
Increases basal body temperature
What triggers the initiation of lactation after delivery in women?
Abrupt decline in circulating estrogens and progesterone
Why do women who do not wish to breastfeed their babies receive estrogen administration?
To stop lactation and milk production
What is the primary effect of estrogen on milk production in women?
It antagonizes the milk-producing effect of prolactin on the breast
What is the primary stimulus for milk ejection and oxytocin release in women?
Suckling and reflex stimulation
What is the composition of colostrum compared to milk?
It contains the same concentration of protein and lactose but no fat as in milk
How long does it take for milk secretion to surge after delivery in women?
Within 1-3 days after delivery
What is the primary difference between the reproductive system of men and women?
Women's reproductive systems show regular cyclic changes
What is the average length of a menstrual cycle in women?
28 days
What is the term for the periodic vaginal bleeding that occurs with the shedding of the uterine mucosa?
Menstruation
What is the primary cause of male sexual behavior and pattern of gonadotropin secretion in some species?
The action of male hormones on the brain in early development
What is the function of the antrum in the ovarian cycle?
To fill with follicular fluid
What is the role of gonadotropins from the anterior pituitary in reproductive development?
To activate the gonads during adolescence
What is the term for the decline in the function of the testes with advancing age?
Andropause
What is the effect of hormones secreted by the gonads during adolescence?
The appearance of features typical of the adult male or female
What is the pattern of ovarian function in human females?
It regresses after a number of years
What is the purpose of the cyclic changes in the female reproductive system?
To prepare for pregnancy and fertilization
What is the dual function of the gonads in both sexes?
The production of germ cells and the secretion of sex hormones
What is the pattern of androgen secretion in the ovaries compared to the testes?
The ovaries secrete small amounts of androgens, while the testes secrete large amounts
At what age range does menopause typically occur?
Between 45 and 55
What percentage of menopausal women experience hot flushes?
75%
What is the cause of hot flushes in menopausal women?
Unknown
What is prevented by estrogen treatment in menopausal women?
Hot flushes
What initiates both the release of LH and the episode of flushing in menopausal women?
Hypothalamus
What is the approximate age range during which menopause typically occurs?
45-55 years
Which hormone is released in episodic bursts at intervals of 30-60 minutes or more during menopause?
LH
What is the percentage of menopausal women who experience hot flushes?
75%
What is the event that initiates both the release of LH and the episode of flushing in menopausal women?
Some estrogen-sensitive event in the hypothalamus
What is the average age at which menopause typically occurs?
52 years
What is the duration for which hot flushes may continue intermittently in menopausal women?
40 years
What is the primary function of the reduction in membrane potential of the ovum after fertilization?
To prevent polyspermy
What is the structural change that occurs in the zona pellucida after fertilization?
It undergoes a change that provides long-term protection against polyspermy
How long does it take for the blastocyst to reach the uterus after fertilization?
3 days
What is the term for the multi-nucleate mass that surrounds the blastocyst after it reaches the uterus?
Syncytiotrophoblast
What is the usual site of implantation of the blastocyst in the uterus?
Dorsal wall
What develops from the trophoblast after implantation?
Placenta
What is the primary function of the corpus luteum during pregnancy?
To secrete estrogens, progesterone, and relaxin, and maintain pregnancy
What hormone secreted by the placenta takes over the function of the corpus luteum after the sixth week of pregnancy?
Estrogen
What is the composition of human chorionic gonadotropin (hCG)?
A glycoprotein containing galactose and hexosamine
What is the effect of progesterone on the uterus during pregnancy?
It inhibits myometrial contractions and prevents prostaglandin production
When does the function of the corpus luteum begin to decline during pregnancy?
After 8 weeks of pregnancy
What is the pattern of human chorionic gonadotropin (hCG) secretion during pregnancy?
It decreases after an initial marked rise
What is the function of LH receptors in theca interna cells?
To convert cholesterol to androstenedione
What is the primary function of granulosa cells in the ovarian cycle?
To convert androstenedione to estradiol
What percentage of circulating estradiol is free?
2%
What is the fate of estradiol, estrone, and estriol in the liver?
They are converted to glucuronide and sulfate conjugates
What is the significance of enterohepatic circulation in the metabolism of estradiol?
It recycles estradiol metabolites back into the bloodstream
What is the role of FSH in granulosa cells?
To increase the secretion of estradiol
What is the typical duration of amenorrhea in women who breastfeed regularly?
25-30 weeks
What is the effect of prolactin on GnRH secretion?
Inhibition
What percentage of women become pregnant again during the suckling period?
5-10%
What is the percentage of anovulatory cycles in the first 6 months after resumption of menses?
almost 50%
What is the primary function of the gonads in both sexes?
Dual function of production of germ cells and secretion of sex hormones
What is the difference between males and females that depends primarily on a single chromosome?
The presence of a Y chromosome
Test your understanding of reproductive development and the role of hormones in the reproductive system. Learn about the activation of gonads during adolescence and the appearance of typical features. Assess your knowledge of male sexual behavior and gonadotropin secretion.
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