Chapter 5 Infancy: Physical Development

Differentiation

The processes by which behaviors and physical structures become more specialized

Failure to thrive (FTT)

A disorder of impaired growth in infancy and early childhood characterized by failure to gain weight within normal limits

FTT is linked not only to slow physical growth but also to cognitive, behavioral, and emotional problems.

Less likely to be securely attached.

Marasmus: A form of FTT that is characterized by wasting away due to diet low in essential nutrients.

Canalization

The tendency of growth rates to return to genetically determined patterns after undergoing environmentally induced change

Nerves

Bundles of axons from many neurons

Neurons

Nerve cells; cells found in the nervous system that transmit messages like reflexes, the perception of an itch from a mosquito bite. People are born with a 100 million neurons.

Dendrites

The rootlike parts of a neuron that receive impulses from other neurons (from the Greek: dendron, meaning "tree" and referring to the branching appearance of dendrites)

Axon

A long, thin part of a neuron that transmits impulses to other neurons through small branching structures called axon terminals. An axon can be up to several feet long if it is carrying messages from the toes upward.

Neurotransmitter

A chemical substance that enables the transmission of neural impulses from one neuron to another.

Myelin sheath

A fatty, whitish substance that encases and insulates neurons, permitting more rapid transmission of neural impulses

Myelination

The process by which axons are coated with myelin. Myelination of motor pathways allows neonates to show stereotyped reflexes, but otherwise neonates' physical activity tends to be random and badly organized. Myelination of the nerves to muscles is largely developed by the age of 2. Although neonates respond to touch and can see and hear quite

Multiple sclerosis (MS)

A disorder in which myelin is replaced by hard, fibrous tissue that impedes neural transmission

Medulla

An oblong-shaped area of the hindbrain involved in heartbeat and respiration. The medulla is vital in the control of basic functions such as heartbeat and respiration. The medullas is part of an area called the brain stem, which may be implicated in sudden infant death syndrome.

Cerebellum

The part of the hindbrain involved in muscle coordination and balance. Latin for little brain. The cerebellum helps the child maintain balance, control motor behavior and coordinate eye movements with bodily sensations.

Cerebrum

The large mass of the forebrain, which consists of two hemispheres. It makes possible the breadth and depth of human learning, thought, memory, and language. Left and right hemispheres

Ulnar grasp

A method of grasping objects in which the fingers close somewhat clumsily against the palm

Pincer grasp

The use of the opposing thumb to grasp objects between the thumb and other fingers

Locomotion

Movement from one place to another

Toddler

A child who walks with short, uncertain steps. Toddlerhood lasts from about 18-30 months of age, bridging infancy and early childhood

Sensation

The stimulation of sensory organs such as the eyes, ears, and skin and the transmission of sensory information to the brain

Perception

The process by which sensations are organized into a mental map of the world

Perceptual constancy

The tendency to perceive objects as the same even though sensations produced by them may differ when, for example, they differ in position or distance

Size constancy

The tendency to perceive objects as being the same size even though the sizes of their retinal images may differ as a result of distance. Size constancy is present in infancy. By 4-5 months shape constancy seems to be established.

Shape constancy

The tendency to perceive objects as being the same shape even though the shapes of their retinal images may differ when the objects are viewed from different positions

Habituation

A process in which one becomes used to and therefore pays less attention to a repeated stimulus

Physical Development

1. Cephalocaudal Development

Development proceeds from the upper part of the head to the lower parts of the body. The brain regulates essential functions such as heart beat. The head is proportionately larger among younger children.

2. Proximodistal Development

Growth and development also proceed from the trunk outward-from the body's central axis toward the periphery. The brain and spinal cord follow a central axis down through the body, and it is essential that the nerves be in place before the infant can gain control over the arms and legs.

3. Differentiation

As children mature, physical reactions become less global and more specific. This infant engages in diffuse motor activity. Within a few months, he will be grasping for objects and holding onto them with a more and more sophisticated kind of grasp.

Nutrition

From birth be fed breast milk or an iron-fortified infant formula. Solid foods are often introduced at 4-6 months.

Infants should be breast fed throughout the first year and longer if possible.

Birth to 6 months: breast milk or formula. No cow's milk until 1 year old.

4-6 months: solid foods. Most calories will come from breast milk. Introduce infant cereal such as rice or barley or pureed meats.

6-8 months: Pureed or mashed fruit and vegetables. Introduce single-item foods one at a time.

