conception and fetal developmental teratogen Flashcards
developing embryo becomes a hollow ball of cells and is called a
blastocyst
where in the fallopian tube is the egg fertilized
outer 1/3rd
how many days does it take for the zygote to make it through the fallopian tube
about 4 days
outer cell mass of a developing zygote that develops into the placenta, helps with implantation
trophoblast
inner cell mass of a developing zygote that develops into the fetus (also called embryonic stem cells)
embryoblast
what day after fertilization does the zygote implant in the uterus (when its implanted its called an embryo)
days 7-10
what are 3 germ cells
ectoderm
mesoderm
endoderm
process where zygote develops germ cells
gastrulation
germ layer that develops outermost layer: skin, nervous system, spinal cord, brain, hair, eye lens
ectoderm
germ layer that develops middle layer: skeleton, muscle, connective tissue, blood vessels, kidney
mesoderm
germ layer that develops innermost layer: lining of GI tract, lungs, bladder, pancreas, thymus, liver
endoderm
when is baby referred to as zygote
immediately after fertilization until implantation
when is baby referred to as embryo
implantation (around day 10) to 8 weeks
when is baby referred to as fetus
8 weeks (post conception) to birth
when is baby most vulnerable to malformation and teratogens
when it is an embryo (10 days - 8 weeks)
first organ of embryo to start functioning (3-4 weeks after conception)
heart
nutrient important for spinal cord development of embryo
folic acid (all sexually active women of childbearing age should take folic acid supplements)
time since first day of last normal menstrual period
gestational age
time since conception (time since first day of last normal menstrual period minus 2 weeks)
conceptual age
2 structures included in fetal membranes
chorion
amnion (closest to baby)
sources of amniotic fluid (3)
maternal blood
resp and GI secretions from fetus
fetal urine
functions of amniotic fluid (6)
- thermal regulation
- cushion
- facilitations symmetrical growth and development
- allows fetal lung development (breathes in and swallows the fluid)
- source of oral fluid
- waste repository
what degrees C and F are considered fever
- 4 F
38. 0 C
volume of amniotic fluid at term
700-1000 mL
critical piece of fetal assessment
volume of amniotic fluid
how many mL is oligohydramnios of amniotic fluid (worried about perfusion, renal anomaly, leak in membranes)
<300 mL
how many mL is polyhydramnios of amniotic fluid (sometimes associated with GI anomaly)
> 2 L
what is LS ratio (tested by amniocentesis)
ratio of lecithin and sphingomyelin in amniotic fluid
ratio of 2:1 indicates mature fetal lungs
how many vessels in umbilical cord
2 arteries
1 vein
what helps umbilical cord to not kink by cushioning vessels
wharton’s jelly
2 factors that help umbilical cord not to kink and cut off blood/oxygen supply
wharton’s jelly
twisting of cord
deoxygenated blood is carried through umbilical arteries or vein
arteries
oxygenated blood is carried through umbilical arteries or vein
vein
fingerlike projections into mom’s intervillous space (pool of blood) that receive oxygen and nutrients and bring back to baby
chorionic villi
a chorionic villi that connects all the way down to mom’s endometrium
anchoring villi
when trophoblasts from fetus line uterine spiral arteries, causing them to dilate and lengthen, giving more blood to the growing fetus. (decreases maternal bp)
vascular remodeling
what event can lead eventually to pre-eclampsia
failure of vascular remodeling
15-20 lobes on placenta that are functional units in anchoring villi
cotyledon
4 functions of the placenta
- endocrine organ
- metabolism
- transport
- immunology
endocrine function of placenta
produces estrogen, progesterone, HCG, human placental lactogen (HPL)
metabolic function of placenta
synthesizes glycogen, fatty acids, cholesterol and enzymes
transport function of placenta
transports gases, nutrients, waste, drugs, etc
immunologic function of placenta
- filters some pathogens (large molecules such as some bacteria)
- prevents rejection (cloaks baby’s DNA)
immunologic function of placenta
- filters some pathogens (large molecules such as some bacteria)
- prevents rejection (cloaks baby’s DNA)
why do we use the 1st day of the mother’s last menstrual cycle for gestational age to determine the due date
because we can’t be completely sure of the date of conception
earliest system of fetus to function
circulatory (heart)
3 shunts that permit most of the fetus’ blood to bypass the liver and lungs
- ductus venosus
- foramen ovale
- ductus arteriosus
shunt that shunts blood to bypass liver to inferior vena cava
ductus venosus
hole between two atria of fetal heart to allows blood to shunt through to the left atrium (blood is already oxygenated, so it can bypass the lungs)
foramen ovale
shunt that allows deoxygenated blood from RV of heart to pulmonary trunk to this shunt into aorta (bypasses lungs)
ductus arteriosus
when does resp system start developing
embryonic stage (continues into early childhood)
MSF
meconium stained fluid
when do the kidneys start functioning
9-11 weeks
*amniotic fluid volume is now indicative of perfusion
when is sex differentiation fully distinguished in fetus
12 weeks
when is hearing and vision developed in fetus
hearing: 24 weeks
vision: 26 weeks
fine hair covering fetus at 20 weeks
lanugo
thick white mixture that covers fetus’ skin, protects skin. thick at 24 weeks, and disappears with continued growth
vernix caeseosa
twins from 2 mature ova
dizygotic
fraternal
twins from one ova that divides
monozygotic
identical
twins that are monozygotic but the cleavage is incomplete
conjoined
concern of twins sharing amniotic sac (mono mono)
cord entanglement
nongenetic factors influencing development (3)
- environmental factors
- teratogen exposure
- poor maternal nutrition (ex: folic acid)
any agent or non-genetic factor that produces permanent abnormal embryonic physical development or physiology
teratogen
principle of teratogen: if mom is exposed to teratogen during first 2 weeks after conception, it will either cause miscarriage or no effect
all or none phenomenon
principle of teratogen: how much of substance was mom exposed to
dose dependency
principle of teratogen: over what period of time was baby exposed to a harmful substance
duration of exposure
principle of teratogen: OTC or Rx meds that affect how moms body utilizes the substance and how it can affect the fetus
drug interactions
principle of teratogen: possibility that something harmful will effect one fetus vs another
host susceptibility
what might teratogens effect during fetal period
structural defects
fetal growth restriction
principle of teratogen: teratogen effects baby more or less depending on what stage in pregnancy fetus was
critical periods for certain effects
when is most critical period for harmful effects of teratogens for fetus
embryonic stage (2-8 weeks)
known/strongly suspected teratogens
- alcohol
- tobacco
- androgens
- ACE inhibitors
- antithyroid drugs
- coumadin/warfarin
- carbamazepine, phenytoin, valproic acid (anti-seizure drugs)
- folic acid antagonist
- cocaine
- lead, mercury
- lithium
- NSAIDs
- tetracycline
- thalidomide
if mom needs blood thinner during pregnancy what med will she get v not get
get: heparin
not get: coumadin/warfarin
known/strongly suspected teratogens: infections
- CMV
- rubella
- syphilis
- toxoplasmosis (uncooked meat and cat feces)
- varicella
