female reproductive physio Flashcards
What are the sources and forms of estrogen? How do they differ in potency?
17beta-estradiol from the ovaries, estrone from adipose tissue, and estriol from the placenta. potency: estradiol > estrone > estriol
What roles do estrogens play in the body? (4 categories)
- development: promote development of genitalia and a female fat distribution
- uterus/ovary stuff: growth of follicle, endometrial proliferation, increased myometrial excitability, upregulation of estrogen, LH and progesterone receptors
- brain stuff: feedback inhibition of LH and FSH, then LH surge; prolactin secretion
- increase transport proteins: sex hormone binding globulin, increase HDL, decrease LDL
How do estrogen levels change in pregnancy? what are the sources of these estrogens?
they go up: 50 fold increase in estradiol from the overy, 1000 fold increase in estriol from the placenta, which is an indicator of fetal well-being.
What should I know about the estrogen receptor?
estrogen receptors are located in the cytoplasm and translocate to the nucleus when bound by ligand.
How is estrogen production regulated in the ovaries? include cell types and enzyme names, and start with the brain
estrogen production:
pulsatile GnRH causes the release of LH and FSH.
LH activates theca cells to produce androstenedione from cholesterol. desmolase is the enzyme. theca cells are on the outside of the ovarian follicle.
FSH activates aromatase within the granulosa cell. aromatase converts androstenedione to estrogens.
What are the sources of progesterone?
corpus luteum, placenta, adrenal cortex, testes
What roles does progesterone play in the body?
- maintains a pregnancy: decreased myometrial contractility, uterine smooth muscle relaxation
- Opposes some of the estrogen effects: decrease estrogen receptor expressivity, prevents endometrial hyperplasia
- increases body temperature (may be used to guess when a woman is ovulating; high progesterone is indicative of ovulation)
- produces thick cervical mucus
- stimulates endometrial glandular secretions and spiral artery development.
- prolactin inhibition
How do progesterone levels change after deliver, and why is this important?
it falls. this disihibits prolactin, allowing for lactation
What are the phases of the menstrual cycle? Describe the hormonal interplay that controls the menstrual cycle. consider ovaries and endometrium. Drawing may be useful
Uterine phases: proliferative, secretory, menstruation.
ovarian phases: follicular (correlates with proliferative) and luteal (corresponds with secretory). follicular phase may vary in length; luteal phase is usually constant 14 days.
FSH rises at day 0 and promotes estrogen. estrogen levels rise to promote an LH surge (day 14). this causes ovulation. progesterone levels rise with LH surge and continue to rise (from corpus luteum). progesterone levels fall –> menstruation.
estrogen peaks right before ovulation, and has a second rise as progesterone peaks
when is follicular growth fastest? What is metorrhagia?
fastest during second week of proliferative phase (follicular)
metorrhagia: intermenstrual bleeding. frequent but irregular menstruation
Describe the genesis of a mature ovum.
oogonium (2N,2C) –> primary oocyte (2N, 4C). The primary oocyte begins meiosis I in fetal life but is arrested in prophase I until ovulation. At ovulation, it finishes meiosis I to form a secondary oocyte (1N, 2C) and a polar body (may degenerate or give rise to 2 polar bodies).
the secondary oocyte is arrested in metaphase II until fertilization (MET a sperm). then it divides to form an ovum (1N, 1C) and a polar body.
if fertilization does not occur within 1 day of ovulation, the secondary oocyte degenerates.
What are the hormonal changes around ovulation?
increased estrogen, increased GnRH receptors on the anterior pituitary. estrogen surge stimulates LH release, which causes rupture of the ovarian follicle and LH release.
temperature will increase because of progesterone induction.
What is the role of hCG? Where does it come from? What is the timing?
comes from the syncytiotrophoblast of the placenta and is detectable in blood 1 week after conception.
it maintains the corpus luteum (remnants of the ovarian follicle), and thus maintains progesterone. it does this by acting like LH (which stimulates corpus luteum). without beta HCG, the pregnancy is not maintained.
in the 2nd and 3rd trimester, the placenta secretes its own estriol and progesterone, and the corpus luteum degenerates.
What is the structure of beta hCG?
2 subunits, alpha and beta.
alpha is similar to alpha units of TSH, LH, and FSH. beta subunit is unique and is detected by pregnancy tests.
What are causes of increased beta HCG?
multiple gestations, pathologic states like hydatidiform mole or choriocarcinoma
