Transcript Module: 10 Developmental Issues, Prenatal Development, and

Human Development
Development Parenting styles Cognition
DNA
Theories of development Conception
Genes
Developmental theorists Assimilation
Genotype Teratogenic effects Threshold effect
Phenotype Imprinting
Accommodation
Gamete
Stranger anxiety Germinal stage
Zygote
Theory theory
Embryonic stage
Attachment Theory of mind Fetal stage
Interaction effect Apgar scale Critical periods
Addiction
Dizygotic/Monozygotic twins
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The sperm and ovum receive only one member of each chromosome pair when cells
divide to produce gametes, and thus have only 23 single chromosomes each
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Gamete-a reproductive cell, a sperm or ovum that can produce a new individual if it
combines with a gamete from the other sex to make a zygote
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Zygote- the single cell formed from the fusing of two gametes, a sperm & an ovum
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How does conception occur?
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Conception occurs when the male gamete (or sperm) penetrates the membrane of
the female gamete (the ovum); the gametes fuse and their genetic material
combines to form one zygote
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Where does the zygote develop?
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The amniotic sac is the fluid-filled pouch in which the embryo will live until birth
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The amniotic sac acts as both a cushion against the environment and as a
temperature regulator
As the head of the spermatozoan enters the ovum, the ovum prevents penetration by another spermatozoan.
Conception: The Incredible Journey
• The ovum can live for 24 hours
• Sperm can live for 72 hours; less than 1% can
live up to one week
• Pregnancy may occur a few days before or
after ovulation
• The ovum may release chemicals to signal its
location
• If a sperm reaches the ovum, it wriggles
violently
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The 23rd pair of chromosomes determines the sex
The chemical on the Y chromosome signals the development of the male organs
The chromosomal make up is XY in the male and XX in the female
In a stressful pregnancy, XY embryos are more likely than XXs to be expelled in a
spontaneous abortion, or miscarriage
Within hours, the zygote initiates human development through the process of
duplication and division
Implantation begins about 10 days after conception, the organism buries into the
placenta for nourishment
Then differentiation begins, this is when cells begin to specialize, taking different
forms and reproducing at various rates
At the eight-cell stage, the organism has stem cells it could develop into a body
part
The cells on the outer side of the of the mass become the placenta-the organ that
will support the life
Certain genes begin to switch on an off during this developmental stage
In some pregnancies, a single zygote splits into two separate identical cells that
develop into genetically identical or monozygotic (MZ) twins
MZ twins have the potential for developing the same physical appearance and
psychological characteristics, but they are also vulnerable to specific diseases
Dizygotic (DZ) or fraternal twins begin life as separate zygotes, and share no more
genes than any other sibling (about 50 percent)
Gestation
• The 1st 2 weeks of prenatal development are
called the germinal period
• The embryonic period begins in the 3rd week
as the formless mass becomes a distinct
being, which is now referred to as an embryo
• A thin line down the middle of the outer layer
of cells is the primitive streak, and the
structure becomes the neural tube, then the
brain and spinal column (the central nervous
system)
• The third week to the eighth week begins the
embryonic phase…the developing mass can now be
considered an embryo
• 5th – 6th week: primitive gonads form
• 7th – 8th week: gonads become testes with Y
chromosome and the SRY gene
• In the 4th week, the cardiovascular system is
functioning; the eyes, ears, nose, and mouth start to
form
• At 5 weeks, the arm and leg buds appear and the
primitive heart is now visible
• By the end of the 2nd month, the developing organism
has all the basic organs and body parts of a human
being, and a unisex structure called the indifferent
gonad
• The fetal period-from the 9th week after
conception, the sex organs begin to take
shape
• By the 12th week, the genitals are fully formed
• A sonogram is readable
• By the 12th week, the genitals are fully formed
• A sonogram is readable
• At the end of the 3rd month, the fetus has all its body
parts
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• *22 weeks-signals the age of viability- the ability of the
fetus to live outside of the body
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• During this time, the brain develops new neurons in a
process called neurogenesis and new connections
between them in a process called synaptogenesis
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• Weight gain during the final 3 months is 41/2 pounds
• The neurological, respiratory, and cardiovascular
systems mature dramatically; brain growth is so
extensive that the brain’s cortex must fold into layers in
order to fit into the skull
Stages of conception
Variables that may affect the fetus…
• Teratology is the study of birth defects; teratogens include
such substance as viruses, drugs, chemicals, stressors, and
environmental hazards that can impair developmental and
lead to birth defects and even death
• The critical periods are times when the body is most
susceptible to teratogenic damage
• For behavioral teratogens that affect the brain and nervous
system, the entire prenatal period is critical
• For some teratogens, the threshold effect is imperative;
this means that the substance is not harmful until the
chemical reaches a certain level
• The interaction effect of teratogens occurs when one
teratogen intensifies the impact of the other
• Zygotes that are formed from abnormal or fragile gametes
may not duplicate, divide, or differentiate
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• * the variable that most often correlates with
chromosomal abnormalities is the mother’s age
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• The most common of the extra-chromosome syndrome is
Down Syndrome (trisomy 21)
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• Persons with Down Syndrome exhibit distinguishing
features of the slanted eyes, rounded face, and a thick
tongue
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• the extra chromosome at site 21 also makes them more
susceptible to heart defects, slow intellectual development,
and by middle age Alzheimer’s disease it’s inherited
• *people with this syndrome age faster than other adults
Baby is born!
