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85 Cards in this Set
- Front
- Back
union of sperm with egg forms zygote
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fertilization
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occurs in ampulla of fallopian tube
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fertilization
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demen deposited as liquid but clot forms within 1 minute to prevent semen leakage & to protect sperm from vaginal acidity
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fertilization
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vaginal acidigy is neutralized so sperm can survive & clot liquifies
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fertilization
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of several million sperm ejaculated into vagina, fewer than 1% survive
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fertilization
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cervix contains maze of folds & outpocketings that can easily trap semen
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fertilization
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cervical mucus becomes thinner for sperm to pass through cervix shortly before ovulation
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fertilization
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approximately one million sperm survive journey through cervix
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fertilization
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uterine cavity filled with watery fluid through which sperm can easily pass
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fertilization
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only a few 1000 sperm enter fallopian tubes & move through assisted cilliary action in fallopian tubes
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fertilization
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only 50-100 sperm actually reach secondary oocyte
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fertilization
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sperm appear to be drawn toward an oocyte by some type of chemical communication
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fertilization
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capacitation
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fertilization
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removes some of protective coating from head of sperm that blocks enzymes stored in acromosome
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fertilization
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small openings form in acrosome & allow enzymes to escape & digest path for sperm into secondary oocyte when sperm approaches secondary oocyte
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fertilization
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blocks entry of additional sperm to prevent polyspermy
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fertilization
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secondary oocyte completes second meiotic division to produce ovum & second polar body
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fertilization
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fusion of sperm with ovum, combination of chromosomes produces zygote to restore diploid condition
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fertilization
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secondary oocyte will degenerate within 24 hours of ovulation unless it is fertilized
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fertilization
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sperm can survive in reproductive tract for up to 7 days
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fertilization
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"window of opportunity" makes fertilization possible during one week window around time of ovulation
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fertilization
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two oocytes are released & each is penetrated by seperate sperm
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fertilization
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dizygotic (Fraternal) twins
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fertilization
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about 30 hours after fertilization
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cleavage
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zygote divides by mitosis to form two identical daughter cells
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cleavage
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mitotic divisions occur every 16-20 hours to produce blastomeres that form solid morula
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cleavage
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occur quite rapidly & blastomeres get progressively smaller but morula remains same as original zygote
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cleavage
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cells of morula become tightly associated through compaction & blastomeres of unequal size start to form a hollow blastocyst
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cleavage
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outer layer of smaller cells will form series of layers around developing embryo
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cleavage
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trophoblast
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cleavage
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form if a single zygote splits completely curing cleavage
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cleavage
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monozygotic (identical) twins
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cleavage
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begins when blastocyst contacts endometrium
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implantation
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spontaneous abortions, or miscarriages, may occur at this time
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implantation
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cells of trophoblast divide & diferentiate to grow into endometrium to anchor it in place
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implantation
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inner cell mass begins to seperate from trophoblast & differentiate into primary germ layers of embryo
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implantation
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ectoderm (outer skin) form skin, hair, nails, neural tissue & linings of mouth & throat
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implantation
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mesoderm (middle skin) form bone cartilage, muscle & parts of heart, kidneys & gonads
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implantation
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endoderm (inner skin) form most of gut, parts of liver & pancreas, lining of digestive tract, respiratory tract & reproductive ducts
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implantation
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four extraembryonic membranes form primary germ layers of the embryo
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implantation
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yolk sac develops from endoderm & mesoderm to produce blood until liver is established
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implantation
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amnion develops from ectoderm & mesoderm to form covering around embryo
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implantation
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amniotic sac fills w/ amniotic fluid to sushion & protect developingn embryo & maintain constant temperature & pressure
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implantation
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allantois develops from endoderm near base of youlk sac to contribute to development of bladder
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implantation
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blood vessels become umbilical vein & umbilical arteries
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implantation
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chorion develops from mesoderm & forms finger-like chorionic villi that penestrate endometrium to establish netork of blood vessels
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implantation
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birth
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parturition
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stage 1 involves cervical effacement & dilation & lasts from 4 to 24 hours
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parturition
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cervix is relatively inflexible & must retract upwards to expose head of fetus
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parturition
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cervical canal is blocked by muscus plug during gestation, and removal of plug creates bloody discharge in vagina
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parturition
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amniotic sac ruptures
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parturition
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contractions occur at short intervals & intensify as cervix completely dilates
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parturition
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stages 2 involves expulsion of fetus and lasts 15 minutes-2 hours
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parturition
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contractions reach maximum intensity at one to two minute intervals
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parturition
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head of fetus rotates from side facing to downward facing & extends forward to pass beneath pubic bone
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parturition
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once head clears birth canal shoulders & rest of body slide past pubic bone
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parturition
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"crowning"
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parturition
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episiotomy
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parturition
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if vaginal canal is too small to permit passage of fetus or if danger of perineal tearing, incision made between vagina & anus
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parturition
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breech birth, a tangled umbilical cord, too large of a baby, or prematurely detached placenta which causes a hemorrhage cause need for a cesarean section
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parturition
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stage 3 involves expulsion of placenta within 15-30 minutes after birth
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parturition
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"afterbirth"
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parturition
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uterine contractions tear placenta from endometrium to expel "afterbirth"
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parturition
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forceful contractions consrict uterine blood vessels to reduce hemorrhage
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parturition
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pregnancy
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gestation
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9 months, 40 weeks, or 266 days
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gestation
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embryonic stage, first 8-10 weeks
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gestation
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characterized by development of major organ systems
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gestation
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fetal stage, last 30-32 weeks
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gestation
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characterized by organ growth & maturation of fetus
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gestation
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corpus luteum secretes estrogens & progesterone to maintain endometrium & prepare mammary glands for lactation
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gestation
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Human chorionic gonadotropin secreted by chorionic villi to maintain corpus luteum to prevent menstruation that would eliminate developing embryo
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gestation
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hCG levels in urine serve as basis for home pregnancy tests
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gestation
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hCG levels may cause nausea & vomiting associated with morning sickness
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gestation
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eventually placenta takes over secretion of hormones needed to maintain pregnancy
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gestation
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steroid hormones released from fetal adrenal cortex
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gestation
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falling progesterone levels increase sensitivity of uterine smooth muscles to oxytocin
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gestation
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oxytocin stimulates uterine smooth muscle to contract (released by posterior pituitary gland)
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gestation
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rising level of oxytocin stimulate production of prostaglandins that will further contribute to uterine smooth muscle contractions
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gestation
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relaxin softens pubic symphasis & dilates cervix (produced by placenta)
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gestation
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fetus drops lower in pelvic cavity in process of "lightening" that reduces pressure on mother's abdomen & diaphragm making it easier for it to breathe
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gestation
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during last week fetus will rotate in uterus to present itself for delivery
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gestation
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head usually moves farther toward cervix in order to exit first
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gestation
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during final weeks may experience false labor characterized by Braxton-Hicks contractions that are irregular & not very strong
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gestation
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true labor characterized by contractions at regular intervals
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gestation
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