Download Biological_Beginnings_pp3

Biological
Beginnings
Chapter Three
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Overview

Genetic Foundations of Child Development

Prenatal Development

Birth of the Baby

Enhancing Caregivers’ Sensitivity
to Newborn Infants
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Genetic Foundations of
Child Development

Structure and Operation of Genes
 Genes – genetic instructions; basic unit of heredity in a living cell; gene
segments are contained on chromosomes
 Chromosomes – organized, rod-like structure that is found in the
nucleus of every body cell; made up of DNA; contains genes that guide
growth and development; normal human cells contain 46
 DNA – deoxyribonucleic acid; spiral-staircase shaped molecule that
guides production of proteins that also guide growth and development

Most genes are universal among children


basic human abilities; language, walking, running, social communication
Some genes are diverse

Predispose height, weight, activity levels, eagerness to learn or content
with existing knowledge, emotionally agreeable or combative, healthy or
vulnerable to disease
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Formation of Reproductive Cells

Gametes- male (sperm) and female (ovum) reproductive cells contain 23
chromosomes (half of each chromosome pair)

Meiosis – the process of cell reproduction and division that forms gametes



chromosomes move together and pair into 23 matched sets in germ cells
chromosomes replicate
crossing-over occurs (pairs of replicated chromosomes exchange segments,
ensuring unique combinations of genes from mother and father)
 pairs of doubled chromosomes separate and the cell divides, forming two new
cells each containing 23 double-structured chromosomes
 first and second meiotic divisions take place
 Conception occurs; the sperm enters the ovum, as two sets of 23 chromosomes
unite to form a zygote with 46 chromosomes

Gender is determined on the 23rd chromosome



XX is female; XY is male
Monozygotic twins (identical) are created when a zygote splits into two
separate cell clusters containing the same genetic instructions
Dizygotic twins (fraternal) are created when two zygotes simultaneously
form and, just as ordinary siblings, contain some similar genetic traits
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Genetic Basis
of Individual Traits

Common mechanisms of genetic transmission

Alleles - genes located at the same point on corresponding
(paired) chromosomes and provide instructions for a particular
physical characteristic

Dominant gene – overriding gene that determines the
characteristic (dark features, e.g., dark hair/ brown eyes)

Recessive gene – influencing gene, primarily when an identical
gene is contained in the allele pair (light features, e.g. blonde
hair/ blue eyes)

Codominance – when both genes of the allele pair, although not
identical, share the influence on a physical characteristic

Polygenic inheritance – when several genes combine to
influence a certain physical characteristic (height)
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Problems in Genetic Instruction

Genetic disorders result in major physical problems and/or mental
retardation

Chromosome abnormalities – uneven division of chromosomes during
meiosis

1 in 150 births may result in:





An extra chromosome
A missing chromosome
A wrongly formed chromosome
Single-gene defects - inherited from one or both parents
Common chromosomal and genetic disorders include (see Table 3-1):
Down Syndrome – extra 21st chromosome
Klinefelter Syndrome – boys only; XXY
Turner Syndrome – girls only; X chromosome, missing second
Huntington Disease (HD)
 Phenylketonuria (PKU)
 Sickle Cell Disease
 Cystic Fibrosis (CF)




Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
The Awakening of Genes

Some genes are inactive and influence
development later during maturation
– tight genetic control of a certain
development aspect
 Canalization

Basic motor skills, e.g., crawling, sitting, walking
 Not canalized – most acquired skills
 Reading, writing, math, social skills

Sensitive periods are critical in physical
development, perceptual ability, brain
development, and language acquisition
 Toxic
substances are particularly dangerous during
prenatal development of limbs, organs, facial
structures, and brain connections
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
The Blending of Heredity and
Environment

Genetics are greatly influenced by environmental and personal factors:








Nutrition
Illness
Medication
Stressful events
Temperature
Exposure to light
Intensity of stimulation
Opportunities for physical activity

Personality and Intellect are the outcomes of both nature and nurture effects

Genetics affect a child’s response to the environment
through three mechanisms:
Passive gene-environment relation – parents genetic tendencies correlate to the
context in which they raise their children
 Evocative gene-environment relation – a child’s own characteristic elicits specific
responses form the environment around them
 Active gene-environment relation - a child’s talent influences the environment

Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Acknowledging Nature and Nurture
in Children’s Lives

Value individual differences among children and
adolescents

The environment (along with genetics) influences every
aspect of development

Intervene when children display intellectual, social, and
emotional struggles

Encourage children to select activities that promote
growth and development
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Prenatal Development
 Growing
new cells
 Moving through the body
 Settling into the interior wall of the uterus
 Taking in nutrition/expelling waste
 Forming and refining basic body structures
 Activating learning abilities