7-10 months: Babies can feed themselves- finger foods, water

8-12 months: soft or cooked table foods

1-2 years: regular table food. Choking is a risk.

Breastfeeding

Natural way to nourish a baby. Promote bonding. Better educated women breast feed. Colostrum is an early form of breast milk that is produced late in pregnancy and following childbirth.

Reduces the risk of early breast cancer and ovarian cancer. It builds the strength of bones.

Breastfeeding has also shown to help mothers respond more calmly to stress.

In order for breast milk to contain the necessary the mother receives the necessary nutrients. One negative is that the mother assumes responsibilities for nighttime feedings.

Brain Development

The brain is the command center of the developing organism. It contains neurons and provides the basis for physical, cognitive, and personal and social development. At birth, the parts of the brain involved in heartbeat and respiration, sleeping and arousal and reflex activity are fairly well myelinated and functional. Myelination of the nerves to muscles is largely developed by the age of 2.

Nervous System

The basic units of the nervous system are neurons. The messages transmitted by neurons account for phenomena as varied as reflexes, the perception of an itch from a mosquito bite. Dendrites are short fibers that extend from the cell body and receive incoming messages from thousands of adjoining transmitting neurons. The axon extends trunkline from the cell body and accounts for much of the difference in length among neurons. Messages are released from axon terminals in the form of chemicals called neurotransmitters. As the child matures, the axons of neurons grow in length, and the dendrites and axon terminals proliferate, creating vast interconnected networks for the transmission of complex messages. Myelination is part of the maturation process that leads to the abilities to crawl and walk during the first year. Infants actually have more connections among neurons than adults do. Connections that are activated by experiences survive.

Motor development

This involves the activity of muscles, leading to changes in posture, movement and coordination of movement with the infant's developing sensory apparatus. Babies can move their head to avoid suffocation . Between 4-6 months infants can grab things. At first it is just a reflex.

Turns from stomach to side.

Turns from stomach to back

Turns from back to stomach

Sits up

Crawls

Creeps-Knees up

Stands up

Starts walking

Full walking

Motor development: Nurture

Nurture determines whether the child will develop skills that reach the upper limits of the range. There may be little purpose in trying to enhance their motor skills. Once children are ready, teaching and practice do make a difference .An athlete needs good training and good genes.

Sensory and Perceptual Development

Development of Visual Acuity: Newborns vision is 20/600. They have dramatic gains in birth to 6 months reaching 20/50. They reach 20/20 at about 3-5 yrs. old.

Peripheral Vision

Neonates cannot perceive visual stimuli that are off to the side by an angle of more than 30 degrees. By 7 weeks: 45 degrees. By 6 months it is about equal with adults.

Visual Preferences

Infants prefer a human face.

Neonates can discriminate their mother's face from a stranger after 8 hours of mother-infant contact.

By 3-5 months infants respond differently to happy, surprised, and sad faces.

By 2 months infant focus on the "what" of things.

Depth Perception

Infants generally respond to cues for depth by the time they are able to crawl 6-8 months. Infants do not usually develop fear of heights until they can move around. Different postures involve the brain in different ways and that infants avoidance of the cliff is connected with their posture.

Hearing

By 18 months of age, the accuracy of their sound localizing ability approaches that of and adult. Infants can discriminate the sounds of their parent's voices by 3 1/2 months. Young infants are capable of perceiving most of the speech sounds present in the world's languages. But after exposure to their native language, infants gradually lose the capacity to discriminate those sounds that are not found in the native tongue.

Perceptual Development

The neonate is neurologically prewired to gather and seek visual information. Children pay progressively more attention to details of objects and people and to make finer and finer discriminations. Attention becomes more selective. Irrelevant information becomes ignored. Children develop from passive, mechanical reactors to the world about them into active, purposeful seekers and organizers of sensory information.

Perceptual Development: Nature

Evidence supports the idea that our inborn sensory capacities play a crucial role in our perceptual development. We do have certain inborn ways of responding to sensory input- certain categories and built in limits that enable us to perceive certain aspects of the world of physical reality. Nature continues to guide the unfolding of the child's physical systems.

Perceptual Development: Nurture.

Children and lower animals have critical periods in their perceptual development. Failure to receive adequate sensory stimulation during these critical periods can result in permanent sensory deficits. Sensory experiences are linked to the very development of neurons in the cortex.