EDUC 107 Lecture Notes - Lecture 3: Miscarriage, Umbilical Cord, Placenta
Document Summary
Weeks of pregnancy are counted from first day of last menstruation - not from conception. A typical pregnancy lasts 40 weeks, through 38-42 is considered normal. Sperm live from 1 - 7 days (average 3 days) The zygote is formed from two gametes creating 46 paired chromosomes - half from the mother and half from the father. Within hours of conception the sperm and egg create a zygote. One sperm enters the ovum, all others are then prevented. Blastocyst: 5-7 days, differentiation of cells begins (baby/placenta & amniotic sac and fluid). An organ that develops in the uterus during pregnancy. The placenta provides nourishment and oxygen to the growing baby and removes waste. Most substances are passed from the mother through the placenta to the baby through the umbilical cord. Some refer to it as the afterbirth because it is excreted from the body following the birth of the baby. In some cultures the placenta carries cultural meaning.
