Female Reproductive System #14-38

16.) What are the phases of the ovarian cycle and what is happening in those phases?

1. Follicular phase- occurs during days 1-13 of an 28-day cycle. FSH and LH stimulate up to about 20 primordial follicles to mature into primary follicles. A few become secondary follicles. Ones that do not mature undergo atresia. Only one secondary follicle in an ovary matures into a vesicular follicle. Under LH the volume of fluid increases within the antrum of follicle and oocyte is forced toward one side of follicle and surrounded by the cumulus oophorus. It finishes meiosis I and 2 cells form a polar body and other cell receives the bulk of the cytoplasm and becomes the secondary oocyte which reaches metaphase II of meiosis before it is arrested again. Secondary oocyte does not complete meiosis unless it is fertilized. If not, it breaks down and regresses about 24 hours later. 2. Ovulation- peak in LH secretion. Follicle cells in the vesicular follicle increase their rate of fluid secretion, forming a larger antrum & causing further swelling within the follicle. The edge of the follicle that continues to expand at the ovarian surface becomes quite thin & eventually ruptures expelling the secondary oocyte. 3. Luteal phase- occurs during days 15-28 of and 28-day cycle. The remaining follicle cells in the ruptured vesicular follicle become the corpus luteum. It secretes progesterone & estrogen that stabilize & build up uterine lining, preparing for possible implantation of fertilized oocyte. If not fertilized it causes menstruation.

26.) What is the acrosome and the acrosome reaction?

Acrosome- cap-like, membrane-bound structure covering the anterior portion of the head of a spermatozoon. Acrosome reaction- after the sperm have made a pathway through the corona radiate, they release digestive enzymes from their acrosomes to penetrate the zona pellucida. The release of enzymes (primarily hyaluronidase & acrosin) from the acrosome is the acrosome reaction.

19.) What is the relationship between FSH and estradiol?

Both are hormones that control the reproductive system and ovulation. Found in both men & women. High levels of estradiol in the blood are detected by the brain which causes a reduction of FSH production.

24.) What is capacitation and how long does it take?

Capacitation- Physiologic conditioning of sperm before they can accomplish fertilization. It occurs in female reproductive tract and can last several hours. A glycoprotein coat and some proteins are removed from the sperm plasma membrane that overlies the acrosomal region of the sperm. The oocyte cytoplasm releases chemotaxic signals (chemicals) to attract sperm to its location. Cumulus Cells around the oocyte release progesterone, which binds to channels found on the flagella and cause an influx of calcium ions. When sperm reach secondary oocyte they attempt fertilization. The first sperm successfully penetrates the zona pellucida and its nucleus enters the second oocyte. Zona pellucida hardens preventing other sperm from binding to.

37.) What is the conceptus, the morula, the blastocyst, embryo, fetus, neonate?

Conceptus- the product of the union of oocyte & spermatozoon at any stage of development from fertilization until birth Morula- 3-4 days post fertilization, located in uterine tube, 16 or more cells present but no change in zygote Blastocyst- days 5-6, located in uterus, outer ring formed of trophoblast, embryoblast is a cell cluster inside blastocyst Embryo- organism in early stages of development, 3-8 weeks of development Fetus- the developing young in the uterus Neonate- a newborn child or mammal

18.) What does the corpus luteum do and how long does it last?

Corpus luteum secretes the sex hormones progesterone and estrogen. These stimulate & support the continuing buildup of the uterine lining & prepare the uterus for possible implantation of a fertilized oocyte. It lasts for about 12-14 days unless it begins receiving HCG from a developing embryo.

27.) What is the cortical reaction and why does it occur?

Cortical reaction- process initiated during fertilization by the release of cortical granules from the egg which prevents polyspermy. (fusion of multiple sperm fertilizing the egg)

14.) Where does estradiol come from, what does it do?

Estradiol- female sex hormone produced by the ovaries, adrenal gland and placenta during pregnancy. It acts as a growth hormone for reproductive organs. Hormone maintains oocytes and triggers events that lead to ovulation.

21.) What are the phases of female sexual response and what is different from male response?

