Infancy: Physical Development Chapter 4: Infancy: Physical Development

Infant Physical Development: Cephalocaudal Proximodistal Differentiation

Cephalocaudal Development: Growth is more rapid in infancy than in any other period after birth. Growth proceeds from the upper part of the head to the lower parts of the body, called: Cephalocaudal An infant has a strong, well coordinated suck but uncontrolled spindly legs. Control of head, before control of arms; sit before crawling or walking. The lower parts of the body must do more growing to reach adult size (cause they get a later start than the head)

Proximodistal Development: Growth also proceeds from the trunk outward, called: Proximodistal Infants gain control over their trunk and shoulders before they can gain control over their arms, hands, fingers. (and upper hips/legs before feet/toes)

Changes in Body Proportions Due to Growth:

Differentiation: As children mature, their physical reactions become less global and more specific. Read pg. 68

Growth Patterns in Height & Weight: Infants double birth weight in: 5 months Infants triple birth weight in:12 months Growth in spurts (95% of the time they are not growing at all! So…….when someone says “he just grew overnight” they are likely correct!) Boys generally reach ½ their adult height by their 2nd birthday, girls by 18 months. Growth in spurts: Read pg. 69

Catch Up Growth: If a child’s growth is slowed due to illness or malnutrition and they finally start to eat again, their rate of growth frequently accelerates to their genetically determined pattern of growth, called: Canalization

Infant Nutrition: Either breast milk or formula up to 1st year & beyond Solid food by 4-6 months Finger foods by end of a year Cow milk by 9-12 months. No peanut butter until after 2nd year No honey or corn syrup until after 1st year. Solids closer to 6 months reduces allergies

Breast Feeding: 70% of women breast feed. 2:5 continue after 6 mo, 1:5 breastfeed longer than 1 year. Has health benefits for mom: lowers risk of breast CA, builds bone strength, helps shrink uterus after delivery. Can transmit HIV and other diseases Can be difficult! Supplement with formula so partner can be part of the feedings.

What are the Benefits of Breast Feeding? Child ill less often (stronger immune system) As infant matures, milk composition changes to meet the infants needs. Less prone diarrhea, constipation & stomachaches. Make easier transition to solid food Higher IQ Resistance to allergies and asthma Reduction in incidence of obesity Reduction in the risk of SIDS

Know! Breast fed and bottle fed babies are similar in physical and psychological development in industrial countries. (not so for developing nations, where bottle feeding is disastrous; because of contaminated water, weaker formula, etc.)

Figure 4.2: Anatomy of a Neuron. “Messages” enter neurons through dendrites, are transmitted along the axon, and sent through axon terminals to muscles, glands, and other neurons. Terminal button=Axon terminal

Development of Brain and Nervous System: An infant is born with nearly 100 billion neurons All the neurons we will ever have we are born with. Myelin develops on the axon of the neuron as a child matures As myelin progresses connections between neurons thicken. Neurons develop by proliferation of dendrites and terminal buttons, and through myelination. There is a link to what the infant can do, and myelinization. Myelinization starts last months of pg and continues to the 2nd year. (some myelinzation happens until adolescence)

Growth Spurts of the Brain: 1st Spurt: Between 4-5 month of prentatal development (due to formation of neurons) 2nd Spurt: 25th wk of prenatal development to 2 years old (due to proliferation of dendrites and terminal buttons)

What is Selective Pruning? As the baby grows, the neurons “prune” called Selective Pruning (use it or lose it!) Neurons that are seldom stimulated are pruned. Read study on pg. 75 Birth 7 yrs 15 yrs

Motor Skill Development: What are motor skills? The activity of the muscles which leads to changes in posture, movement, and the coordination of movement with the senses. Motor Skills Consist of: Lifting/holding the torso and head. Control of the hands Locomotion

1. Lifting/Holding the Torso and Head: Is adaptive in that it prevents suffocation. 1 month: Infants can raise their heads 2 mo: Infant lifts their chest while lying on their stomach 3-6 mo: Infants can hold their head up themselves (with no support)

2. Control of Hands: Reflexive at first, then at 4-6 months infants grasp objects successfully a. Ulnar: (4-6 mo) Holding objects clumsily between their fingers and their palm. b. Pincer: (9-12 mo) Using the thumb and first finger to pick up tiny objects. 4-6 months can transfer objects from hand to hand. 11 mo hold objects in each hand Stacking blocks: 2 by 15 mo, 3 by 18 mo, and 5 by 24 mo

Watch a Baby Feed Themselves: They can grasp an object well, but have a hard time putting it in their mouth. (Coordination of motor movement develops gradually)

3. Locomotion: Movement from one place to another Infants move their bodies in a sequence of steps (though children often skip steps!) Locomotion Milestones: a. Roll over both ways: 6 mo b. Sit up: 7 mo c. Crawl by: 8-9 mo d. Creeping: about 1 mo after crawling

3. Locomotion, cont. Milestones, cont. e. Standing by 8-9 mo (overlaps with creeping and crawling) f. Walk with support: 8-9 mo g. Pull to stand: 10-11 mo h. Walking by 12-15 mo i. Climb steps, kick ball, walk backward, jump by 2 years

When an Infant Begins to Walk they are Called a: Toddler Toddlers fall frequently because they are bow legged, inexperienced, and top heavy “like a bowling ball on toothpicks”

Know! Maturation (Nature) and Experience (Nurture) play indispensable roles in motor development Read pg. 77 and pg. 78

Sensory/Perceptual Development: Vision 20/50 by 6 mo Peripheral vision like an adult by 6 mo Infants prefer to look at the human face (at first the edges, then the inside)

Depth Perception: Tells us whether objects are near or far. By 6-8 months crawling infants refused to crawl over the “visual cliff” 8 out of 10 infants refused to venture out onto the seemingly unsupported surface. (even with mom’s beckoning on the other side)