Download Chapter 4 Outline

Chapter 4 Outline
I. Prenatal Development: Three Stages
 Gestation: The approximately 9-month or 266 day period of development between
conception and birth.
 Gestational age: The time since conception.
 Germinal, Embryonic, Fetal: Three stages of prenatal development when zygote
grows into an embryo and then a fetus.
 Morphogens: Molecules which are switched on after fertilization and begin sculpting
arms, fingers, vertebrae, ribs, a brain, and other body parts.
 Cephalocaudal principle: Principle that development proceeds in a head to tail
direction; upper parts of the body develop before lower parts.
 Proximodistal principle: Principle that development proceeds from within to
without: parts of the body near the center develop before the extremities.
A. Germinal stage (Fertilization to 2 Weeks)
 Rapid cell division, increasing complexity and differentiation and implantation in
the wall of the uterus.
 Mitosis: Rapid cell division and duplication.
 Blastocyst: Fluid filled sphere which floats freely in the uterus for a day or two
and then begins to implant itself in the wall of the uterus.
 L-selectin: A protein which coats the trophoblast and stops the blastocyst’s freefloating forward motion.
 Embryonic disk: Formed when some cells around the edge of the blastocyst
cluster to one side. A thickened cell mass from which the embryo begins to
develop, begins to separate into two layers.
 Ectoderm: Upper layer—skin, nails, hair, teeth, sensory organs, nervous system.
 Endoderm: Lower layer—digestive system, liver, pancreas, salivary glands,
respiratory systems.
 Mesoderm: Middle layer comes later—inner layer of skin, muscles, skeleton,
excretory, circulatory systems.
 Amniotic sac: Fluid filled membrane that encases the developing baby, protecting
it and giving it room to move.
 Amnion and chorion: The outer layers of the amniotic sac.
 Placenta: Delivers oxygen and nourishment and removes waste through the
umbilical cord.
 Umbilical cord: Connects placenta to embryo.
B. Embryonic stage (2 to 8 Weeks)
 Second stage of gestation, characterized by rapid growth and development of
major body
systems and organs.
 Trimester: Three-month period of pregnancy
 Spontaneous abortion: Natural expulsion from the uterus of an embryo or fetus
that cannot survive outside the womb; also called miscarriage.
 Stillborn: Dead at birth
C. Fetal stage (8 Weeks to Birth)
 Final stage of gestation, characterized by increased detail of body parts and
greatly enlarged body size.
 Ultrasound: Prenatal medical procedure using high-frequency sound waves to
detect the outline of a fetus and its movements, so as to determine whether a
pregnancy is progressing normally.
II. Prenatal Development: Environmental Influences
 Teratogenic: Birth defect-producing factor.
 Transforming growth factor alpha: Particular variant of a growth gene. Fetuses
with this gene have six times more chance of developing cleft palate if the mother
smokes while pregnant.
A. Nutrition and Maternal Weight
 Mothers should gain between 15 to 25 pounds during pregnancy.
 Risk factors associated with obesity
B. Malnutrition
 Dietary supplements may lessen the effects of maternal malnutrition.
C. Physical Activity and Strenuous Work
 Pregnant women should exercise moderately.
D. Drug Intake
 Medical Drugs
o Thalidomide: Tranquilizer that caused stunted or missing limbs, severe
facial deformities, and defective organs.
 Alcohol
o Fetal alcohol syndrome (FAS): Combination of mental, motor,
developmental
abnormalities, and disorders of the central nervous system.
 Nicotine
 Caffeine
 Marijuana and Cocaine
E. HIV/AIDS
 Acquired Immune Deficiency Syndrome (AIDS): Disease caused by human
immunodeficiency virus (HIV) that undermines effective functioning of the
immune system.
 Perinatal transmission: The virus may cross over to the fetus’ bloodstream
through the placenta during pregnancy, labor of delivery, or after birth,
through breast milk.
F. Other Maternal Illnesses
 Toxoplasmosis: An infection caused by a parasite harbored in the bodies of
cattle, sheep,
pigs, and cats.
G. Maternal Stress
H. Maternal Age
I. Outside Environmental Hazards
J. Paternal Factors
 Outside environmental factors
 Drug use
 Paternal age
III. Monitoring Prenatal Development
A. Disparities in Prenatal Care
 Rates of low birth weight and premature births have increased.
 Use of prenatal care varies by age and ethnic group.
B. The Need for Preconception Care
 Physical examinations
 Vaccinations
 Risk screening
 Counseling