Female Physiology Flashcards
In general, lack of hormonal signals leads to a____ phenotype; hormone signals are required to develop into the ____ phenotype.
female
male
absence of the Y chromosome leads to the development of the_____. The most important gene product in this regard is ________ which is now known to be encoded by the SRY (sex-determining region of the Y chromosome).
ovaries
H-Y antigen
Once the ovaries form, there is the lack of production of________ and__________
In the absence of these two hormones, the Wolffian ducts regress and the male genitalia do not form, and the mullerian ducts develop into the female reproductive tract.
androgens
mullerian- inhibiting factor
In males, androgens induce the development of the male internal and external genitalia, and_____ induces the regression of the mullerian ducts.
MIF
________from the placenta and fetal _______dramatically stimulate the production of oogonia within the ovaries (this occurs in the FETUS)
hCG (human chorionic gonadotropin)
FSH and LH
Between 2 and 6 months of post-natal age, ______peak again. The exact purpose of this is in females is not well established since the ovaries don’t respond; in males, this burst of gonadotropins does stimulate the testes to produce androgens.
FSH and LH
Before the first menstrual cycle (menarche), the____ secretes FSH and LH which induces ovarian function
pituitary
The pathways to DHEA and androstenedione are catalyzed by the _____ in the adrenal cortex.
same enzymes
17 alpha hydroxyprogesterone/prognenolone
Our three estrogens are produced by what enzyme from either testosterone or androstenedione
Aromatase
What are the primary secretory products of the ovary.
Estradiol and estrone
Estriol is usually only found in significant amounts in the blood in
pregnant women
GnRH pulses commence at about 9 years of age, what is the purpose?
This leads first to an increase in FSH and then LH. These restart ovarian follicular development and the production of estradiol by steroidogenic tissue. The increase in estrogen leads to (a) the growth spurt (see the growth hormone lecture), and the development of the secondary sex characteristics
the onset of menstrual cycles is usually the_______ occurrence during puberty._______ induces the closure of the growth plates in long bones and leads to an end to the growth spurt.
last
Estrogen
Understand peak of LH and FSH as well as estradoil in menstral cycle
If pregnancy does not ensue and____ is not released by the trophoblast into maternal blood, the corpus luteum dies and progesterone and estrogen decrease.
This loss of negative feedback leads to an increase in_____ that induces maturation of the next group of follicles
hCG
FSH
A dominant follicle forms (at about 4 days) and begins to release_____ autonomously which will decreases FSH (and LH) via negative feedback.
The decrease in FSH leads to :
estrogen
atresia of the non-dominant follicles
As the dominant follicle grows, it produces more and more estrogen, When estrogen peaks, it induces a switch in the hypothalamic-pituitary unit (at least in part due to kisspeptin release in the hypothalamus) from negative to positive feedback so that estrogen stimulates a surge in
LH
The _____stimulates ovulation and the formation of the corpus luteum.
LH surge
The corpus luteum produces enormous amounts of_____ and to a lesser degree estrogen, both of which inhibit LH and FSH secretion
progesterone
In the early follicular phase, the dominant follicle produces estrogen that acts LOCALLY to stimulate the induction of _______ on granulosa cells which allows the follicle to survive the decrease in FSH that occurs in this phase
FSH receptors
In the middle of the follicular phase, local estrogen positive feedback induces what three things?
more FSH as well as LH receptors on granulosa cells
proliferation of granulosa cells.
As estrogen peaks at the late follicular phase, local estrogen positive feedback has induced a large number of granulosa cells. The large increase in estrogen in the blood has induced positive feedback stimulation of
LH and FSH leading to the LH surge.
The theca cells, under the control of_____, produce androgens that diffuse into the granulosa cells.
luteinizing hormone (LH)
In mature follicles, follicle stimulating hormone (FSH) acts on ____ cells to stimulate aromatase activity, which converts the androgens to estrogens.
granulosa
Proliferative phase occurs during the follicular phase and is the growth of the myometrium stimulated primarily by_____.
estrogens
The secretory phase occurs during the luteal phase due to____ (primarily) from the corpus luteum.
progesterone
Uterine spiral artery vasoconstriction is signaled by the decline of progesterone (and estrogen) at the end of the luteal phase; this leads to
sloughing of the myometrium and the menstrual bleed.
as soon as fertilization occurs, development occurs as the fertilized egg moves down the fallopian tube. The blastocyst enters the uterine cavity occurs at about 5 days after
the LH peak (about 4 days after fertilization).
