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27 Cards in this Set
- Front
- Back
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Prenatal Development
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A. Conception
B. Developmental Processes C. Early Development D. Fetal Behaviour E. Fetal Experience F. Fetal Learning G. Hazard to Prenatal Development |
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Conception
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Results from the union of two gametes, the egg and the sperm
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Gametes
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Produced through a specialized cell division, which results in each gamete's having only half the genetic material of all other normal cells in the bofy
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Zygote
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The fertilized egg, or zygote, has a full complement of human genetic material, half from each parent
Marks the beginning of prenatal development 46 Chromosomes total 23 from each parent |
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Developmental Processes
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Four major developmental processes that transform a zygote into an embryo then into a fetus.
1. Cell division - results in the proliferation of cells 2. Cell migration - movement of cells from point of origin to somewhere else in embryo 3. Cell Differentiation - transforms embryo's unspecialized stem cells into different types of cells 4. Apoptosis - genetically programmed cell death |
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Early Development
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By 4th day after conception, zygote arranges itself into a hollow sphere of cells with a bulge of cells, the inner cell mass, on one side.
This inner cell mass will eventually transform into the embryo. |
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Twins
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Identical twins orginate from the splitting in half of the inner cell mass
Fraternal twins result when two eggs are released into the fallopian tube at the same time and are fertilized by different sperm |
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Embryo
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After implantation, the inner cell mass becomes the embryo and the rest of the cells develop into its suport system
The neutral tube is a U-shaped groove formed from the top layer of differentiated cells in the embryo, it eventually becomes the brain and the spinal cord |
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The Embryo Support System
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Includes:
Placenta - permits the exchange of materials between the bloodstream of the fetus and the mother Umbilical Cord - the tube that contains the blood vessels that travel from the placenta to the developing organism and back again |
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Protecting the Fetus
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Placenta membrane - barrier against some but not all toxins and infectious agents
Amniotic sac - membrane filled with fluid in which the fetus floats, provides a protective buffer for the fetus |
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Fetal Experience
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Sensory structures are present relatively early in prenatal development and play an important role in fetal development and learning
Visual experience - negligible Tactile stimulation - result of own activity and can taste/smell amniotic fluid Sound - responds to from at least 6th month of gestation |
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Fetal Learning
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- Newborn infants have been shown to recognize rhymes and stories presented before birth
- They also prefer smells, tastes, and sound patterns that are familiar because of prenatal exposure |
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Habituation
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The fetus decreases responses to repeated or continued stimulations, happens at around 32 weeks
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Miscarriage
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- Most common misfortune in prenatal development
- Around 45% or more of conceptions result in very early miscarriage - About 15-20% of pregnancies of which woman are aware are miscarried - The majority of embryons that miscarry very early have sever defects |
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Environmental Influences
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Teratogens are environmental agents that have the potential to cause harm during prenatal development
*Timing is a crucial factor in the severity of the effects of potentially harmful agents. Many agents cause damage only if exposure occurs during a sensitive period in development |
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Teratogens
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- Most teratogens show a dose-response relation
- Increases in exposure to potential teratogens are associated with greater probabilities of fetal defects with more sever problems - Includes legal as well as illegal substances *Individual differences also influence the effects of teratogens |
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Legal Drugs
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Ie. Cigarettes
- Smoking during pregnancy is liked to retarded growth and low birth weight - Linked to SIDS (Sudden Infant Death Syndrome) ie. Alcohol - Maternal alcoholism can lead to FASD (Fetal Alcohol Spectrum Disorder), which is associated to mental retardation, facial deformity, etc |
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Illegal Drugs
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- Approximately 4% of pregnant women in the US use illicit drugs
- Marijuana is suspected of affecting memory, learning, and visual skills after birth - Cocaine exposed children have reported cognitive and social deficits |
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Maternal Factors
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- Age, nutrition, disease, and emotional state of the mother have an impact on prenatal development
- Infants born to girls aged 15 < are 3-4 times more likely to die before their first birthday than those aged 23-29 |
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The Newborn Infant
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- State of Arousal
- Negative Outcomes at Birth |
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State of Arousal
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- The infants level of arousal and engagement in the environment
- Ranges from deep sleep to intense activity - Important influence in the newborn's exploration of the world |
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Six States of Arousal
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1. Active Sleep
2. Quiet Sleep 3. Crying 4. Active Awake 5. Alert Awake 6. Drowsing |
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Sleep
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- Newborns sleep twice as much as young adults
- REM sleep constitutes 50% of a newborn's total sleep time and declines to only 20% by 3-4 years of age |
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REM (Rapid Eye Movement) Sleep
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An active sleep state associated with dreaming in adults and is characterized by quick, jerky eye movements under closed lids
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Non-REM Sleep
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A quiet of deep sleep state characterized by the absence of motor activity or eye movements and by regular, slow brain waves, breathing, and heart rate
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Why so much time in REM sleep?
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According to autostimulation theory, brain activity during REM sleep in the fetus and newborn makes up for natural deprivation of external stimuli and facilitates early development of the visual system
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Crying
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- Early in infancy, crying reflects discomfort or frustration
- Crying gradually becomes more a communicative act |
