SUSS PSY 207 STUDY UNIT 2 (CHAPTER 4.1 and 4.2 Prenatal Development and…
SUSS PSY 207 STUDY UNIT 2
CHAPTER 4.1 and 4.2 Prenatal Development
Events of the prenatal period can have
on the individual’s physical health and mental development.
The developing organs are particularly
sensitive to damage
at the time when the specific organ is undergoing rapid development.
2. The Embryonic Period
Occurs from 3rd - 8th week.
occurs. It is a process in which every major organ takes shape, in at least a primitive form, develops. Such developments include:
The heart is beating four weeks after conception.
Primitive nervous system emerges during the 2nd month.
Sexual differentiation begins during the 7th and 8th weeks.
differentiates into different layers:
development includes the
membrane which would progress to form the placenta. A
is also formed to protect the developing child from harmful substances in the mother’s bloodstream.
of the blastocyst give rise to other cell structure which would develop into
3. The Fetal Period
Last from week 9 to birth
In the 3rd month, distinguishable external sex organs appear, and bones and muscles develop; fetus begins to move.
Between the 10th and 20th week,
(the rapid proliferation of neurons) occur; neurons then engage in
to form specialised functioning units e.g. into visual or auditory neurons.
Age of viability
is about 23 weeks after conception; at this age, the fetus has a chance of surviving outside the womb.
1. The Germinal Period
Occurs in the first 2 weeks
The zygote divides multiple times
, forming the
At the end of week 1, the blastocyst implants into the uterus wall.
Teratogens and the Mother's state
A teratogen is any disease, drug, or another environmental agent that can harm a developing fetus
Teratogens: Factors to consider
Dosage and duration.
The greater the level of exposure and the longer the exposure to a teratogen, the more likely it is that serious damage will occur
Susceptibility to harm is influenced by the genetic makeup of the unborn child as well as the mother’s genotype. Some fetuses are more (or less) resistant to teratogens and some mothers are more (or less) able to detoxify teratogens.
. The effects of a teratogenic agent are worst during the critical period when an organ system grows most rapidly
The effects of a teratogen depend on the quality of both the prenatal and the postnatal environments.
Types of teratogens
Thalidomide is a drug used widely in the late 1950s to relieve morning sickness
had specific effects on development
, depending on which structures were developing when the drug was taken.
Taking thalidomide during the first two months of pregnancy resulted in
stunted limbs or deformed sense organs
in the unborn baby.
If the mother waited until 35 or 36 days after conception before using thalidomide, her baby was usually not affected.
restricts blood flow
to the fetus and increases the risk of a miscarriage, premature birth, and low birth weight.
Babies of smokers are also more susceptible to
respiratory, cognitive and conduct problems
Heavier smoking also raises the risk of
sudden infant death syndrome (SIDS)
, in which a sleeping baby suddenly stops breathing and dies.
Alcohol readily crosses the placental barrier and disrupts neural development.
The most severe effect of alcohol is a cluster of symptoms called
Fetal alcohol syndrome (FAS)
, which causes damage to the central nervous system, resulting in:
Low IQ scores (many are mentally retarded)
Hyperactive behaviour and attention deficits.
Mental health problems later in life
Distinct facial abnormalities
Diseases and Infections
can lead to blindness, deafness, heart defects and mental retardation. It is m
ost dangerous during the first trimester
when the ears, eyes, heart and brain are rapidly taking form.
Sexually transmitted infections such as HIV simplex and syphilis can cause damage to the eyes and brain.
HIV-infected mothers can transmit the virus to their babies
(1) prenatally, if the virus passes through the placenta;
(2) perinatally, when blood may be exchanged between mother and child as the umbilical cord separates from the placenta; or
(3) postnatally, if the virus is transmitted during breast-feeding
from X-rays and cancer treatments can cause
, spontaneous abortions and various
Prenatal exposure to heavy metals (e.g. lead) is linked to premature birth, low birth weight, and impaired intellectual functioning.
Prenatal exposure to other pollutants such as polychlorinated biphenyls (PCBs) are also associated with poor reflexes in infancy and later learning difficulties.
