Term
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Definition
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Term
| Where does fertilization occur usually? |
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Definition
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Term
| When must sperm be introduced into female reproductive tract? Why? |
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Definition
| Within 5 days before ovulation. Sperm are viable for 5 days- oocyte is viable for 12-24 hours |
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Term
| Why are sperm initially incapable of fertilization? |
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Definition
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Term
| Where does capacitation occur? |
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Definition
| In femal reproductive tract |
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Term
| Can deposited sperm fertilize oocyte? |
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Definition
| No, they need capacitation |
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Term
| How long does capacitation usually take? |
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Definition
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Term
| What occurs during capacitation? |
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Definition
Molecules in semen aid capacitation
Increased tail movement (swiming)
Plasma membrane altered so they can attach to ovum |
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Term
| How many sperm are deposited into vagina during copulation? |
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Definition
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Term
| Where do sperm swim to? What are they aided by? |
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Definition
| Swim to uterus and uterine tube, aided by contractions of uterus and uterine tube |
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Term
| How many sperm make it to uterine tubes? |
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Definition
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Term
| What is the protective layer of cells around ovum called? |
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Definition
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Term
| What are the events of fertilization? |
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Definition
| Sperm reach ovum and try penetrating corona radiata, when through they bind to sperm-binding proteins on the zona pellucida. The acrosome reaction is then triggered, enzymes break through zona pellucida allowing sperm access to oocyte. |
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Term
| What is the zona pellucida? |
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Definition
| protective cover around oocyte |
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Term
| What is the acrosome reaction? |
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Definition
| release of enzymes from sperm head. |
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Term
| What happens to the first sperm to access oocyte? |
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Definition
| It binds to receptor on oocyte plasma membrane. It is transported into the cytoplasm of the oocyte. Fusion occurs and sperm binding proteins become inactivated. Outer layer of oocyte hardens preventing more sperm from coming in. |
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Term
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Definition
| When the sperm is transported into the cytoplasm and they lose tail. |
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Term
| Inside the cytoplasm what happens to the sperm? |
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Definition
| Sperm plasma membrane disintegrates, chromosomes from sperm and ovum migrate to center. Now known as a zygote and cell division occurs |
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Term
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Definition
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Term
| When does implantation occur? |
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Definition
| 6-9 days post fertilization |
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Term
| Which cells are responsible for implantation? |
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Definition
| outer layer of cells on the early embryo |
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Term
| How does the early embryo implant? |
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Definition
| secretes enzymes that digest portion of endometrial cells, release molecules that stimulate endometrial secretions, infiltrates endometrial tissue and starts to develop placenta. |
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Term
| What do proteins on the outer layer of the embroy recognize? |
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Definition
| Proteins on endometrial cells. Embryo will stick to endometrium causing it to swell and increases glycogen stores. |
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Term
| What cells start to form a placenta and when? |
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Definition
| Cells from both embryo and endometrium start to form placenta soon after implantation. |
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Term
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Definition
organ specialized for exchange of molecules (O2, CO2, nutrients, wastes) between maternal blood and fetal blood.
