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.

The embryo is called a fetus at 9 weeks and looks unmistakably human Prenatal Development 60 Days 40 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 2nd month the developing human from 9 weeks after conception up to birth.

Vocabulary Review Teratogens: harmful agents like chemicals or viruses that can reach the embryo or fetus Fetal alcohol syndrome: Physical and cognitive abnormalities caused by a pregnant woman’s heavy drinking

Automatic Reflex Behaviors Rooting reflex: turn toward touching cheek, open mouth and seek nipple

Automatic Reflex Behaviors Habituation: decreasing responsiveness with repeated stimulation Newborns prefer novel stimuli