Phases of Prenatal Growth
 Period
of the zygote
 Period of the embryo
 Period of the fetus
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Period of the Zygote (2 weeks)

A woman’s ovum

surrounded by protective cells, develops from one of two ovaries during the
middle of the menstrual cycle
 Enters the fallopian tube and is guided by fringelike cell structures into the uterus

A man’s sperm


Swim vigorously to reach the ovum (egg) traveling through the fallopian tube
A single sperm attaches and enters into the ovum (conception)

Upon conception, the ovum creates exterior layers that prevent additional
sperm from attaching; chromosomes combine and a zygote is formed;
mitosis occurs

Mitosis – cell duplication process by which chromosomes are preserved to
grow a human being (or other organism)

In the first week, the zygote divides into 16 cells and attaches to the wall of the
uterus
 The zygote then separates into the future embryo and placenta
 Cells begin to specialize to form the nervous system and the brain, while
hormones are released telling the body to cease menstruation
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Period of the Embryo (week 2 - 8)

Major body structures and life support are formed

Placenta grows larger, stronger, and more refined; forms
umbilical cord




Provides food, liquid, oxygen
Removes waste
Secretes hormones to sustain embryonic growth
Embryo develops







Head and heart
From top to bottom (head first, feet last)
From inside to outside (torso before limbs, arms and legs before
hands and feet)
Neural tube (eventual brain and spinal cord) forms
Internal organs appear
Buds and limbs develop
Fingers and toes are recognizable at 8 weeks
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Period of the Fetus (week 9 to birth)

Grows in size and weight, sensory abilities, brain
structures and organs needed for survival

Third month





Four month







Skin is red and wrinkled; body is lean; fingernails are evident
Development of respiratory and central nervous system continues
Seventh month (avg. weight 2 lb. 14 oz.)



Rapid growth in length (height) continues
Fine hair growth covers body
Movement is felt by mother
Sixth month (avg. weight 1 lb. 13 oz.)


Rapid growth in length (height)
Slow weight increase
Hair growth on head and eyebrows
Fifth month


Head is large, slows growth
Eyes move into place; increasingly human-looking
Genitalia form
Reflex and muscular movement (although not felt)
Eyes open; eyelashes and toenails form
Body fills out
Eighth month (avg. weight 4 lb. 10 oz.)


Skin becomes pink and smooth; fat growths beneath skin
Testes descend (in males)
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Medical Care

Preparing for pregnancy (starts before
conception)
 Watch diet
 Take approved vitamin supplements
 Exercise
 Avoid alcohol and drugs (includes OTC

meds)
Other factors
 Hypertension or diabetes
 Under age 17 = low birth weight
 Mothers over 35 and fathers over
40 = higher risk for
genetic problems

Seek a genetic counselor
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Avoiding Harmful Substances

Teratogens – potentially harmful substance that can cause problems during
prenatal development










Prescription or non-prescription drugs or
Infectious agents, e.g., rubella, syphilis, HIV
Environmental chemicals, e.g., lead or polychlorinated biphenyls
Alcohol causes FAS - (Fetal Alcohol Syndrome) delayed physical and motor
development, facial abnormalities, mental retardation, impulsivity and other
behavior problems, learning disabilities or minor physical problems
Nicotine - low birth weight and occasionally miscarriage
Marijuana – premature birth, low birth weight, tremors, and/or oversensitivity to
certain stimuli
Cocaine – premature birth, low birth weight, small head size, lethargy, irritability
Heroin – premature birth, miscarriage, small head size, irritability, respiratory
problems, death
HIV and AIDS – Delayed motor skills, language, and cognitive development;
major health risks and problems
Maternal anxiety also contributes to low birth weight, irritability, and
problems with attention and dealing with negative emotional issues
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Sensitive Periods in Prenatal
Development
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Examples of Risk Factors for
Healthy Neurological Development
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Implementing Medical Procedures

Ultrasonography – detects age, major abnormalities,
and number/gender of fetuses

CVS (Chorionic Villus Sampling) for high risk
pregnancies





Invasive procedure performed at 7-12 weeks
Needle inserted into abdomen or tube guided through cervix to
collect chorionic villi (blood vessels)
Used to detect chromosomal abnormalities
May damage embryo/fetus arm or leg; cause miscarriage (rare)
Amniocentesis –



Needle inserted into abdomen; fluid drawn from uterus
Fetal protein and cells analyzed for neural tube defects or
chromosomal abnormalities
May cause fetal trauma, infection, or miscarriage
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Supporting Parents,
Protecting Babies








