PSYC 1010 Lecture Notes - Lecture 9: Fetal Alcohol Spectrum Disorder, Prenatal Development, Preterm Birth

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4 Mar 2015
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PSYCH 1010: Chapter 11 – By: Shayan
HUMAN DEVELOPMENT ACROSS THE LIFE SPAN
-Two themes that permeate the study of human development: transition and
continuity
-Craig Keilburger founded Free the kids at age 12, was nominated for Nobel
peace Prize in his teens
-Recently the age of retiring has been challenged – 65 too old?
-Development: the sequence of age-related changes that occur as a person
progresses from conception to death
Includes both biological and behavioural changes
-Divide lifespan into four broad aspects:
1) Prenatal periods between conception and birth
2) Childhood
3) Adolescence
4) Adulthood
PROGRESS BEFORE BIRTH: PRENATAL DEVELOPMENT
-Development begins with conception
-Conception occurs when fertilization creates a zygote: one-celled organism
formed by union of sperm and egg
-Each of your cells contains enduring messages from your parents carried on the
chromosomes that lie within the nucleus
-Each chromosome houses genes: functional units in hereditary transmission,
carry the details of your hereditary blueprints
-Prenatal period: extends from conception to birth, usually encompassing nine
months of pregnancy
-Development during pregnancy very rapid
-If you always developed this fast, but your first birthday you would weigh almost
100kg
-Rapid rate tapes off dramatically in few weeks before you’re born
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THE COURSE OF PRENATAL DEVELOPMENT
-Divided into three phases:
1) Germinal stage (first two weeks)
2) Embryonic stage (two weeks to two months)
3) Fetal stage (two months to birth)
Germinal Stage
-Germinal stage: first phase of prenatal development, encompassing first two
weeks after conception
-Begins when a zygote is created through fertilization
-Within 36 hours, rapid cell division begins and zygote becomes microscopic
mass of multiplying cells
-Mass of cells slowly migrates along mothers fallopian tube to uterine cavity
-On about the 7th day, cell mass begins to implant itself into uterine wall (process
takes about a week)
-Many zygotes get rejected
-During implantation, placenta begins to form
-Placenta: structure that slows oxygen and nutrients to pass into fetus from
mother’s blood stream, bodily wastes pass out to the mother from here, blocks
the passage of blood cells keep both blood streams separate
Embryonic Stage
-Embryonic stage: second stage of prenatal development, lasting from two weeks
until end of the second month
-Most ital. organs and bodily systems begin to form in developing organism – now
called embryo
-Structures like heart, spine, brain emerge gradually as cell division becomes
more specialized
-Arms, legs, hands, feet, fingers, toes, eyes, ears already noticeable
-Period of great vulnerability as everything is developing, if anything interferes it’s
a problem
-Most miscarriages occur in this period
-Most major structural birth defects also due to problem occurring in this stage
Fetal Stage
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-Fetal stage: third stage of prenatal development, lasting from two months to birth
-First two months bring rapid bodily growth – muscles and bones begin to form
-Body now called fetus
-Fetus becomes capable of physical movements as skeletal structures harden
-Organs formed in embryonic stage continue to grow and gradually begin to
function
-Sex organs start to develop during third month
-During final three months, brain cells multiply at brisk pace
-Layer of fat deposited under skin to provide insulation, and respiratory and
digestive system mature
-Between 22-26 weeks fetus reaches age of viability: age at which baby can
survive in the event of premature birth (23 weeks only have 10-20% chance of
survival)
-75% survival rate at 26 weeks
ENVIRONMENTAL FACTORS AND PRENATAL DEVELOPMENT
-Everything mother does can affect fetus because of linked placenta
-Teratogens: external agents, such as drugs or viruses, that can harm embryo or
fetus
Maternal Drug Use
-Marijuana, tobacco, as well as prescription drugs
-All “recreational” drugs can be harmful, with sedatives, narcotics, cocaine being
especially harmful
-Babies of heroin users born addicted to narcotics and have increased risk of
early death due to prematurity, birth defects, respiratory difficulties, and problems
associated with their addiction
-Prenatal exposure to cocaine associated with increased risk of birth
complications and variety of cognitive deficits that are apparent in childhood
-Prenatal marijuana exposure shown to be linked to disturbances in executive
functioning associated with prefrontal part of brain at age 3
-Causes disturbances in attention/impulsivity and problem-solving areas
-Impact of prescribed drugs on embryo or fetus varies greatly depending on drug,
dose, phase of prenatal development
-Alcohol consumption also shows many risks
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