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Question 2

timing of fertilization

Answer 2

constrained by the need for high estrogen, short lifespan of the ovumimplantation must occur after the uterus has –> w/in 1 day of ovulationbeen primed by progesterone.

Question 3

hCG

Answer 3

rescues Corpus Luteumat 10th day post ovulation (day or two after implantation) -> blastocyst secretes hCG -> inhibits LH and FSH secretion and maintains C.L. Progesterone secretion (until placenta takes over progesterone secretion)levels peak at 1st trimesterAlso:Stimulates steroid synthesis in fetal adrenals Stimulates fetal gonads (testosterone production)Suppresses maternal lymphocytes and reduces the possibility of immuno-rejection of the fetus

Question 4

Estrogen aid in Sperm travel

Answer 4

+ antiperistaltic contractions -> propel toward oocytedecrease viscosity of cervical mucusIncrease glycogen secretion in vagina and increase vaginal pH

Question 5

pre-implantation progesterone role

Answer 5

decreases E2 effect on contractilityincrease # secretory cells lining oviduct and uterus -> nutrients for embryostructural changes in endometrium initiating placental formation

Question 6

pre implantation zygote

Answer 6

embryo 3-4 days in oviduct -> morula - isthmus contraction due to estrogen holds it hereprogesterone relaxes oviduct -> moves to uterusfloats here for 3 days -> blastocyst - outer - trophblastic cells - inner - inner cell mass/fetus

Question 7

decidua

Answer 7

edema, vascularization and nutrient storage in endometrium after syncitiotrophoblast invades -> nutrients for for embryo until placenta

Question 8

placental formation

Answer 8

3rd month of pregnancyderived from trophoblastic and decidual tissuesyncytiotrophoblast (chorion) continues to dig out lacunea -> fill with maternal blood as chorion digests decidua capillaries -> embryonic capillaries grow into trophoblast cords (placental villi)

Question 9

Functions of the Placenta

Answer 9

Exchange of gases between fetus and mother Delivery of nutrients from mother to fetusDelivery of antibodies from mother to fetus Removal of fetal waste

Question 10

placental Secretion of hormones

Answer 10

human chorionic gonadotropin (hCG), progesterone, estrogen, and human chorionic somatomammotropin

Question 11

Human Chorionic Somatomammotropin (hCS).

Answer 11

both GH and PRL activitiesmay act on the fetus as a stimulus for the production of IGFsmay cause maternal insulin dependence

Question 12

progesterone role in pregnancy

Answer 12

early pregnancy: provides nutrients to the embryo, prevents menstruation, and maintains decidual tissue. 2nd and 3rd trimesters: prevent uterine contractions.stim development of mammary alveoli

Question 13

estrogen role in pregnancy

Answer 13

stimulates the growth of the uterine myometriumstimulates mammary gland growthstimulates the production of prolactin.

Question 14

fetal-placental estrogen production

Answer 14

Pregnenolone from the placenta -> fetal adrenal converts to DHEA and sulfonates, rendering it inactive -> In fetal liver, 16-hydroxylase acts on DHEA-S -> 16-OH DHEA-S -> placenta has aromatase and produces estriol

Question 15

fetal-placental proesterone production

Answer 15

maternal compartment -> cholesterol -> placenta synthesizes pregnolone -> Progesterone .

Question 16

pre-parturition

Answer 16

increased estrogen -> increased oxytocin receptors on myometriumrelaxin -> softens cervix, relaxes ligamentsest/prog increases -> uterus more prone to contraction

Question 17

trigger of labor

Answer 17

Placental CRH -> stimulates local production of prostaglandins, increasing uterine contractility, stimulates directly the fetal zone of the adrenal cortex, resulting in increased estrogen productioncortisol important in counteracting role of progesterone in inhibiting CRH

Question 18

parturition

Answer 18

increased prostoglandins, estrogen, oxytocin, relaxinprostaglandins: : 1) stimulation of the uterine smooth-muscle contraction, 2) potentiation (together with estradiol) of oxytocin-induced contractions by promoting formation of gap junctions between smooth muscle cells, and 3) softening, dilatation, and thinning of cervix.oxcytocin: - increase intracellular Ca2+ -> contraction- prostaglandin productionestrogen: increases # of oxytocin receptors on uterus+ feedback -> contraction -> pressure on cervix -> + oxytocin -> stim more contraction (ferguson relflex)

Question 19

aids in bleeding stoppage post delivery

Answer 19

continued contraction –> constricts vesselssometime oxytocin given