PSYC 2450 Chapter Notes - Chapter 4: Ventouse, Prenatal Care, Cretinism
21 Oct 2013
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Document Summary
Gestational age usually takes place from the first age of an expectant mother"s last menstrual cycle, and usually has a normal range of 38-42 weeks. After conception happens (usually marked by a missed menstrual period), prenatal development takes place in three stages: germinal, embryonic and fetal. The genes responsible for this transformation are in a specific identifiable group and produce molecules called morphogens. Morphogens are turned on after fertilization and shape all the different parts of our bodies. Growth and motor development occur from the top down and from the centre of the body outward (see cephalocaudal and proximodistal principles). Cephalocaudal means head to tail in latin and is demonstrated in that an embryo"s head, brain and eyes develop earliest and are disproportionately large until the rest of the body catches up. During the germinal stage, the zygote undergoes cell division (mitosis), becomes more complex, travels down the fallopian tubes, and is implanted into the wall of the uterus.
