EX 2; Reproductive Endocrinology Flashcards
What are the three sex steroids secreted by the gonads
progestins
androgens
estrogens
What is the primary male hormone
testosterone, which is an androgen
Testosterone is more or less potent than DHEA or androgestenedione
more potent
What is the primary female hormone
estradiol, which is an estrogen
What is estrogen produced from
testosterone by an aromatase
This is the primary ovarian steroid during part of the menstrual cycle and during pregnancy
progesterone
This is secreted from pacemaker cells that produce bursts secretion is pulsatile
GnRH
gondaotropin (LH and FSH) secretion is pulsatile and results in what
pulsatile secretion of steroids
Continuous, non-pulsatile GnRH will inhibit what
FSH and LH secretion
which hormones have negative feedback on both GnRH and LH/FSH
gonadal hormones
positive feedback of this controls ovulation in females
estradiol
Which cells induce mitotically active spermatogonia and meiotic spermatocytes
spermatic cells (gametes) produce 400 million sperm/day
These cells lie outside the seminifieroud tubules and synthesize T in response to LH actions of T
leydig cells
What is the role of Leydig cells in the gonad
regulate spermatogenesis
What is the role of Leydig cells elsewhere in the body besides the brain or gonads
produce secondary sex characteristics
What is the role of leydig cells in the brain
regulates sexual behavior
testosterone aromatizes into estrogen and sertoli cells to estradiol
These cells line the seminiferous tubule
sertoli cells
What is the role of sertoli cells in regulating spermatogenesis
regulate spermatogenesis in response to FSH
What is the role of sertoli cells in T sequestering
producing androgen binding proteins which sequesters T in the testis (so there is always enough T)
Sertoli cells secrete inhibin, which does what
its a peptide hormone that regulates FSH secretion
Sertoli cells secrete tubular fluid, which does what
provides nutrient support for the spermatozoa
The leydig cells synthesize testosterone in response to what
LH
As T diffuses into the seminiferous tubules it has a negative feedback on what
GnRH and LH; regulating its own secretion
Sertoli cells synthesize inhibit in response to what
FSH
Inhibin has negative feedback on what
negative feedback actions in pituitary to regulate FSH
Sertoli cells also produce this, which sequesters T needed for spermatogenesis
androgen binding protein (ABP)
Sertoli cells convert (aromatize) some testosterone to what
estradiol
Testosterone is converted to dihydrotestosterone (DHT) (a very potent non-aromatizable androgen) by what
5α-reductase
What is used to convert testosterone to estradiol
aromatase
also converts androstenedione in the brain and bone
The therapeutic manipulation of testicular hormone enzymes is used to treat what two conditions
cancer therapies baldness treatment (DHT on hair follicles) 5α-reductase inhibitor
Testicular hormones can have what three reproductive effects
sexual differentiation of an XY fetus
development of secondary sex characteristics
expression of sexual behavior
What three other effects can testicular hormones have on the body
interact with growth hormone to stimulate skeletal growth
stimulate muscle growth (T is anabolic)
regulate red blood cell synthesis
The oocytes in the ovary are arrested in which state
meiosis I; enclosed in a follicle
These cells lie outside the follicle, like Leydig cells
theca cells
These are the epithelial cells of the follicle
granulosa cells
After ovulation, the remaining theca and granulosa cells transform into what
luteal cells of the corpus luteum
The ovary secretes which three hormones
E
P
Inhibin
What kind of feedback is the cyclical function of the ovary regulated by
positive and negative feedback
Theca cells synthesize this in response to LH
androstenedione
granulosa cells convert androstenedione to what
estrone then to estradiol
estradiol has what affect on the granulosa cell
stimulates granulosa cell function
Granulosa cells secrete this, in response to FSH
inhibin
When the follicle is developing, estradiol inhibits what
GnRH and LH
Inhibin inhibits what secretion
FSH
What are the six effects of estradiol
mitogenic (stimulates cell growth) regulate oocyte development female secondary sex characteristics bone deposition mood arterial function; vasodilation
What are the two stages of the ovarian cycle
follicular and luteal
each lasts 14 days
What are the first two stages of the ovarian cycle
gonadotropin rise and follicular development
gonadotropin rise and follicular development leads to what
an increase in estradiol (an inhibin) and dominant follicle selstion
How is the dominant follicle selected
Whichever one gets the biggest dose of FSH
After the follicle is selected then what occurs
estradiol peak
GnRH and LH surge due to positive feedback actions of E
After the completion of meiosis 1 and ovulation, this forms
corpus luteum
After the corups luteum forms what increases and is inhibited
E and P increases
gonadotropins are inhibited
The CL regresses and then what
there is a decrease in steroids
gonadotropin rises, and start over.
