Physical Development in Infancy

Neurons

The cells in the nervous system.

Dendrites

Branch-like extensions that receive signals from other neurons and transmit them toward the cell body.

Cell Body (Soma)

The main part of the neuron containing the nucleus, which processes information and maintains cell function.

Nucleus

Located within the soma; contains genetic material.

Axon

A long, tube-like structure that transmits electrical impulses away from the cell body to other neurons or muscles.

Axon terminals

Endings of the axon where signals are transmitted to the next neuron.

Myelin Sheath

A fatty covering around the axon that insulates and speeds up signal transmission.

Synapse

The gap between neurons where neurotransmitters are released to transmit signals to the next neuron.

Neurotransmitters

Chemicals that transmit signals between neurons across synapses.

Dopamine

A neurotransmitter associated with reward, motivation, and movement.

Serotonin

A neurotransmitter associated with mood, sleep, and appetite.

Acetylcholine

A neurotransmitter associated with learning, memory, and muscle action.

GABA

The main inhibitory neurotransmitter, which calms activity.

Glutamate

The main excitatory neurotransmitter.

Synaptogenesis

The formation of new synapses between neurons, starting in early fetal development and continuing throughout life.

Synaptic Pruning

The elimination of weaker, less-used synapses to make neural networks more efficient, peaking during childhood and adolescence.

Phonemic Discrimination

Infants' early ability to perceive and differentiate phonemes from all languages.

Early Sensitivity

Infants are born with the ability to perceive and differentiate phonemes from all languages.

Perceptual Narrowing

By around 6-12 months, infants stop showing sensitivity to phonemes not used in their native language.

Plasticity

The brain's ability to change and adapt in response to experience, greatest during the first years of life.

Experience-Dependent Plasticity

New synapses form in response to unique individual experiences (e.g., learning a new skill or language).

infant brain is highly sensitive to injury

The rapid growth and development of the infant brain make it vulnerable to damage.

shaken baby syndrome

A severe injury that can cause blood vessel damage and ruptures in neural connections in an infant's brain, leading to severe disability or death.

Fontanelle

The soft spot on a baby’s head, an area where the skull bones have not yet fused, allowing for flexibility during birth and brain growth.

REM sleep

Rapid eye movement sleep, which composes about half of total sleep in newborns and declines to about one third by 6 months.

SIDS risk

Increased risk of Sudden Infant Death Syndrome associated with bedsharing due to softer sleep surfaces, pillows, blankets, and risk of accidental overlaying by parents.

Cry It Out (Sleep Training)

A sleep training approach where parents allow their baby to cry to adapt to sleeping without external soothing and promote independent sleep.

DHA

A key fatty acid found in breast milk that is beneficial for infant development.

colostrum

The first form of milk produced by mammary glands immediately following delivery of the newborn; it contains immunoglobulins.

immunoglobulins

Antibodies found in colostrum that provide immune protection to infants.

lipase and other enzymes

Components of breast milk that aid in digestion and nutrient absorption for infants.

Infant formula

A scientifically developed milk substitute that provides essential nutrients for newborns and infants who are not breastfed or are partially breastfed, mimicking breast milk but lacking antibodies.

lacks antibodies

A key difference between infant formula and breast milk, as formula does not provide the immune antibodies found in breast milk.

Malnutrition

Lack of proper nutrients and a balanced diet, which can lead to delayed growth and lower IQ scores later in life.

Undernutrition

A form of malnutrition that can occur even if children are not severely malnourished, involving common deficiencies like fatty acids, iron, calcium, and vitamin D.

WIC (Women, Infants, and Children Program)

A benefit program offering free formula and baby food for infants up to 12 months, food vouchers for pregnant and postpartum mothers, and breastfeeding support.

SNAP (Supplemental Nutrition Assistance Program)

A benefit program providing assistance for food purchases.

Obesity

A condition where weight is greater than 20\% above the average for a given height, in infants.

Gross Motor Skills

Large muscle movements that allow for activities like sitting upright unsupported (by 6months), crawling (by 8-10months), and walking unsupported (by 1year).

Fine Motor Skills

3months-coordinate movement of limbs; 4months-begin reaching; 2years- can drink from a cup without spilling

Pincer grasp

A precise motor control movement involving the thumb to index finger, which improves greatly with age.

Cultural factors influence timing of motor milestones

The specific timing of when infants achieve motor skills can vary significantly across cultures due to different caregiving practices and environmental contexts.

Visual Cliff Test

A test used to assess depth perception and fear of heights in infants.

Face Preference

Infants show preferences for certain facial configurations, suggesting early social processing abilities.

Auditory Perception

The ability to hear and interpret sounds, including sound localization and language discrimination.

Language discrimination

Infants' ability to distinguish their native language from other languages, and their mother’s voice from other women’s voices.