Prenatal Development and the Newborn Conception Of the 200 million or so sperm that are released, relatively few make it to the egg. Digestive enzymes are released that allow the sperm to penetrate the outer layer and fertilize the egg. The fertilized egg is called a Zygote. Once the egg is fertilized a chemical reaction blocks the other sperm. Conception Prenatal Development About 10 days after conception the egg attaches to the uterine wall. The inner cells become the embryo, the outer cells become the placenta. Over the next 6 weeks organs begin to develop and the heart starts to beat. Prenatal Development 40 Days 60 Days 4 Months The embryo is called a fetus at 9 weeks and looks unmistakably human Prenatal Development The placenta transfers nutrients and oxygen to the baby and screens out many harmful substances. Teratogens such as viruses or drugs can harm the baby Fetal alcohol syndrome (FAS) results in physical and cognitive abnormalities. Vocabulary Review Zygote: Embryo: Fetus: the fertilized egg the developing human from about 2 weeks after conception through the 2 nd month the developing human from 9 weeks after conception up to birth. Vocabulary Review Teratogens: Fetal alcohol syndrome: harmful agents like chemicals or viruses that can reach the embryo or fetus Physical and cognitive abnormalities caused by a pregnant womans heavy drinking Infancy and Childhood Infant Brain Development You are born with most of the brain cells you will ever have. Neural networks grow rapidly, as illustrated here. From age 3-6 the most rapid growth is in frontal lobes Infant Brain Development Association areas develop last with a surge in thinking, memory & language Use it or lose it pruning process occurs Infant Motor Development Infants learn to roll over, sit, stand, walk & run Physical Development Maturation and Infant Memory Infantile amnesia