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PS102 Chapter Notes -Puberty, Preterm Birth, Sex Organ

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Carolan Wood

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Human Development across the Life Span 11/25/2014
Development is the sequence of age-related changes that occur as a person progresses from conception to
Progress before Birth: Prenatal development
Conception occurs when fertilization creates a zygote
Zygote is a one celled organism formed by the union of a sperm and an egg
The prenatal period extends from conception to birth, usually encompassing nine months of pregnancy
The Prenatal period is divided into three phases:
(1) Germinal Stage
is the first stage of the prenatal development, encompassing the first two weeks after conception
begins when the zygote is created through fertilization
within 36 hours, rapid cell division beings and the zygote becomes a microscopic mass of multiplying cells.
The mass of cells slowly migrates along the mother’s fallopian tube to the uterine cavity.
The seventh day the cell mass begins to implant itself in the uterine wall
During the implantation process the placenta begins to form
The placenta is a structure that allows oxygen and nutrients to pass into the fetus from the mother’s
bloodstream, and bodily wastes to pass out to the mother
This is critical exchange- it blocks the passage of blood cells, keeping the fetal and maternal bloodstreams
(2) Embryonic Stage
Is the second stage of prenatal development, lasting from two weeks until the end of the second month
During this stage most of vital organs and bodily systems begin to form in the developing organisms, which
is called the embryo.
Structures such as the heart, spine and brain emerge gradually as cell division becomes more specialized
Arms, legs, hands, feet, fingers, toes, eyes and ears are already discernible
The embryonic stage is a period of great vulnerability because virtually all of the basic physiological
structures are being formed.
Most miscarriages occur during this period and major structural birth defects are also due to problems that
occurs during the embryonic stage
(3) Fetal Stage
is the third stage of prenatal development, lasting from two months through birth
The first two months of the fetal stage begin rapid bodily growth, as muscles and bones begin to form
The developing organism, called the Fetus, becomes capable of physical movements as skeletal structures
Organs formed in the embryonic stage continue to grow and gradually function
Sex organs start to develop during the third month
During the final three months of the prenatal period, brain cells multiply at a brisk pace.
A layer of fat is deposited under the skin to provide insulation, and the respiratory and digestive system
Sometime between 22 weeks and 26 weeks the fetus reaches the age of viability- the age at which a baby
can survive in the event of premature birth
Teratogens are any external agents such as drugs or viruses, that can harm an embryo or fetus
Fetal alcohol syndrome is a collection of congenital (inborn) problems associated with excessive alcohol
use during pregnancy
Motor Development:
Refers to the progression of muscular coordination required for physical activities
Basic Principles:
The cephalocanudal trend- the head-to-foot direction of motor development
Children tend to gain control over the upper part of their bodies before the lower part (learning to crawl)
The proximodistal trend is the centre-outward direction of motor development
Children gain control over their torso before their extremities (reach for things by twisting their entire body,
extending their arms)
Maturation is development that reflects the gradual unfolding of one’s genetic blueprint
Physical changes that come with age- as opposed to experience and learning.
Developmental Norms indicate the median age at which individuals display various behaviors and abilities
Temperament refers to characteristic mood, activity level, and emotional reactivity
Alexander Thomas and Stella Chess conducted a major longitudinal study of the developmental of
In a longitudinal design, investigators observe one group of participants repeatedly over a period of time
In a cross-sectional design, investigators compare groups of participants of differing age at a single point in
Ex. Tracing the growth of children’s vocab with 50 six year olds, 50 eight year olds and 50 ten year olds.
Cohort effects occur when differences between age groups are due to the groups growing up in different
time periods
Early Emotional Development: Attachment
Attachment refers to the close, emotional bonds of affection that develop between infants and their
Six to eight months, they show a preference for the mother and prtest when separated from her
Separation anxiety- emotional distress seen in many infants when they are separated from people with
whom they have formed an attachment
Theories of Attachment
Harlow removed monkeys from their mothers at birth and raised them in the laboratory with two types of
artificial “substitute mothers”
Bowlby argues that there must be a biological basis for attachment
Also asserted that adults are programmed by this behaviour and to respond with warmth, love and