The Mother’s State
Factors that affect the quality of the prenatal environment:
Mother's emotional condition
Mother's nutritional condition
Chronic maternal stress can result in premature birth or stunted prenatal growth, leading to low birth weight.
Acute maternal stress during the first trimester is linked to an increased likelihood of
Maternal depression during pregnancy may
contribute to motor delays in new-borns
Maternal malnutrition affects prenatal development differentially,
depending on when it occurs.
Malnutrition in the 1st trimester can disrupt the formation of the spinal cord, resulting in fewer brain cells or causing stillbirth.
Malnutrition in the 3rd trimester results in smaller neurons, a smaller brain, and a physically smaller child.
Typical and safest age range for pregnancy is from about age 20 to 40 years.
Young mothers (19 years of age or younger) have higher rates of birth complications such as premature deliveries and stillbirths.
Older women have increased risk of miscarriage, stillbirth and low birth weight babies.
CHAPTER 3.3 and 3.5: Genes, Environment,
Studying Genetic and Environmental Influences
It is the scientific study of the extent to which
genetic and environmental differences
among people or animals are
responsible for differences
physical and psychological
Presents contributions of both genetic and environmental factors to differences among people.
estimate the heritability
Types of study
Adoption studies examine if children adopted early in life are psychologically similar to their biological parents, whose genes they share, or are they similar to their adoptive parents, whose environment they share.
If adopted children resemble their biological parents, genetics influence is stronger.
of Adoption studies
A criticism of such studies is that the
provided by the biological mother may also influence development.
Family studies are Complex studies involving siblings who have different degrees of genetic similarity – twins, siblings, half-siblings, unrelated step-siblings
Twin study involves determining whether identical twins reared together are more similar to each other in traits of interest than fraternal twins reared together.
More complex twin studies include not only identical and fraternal twin pairs raised together but also identical and fraternal twins raised apart
If genes matter, identical twins should be more similar
of twin studies:
identical twins could be more psychologically similar than fraternal twins, even if they were separated at birth because they
shared a more similar prenatal environment
than fraternal twins did.
Second, the fact that identical twins are often treated more similarly than fraternal twins could explain their greater psychological similarity. More likely,
twins’ similarities result in their being treated similarly
is the proportion of all the
variability in the trait
within a large sample of people that can be
linked to genetic differences
among those individuals.
E.g. To say that measured intelligence is heritable, then, is to say that differences in tested IQ among the individuals studied are to some degree attributable to the different genetic.
Three factors that contribute to differences in individuals:
Shared environmental influences
Non-shared environmental influences
Estimating gene Influences
It is the percentage of pairs studied in which if one member has the characteristic, the other does as well.
e.g. If one of the identical twins develops schizophrenia, what is the likelihood of the other twin also developing schizophrenia?
Researchers also calculate the correlation coefficients for characteristics that can be present in varying degrees
The effects of our genes depend on what kind of environment we experience, and
how we respond to the environment depends on what genes we have.
ways in which a person’s genes and his environment or experiences are interrelated:
Passive gene-environment correlations
Parents provide both genes and home environment
e.g. Extraverted parents not only transmit their “extraverted” genes to their children but also, because they are extroverted, create a highly extraverted home environment—inviting their friends over, taking their children to social gatherings, etc. The combination of “extraverted” genes and an extroverted environment may make their children more extroverted than they would otherwise be
Evocative gene-environment correlations
Individual’s personality evokes reactions from others.
e.g.The smiley, sociable baby is likely to evoke more smiles and social stimulation—and more opportunities to build social skills—than the wary, shy baby.
Active gene-environment correlations
Children’s genotypes influence the kinds of environments they seek.
an e.g. The individual with a genetic predisposition to be extroverted is likely to go to parties, invite friends over, join organizations, collect Facebook friends, etc.
Epigenetic Effects on
Epigenetic effects describe how environmental factors influence the expression of particular genes. factors such as diet, stress, and early parental care leave records, chemical coding on top of certain genes that excite or inhibit gene expression.
The genes themselves are not altered when epigenetic effects occur. Rather, their expression is altered