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Terms in this set (53)
Menstrual cycle involves both?
Uterus and ovaries.
The menstrual cycle is controlled by signals send from and hormones produced by 3 different areas, which are?
Aka: Hypothalamus-Pituitary-Ovarian Axis (HPO-axis)
The Gonadotropin Hormone (GnRH) starts everything. It is secreted by little pulses by the?
This GnRH secretion causes the anterior pituitary to make?
Follicle stimulating hormone (FSH) and Luteinizing hormone hormone (LH).
FSH stimulates what?
Follicles, so that they can grow and produce estrogen.
FSH --> follice --> estrogen.
LH has many jobs to do, but one of the jobs is to promote ovulation.
LH --> ovulation.
Ovarian and Uterine cycle
Ovarian cycle has 3 phases:
1. Follicular phase
2. Ovulatory phase
3. Luteal phase
Uterine cycle has 3 phases:
1. Proliferative phase
2. Secretory phase
3. Menstrual phase
Day 1 of menstrual bleeding (day 1 of the cycle):
This phase ends just prior to ovulation.
- most variation in length, 10 - 17 days (but can vary from woman to woman and cycle to cycle).
- a lot of actions with the follicles and FSH is key.
What are follicles?
Little fluid filled sacs with an immature egg in the middle.
Baby girls are born with about a million avarian follicles and many are just absorbed and go away during childhood.
When reaching puberty she has about four hundred thousand left that are eligible to develop into mature eggs.
During the 1st half of the follicular phase about 10-20 follicles are recruited and start growing and these follicles are estrogen factories.
As the follicular phase moves forward all these growing developing follicles are competing madly against each other to be the dominant follicle.
Estrogen at the follicular phase is at a moderate level:
These moderate levels of estrogen act on the hypothalamus and anterior pituitary to inhibit FSH and LH secretion in a classic
negative feedback loop
One follicle becomes dominant!
The other follicles give up and undergo atresia (breakdown).
Day 7 through end of follicular phase, the dominant follicle:
continues to mature and produce
high levels of estrogen
, which eventually stimulate FSH and LH in a
classic positive feedback loop
Because FSH and LH are now positively affected:
Now here comes the ovulation inducing LH surge and this brings us to the end of the follicular phase.
The dominant follicle are bulging on the surface of ovary, ready to?
Positive and negative feedback:
Ovulation happens in relationship to LH surge:
32-44 hours after LH surge starts and 10-12 hours after LH peaks.
LH surge is predicted by ovulation predictor kits for couples to know when ovulation is expected.
Ovulation happens when:
the dominant follicle starts to protrude, the sac ruptures and the oocyte (egg) is extruded.
Begins with ovulation and ends when new cycle begins.
Luteal phase is almost always reliable in all women. This phase lasts 14 days
It is called the luteal phase because after ovulation the walls of the dominant follicle (dominant one) colapses and under goes changes and takes up certain pigmentation to form the corpus luteum (CL) - yellow body.
CL --> luteal phase.
CL produces large amounts of?
Progesterone suppresses the growth of?
Progesterone causes an elevation in?
Basal body temperature.
When a woman measure her BBT she know whether or not she is ovulated.
Temperate will only rise after ovulation has occurred.
Progression of early follicular phase.
If concetoption does not occur, the CL rapidly regresses rapidly after ______ days after ovulation.
As the CL declines we see decreasing?
Progesterone levels, than menstruation begins.
Proliferative (growing and multiplying) phase:
~ cycle days 5 (about the time where bleeding ends) through 14.
________ causes this proliferation to occur.
Recall what is happening in the ovaries. Follicles are growing and the dominant follicle is being selected and all are producing a lot of estrogen.
So the endometrium is proliferating with the endometrial glands and stroma regenerating and the endometrium thickening.
Important things happen in the cervix as well (gateway to the uterus). Again, stimulated by estrogen the endocervical glands produce thin clear mucus to lubricate the vagina and facilitate sperm capture and transport.
Changes to help a woman to get pregnant.
Estrogen dominant phase.
~ cycle day 14 through 28.
Because of the CL, progesterone is going to dominate and act on estrogen-primed endometrium.
The endometrium thickens and secretes glycogen, mucus and other substances.
At this point in the cycle a woman's body acts as if she has conceived that mid-cycle and needs to protect the new conceptive.
Progesterone encourages uterine quiescence (quite and lazy), as in no cramping.
So if there is a brand new conceptive travelling and trying to implant the uterus won't contract it out.
Progesterone will also make cervical mucus very?
thick and sticky, assuming that the lucky sperm got in and done its job.
The thick and sticky cervical mucus will keep what out?
These progesterone related functions causes changes to help a woman stay pregnant if she has conceived.
The thick plug of cervical mucus is one of the primary ways that progestin based contraceptives prevent pregnancy.
If she has not conceived, now at day 25 this is when the CL is degenerating.
When the levels of estrogen, especially progesterone, that have been produced by the CL drop off as the CL recedes, the endometrium begins to be deprived of all of the hormones that is being relied on for these weeks, that brings us to the true beginning of the cycle. Cycle day 1 and lasts about 5 days in most women.
Remember that the robust level of hormones that made the endometrium thick and secreatory are now going and gone.
The endometrium starts to shrink and the spiral arterioles are starting to constrict ... decreased blood flow and oxygenation to endometrium. This causes ischemia and discomfort for some women.
The ovary is entering the follicular phase at the same time that the uterine phase is entering the menstrual phase.
Cycle day 1 for both phases.
Ovarian and Uterine Cycle:
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