Studied by 2 people
when does gestation start?
from last period, abt 280 days
how long is an oocyte fertilizable?
up to 24 hours
how long are sperm viable?
1-2 days
what do acrosomal proteins do?
break down egg’s corona radiata & zona pellucida
what happens when one sperm binds to receptors on the egg?
slow block to polyspermy: cortical reaction: zona pellucida hardens & sperm receptors clip off
ovum and sperm pronuclei fuse, creating a
zygote
process of zygote → blastocyst is
cleavage
what adheres to, digests, and implants in the endometrium
trophoblast
how long does implantation take?
abt 12 days after ovulation
what stims the corpus luteum to stay alive?
hCG produced by blastocyst
when do human chorionic gonadotropin (hCG) levels decline? why?
after four months, placenta takes over
what forms the placenta?
embryonic (chorionic villi) & maternal (endometrial decidua) tissues
superior surface of embryonic disk (epiblast) forms
amnion
the fluid-filled amnion does what?
protects embryo from physical trauma, adhesion, temp & allows movement
what develops from the hypoblast of the embryonic disk?
yolk sac
what does the yolk zac do?
formation of early blood vessels
what forms the structural basis of the umbilical cord?
allantois
what is the outermost membrane of the placenta?
chorion
what is the conversion of the epiblast from a bilaminar disc into a trilayer embryonic disc consisting of ectoderm, mesoderm, and endoderm
gastrulation: germ layer formation
blastocyst → embryonic disk, aka:
gastrula
what’s the first step of gastrulation?
formation of primitive streak
what are the embryonic membranes?
allantois, amnion, chorion, yolk sac
what does the endoderm form?
mucosa of digestive & respiratory systems
what does the ectoderm form? (including neural tube)
nervous system & epidermis of skin
what’s the first event of organogenesis?
neurulation: producing brain & spinal chord
what does the mesoderm form?
all other organ systems & tissues
what does the mesoderm turn into?
notochord, paired somites (vertebrae), & paired masses of intermediate and lateral plate mesoderm
what brings blood supply into embryo?
umbilical vein
what does the ductus venosus do?
allows most of blood to bypass liver
what are the two fetal pulmonary shunts?
foramen ovale & ductus arteriosus
when does the heart start pumping blood?
by 3.5 weeks
all organ systems are laid down by the end of the ___ period
embryonic
how much does the conceptus grow during the fetal period?
from 22mm to 360mm, from less than an ounce to seven pounds+
anatomical effects of preg:
lordosis, waddling gait, weight gain: abt 28lbs
metabolic effect of preg:
human placental lactogen (hPL): growth & glucose sparring for fetus
physiological changes during preg:
constipation, dyspnea, heartburn, morning sickness, more urine (stress incontinence)
when does parturition usually occur?
abt 15 days from due date (280 days from period)
BIRTH when estrogen levels are high enough, they induce ___ receptors on myometrial cells & inhibit ___ quieting effect of uterine muscle. weak _____ start
oxytocin, progesterone, contractions
birth: fetal cells produce ____, which stim ______ production by placenta
oxytocin, prostaglandin
distension of cervix activates hypothalamus, and ____ is released from mother’s ____ (positive feedback loop for true labor)
oxytocin, posterior pituitary
what is the dilation stage?
onset of rhythmic contractions until cervix is fully dilated
full cervical dilation → birth is
expulsion stage
afterbirth is aka
placental stage
how does first inspiration occur?
umbilical chord is clamped, co2 in blood
once lungs are inflated, breathing is eased by presence of
surfactant
how long is transition? when infant is physiologically unstable & adjusting
8 hours
inflation causes pressure changes in circulation, and as a result
occluded blood vessels become fibrous cords, foramen ovale into fossa ovalis
breasts are prepped during preg for lactation by
est, prog & hpL (human placental lactogen)
premilk fluid, fat-poor, protein, vit a, minerals (produced at end of preg & for first 2-3 days after birth)
colostrum
true milk is produced on day __ in response to ___
3, suckling
suckling → hypo → anterior pituitary: ___ (milk production) & posterior pituitary: ____ (milk let-down)
prolactin, oxytocin
most-used ARTs
ivf, gift, & zift
ivf + zift: ___ gift: ____
in vitro, in vivo
what has abt 16 cells and no fluid? what has fluid?
morula, blastocyst
which system is not operational by 4-6 months?
respiratory system
what are preg tests looking for?
hCG (human chorionic gonadotropin)
what does hCG do?
maintains viability of corpus luteum until placenta takes over production of est & prog
the outer layer of the blastocyst, which later attaches to the uterus is the
trophoblast
in fetus, ductus arteriosus carries blood from
pulmonary trunk to aorta
umbilical vein carries oxygen and food to fetus / placenta?
fetus
skeletal muscles, heart & skeleton are derived from which germ layer?
mesoderm
blood cells cannot pass through placental barriers, but what can?
amino acids, antibodies, gases, & glucose
the notochord forms
nucleus pulposus (part of intervertebral discs)
sclerotome forms
ribs & vertebrae
neural tube forms
brain
placenta formation! ____ breach the uterine wall and begin reshaping bv there. these remodeled vessels become a source of maternal blood.
cytotrophoblasts
____ elaborate when touching maternal blood to form the placenta
chorionic villi
inner cell mass → extraembryonic mesoderm, mesoderm + ____ = chorion
trophoblast
two problems w breech
skull isnt a wedge to dilate cervix, not suctioned free of mucus, cant breathe in birth canal
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Flashcard (23)