Endocrinology of GYN Flashcards
What is the hormone that the hypothalamus releases to induce LH and FSH?
GnRH
What is the effect of prolactin on GnRH secretion?
Inhibits
What are the basophils and acidophils of the anterior pituitary?
BFLAT
A PiG
What are the three major hormones that are secreted by the ovaries?
Estrogen
Progesterone
Inhibins
What is the average duration of the female menstrual cycle?
20-45 days, usually 28 days
What happens, generally, to the ovaries each menstrual cycle?
Follicle matures and one ovum is released from the ovary each month
What are the two major phases of the menstrual cycle?
Follicular phase
Luteal phase
What are the major events in the follicular phase of the menstrual cycle? (2)
Follicle development
Endometrial proliferation
What are the major events in the luteal phase of the menstrual cycle? (3)
- Corpus luteum formation
- Endometrial differentiation
- Menses
What are the levels of LH/FSH, estrogen, and progesterone during the follicular phase?
all relatively low until peak of estrogen and LH/FSH midcycle
What are the levels of LH/FSH, estrogen, and progesterone during the luteal phase?
Relatively high levels of estrogen and progesterone, but baseline levels of LH and FSH
Describe the levels of inhibins during the follicular and luteal phase of the menstrual cycle?
Inhibin B is at moderate levels in the follicular phase until peaks midcycle
Inhibin A is high in the luteal phase
How is GnRH released from the hypothalamus?
Pulsatile release, usually ever 5-25 minutes
What is the difference in the pulsatile release of LH/FSH in the follicular vs the luteal phase?
More pulses in follicular phase than in the luteal phase
Describe the levels of estrogen throughout the menstrual cycle.
Moderate levels in the follicular phase before peaking mid cycle. Returns to moderate levels in the luteal phase
Describe the levels of progesterone throughout the menstrual cycle.
Low throughout the follicular phase, then becomes high in the luteal phase
When does positive feedback occur with estrogen?
The peak at the midcycle
Which has a higher level of inhibition from estrogen: the pituitary or the hypothalamus
Pituitary
What cells synthesize inhibin A and B?
Granulosa cells of the ovary
What is the major function of inhibin A and B?
Negative regulation of the HPG axis
Which is high in the follicular phase and which is high in the luteal phase: inhibin A and B
Inhibin A is high in the luteal phase
Inhibin B is high in the follicular phase
What hormone does inhibin B play a role in?
FSH–spike leads to a reduction in FSH
What hormone does inhibin A play a role in?
Secreted from the corpus luteum to inhibit LH
What cells synthesize androstenedione in the follicular phase? What is the signal that regulates this?
Theca cells synthesize androstenedione in response to LH
What cells convert androstenedione to estradiol in the follicular phase? What is the signal that regulates this?
Granulosa cells
Controlled by FSH
True or false: unlike the luteal phase, there is a role for both LH and FSH in the follicular phase
True
What is the G proteins that is coupled to LH receptors? FSH receptors?
Gs for both
What is the effect of estrogen on the HPA axis during the follicular phase? What happens to the estrogen concentration during this phase?
Estrogen inhibits the HPA axis, but there is an increase in estrogen production
What happens in the follicular phase to the granulosa cells and the theca cells?
Granulosa cells proliferate
Theca cells develop
What is the role of the theca externa?
Capsule of the follicle
What is the role of the theca interna?
Hormone producing part of the cell
What is the role of the granulosa cells?
Secretion of hormones
How many follicular cells develop during the follicular phase?
6-12
What happens to the number and sensitivity of the theca and granulosa cells in the follicular phase?
Increased sensitivity to hormones and increase in cell number
What are the three major events that are occurring in the follicular phase that enables an increase in estrogen despite negative feedback?
- estradiol increases expression of FSH receptors on granulosa cells
- Estradiol and FSH increased expression of LH receptors on theca cells
- Rise in estradiol and a slight rise in LH from the anterior pituitary induce proliferation of the thecal cells resulting in an increase in follicular secretion
When the most mature of the follicles releases from the ovary during ovulation, what happens to the remaining follicles? What causes this?
The 5-11 immature follicles undergo atresia
This may be caused by the decline in FSH levels
What are the cells that secrete inhibin B? What role does this play?
Granulosa cells
exerts a negative feedback on anterior pituitary to decrease FSH secretion
What is the major role of estrogen on the uterine lining? Progesterone?
estrogen builds up the uterine lining, whilst progesterone increases differentiation
What are the 5 major events occurring in the uterine lining with estrogen secretion during the follicular phase?
- Proliferation of epithelial cells
- Proliferation of stromal cells
- Growth of endometrial glands
- Blood vessel development
- Mucus secretion
What is the signal for ovulation to occur? When does this occur?
Surge in estrogen, FSH, and LH
This occurs at day 14
How does LH promote release of the ovum from the follicle?
Promoting remodeling of the follicle through changes in gene expression patterns and cell signaling events
What hormone is absolutely required for ovulation?
LH
What are the three enzymes that are upregulated by follicles to allow follicular remodeling?
- COX-2
- Plasminogen activator
- MMP
What is the effect of progesterone on basal body temperature?
Increases by 0.75 ish degrees
What forms the corpus luteum?
Thecal, granulosa, fibroblasts, endothelial, and immune cells
What are the hormones that the corpus luteum produces?
Estradiol
Progesterone
How long does it take for the corpus luteum to reach maturity?
7-8 days
Which hormone plays the key role in steroidogenesis in the follicular phase? Luteal phase?
