Chapter 5: Physical Growth 1

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• Chapter 5 Physical Growth 1
• Psych 2500
• Lecture 8
• January 31, 2008

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Today

• Quiz 2
• Finish notes from chapter 4
• Physical Growth Part 1
• Course of physical growth
• Brain development
• Factors that influence physical growth

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Growth Curve Distance
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Growth Curve Velocity
Growth Spurts
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Growth Patterns

• Cephalocaudal
• Proximodistal

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Changes in body size

• Birth to age 2
• Growth slows in childhood
• Then a growth spurt occurs in adolescence

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Changes in Body Proportions
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Hormonal Changes in Puberty

• Growth hormone thyroxine increase around ages 8
  to 9

• Estrogens
• More in girls
• Adrenal estrogens
• Androgens
• More in boys
• Testosterone

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Growth change in puberty

• Increased secretion of sex hormones
• Leading to sexual development

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Worldwide Variations in Body Size

• Shortest children
• South America, Asia, Pacific Islands, parts of
  Africa
• Tallest children
• North Central Europe,
• Australia, Canada, U.S.
• Also ethnic variations in growth rate

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Sex Differences in Gross Motor Skills

• Physical
• Childhood small differences
• Adolescence boys develop more strength, speed,
  endurance
• Social
• More athletic pressure on boys
• May lead to more practice

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• What important developments
• occur in the brain?

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Brain Development

• Rate of neural development is amazing in fetal
  period 250,000 new neurons per minute

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Neuron

• Nerve cell that stores transmits neural
  information
• Uses electrical chemical signals
• A single dendrite may have as many as 80,000
  connections

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Role of the environment
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Development of neurons

• Cell production
• Cell migration
• Cell elaboration
• How do our brains become faster more efficient?
• Specialization of the hemispheres

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Regions of the Cerebral Cortex
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Brain Plasticity

• In infants and young children, parts of brain are
  not yet specialized
• Recover better from brain injury
• Older children, even adults,
• have some plasticity

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Sensitive Periods in Brain Development

• Stimulation vital when brain is growing rapidly

• Experience-Expectant Growth
• Experience-Dependent Growth

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Factors That Affect Physical Growth

• Heredity
• Nutrition
• Infectious Disease
• Emotional Well-Being

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Benefits of Breastfeeding

• Disease protection
• Nutritionally complete
• More digestible
• Better jaw and tooth
• development

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Potential Nutrition Problems

• Little focus on eating
• Too few meals with family
• Not enough fruits and vegetables
• Too many fried foods
• and soft drinks
• Poverty and lack of
• nutritional food

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Malnutrition

• Marasmus
• Kwashiorkor

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Causes of Obesity

• Overweight parents
• Early rapid growth or malnutrition
• Low SES

• Family eating habits
• Response to food cues

• Low physical activity
• Television
• Cultural dietary conditions

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TV Viewing Body Fat Gains
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Infectious Disease and Malnutrition

• Poor diet suppresses immune system
• Illness reduces appetite
• Diarrhea a danger
• Oral rehydration
• therapy and zinc
• can help

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Emotion and Well-Being

• Nonorganic failure to thrive
• Psychosocial dwarfism