Also secretes hormones as an important endocrine organ |
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Term
| In the placenta, is there a direct exhange of blood? |
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Definition
| No, it is seperated by the thin wall of the placenta. |
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Term
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Definition
| enzymes dissolve portions of endometrium called sinuses that are filled with maternal blood, the fetal blood vessels invade sinuses |
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Term
| Where is the exchange of molecules between mother and fetus? |
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Definition
| In the sinuses. Seperated by the thin walls of placenta |
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Term
| Blood from of fully developed fetus comes from what? |
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Definition
Maternal- uterine artery and vein
Fetal- umbilical artery and vein located in umbilical cord. |
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Term
| What happens in terms of hormones after 2 weeks of pregnancy? |
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Definition
| Placenta starts to secrete the hormone human chorionic gonadotropin (hCG) |
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Term
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Definition
| Maintains function of the corpus luteum in ovary by maintaining secretion of progesterone and estrogen by ovary. |
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Term
| What is detected in home pregnancy tests? |
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Definition
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Term
| What maintains the thickened highly vascularized endometrium and thus maintains pregnancy? |
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Definition
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Term
| What does progesterone inhibit? |
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Definition
| Contraction of uterine smooth muscle |
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Term
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Definition
| Abortion drug, blocks the action of progesterone so that the uterine lining is sloughed along with embryo |
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Term
| How long does the corpus luteum continue to secrete progesterone and estrogen? |
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Definition
| 2-3 months, first trimester |
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Term
| What happens after the first trimester (2-3 months)? |
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Definition
| Placenta starts to now secrete progesterone to maintain pregnancy. hCG secretion stops and the corpus luteum in ovary degenerates. |
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Term
| After first trimester, what maintains endometrium? |
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Definition
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Term
| hCG secreted from -- sustains -- which secretes-- for the first 2-3 months until -- secretes -- for the remainder of the pregnancy. |
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Definition
| placenta sustains corpus leteum which secretes estrogens and progesterone for the first trimester, until the placenta starts secreting estrogens and progesterone for the remainder of the pregnancy |
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Term
| What prevents ovulation during pregnancy? |
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Definition
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Term
How does progesterone inhibit ovulation during pregnancy?
What type of control is this? |
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Definition
Progesterone inhibits GnRH, LH and FSH release, preventing LH surge (no follicle decelopment or ovulation).
Negative control on anterior pituitary/hypothalamus |
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Term
| What are birth control pills? |
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Definition
| Combination of synthetic progesterone and estrogen. |
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Term
| How do birth control pills usually come? |
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Definition
In 28 day dispensers (one per day)
21 days have hormones, 7 days have a placebo. Normal mensturation during 7 days of placebo |
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Term
| What is the morning after pill/Plan B? When can it be used |
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Definition
| Very high does of progesterone and estrogen- prevents ovulation and interfere with implantation. Used up to 72 hours after sex- 80% effective. |
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Term
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Definition
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Term
| During the last month of pregnancy what does the placenta secrete? |
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Definition
| Mostly estrogen, less progesterone |
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Term
| What do the high levels of blood estrogen increase in the last month of pregnancy? |
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Definition
| Increase the number of oxytocin receptors on uterus smooth muscle cells. |
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Term
| What is oxytocin a stumulate for? |
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Definition
| A powerful stimulant for uterine contraction |
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Term
| What is occuring when the uterus first starts to contract? |
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Definition
| Baby moves from head up to head down towards cervix |
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Term
| Contractions push the babies head into- |
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Definition
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Term
| Stretch receptors in cervic signal what? What type of feedback is this? What eventually happens? |
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Definition
| signal hypothalamus/posterior pituitary to secrete more oxytocin to travel to uterus to cause greater uterine contractions- pushing further into cervix, triggering more contractions. Positive feedback. Eventually a strong enough contraction pushes baby out. |
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Term
| Summary of the positive feedback system during labor- |
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Definition
| oxytocin secreted from posterior pituitary-> Strengthen uterine contractions -> Pressure of fetus against cervix -> Stimulates oxytocin from the beginning |
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Term
| What ripens the cervix of the uterus? |
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Definition
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Term
| How much does the cervix have to be dilated for childbirth? |
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Definition
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Term
| What is the trigger for parturition? |
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Definition
| unknown, theory suggests signal comes from fetus. |
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Term
| What is the signal theory for parturition? |
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Definition
| Fetal placenta secretes corticotropin releasing hormone (CRH)-> to fetal anterior pituitary _> ACTH _> causes fetal adrenal gland to secrete estrogen precursors when fully developed -> estrogens entering maternal blood stream -> increases oxytocin receptors in myometrium |
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Term
| What can be used to predict partuition? |
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Definition
| steady increase in CRH by placenta |
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