Phys Embryo & Fetal Dev Flashcards
production of birth defects
teratogenesis
non-reversible morphological defects present at birth (internal, external, and microscopically)
malformations
what is the leading cause of infant mortality?
birth defects
which organ system is the major cause of death in infants?
congenital heart defects; can lead to life-long risks
which nutrient is especially important to consider during pre-conception status? why?
folate; up to 70% of neural tube defects have been attributed to folate deficiency
what is the organogenic period?
Day 17-57
critical growth period in which cells start to organize into different cell types
aka teratogenic period bc embryo is most vulnerable to developing birth defects
distinguish between hyperplasia and hypertrophy
hyperplasia = increasing cell # hypertrophy = increasing cell size
day 17 to 8 weeks = what kind of growth?
hyperplasia
after 8 weeks = what kind of growth?
hypertrophy
sperm + egg = ?
zygote
what kind of factors can influence fertilization?
- alcohol (even in males)
- toxins
- medications
process in which the fertilized egg divides and the zygote cleaves (increase in cell #)
blastogenesis
morula
egg with a mass of cells; forms a cavity to result in a blastocyst
blastocyst
has a space w/cells inside called embryoblasts (embryo); outer called trophoblasts (placenta)
penetrates endometrium and releases proteolytic enzymes and enable implantation
time span of pre-implantation period
<1 week
what happens during the pre-implantation period
- increase in cell number but no increase in cell size
- potential exposure to toxicants: no effect, slight decrease in growth, or lethality
time span of gastrulation phase
2-3 weeks
what happens during the gastrulation phase?
- cell migration through primitive streak
- formation of 3 germ layers (ecto, meso and endoderm)
- very susceptible to teratogens
which derm comprises brain, CNS, and skin?
ectoderm
which derm comprises voluntary muscles, CV and excretory systems?
mesoderm
which derm comprises the digestive and respiratory systems and glandular organs?
endoderm
when is the general shape of the embryo beginning to manifest?
days 27-29 post-ovulation
time span of organogenesis
3-8 weeks
what happens during the organogenesis phase?
- organs and body structures established
- cell proliferation, cell migration, cell-cell interactions and tissue re-modeling
- extremely susceptible to teratogenesis
- periods of maximum susceptibility for each forming structure
time span of fetal/neonatal phase?
8 weeks to birth
what happens during the fetal/neonatal phase?
- tissue differentiation, growth and physical maturation
- toxic exposure –> effects on growth and functional maturation
- CNS and reproductive abnormalities, behavioral and motor deficits
what happens during the 8th week of gestation?
accelerated development of placenta
