Pregnancy and Embryonic Development - Anatomy Final

Prenatal Development Stages

40 weeks/9 mo

• pre-embryonic

• embryonic

• fetal

• 1st trimester

• 2nd trimester

• 3rd trimester

pre-embryonic stage

• called embryo

• fertilization to implantation

• 2 weeks

embryonic stage

• called embryo

• implantation to 8th week

fetal stage

• called fetus

• 9th week and on

first trimester

• rudiments of all organs appear

• most dangerous - only 40% of conceptions survive

• 4 events (CIPE)

  • cleavage: cells divide, blastocysts form

  • implantation: in lining, germ layers (ecto-, meso-, endo- derm) form, form specialized tissues

  • placentation: placenta develops

    • placental circulation: arteries: fetus to placenta, single vein: blood to fetus

  • embryogenesis: 4-8 weeks, organs form

second trimester

• fetus covered by amnion

• fetus grows faster than placenta

• further organ systems develop

• fetus resembles human shape

third trimester

• all organs functional

• rapid growth

uterus changes

• 7.5 to 30 cm

• 5L of fluid

• 22 lbs

• organs displaced

• baby drops to prep for delivery

• sunny side up - face faces out

labor

strong, rhythmic contractions

3 stages:

• dilation cervix 10 cm, fetus pushed into canal, amnion ruptures

• expulsion: fetus out

• placental: placenta out

premie: under 36w and over 1kg

usually die: under 24w and under 600g

neonatal period

birth to 1mo

• lungs fill with air

• close ductus arteriosus and foramen ovale

• HR drops to 80-130 bpm

• breath 30-60 bpm

• kidneys filter blood

• active digestion

• metabolic rate increases for warmth