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