conception & fetal development ch 12 Flashcards
fertilization
occurs in the ampulla of the fallopian tube (outer third)
capacitation
physiologic change that removes the protective coating from the heads of the sperm
cleavage
mitotic cellular replication
begins within 30 hours after fertilization and ends with formation of blastocyst
morula
a 16 cell solid ball of cells with no increase in size (cels are smaller than orignal)
produced within three days
trophoblast
- gives rise to the placenta
- outer layer of cells surrounding the blastsocyt
embryoblast
- gives rise to the embryo
- inner cell mass of the blastocyst
blastocyst
the whole structure of the developing embryo
6-10 days after conception
- trophoblast secretes enzymes that enable it to burrow into the endometrium until blastocyst is completely covered
- implantation
chorionic villi
- fingerlike projections that develop out of the trophoblast and extend into the blood filled spaces of the endometrium
- vascular processes that obtain O2 & nutrients from the maternal bloodstream and dispose of CO2 & waste products into maternal blood
after implantation, endometrium is called ____
decidua
primary germ layers
form third week after conception
ectoderm (outer layer)
epidermis
nails, hair
CNS & PNS
floor of amniotic sac
mesoderm (middle layer)
bones, teeth muscles dermis & connective tissue cardio system spleen urogenital system
endoderm (lower layer)
- epithelial lining of respiratory & digestive tracts
- liver, pancreas, bladder
- reproductive system
- yolk sac
embryo
day 15- 8 weeks after conception
oligohydramnios
- less than 300 mL of amniotic fluid
- assoc with renal abnormalities
polyhydramnios or hydramnios
- more than 2 L of amniotic fluid
- assoc with GI defects and other abnormalities
umbilical cord
- surrounded by Wharton’s jelly (prevents compression of vessels)
- 2 arteries, one vein
endocrine function of the placenta
hCG (human chorionic gonadotropin)- preserves fx of corpus luteum
hPL (human placental lactogen) - increases insulin resistance & facilitates glucose transport across the placenta
progesterone - maintains endometrium, decreases uterine contractility, stimulates breast dev. & maternal metabolism
estrogen - increases toward end of pregnancy; stimulates uterine growth, utero-placental blood flow, breast growth & contractility of uterus
fetus
9 weeks until end of pregnancy
viability
24 weeks
teratogens
greatest effect during the embryonic pd from days 15 to 60
