Menstrual cycles Flashcards
Initiation of pregnancy for the sperm
Sperm must move from the vagina through the uterus and into the fallopian tube. Egg and sperm have to meet within 6-24 hours after ovulation
how long after ovulation do the sperm have to meet an egg>?
6-24 hours
What must happen to the sperm that allows them to penetrate the zona pellucida surrounding the egg?
capacitation
Where does fertilization occur?
upper oviduct
survivability (fertilizability) of the ovum?
6-12 hours
survivability of the sperm?
1-2 days
Sexual interest in women peaks when?
Midcycle (right around the time of ovulation) and just before menstruation
volume of ejaculation
1-3 ml, 100 million sperm in each ml
Cervical mucus thinning occurs mid cycle and is stimulated by
estrogen
motility of the female tract
Prostaglandins in semen, estradiol, oxytocin
Highest chance of pregnancy
The day of ovulation or 1-2 days prior. Up to five days prior since thats how long the sperm can survive. Pregnancy chances decrease to zero by one day after ovulation since the egg is only fertilizable for about 6-12 hours
At birth, 1 million germ cells
at puberty, 300,000
When does menopause start
when all eggs are gone…estrogen falls, FSH and LH rise
Cycle
Follicle secretes mainly estrogen (increasing amounts for the first two weeks).
- The estrogen is made by the granulosa cells which make it out of the androgens produced by the thecal cells stimulated by LH The granulosa cells are stimulated by FSH
How many follicles develop in each cycle?
only one, this dominany follicle secretes substances that cause the others to regress
What makes inhibin and what does inhibin do?
Granulosa cells, it turns off FSH after the follicular phase is over and throughout the luteal phase
Cycle starts when
first day of bleeding….period is the start of a cycle not the end
Basal body temp rises when
directy after ovulation
FSH rises at the end of a cycle and through the period. Why
Because Estrogen, Progesterone, and Inhibin have fallen to allow FSH to rise and begin to stimulate growth of new follicle
Estrogen rises throughout the follicular phase why?
When it reaches a certain point it stops being an inhibitory hormone and causes a spike in FSH and LH
midcycle LH surge leads to
ovulation
BC pills prevent
MIDCYCLE LH SURGE
Rise in progesteron around midcycle tells you:
Follicle is changing to corpus luteum
Why does Basal body temperature go up?
Progesterone resets the temperature control
Endometrial phases during menstrual cycle
- Menstrual phase (5 days)- sloughing off of uterine lining
- Proliferative Phase (11 days)- glands that are lined by secretory cells which secrete things like glucose into the uterine lumen to keep the blastocyst viable
- Secretory phase- persists through teh luminal phase
What provides blood to the proliferative phase and secretory phase uterine linings
spiral arteries
During the Follicular phase: Hypothalamus secretes
GnRH
GnRH tells the gonadotrophs to secrete what?
FSH and LH
FSH stimulates what in the ovary?
Granulosa cells
Granulosa cells mak what
Estrogen (from the androgens produced by thecal cells) and Inhibin
LH stimulates what
Thecal cells
Thecal cells produce what
Androgen which is used to make estrogen
Inhibin feeds back where
Anterior pituitary and hypothalamus to decrease LH and FSH
KNOW CHART IN NOTES
ok
FSH does what to Granulosa cells
causes them to proliferate and produce Estradiol
Estradiol stimulates more proliferation in granulosa cells
This is positive feedback
Ovulation is triggered by
midcycle LH surge
During ovulation, the follicular membrane
ruptures after being attacked by proteolytic enzymes
Variation in length of a woman’s menstrual cycle is caused by
length of the follicular phase, ie, time for dollicle to develop and the ovum be released
hCG
keeps the corpus luteum from degenerating
Luteal phase highlight
The development of corpus luteum
Corpus luteum begins to develop when
a few days before ovulation (see this by spike in progesterone)
How long does the CL last
2 weeks but it is degenerating in the last 5 days. This is called luteolysis
CL secretes
estrogen, lots of progesterone, 17 hydroxyprogesterone and inhibin
17 hydroxy does what>
who cares