Female sexual response 1. Excitement phase 2. Orgasm 3. Resolution phase Male sexual response 1. Erection 2.Orgasm 3. Ejaculation 4. Resolution Phase 5. Refractory period Difference- males have an additional step as the internal urethral sphincter is contracted so no urine enters the urethra during ejaculation.

31.) What is the difference between identical and fraternal twins?

Fraternal twins develop from 2 separate eggs and are fertilized by 2 different sperm. (can be hereditary) Identical twins have the same genes, look alike and are the same sex.

15.) Where does FSH come from, what does it do?

GnRH is released from the hypothalamus FSH& LH are released from the anterior pituitary FSH causes the follicles to develop. Follicles secrete estrogen. The anterior pituitary releases a surge of LH. Ovulation occurs. Corpus luteum- high levels of progesterone & estrogen inhibit production of FSH & LH Corpus albicans- decline in estrogen releases inhibition of anterior pituitary release of gonadotropins. FSH & LH can be made again.

20.) What are the phases of the menstrual cycle and what is happening during those phases?

Menstrual phase- approx. 1-5 days, is marked by sloughing of the functional layer and lasts through menstrual bleeding Proliferative phase- approx. day 6-14, initial development of the new functional layer of endometrium overlaps the time of follicle growth and estrogen secretion by the ovary Secretory phase- approx. days 15-28, increased progesterone secretion from the corpus luteum results in increased progesterone secretion from the corpus luteum results in increased vascularization and development of uterine glands. Corpus luteum degenerates and progesterone level drops if fertilization does not occur. Without significant levels of progesterone, the functional layer lining sloughs off, and the next uterine cycle begins with menstrual phase.

23.) What is the orgasmic platform?

Orgasm- refers to the time period where there are intense feelings of pleasure, a feeling of release tension, feeling of warmth, pelvic throbbing. The vagina and uterus contract rhythmically for a period of many seconds.

17.) When does ovulation happen and why?

Ovulation occurs on day 14 of a 28-day ovarian cycle. It is the release of the secondary oocyte from a vesicular follicle. Only one ovary ovulates each month. Occurs when there is a peak in LH secretion.

36.) What is RU-486 and how does it work?

RU-486 aka "abortion pill" approved for women up to 7 weeks pregnant. Contains steroid mifepristone which interferes with the body's production of progesterone. RU486 stops fertilizing egg from attaching to the lining of uterus.

34.) What is human chorionic gonadotrophin, what secrets it, and what does it do?

Secondary oocyte is fertilized and successfully implants in the uterine lining becomes a pre-embryo that starts to secrete human chorionic gonadotrophin. Hormone enters mother's blood and acts on the corpus luteum. hCG mimics the effects of LH and continues to stimulate the corpus luteum. Corpus Luteum continues producing progesterone and estrogen which maintains uterine lining. 3 months later- placenta of the developing fetus starts producing its own progesterone and estrogen. Corpus luteum forms corpus albicans.

22.) What is vaginal transudate and what is the tenting effect?

Vaginal transudate- provides lubrication

25.) How long is an oocyte viable; how long is a spermatocyte viable?

When sperm and oocyte plasma membranes come into contact, they immediately fuse. Only the nucleus of the sperm enters the secondary oocyte then completes the second meiotic division and forms an ovum. The nucleus of the sperm and the nucleus of the ovum are called pronuclei because they have a haploid number of chromosomes. Pronuclei come together and fuse forming a single nucleus that contains a diploid number. (23pairs) This becomes a zygote.

32.) What happens to the zygote when it travels down the fallopian tubes?

Zygote travels down the fallopian tubes toward the uterus to implant in the uterine lining.

28.) Why are there slightly more male babies in hospital nurseries than female babies?

circumcision?

29.) Who do you get your mitochondrial chromosome from?

from your mother

35.) What is progesterone, where does it come from, and what does it do?

progesterone- a steroid hormone released by the corpus luteum that stimulates the uterus to prepare for pregnancy.

30.) What are the cleavage divisions?

zygote, 2-cell stage, 4-cell stage, 8-cell stage, Morula, blastocyst