Human Development

1

PHYSICAL GROWTH AND AGING ACROSS THE LIFESPAN

Module 1 – Week 3– Ch. 3: Physical Growth and Aging Across the Lifespan

Cephalocaudal (top-down)

Proximodistal (middle-out)

Principles of Growth

Module 1 – Week 3– Ch. 3

2

Hierarchical  Integration

simple skills integrated 

into complex skill sets

Independence  of Systems

different systems  develop at 

different rates

Module 1 – Week 3– Ch. 3

Physical Growth in Infancy

Age Weight Height

Birth 7.5  pounds 

20  inches

5  months

15  pounds

25  inches

12  months

22  pounds

30  inches

2  years

30  pounds

36  inches

Module 1 – Week 3– Ch. 3

3

Preschooler Changes in Body Shape and Structure

2 - 6 years old

Slender and Lengthen

Head – 1/6 of Body

Preschooler fat burns off

Internal physical changes occur

◦ More Muscle

◦ Stronger Bones

Module 1 – Week 3– Ch. 3

Middle Childhood Growth

6 - 11 years old

Slow and Steady 2 – 3 inches / year 5 – 7 pounds / year Girls Taller

Wide variation Nutrition Health Genetics Family Stress

Module 1 – Week 3– Ch. 3

4

Puberty Biological changes during adolescence • Rapid, asynchronous growth

Hormones: estrogen & androgen • Dev. of primary and secondary sex characteristics 

Dramatic physical changes • Adult‐size body • Sexual maturity

Module 1 – Week 3– Ch. 3

Sex Differences in Body Growth

Sex Primary  Characteristics

Secondary  Characteristics

Male Testes, Penis, Scrotum,  Seminal Vesicles, Prostate

Pubic Hair, Body Hair,  Muscular Development, Facial  Hair, Voice,  Shoulders Broaden

Female Ovaries, Fallopian Tubes,  Uterus, Vagina

Pubic Hair, Body Hair,  Muscular Development, Breasts,  Voice, Pelvis Widens

Module 1 – Week 3– Ch. 3

5

Boys Girls

Growth Spurt

Starts at 12 ½ Starts at 10

Proportions Shoulders broaden, Legs lengthen

Hips broaden

Muscle-fat Ratio

Gain more muscle, Aerobic efficiency

Gain more fat

Module 1 – Week 3– Ch. 3

Physical Growth in Early Adulthood

•Physical development and maturation complete

•Peak of physical capabilities

•Senses at peak

•Brain reaches maximum size and weight

•Grey matter continues to be pruned and myelination  increases

Module 1 – Week 3– Ch. 3

6

Physical Transitions in Middle Adulthood

•Gradual changes in body’s capabilities

•Depends in part on self-concept and lifestyle

Module 1 – Week 3– Ch. 3

Physical Transitions in Older People

Primary Aging

• Universal and irreversible changes

Secondary Aging

• Changes due to illness, health habits, or individual differences

• Not due to age itself

• Not inevitable

Module 1 – Week 3– Ch. 3

7

Reflexes

Module 1 – Week 3– Ch. 3

Reflexes: Protective Reactions Reflexes: organized involuntary responses that 

occur automatically in presence of certain stimuli

Module 1 – Week 3– Ch. 3

8

Some Basic Reflexes in Infants (1 of 2)

Reflex Approximate Age of Disappearance

Description Possible Function

Rooting reflex

3 weeks Neonate’s tendency to turn its head toward things that touch its cheek.

Food intake

Stepping reflex

2 months Movement of legs when held upright with feet touching the floor.

Prepares infants for independent locomotion

Swimming reflex

4-6 months Infant’s tendency to paddle and kick in a sort of swimming motion when lying face down in a body of water.

Avoidance of danger

Moro reflex

6 months Activated when support for the neck and head is suddenly removed. The arms of the infant are thrust outward and then appear to grasp onto something.

Similar to primates’ protection from falling

Some Basic Reflexes in Infants (2 of 2)

Reflex Approximate Age of Disappearance

Description Possible Function

Babinski reflex

8 to 12 months An infant fans out its toes in response to a stroke on the outside of its foot.

Unknown

Startle reflex

Remains in different form

An infant, in response to a sudden noise, flings out its arms, arches its back, and spreads its fingers.

Protection

Eye-blink reflex

Remains Rapid shutting and opening of eye on exposure to direct light.

Protection of eye from direct light

Sucking reflex

Remains Infant’s tendency to suck at things that touch its lips.

Food intake

Gag reflex Remains An infant’s reflex to clear its throat. Prevents choking

9

The Growing Brain

•Brain grows faster than any other part of body

•Increase in number of interconnections among cells, which supports more complex communication between neurons, permits rapid growth of cognitive skills

•Amount of protective myelin increases

•Synapptic pruning

Module 1 – Week 3– Ch. 3

Environmental Influences on Brain Development

Relatively great  brain plasticity Relatively great  brain plasticity Sensitive period 

usually occurs early  in development

Sensitive period  usually occurs early  in development

Module 1 – Week 3– Ch. 3

10

MOTOR SKILL DEVELOPMENT

Module 1 – Week 3– Ch. 3

Milestones of Motor Development

50% of children are able to perform each skill at the month indicated. Is knowledge of these averages helpful or harmful to parents?

Module 1 – Week 3– Ch. 3

11

Significant Gross Motor Skills in Early Childhood (3 – 6)

Module 1 – Week 3– Ch. 3

Gross Motor Skills in middle childhood (6 – 12)

Module 1 – Week 3– Ch. 3

12

Fine Motor Skills

PALMAR GRASP @ 3  MONTHS PINCER GRASP @ 8 MONTHS

Module 1 – Week 3– Ch. 3

PERCEPTUAL DEVELOPMENT

Module 1 – Week 3– Ch. 3

13

Learning the World

• Physical stimulation of the sense organs.

Sensation

• Interpreting and analyzing stimuli from  the brain and sense organs. 

Perception

Module 1 – Week 3– Ch. 3

Perceptual Systems

VISUAL

AUDITORY

SMELL & TASTE

TOUCH

Module 1 – Week 3– Ch. 3

14

Infant Vision Visual Acuity Patterns & Colors Depth

(Visual Cliff)

Newborns = 20/200 – 20/600 6 - 12 months = 20/20

6 - 12 months3 - 6 months

Module 1 – Week 3– Ch. 3

Smell and Taste

Smell •Well developed at birth •Helps in recognition of mother early in life •Used to distinguish mother's scent (only in breastfed babies); cannot distinguish father on basis of odor

Taste •Have innate sweet tooth •Show facial disgust at bitter taste •Develop preferences based on what mother ate during pregnancy

Module 1 – Week 3– Ch. 3

15

Loss and inhibited perception

•Affects individuals at various

stages of life, to various extents

•Results often lead to challenges

in navigating everyday life

TEST

Module 1 – Week 3– Ch. 3

The Power of Touch

•Touch is one of most highly developed sensory systems in a newborn

•Even youngest infants respond to gentle touches

•Several of the basic reflexes present at birth require touch sensitivity to operate

Module 1 – Week 3– Ch. 3