0-2 weeks

fertilization to just before cell mass attaches to uterus wall

zygote, blastocyst

cells on inside

become new organism

outer layer of cells

will develop into life-support systems

2-8 weeks

groundwork for all body structures and internal organs begins

embryonic disk begins to form 3 cell layers (ectoderm, mesoderm, endoderm)

outer

nervous system, skin, sense organs

middle

muscles, skeleton, circulatory system, excretory system

inner

digestive system, lungs, glands

9 weeks - birth

complex physical structures, organize and connect, external genitals formed, heartbeat audible, behavioral changes (suck thumb, make fist)

white cheese-like substance

protects skin from becoming chapped

white, downy hair

helps vernix stick to skin

22-26 weeks

age at which fetus can survive if born early

mothers read the cat in the hat and other stories

after birth, infants played the stories

responded to the cat in the hat more than other stories, possibly due to rhthym

support neurons

do not conduct impulses

can replicate throughout life

forming of connections between neurons

primarily make too many connections

"pruning" process through experience

maternal nutrition

intense emotional stress

maternal age- complex relationships

dose- duration and degree

timing of exposure

genetic predispositions

presence of other factors

prescription and nonprescription medicine

illegal drugs

cigarette smoking

alcohol

infectious diseases (HIV/AIDS)

environmental pollution (mercury)

toxins can lead to abnormal sperm

later age associated with some birth defects