PSY210H5 Lecture Notes - Lecture 2: Prenatal Development, Muscular System, Fetus
Document Summary
Zygote in first trimester (1-2 weeks: developing organism from the unionization of sperm and egg (aka. blastocyst, the germ disc (cluster of cells) eventually develops into the fetus. Embryo begins during first trimester, ends second trimester (2-8 weeks) *vulnerable: development of all major physiological structures and organs. Ectoderm outer layer; forms hair, skin, and nervous system. Mesoderm middle layer; forms muscles, bones, and circulatory system. Endoderm inner layer; forms digestive system and lungs: amniotic fluid cushions embryo and maintains constant temperature, mother"s blood flows through villi (projections from blood vessels) Fetus organism at the beginning of second trimester (9 weeks - birth: development of muscular system and cns, reflexes appear in 5 months; eyes can open and close, third trimester: Eyes open (sensitive to light); auditory system experience sound. Taste receptors are functional preferences to certain tastes. Amniotic fluid and breast milk are flavoured by what mother eats: fetal auditory system. Low-pass filtered sound (muffled) high frequencies are removed.
