reproductive endocrinology Flashcards
testosterone (the primary male sex hormone) is an __________
androgen
_________ is more potent than DHEA or androstenedione
testonsterone
what are the 2 primary female sex hormones? what class of hormone are they?
1) estradiol- an estrogen
2) progesterone- a progestin
how is estradiol produced?
from testosterone by AROMATASE
when is progesterone the primary female sex steroid?
during part of the menstrual cycle and during pregnancy
the secretion of GnRH is _________
pulsatile- due to control by neuroendocrine system
continuous, nonpulsatile GnRH will inhibit _____ and _____ secretion
FSH and LH secretion
gonadal hormones have negative feedback actions on both _______ and ________
GnRH and LH/FSH
during what time does GnRH stimulate LH and FSH in women?
ovulation
the positive feedback action of ______ controls ovulation in females
estrogen
what cells synthesize testosterone in response to LH in males?
leydig cells
__________ cells line the seminiferous tubules
sertoli cells
what are the functions of the sertoli cells?
1) regulate spermatogenesis
2) produce androgen binding protein (ABP)- sequesters testosterone in testis
3) secrete inhibin- regulates FSH secretion
4) secrete tubular fluid
5) aromatize testosterone into estradiol
testosterone has a negative feedback action on _____ and ______
GnRH and LH
what does inhibin reduce?
production of FSH
what enzyme converts testosterone to DHT?
5-alpha-reductase
what molecule acts on hair follicles, and can cause baldness in men?
DHT (dihydrotestosterone)
oocytes are arrested in _________. what are they enclosed in?
arrested in meiosis 1
enclosed in a follicle
what cells of the ovary produce testosterone/androstenedione (androgens) in response to LH?
theca cells
what is the function of the granulosa cells in the ovary?
aromatize androstenedione (androgens) into estradiol in response to FSH
also produce inhibin
the theca cells synthesize ___________ in response to LH
androstenedione
granulosa cells convert the androstenedione into ______
estradiol
while the ovarian follicle is developing, ______ inhibits both GnRH and LH
estradiol
what are the 2 phases of the ovarian cycle?
folicular and luteal
_____ will cause a surge of gonadotropins during the ovarian cycle, causing ovulation
estrogen
when does the ovarian cycle begin?
begins with menstrual flow when CL regresses
t/f: during the ovarian cycle, estrogen will stimulate the proliferation of the endometrium
true
the corpus luteum will regress when _____________ levels are too low
gonadotropins
if pregnancy occurs, the placenta will produce what hormone?
human chorionic gonadotropin (hCG)
what is the function of hCG?
maintains luteal steroidogenesis until the placenta fully develops
after menopause, the body must rely on _________ androgens
adrenal
what 2 hormones are elevated after menopause? why is this?
LH and FSH are very high
there is no negative feedback placed on them anymore
the physiological consequences of menopause are mostly due to what?
decreased estrogens
what are the 2 ducts/tubules associated with undifferentiated gonads? which remains in women? in men?
mullerian and wolffian ducts
men- wolffian ducts remain
women- mullerian ducts remain
what are the 2 hormones produced by fetal testes that regulate the differentiation of the wolffian ducts?
testosterone (stimulated proliferation of wolffian ducts)
mullerian inhibiting substance
a lack of _________ causes the regression of the wolffian duct system
testosterone
what causes congenital adrenal hyperplasia?
results from a mutation in steroidogenic enzymes
what is the genotype of someone suffering from congenital adrenal hyperplasia? what is their phenotype?
XX
their phenotype is more male than female
which genital ducts/tubules remain in someone with congenital adrenal hyperplasia?
BOTH the mullerian and wolffian ducts present
what male sex structures are dependent on DHT production?
penis, scrotum and prostate
a deficiency in 5-alpha-rdeuctase will result in what?
a failure of differentiation of the external genitalia
what event completes sex differentiation in someone lacking 5-alpha-reductase?
increased testosterone production during puberty
what causes androgen insensitivity?
a loss of functional androgen receptors
what is the genotype of someone with androgen insensitivity? what is the phenotype?
genotype= XY
phenotype= female
t/f: people suffering from androgen insensitivity have no internal genitalia
true
they also lack both wolffian and mullerian ducts
what is the source for the increased hormone levels during pregnancy?
the placenta
placental _________ stimulates growth of myometrium
estradiol
placental __________ reduces uterine contractility and stimulates vasodilation
progesterone
what hormone supports luteal steriodogenesis?
hCG