The menstrual cycle begins when
when the CL regresses and steroid support to the uterine epithelium (endometrium) diminishes
This stimulates proliferation of the endometrium
E from developing follicles
The follicular phase ends when
with ovulation and formation of the CL
Luteal P and E stimulate what four things
uterine secretory activity
increase glandular production of glycogen
increase angiogenesis
decrease in contractility
If there is no pregnancy, what occurs
the CL regresses
steroids decrease
and the cycle starts over
If there is pregnancy, what occurs
the placenta produces human chorionic gonadotropin (hCG); this is what pregnancy tests detect
it is structurally similar to LH
hCG does what
maintains luteal steroidogenesis until the placenta fully develops
This is the cessation of the menstrual cycle due to ovarian failure
menopause
What two things occur during menopause
loss of ovarial follicles due to atresia of oocytes
reduced steroidogenesis
What are the hormonal consequences of menopause
steriods; must rely on adrenal androgens, similar to pre-pubertal condition
there is an increase in gonadotropins due to lack of negative feedback
What are the physiological consequences of menopause usually associated with
decreased estrogens
This protein direst the indifferent gonad to become a testis
SRY
Fetal testis produce what two hormones that regulate differentiation of the internal genitalia
testosterone
mullerian inhibiting substance
What does T regulate in the internal genetalia
stimulates the proliferation of the Wolffian duct system
True or False
The fetal ovary will produce differentiating factors
False, it does not
lack of T, does not cause Wolffian system to grow
lack of MIS results in proliferation of Mullerian
What are the three components of the undifferentiated fetal genetials
genital tubercle
urogenital fold
labiosacral gold
These stimulate differentiation of the external genitalia
androgens; mainly T and DHT secreted by the testes
lack of these androgens results in female development
What does the genital tubercle develop into in both males and females
glans of penis
glans of clitoris
What does the urogenital fold develop into in both males and females
urethra and surrounding penis
labia minor and urethral opening
What does the labiosacral fold develop into in both males and females
scrotum and skin of penis
labia majora
This is also sexually differentiated due to the effects of T aromatized to E
the brain medial pre-optic area; much larger in males
This results from a mutation in the steriodogenic enzymes
congenital adrenal hyperplasia; disruption in normal sexual differentiation
In congenital adreanal hyperplasia, the synthesis of cortisol is impaired, which leads to what
decrease in negative feedback resulting in increased stimulation of adrenal cortex and an increase production of adrenal androgens
Increased adrenal androgens will have what affect on males/females
it will not disrupt make development, only female
Someone with genotype XX with congenital adrenal hyperlasia, will have what symptoms
phenotype is more male
will have ovaries as gonads
but will have wolffian and muellerian ducts
and will have both a penis and vagina
What will have if there is 5α-reductase deficiency
development of the penis, scrtum, and prostate is DHT dependent
enzyme deficiency results in failure of differentiation of the external genitalia
What completes differentiation involving a 5α-reductase deficiency
increased T secretion with the onset of puberty
Someone with a genotype of XY with 5α-reductase deficiency will have what type of symptoms
phenotype is female at birth until puberty
will have testes
will have a penis with Wolffian ducts
will have a normal male appearance after puberty
Androgen insensitivity is due to what
a loss of a functional androgen receptor
Someone with a genotype of XY will have type of symptoms with androgen insensitivity
phenotype is female
will have testes
no coffin or mullein ducts
will have a short vagina
This support luteal steroidogeneis during pregnancy
hCG
This stimulated the growth of the myometrium
placental estradiol
This reduces uterine contractility and stimulates vasodilation
placental progesterone
What are three considerations of the pregnant dental patient
more susceptible to gingivitis and periodontitis due to elevated steroid level
medications and radiographs may affect the fetus
comfort during exam or procedure