Follicular phase = FSH and LH
Luteal phase = LH
Androstenedione is converted into estradiol in what cells during the luteal phase? What hormone controls this?
Luteinized granulosa cells
LH
What is the precursor to progesterone? What happens in the luteal phase to increase this in the granulosa cells?
Cholesterol
Increased LDL receptors
What is the order of arteries from the basement membrane of the uterine lining to the surface?
Arcuate
Radial
Straight
Spiral
What causes the decline in progesterone and estradiol levels during the luteal phase?
Negative feedback on the HPA axis by progesterone and inhibin A
When in the menstrual cycle does the corpus luteum regress? What does it turn into? What happens to steroid production at this point?
26th day
Corpus albicans
Decline in steroid production
What are the chemical changes that occur in the uterus when estrogen and progesterone levels drop? (2)
Release of proteolytic enzymes that cause lysis of the tissues
Increases of prostaglandin production to increases myometrial contraction
Where in the uterus does fertilization usually occur?
isthmus of the fallopian tube
What is the outer layer of the oocyte? What happens to this when sperm binds?
Zona pellucida
Changes to prevent further fertilization by sperm
What is the sperm+ oocyte called when it expresses enzymes that allows it to penetrate into the endometrium?
Blastocyst
What are the cells on the oocyte and uterus that allows for attachment of the egg to the uterus? What mediates this attachment?
Trophoblast cells on oocyte
Stromal cells on the endometrium
Integrins mediate the attachment
The trophoblasts on the oocyte differentiate into what two cell types? What is the role of each of these?
Cytotrophoblast
Syncytiotrophoblast
What is the role of the syncytiotrophoblast? What do these turn into/form?
Sends out protrusions and invades the endometrium
Primary chorionic villi
What are the four fetal components of the early placenta? (4)
- Syncytiotrophoblasts
- Cytotrophoblasts
- Mesenchyme
- Fetal blood vessels
What is contained within the intervillous space?
Blood trapped between the fetal villous and maternal endometrium
What are the maternal components of the placenta? (2)
Decidual cells
Maternal arteries and veins
What is the role of hCG in pregnancy?
Placenta makes it, and it stimulates ovarian steroidogenesis
After what gestational week is the maintenance of the pregnancy no longer dependent on the corpus luteum for steroid synthesis?
8
What are the three main roles of progesterone in pregnancy?
- inhibit prostaglandin production
- Impact immune response
- suppress uterine contractions
What are the three main roles of estrogen in pregnancy?
- Stimulate uterine growth
- thicken the vaginal epithelium
- growth and development of mammary epithelium
hCG acts similarly to what other hormone?
LH–they bind to the same receptor
After 8 weeks, what happens to hCG, estrogen, and progesterone production?
Switches from corpus luteum production to placental production
What is the only hormone involved in pregnancy that the placenta does NOT secrete? What produces this?
DHEA
Maternal adrenal glands and fetal liver
What cells of the placenta produce hormones?
Syncytiotrophoblasts
What part produces hCG?
Placenta
What part produces hPL?
Placenta
What part produces CRH?
placenta
What is the main role of hCG?
Maintains corpus luteum and thus ovarian steroid production for the first 7-8 weeks of gestation
When does hCG become detectable? Peak?
6-8 days after implantation
peaks at 10 weeks
What cells produce hCG?
Syncytiotrophoblast
What is the role of hPL?
- fetal metabolism
- Fetal growth and development
- Stimulates IGF, insulin, and surfactant production
What cells produce hPL?
Syncytiotrophoblasts
When does hPL secretion begin? What happens to levels throughout pregnancy?
About week 6
Increases throughout pregnancy
What is the role of CRH?
- Onset of labor
- Prostaglandin production
- maintain blood flow in placenta
What cells produce CRH? What happens to levels throughout pregnancy?
Syncytiotrophoblasts and trophoblasts
Increases slowly throughout pregnancy, but really peaks during labor
Draw out the cholesterol pathway
Draw
What are the three major physiological roles of progesterone and 17-hydroxyprogesterone in pregnancy?
- Inhibit prostaglandin production
- Suppress uterine contractions
- Modulate immune response
What cells produce progesterone and 17-hydroxyprogesterone?
Corpus luteum for first 8 weeks, then placental syncytiotrophoblasts
Where does the cholesterol come from for the synthesis of progesterone and 17-hydroxyprogesterone by the placental syncytiotrophoblasts?
Maternal LDL
What is the role of DHEA in pregnancy?
Substrate for estrogen synthesis
What cells produce DHEA in pregnancy?
Maternal adrenal gland
Fetal adrenal glands and liver
What are the 6 roles of estrogen in pregnancy?
- Stimulate uterine growth
- Promote prostaglandin synthesis
- Thicken vaginal epithelium
- Oxytocin sensitization
- Mammary epithelium development
- Inhibition of milk production
What hormone stimulates uterine growth?
Estrogen
What hormone promotes prostaglandin synthesis?
Estrogen
What hormone is involved in fetal growth and metabolism?
hPL
What hormone increases oxytocin sensitization?
Estrogen
What hormone increases mammary epithelium development, but inhibits milk production?
Estrogen
What hormone maintains blood flow in the placenta?
CRH
What cells produce estrogen?
Corpus luteum for the first 8 weeks, then syncytiotrophoblasts after
Placental estrogen production needs androgen precursors from what?
Fetal adrenal gland
Draw out last chart.
Draw
