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Explore the biosocial development of infants in the first two years of life, including body size changes, sleep patterns, brain development, sensory abilities, motor skills, and the impact of stress on the brain.
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The Developing Person Through the Life Span The First Two Years: Biosocial Development
Body Changes Body Size • Average weight: double the birthweight by month 4, triple it by age 1, much of it is fat • Average height: grow 14 inches from birth to age 2 These numbers are norms, an average measurement.
Body Changes Body Size • Head-sparing- biological mechanism that protects the brain when malnutrition disrupts body growth. • The brain is the last part of the body to be damaged by malnutrition. • Percentile- point on a ranking scale of 0 to 100. • 50th percentile is the midpoint with ½ the sample being higher and ½ lower.
Sleep • Average newborn sleeps 16 hours per day • Specifics vary due to age, characteristics, and social environment • Ample sleep correlates with normal brain maturation, learning, emotional regulation, academic success and psychological adjustment
Sleep • REM Sleep: Rapid eye movement sleep, dreaming, rapid brain waves • Slow-wave sleep: quiet sleep, increases at 3-4 months • Co-sleeping: custom of parents and children sleeping close to one or both parents, as opposed to in a separate room, more common in Asia, Africa and Latin America than in Western cultures
Brain Development • Neuron- the billions of nerve cells in the central nervous system. • Cortex- the outer layers of the brain. • Axon-a fiber that extends from a neuron and transmits electrochemical impulses from that neuron to the dendrites of other neurons.
Brain Development • Dendrite-a fiber that extends from a neuron and receives electrochemical impulses transmitted from other neurons via their axons. • Synapse-the intersection between the axon of one neuron and the dendrites of other neurons. • Neurotransmitter- a brain chemical that carries information from the axon of a sending neuron to the dendrites of a receiving neuron.
Transient Exuberance • The great but temporary increase in the number of dendrites in an infant’s brain from birth to age 2 • Enables neurons to connect and communicate with other neurons • This is followed by pruning where unused neurons and misconnected dendrites die
Stress and the Brain • If it (life?) produces too many stress hormones in infants, the brain will not be able to have normal stress responses. • Occurs in infants who are terrified and experience other forms of stress. • Can continue to occur when the infant is an adult • early life stress (ELS) may induce persistent hyper-sensitivity to stressors
Necessary and Possible Experiences Experience-related aspects of brain function: • Experience-expectant: require basic common experiences to develop normally • Experience-dependent: these happen to some infants but not all, not necessary for brain function (i.e. language baby hears)
Brain Development • prefrontal cortex: the area for anticipation, planning, and impulse control • Shaken baby syndrome- a life-threatening injury occurring when an infant is forcefully shaken back and forth, rupturing blood vessels and breaking neural connections . • Self-righting- inborn drive to fix a developmental deficit • All people have self-righting impulses for physical and emotional imbalances.
Sensation and Movement • Sensation- The response of a sensory system (eyes, ears, skin, tongue, nose) when it detects a stimulus. Raw data • Perception- The mental processing of sensory information when the brain interprets a sensation. What you make of the data • Sensory development- typically precedes intellectual and motor development
Sensation and Movement Hearing develops during the last trimester of pregnancy and is already quite acute at birth; the most advancedof the newborn’s senses. Vision is the least mature sense at birth. • Newborns focus only on objects between 4 and 30 inches away. • Binocular vision, the ability to coordinate the two eyes to see one image, appears at 3 months.
Smelling, Tasting, and Touching • Smelling, Tasting, and Touching function at birth and aid the baby’s adaption to the social world • Babies recognize each person’s smell and handling • Infant senses function to help babies join the human family Basic Infant Care differs by culture • Massage important in some cultures
Sensation and Movement • Gross motor skills- Physical abilities involving large body movements, such as walking and jumping. • Fine motor skills- Physical abilities involving small body movements, especially of the hands and fingers, such as drawing and picking up a coin.
Ethnic Variations • Gene differences in different ethnic groups • Cultural patterns of child rearing affect sensation, perception, and motor skills
Surviving in Good Health • About 10 billion babies were born 1950-2010 worldwide • More than 2 billion died before age 5 • Immunization has saved many people • The risks of diseases are far greater than the risk from immunization.
Surviving in Good Health Nutrition • For every infant disease (including SIDS), breast-feeding reduces risk and malnutrition increases it. • Breastfed babies are less likely to develop allergies, asthma, obesity, and heart disease. • As the infant gets older, the composition of breast milk adjusts to the baby’s changing nutritional needs.
Malnutrition • Protein-calorie: when not enough food of any kind is consumed • Stunting: being too short for your age due to severe and chronic malnutrition • Wasting: being very underweight due to malnutrition
Malnutrition • Marasmus: severe malnutrition during infancy where child stops growing, tissues waste away and then usually dies • Kwashiorkor: disease of chronic malnutrition during childhood where child becomes more likely to get other diseases such as measles, diarrhea and influenza