Psychology 92

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Psychology 92
2010-03-01 04:26:34
Chapter 4

Prenatal Development and Birth
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  1. germinal period
    The first two weed of prenatal development after conception, characterized by rapid cell division and the beginning of cell differentiation.
  2. embryonic period
    The stage of prenatal development form approximately the third through the eighth week after conception,during which the basic forms of all; body structures, including internal organs, develop.
  3. fetal period
    The stage of prenatal development from the ninth week after conception until birth, during which the organs grow in size and mature in functioning.
  4. blastocyst
    a cell mass that develops from the zygote in the first few days after conception, during the germinal period, and forms a hollow sphere in preparation for implantation.
  5. placenta
    The organ that surrounds the developing embryo and fetus, sustanining life via the umbilical cord. The placenta is attached to teh wall of the uterus.
  6. implantation
    Ther process, beginning about 10 days after conception, in which the developing organism burrows into teh placenta that lines the uterus, where it can be nourished and protected as it continues to develop.
  7. embryo
    The name for a developing organism from about the third through the eighth week after conception.
  8. fetus
    The name for a developing organism from the inth week after concepton until birth.
  9. age of viability
    The age (about 22 weeks after conception) at which a fetus might survive outside the mother's uterus if specialized medical care is available.
  10. teratogens
    Agents and conditions, including viruses, drugs, and chemicals, that can impair prenatal development and result in birth defects or even death.
  11. behavioral teratogens
    Agents and conditions that can harm the prenatal brain, impairing the future child's intellectual and emotional functioning.
  12. risk analysis
    the science of weighing the potential effects of a particular event, substance, or experience to determine the likelihood of harm. In teratology, risk analysis attempts to evaluate everything that affects the chances that a particular agent or condition will cause damage to an embryo or fetus.
  13. critical period
    In prenatal development, the time when a particular organ or other body part of the embryo or fetus is most susceptible to damage by teratogens.
  14. threshold effect
    A situation in which a certain teratogen is relatively harmless in small doses but becomes harmful once exposure reaches a certain level (the threshold).
  15. interaction effect
    The result of a combination of teratogens. Sometimes risk is greatly magnified when an embryo or fetus is exposed to more that one teratogen at the same time.
  16. fetal alcohol syndrome (FAS)
    A cluster of birth defects, including abnormal facial characteristics, slow physical growth, and retarded mental development, caused by the mother's drinking alcohol while pregnant.