PSYB20H3 Chapter 3: Chapter 3 Notes
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Gestation- prenatal period of development, b/w conception and birth (37-41 weeks) Prenatal development takes place in 3 stages: germinal, embryonic and fetal. During these stages fertilized ovum/zygote, grows into an embryo and then a fetus. Both before and after birth, development proceeds according to 2 fundamental principles: growth and motor development occur from top down and from centre of body outward. Cephalocaudal principle (head to tail)- dictates that development proceeds from head to lower part of trunk. Proximodistal principle (near to far)- development proceeds from parts near the centre of body to outer o(cid:374)es e. g. e(cid:373)(cid:271)r(cid:455)o"s head a(cid:374)d tru(cid:374)k de(cid:448)elop (cid:271)efore the li(cid:373)(cid:271)s . Germinal stage- includes first 2 weeks of development after fertilization during this time, zygote divides, becomes more complex, and is implanted in wall of uterus. W/in 36 hours after fertilization, zygote enters a period of rapid cell division and duplication, or mitosis.
