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