Encourage women to evaluate their health before
pregnancy
Remind sexually active women also to be health
conscious
Encourage new mothers to seek medical care
Remind expectant mothers to avoid teratogens
Encourage them to relax and speak their minds
Talk to fathers about their experiences and feelings
Advise parents about appropriate care when children
have been exposed to teratogens
Intervene when mothers continue substance abuse after
birth
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Birth of the Baby

Preparation for Birth
 Child




birth classes provide:
Relaxation and breathing techniques for focus, pain
management, reduction of fear, effective use of muscles
during birth
Support from a birth coach (spouse, partner, friend, family)
Basic education about physiology and mechanics of delivery,
positions, pain options, and medical interventions
Support for decisions about where and when birth may occur



Hospitals
Community birth centers
Home settings
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
The Birth Process


Typically at 38 - 40 weeks, both a mother’s hormonal
changes and the maturation of the fetus trigger birth
Braxton Hicks contractions exercise the uterine muscles
without opening the cervix


95% head-downward position
Cesarean delivery may result:



Breech position – butt or legs first
Sideways position – shoulder first
Several days before labor, the mother experiences





Decent of baby into pelvis
Rush of energy
Weight loss of 1 to 4 pounds from hormonal changes
Vaginal secretions
Difficulty sleeping
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
The Birth Process (cont’d)

First stage of labor
Regular contractions and widening of cervix to 10 cm (4”) dilation
 Pelvis and back pain
 First time mothers 12 - 16 hours;
6 - 8 hours for second birth or more
 Contractions become stronger and longer


Second stage of labor

Cervix is fully dilated, baby proceeds down birth canal
 Baby is born
 This process may last ½ to 2 hours (first baby)

Third stage of labor

Afterbirth expelled by uterus (placenta and fetal membranes)
 Usually baby is alert, looking around the room
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Complications and Interventions

Midwives, coaches, and medical staff may relieve pain without using meds







Warm whirlpool
Massage
Music
Hypnosis
Biofeedback
Visual images of the cervix opening
Physicians may use meds and interventions, e.g.,






Analgesics
Epidural analgesia (spinal injection)
Anesthetics
Opioids (a.k.a. narcotics)
Induced labor using Pitocin
Cesarean delivery (30%)





Fetal distress
Mother’s health problems
Failure for labor to progress
Birth canal infections
Presence of multiple babies
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Babies at Risk

Premature infant – babies are considered premature if born
before the end of week 37

Premature labor is triggered by


Seriously premature babies suffer from


Infection, multiple gestations (twins or triplets), fetus abnormalities,
death of fetus, uterine or cervical abnormalities, serious disease in
mother
Breathing problems, anemia, brain hemorrhages, feeding problems,
instability in temperature
Babies born small for date are at risk for

Neurological deficiencies, structural problems with body parts, difficulty
with breathing and vision
 Low birth size and weight after sufficient time in the uterus is often
caused by exposure to teratogens or chromosomal abnormalities
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Developmental Care for
Babies at Risk

Fragile infants need

Medical staff to




Reduce their exposure to noise and light
Regulate the amount of handling
Position them in a way that increases circulation
Parents to







Stay actively involved during infant care
Stay informed of the infant’s needs
Arrange a proper activity schedule to ensure sleep and rest
Cuddle and carry them often and for long periods
Swaddle them in a blanket with arms bent allowing the baby’s
hands to reach their mouth for sucking
Massage them
Stay informed through early childhood development
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Enhancing Caregivers’ Sensitivity
to Newborn Infants

Talk about the baby’s sensations (physiological detection of
environmental stimuli) and perceptions (interpretation of sensations)

Point out the newborn’s states of arousal (sleepiness and
wakefulness) and reflexes (automatic motor response to stimuli)
experienced throughout the day

Encourage parents to become aware of their baby’s responses to
certain stimuli

Suggest different types of soothing techniques, i.e., listening to a
clothes dryer, nursing, sleeping on father’s chest, riding in a car

Model sensitivity to baby’s interaction preferences

Teach parents how to perform care-taking functions, e.g., feeding,
bathing, diaper changing, and proper carrying or holding

Offer continued support for parents of fragile infants
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Summary

All children are born with a set
of genetic instructions that are
mostly similar

Prenatal growth consists of
three periods: the zygote, the
embryo, and the fetus

Unique gene differences also
predispose children to look
and act in different ways


Both genetics and the
environment affect children’s
abilities and achievements
Avoiding teratogens, seeking
medical care, reducing stress,
nutrition, and exercise are all
important factors during and
after pregnancy

Family and professionals are
critical in guiding new parents
through the expectations and
adjustments involved in the
birth process
Teresa M. McDevitt and Jeanne Ellis Ormrod
Child Development and Education, third edition
Copyright ©2007 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.