What are reflexes?
• Reflexes are involuntary responses to stimuli
• What are some examples of reflexes?
• Rooting, Babinski, stepping
• The infant is born around the 38 week of pregnancy (9 ½ months)
• Newborns are born with survival reflexes that prepare them for
their new world
• Tonic neck reflex
• When the baby is laid on its back, baby turns its head and extends
arms to same side, helps develop eye/hand coordination
• Moro reflex
• When baby is dropped or hears a loud noise, baby extends arms
and legs and quickly brings them in as if trying to grasp something
• Withdrawal reflex
• When a soft pinprick is applied to baby, the sole of baby’s foot,
baby flexes the leg, helps protect the infant from harmful stimuli
Motor Development
First, infants begin to roll over. Next, they sit
unsupported, crawl, and finally walk.
Experience has little effect on this sequence.
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Baby Preferences
• The infant is born with an acute auditory
sense? Why do you think this is?
• Newborns have a preference for human faces,
which human face do you think newborns
prefer most?
• Newborns have a preference for the smell of
their mother’s milk
• Newborns have a preference for sweet tastes
Habituation
• One way we learn about the cognitive
development of babies is by measuring their
behavior in response …sucking responses
• Another approach to understanding cognitive
development is by observing the behavior of
infants is through the use of habituation
technique
• Habituation refers to the decreased
responsiveness toward a stimulus after it has
been presented numerous times in succession
• Organisms, including infants, tend to be more
interested in things the first few times they
experience them and become less interested in
them with more frequent exposure
Maturation and Infant Memory
Developmental psychologists
have used habituation to help
them understand what babies
remember and understand
Although they may not
consciously remember, babies
are capable of learning.
3-month-old infants can learn
to move a mobile by kicking.
(Rovee - Collier, 1989, 1997.)
Remember the habituation
procedure
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Infant Brain Development
• The newborn’s brain contains more neurons than it will ever
need, 70 % are located in the cortex
• In the womb, the brain forms nerve cells at one quarter mil/m
• Each neuron consists of a single axon and many dendrites
• The dendrites show an estimated fivefold increase in density
within the cortex from birth until age 2
• Transient exuberance is a an increase in neural connections
over the first two years have been called (use it or lose it)
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• If too many stress hormones are produced early on, cortisol is
released and the developing brain becomes incapable of
normal stress responses
• From age 3-6, the most rapid growth is in the frontal lobes
• The developing brain enables physical coordination
How the brain develops
Cognitive Development
Cognition refers to all the
mental activities associated
with thinking, knowing,
remembering, and
communicating.
Developmental
psychologist Jean Piaget
believed that children
reason differently than
adults and that a child’s
mind develops in a series of
stages.
Jean Piaget (1896–1980)
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Schemas
Piaget felt that the driving force behind our intellectual
progression is an unceasing struggle to make sense of
our experiences and that to do this maturing brains
build schemas.
Schemas are concepts or frameworks that
organize and interpret information.
To use our schemas Piaget proposed that we assimilate
new experiences, or interpret them according to our
schemas and then adjust or accommodate our schemas
accordingly.
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• Theory-theory is the idea that children attempt to
construct theories to explain everything they see and hear
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• As preschoolers develop informal theories that attempt to
answer basic question about mental process-thoughts,
emotions, beliefs, motives, and intentions-they acquire a
theory of mind
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• By age 4, young children come to realize that mental
phenomena may not reflect reality and that people can
deliberately deceived or fooled
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• Theory of mind is strengthened by a combination of factors,
including maturation of the brain’s prefrontal cortex
• Schemas- our understanding of the world
Egocentrism
Piaget concluded that preschool children are
egocentric. They cannot perceive things from
another’s point of view.
When asked to show her picture to mommy, 2-yearold Gabriella holds the picture facing her own eyes,
believing that her mother can see it through her
eyes.
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Preoperational Stage
Piaget suggested that from 2 years old to about 6-7 years old,
children are in the preoperational stage—too young to
perform mental operations. For example, in this stage do not
understand the concept of conservation, the principle that
quantity remains the same despite changes in shape.
This preoperational child does not yet understand the principle of conservation of
substance. Video…
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