Implantation usually occurs at about 7 days. Once a connection is made between the trophoblasts from the conceptus (shown on the next slide) and the maternal blood,____ from the trophoblasts is secreting into maternal blood and “rescues” the corpus luteum
hCG stimulates estrogen and progesterone release from the corpus luteum of pregnancy which has what 2 functions?
(a) inhibits gonatropin secretion preventing menstrual cycles during pregnancy and
(b) stimulates continued growth of the endometrium to nurture the growing implanted embryo and fetus.
Steroidogenesis in Fetus: LDL is taken up–> converted to cholesterol which is–> pregnenolone in the mitochondria.
What are the two fates of Pregnenolone?
Pregnenolone passes into the fetus where it can be taken up by the fetal adrenal and processed to adrenal steroid end-products
OR
Pregnenolone is converted to progesteronein the SER and progesterone is secreted into the maternal circulation.
Maternal adrenal testosterone is converted to____ in the trophoblast.
estradiol
The fetal adrenal (using progesterone from the trophoblast ) makes____ and then sulfates it (sulfatase enzyme).
DHEA
DHEA from the maternal adrenal and DHEAS from the fetal adrenal cortex is converted to____ in the placenta.
estrone
Fetal DHEAS is converted to 16OH-DHEAS in the fetal liver. 16OH-DHEAS is converted to estriol in the placenta. THEREFORE, measurement of_____ in maternal blood can be used as an index of fetal distress as it assesses fetal adrenal and hepatic function (as well as placental health).
estriol
_____peaks in the first trimester of pregnancy. Since the_____ is responsible for most of the estrogen and progesterone in the 2nd and 3rd trimesters, the corpus luteum is no longer necessary and hCG wanes.
hCG
placenta
What happens to GH and ACTH levels during pregnancy, what about LH and FSH levels?
GH and ACTH secretion are unchanged LH and FSH levels are low because of negative feedback of estrogen and progesterone (from the corpus luteum in the 1st trimester and then the placenta in the 2nd and 3rd trimesters.
In pregnancy, the early increase in_____ stimulates the maternal thyroid; the thyroid hormone crosses the placenta and is involved in early fetal development .
TSH
TSH is essentially the same as before pregnancy despite the fact that
total T4 is increased due to increased TBG
hCG role in pregnancy
hCG is a glycoprotein with homology to FSH, LH, and TSH). Human placental lactogen (hPL) is also described in a previous slide. Since it has homology to GH, it is thought to contribute to the insulin-resistant state that occurs in pregnancy. (This aids increases in glucose supply to the placenta and therefore the fetus). The burst in CRH at the end of pregnancy is hypothesized to contribute to the onset of parturition (labor and delivery) although this has not been firmly established. This “placental clock” theory is thought to work through ACTH in some way.
There is a huge rise in ______ by the 3rd trimester of pregnancy
testosterone
During pregnancy, total thyroid hormone increases because ________
However, ______ do NOT change because they are regulated by negative feedback on the pituitary thyrotrophs. So, in the steady state, plasma TSH, Free T4, and Free T3 are the same as before pregnancy.
binding proteins increase.
free T4 and free T3
Why does Blood pressure DECREASE during pregancy?
Why does CO and heart rate increase?
The placenta is a parallel circulation. Adding it decreases TPR (remember 1/R = 1/R1 + 1/R2 + 1/Rn for parallel resistances).
CO and HR go up to increase perfusion to the plancenta
Everything supports an increase in minute ventilation to enable increased O2 consumption and CO2 production by the fetus. In fact, not only do pregnant women display hyperpnea, they occasionally actually
hyperventilate
In pregnancy, _______ increases to support the large increase in CO: In a healthy pregnancy, most plasma electrolytes do not change significantly.
Blood volume
In pregnancy, Hematocrit decreases slightly because
the increase in plasma volume is larger than the increase in red cell mass
Large increase in _____ makes sense to process the increased plasma flow and increased metabolites from increase in metabolic rate due to fetus. The return of renal blood flow at the end of pregnancy is somewhat of a puzzle since GFR is maintained.
renal blood flow
Total rates of secretion of gonadotropic hormones throughout the lives of female and male human beings, showing an especially abrupt increase in gonadotropic hormones at_____ in the female. Therefore, the loss of ovarian steroids releases the hypothalamic-pituitary unit from negative feedback, leading to a large increase in gonadotropin secretion in post-menopausal women.
menopause
What is responsible for oestoporisis in post menopausal women?
Decreased estrogen/testosterone leading ot increased bone resorption and decrease in bone formation
