The Role of Heredity
Most traits are polygenic, meaning that they are influenced by multiple genes. We categorize between dominant versus recessive genes.
Genotype verses Phenotype
Genotype- refers to a person's genetic inheritance
Phenotype- refers to observed characteristics or what is expressed, BASED ON BOTH HEREDITY AND ENVIRONMENT
Bronfenbrenner's Ecological Model of Development
(2004) Based on the notion that development involves an interaction between the individual and their context or environment.
He described 5 Environmental Systems (or levels):
Mesosystem - interaction between elements of a child's microsystem that influence development
Critical Periods vs Sensitive Periods
- Critical Periods- specific, predetermined periods of time during biological maturation when an organism is particularly sensitive to certain stimuli that can have either a positive or negative impact on development. - Sensitive Periods- longer in duration and more flexible than "critical periods"; not tied as closely to chronological age or maturation stage IE: attachment, language acquisition
Three stages of Pre-natal Development and their definitions
- Germinal Stage (Wks 0 - 2)
- Embryonic Stage (Wks 3-8)
- Fetal Stage (9 Wks - Birth)
- FETUS REACHES VIABITY between 22 and 26 WEEKS
Describe "normal" human chromosomes
- 46 Chromosomes
- 23 Pair: 22 pair of Autosomes 1 pair of Sex Chromosomes
- XX female XY male
Chromosomal Disorders due to dominant or recessive genes: examples
Huntington's - inheritance of one dominant gene (Dominant Gene Disorder)
PKU- inheritance of a pair of recessive genes (Recessive Gene Disorder)
3 Disorders due to Chromosomal Abnormality and incorrect number of chromosomes (chromosome variability)
Down Syndrome - Extra chromosome #21
Klinefelter Syndrome - Abnormality in sex chromosome; in MALES only- due to presences of 2 or more X chromosomes and a Y chromosome. (Extra X chromosome)
Turner Syndrome - Abnormality in sex chromosome; in FEMALES only; due to presence of a single X chromosome.
Prader-Willi Syndrome and Angelman Syndrome
Caused by chromosomal deletion; causes some level of intellectual disability, obesity, and often OCD behaviors.
Substances that cause birth defects. Especially vulnerable at 3-8 weeks, or during the Prenatal Embrionic Stage EI: Alcohol, Cocaine, Nicotine, Lead,
Effects of teratogens: Exposure to fetal alchohol
May cause Fetal Alcohol Spectrum Disorder (FASD); describing a large range of conditions that are largely irreversible, involving physical, behavioral, and/or cognitive abnormalities. FAS is the most severe form of FASD.
Effects of teratogens: Exposure to Cocaine
When used by pregnant women, increases the risk for spontaneous abortion and stillbirth. Babies born to cocaine users are at high risk for SIDS, seizures, low birth weight, and reduced head circumference. Babies may have a high-pitched cry and an exaggerated startle response, along with sleep and feeding difficulties
Effects of teratogens: Maternal Health Conditions and their effects
- heart defects, blindness, deafness, intellectual disability
- 20-30% chance of passing to child
- LBW, stillbirth, Miscarriage
- misc,arriage, painful labor, premature delivery, baby w/LBW, hyper, irritable, other problems
Complications during birth
Anoxia - prolonged oxygen shortage
-delayed motor and cog development
- intellectual disability
- cerebral pulsy
Rutter's Indicators (risk of psychiatric disturbance - developmental)
(1985)Described by Rutter;
The following 6 Family Risk Factors:
- severe marital discord
- low SES
- overcrowding or large family size
- parental criminality
- maternal psychopathology
- placement of the child outside the home
Impact of early stress on development; what characteristics lead to more positive outcomes according to research?
Research suggests that high-risk babies are less likely to have negative outcomes when the babies experience
- fewer stressors following birth
- have an easy temperament
- marked by a high degree of social responsivity and good communication skills
Most common symptoms of congenital CMV
(Congenital Mom Virus) (herpes strain)
- Some degree of intellectual disability
- Hearing and Vision impairments
(3 correlation proposals)
When children inherit genes that predispose them towards particular traits, and then parents provide a perfect environment that encourages that trait.
When a child's genetic make up evokes reactions from parents and others that reinforce their genetic makeup (cooperative, attentive, smart)
"Potential Range" of reaction for certain traits; and that an individuals ultimate status depends on environmental factors.
- RESTRICT ENVIRONMENTAL INFLUENCE
- Used to describe characteristics in which genotype restricts phenotype to a small number of outcomes.
- A measure of the ability of a genotype to produce the same phenotype regardless of variability of its environment.
Brain growth facts
Brain at 25% of it's adult weight at birth
By age 2, it has reached about 80% of adult weight.
Growth due to increase of connections and formation of glial cells (responsible for myelinization) rather than generation of additional neurons
Cerebral Cortex is almost completely undeveloped, and **[the prefrontal cortex may not be fully developed until the mid-20's]**
Least well-developed at birth: PREFRONTAL CORTEX
How the Aging Brain compensates for atrophy of neurons in adulthood
The brain compensates for atrophy of neurons in adulthood by:
- Forming new synaptic connections
- Creating new neurons in the hippocampus and possibly other areas
Define 2 reflexes present in a newborn
- when the soles of the feet are tickled and toes splay out and up
- flings arms and legs out in response to a loud noise or sudden loss of physical support
What type of visual stimuli do newborns prefer, and when does there visual accuity reach that of an adults's?
- They prefer high-contrast patterns
- At about 6 months their visual acuity is close to an adult's
- Sensitivity to kinetic cues show up first
Describe newborn hearing
- Newborns are only slightly less sensitive to sounds than adults
- Localization is evident in newborns but seems to disappear between 2 and 4 months, only to improve the rest of the first year.
Describe pain in full-term infants who undergo painful medical procedures during infancy
They have been shown to later exhibit heightened responsivity to pain
Describe the average developmental ages of abilities to stand, walk (take steps alone), use the toilet, and exhibit a preference for right or left hand.
- Stand at 9-10 months
- Walk by 12 months
- 50% of 24-month olds use toilet during the day
- By 4 years old most children exhibit a stable preference for right or left hand
When do gender differences in motor development become apparent?
Differences become apparent in middle school, when:
- Girls become superior in terms of flexibility, agility, and balance (FAB)
- Boys become superior in terms of strength and gross motor skills (SMS)
What has research shown to be consequences of early physical maturation in each gender?
- For girls, early maturation is associated with a number of negative consequences, such as low academic achievement, drug and alcohol abuse, and increased risk for developing depression or an eating disorder.
- For boys, early maturation is associated with greater popularity, superior athletic skills, and 3 D's: increased risk of drug and alcohol use, delinquency, and depression.
- LATE ONSET PUBERTY may be more beneficial for females
Changes in sensory and psychomotor function associated with aging: VISION CHANGES in older people
- Presbyopia, an inability to focus on close objects
- loss of visual acuity
- reduced depth and color perception
- increased light sensitivity