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Developmental Issues, Prenatal Development,

and the NewbornModule 7

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Developmental Issues, Prenatal Development, and

the NewbornPrenatal Development and the Newborn Two Major Developmental

Issues Conception and Prenatal

Development The Competent Newborn

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Prenatal Development and the Newborn

BIG QUESTION: How, over time, did we come to be who we are? From zygote to

birth, development progresses in an orderly, though fragile, sequence.

People used to think that babies began life as a “blank slate” with an empty brain and no abilities. We now know that they

are born with innate abilities.

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ConceptionA single sperm cell (male) penetrates the

outer coating of the egg (female) and fuses to form one fertilized cell.

Lennart Nilsson/ Albert B

onniers Publishing Com

pany

Lennart Nilsson/ Albert B

onniers Publishing Com

pany

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Prenatal DevelopmentPrenatal Period: the 9 months b/w conception and birth. A zygote is a fertilized egg with 100 cells that become increasingly diverse. At about 14 days the zygote turns into an embryo (a

and b).

Lennart Nilsson/ Albert B

onniers Publishing Com

pany

Biophoto Associates/ Photo R

esearchers, Inc.

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Embryonic Stage

• During this stage-the genetic plan determines how all the organs will begin to form.

• Differentiation: embryo’s cells begin to specialize.

• Before differentiation, embryonic stem cells are capable of forming into any organs of the body.

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Prenatal DevelopmentAt 9 weeks, an embryo turns into a fetus (c

and d). Teratogens are chemicals or viruses that can enter the placenta and

harm the developing fetus.Lennart Nilsson/ Albert B

onniers Publishing Com

pany

Lennart Nilsson/ Albert B

onniers Publishing Com

pany

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Prenatal Development of the Brain

• Brain grows new neurons at 250,000 per minute.• By birth, it has produced 100 billion.• As the new brain cells are produced, they actually

migrate out of the neural tube and then extend their axons and dendrites to make connections with other newly formed neurons.

• **How they do this is part of ongoing research.• *the basic plan for wiring the brain—must be

contained in the genetic code.

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Teratogens: Prenatal Toxins

• Although the placenta screens out some potentially dangerous substances, many can pass through-including viruses like HIV, certain drugs, and other chemicals-heroin, nicotine, alcohol.

• Fetal Alcohol Syndrome (FAS)-symptoms can include mental retardation, poor motor coordination, impaired attention, and hyperactivity.

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The Competent NewbornNeonatal PeriodInfants are born

with reflexes that aid in survival,

including rooting reflex which helps them locate food.

Ex. Rooting, grasping, postural

reflex

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Habituation

• Defined: a decrease in responding with repeated stimulation.

• A novel stimulus gets attention when first presented but the more often its presented, the weaker the response becomes.

• This seeming boredom with familiar stimuli gives us a way to ask infants what they see and remember.

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Recovery

• Following Habituation to one stimulus, the tendency for a second stimulus to arouse new interest—often used to test whether infants can discriminate between stimuli.

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Novelty Preference Procedure

• Used it to ask 4 month olds how they recognize cats and dogs.

• 1. first showed pictures of cats and dogs• 2. Found that after looking at a series of

cats or a series of dogs, they looked at hybrid.

• Shows that they focus on face first-not body.

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The Competent Newborn –Neonatal Period

Offspring cries are important signals for parents to provide nourishment. In animals and humans such cries are quickly attended to and relieved.

why? Because it’s a behavior parents are predisposed to find highly unpleasant and very

rewarding to relieve.

Carl and Ann Purcell/ C

orbis

Lightscapes, Inc. Corbis