Chapter 4: Physical Development: Body, Brain, and Perception Physical Growth and the Development of Motor Coordination By Kati Tumaneng (for Drs. Cook & Cook)

Physical Growth Average newborn weighs 7.5 lbs. and is 20 inches long. Birth weight doubles by 5 months. Girls reach 50% of adult weight by age 9, boys by age 11. Length increases by 50% in first year. By age 2 have attained more than 50% of adult height. Growth hormone production peaks during sleep. Clinical Growth Charts:

Physical Growth Adolescent Growth Spurt – Increase in growth associated with the onset of puberty. Sparked by sex hormones Occurs at age 12 for females, age 14 for males Girls briefly taller on average than males around ages Spurt lasts longer for males who average 5 inches taller than females by age 18. Puberty (AAP):

Average Body Weight for Girls and Boys ages 2-20 years

Height Curves for Girls and Boys

Sexual Maturation Sex hormones stimulate growth in the reproductive system: Androgens – Released in greater concentration in males. Estrogens – Released in greater concentration by females. As with growth, sexual maturation earlier for girls with menarche (first menstrual period) occurring between ages 12 and 13. Most boys enter puberty 1-2 years later. Over last 100 years, children larger and maturing faster – the secular trend.

Sexual Maturation Psychological Effects For many adolescents, it is a confusing and awkward time. Changing body image. Girls tend to become less satisfied with body. Boys tend to become more satisfied. Early-maturing girls and late-maturing boys often most dissatisfied.

Reflexes: The Infant’s First Coordinated Movements Reflexes – Involuntary movements that are elicited by environmental stimuli. Purposes vary – nourishment, exercise, protection Three classes: Primitive – Help the infant find nourishment or served protective functions during earlier periods of evolution. Postural – Help infants keep their heads upright, maintain balance, and roll their heads in the direction of their body lean. Locomotor – Mimic Locomotor movements such as crawling, walking, and swimming. Begin to disappear as early as 4 months as brain develops more voluntary control.

Voluntary Movements: The Motor Milestones Cephalocaudal pattern – Head-to-toe 1 month – hold head up 3 months – roll over 6 months – sit upright without support 7 months – crawling; stand by holding onto support 12 months – first steps

Voluntary Movements: The Motor Milestones

Proximodistal – Nearer-to-farther (from body’s center) 4-5 months – voluntary control over upper arm; palmer grasp, wrap all 4 fingers and thumb around an object 10 months – more advanced pincer grasp, using thumb opposite forefinger 15 months – can hold a pen; make scribbles using large muscles in upper arms 2-3 years – “tripod” grasp for holding pen 4 years – fine-motor coordination; print a few letters 5 years – more control over printing; write name 6 years – print whole alphabet and numbers to 10

Voluntary Movements: The Motor Milestones

Trends mirror brain development Dynamic systems theory describes motor development in terms of complex interacting forces Neurological development, parental encouragement, cognitive systems, opportunity to exercise, cultural factors all work together to propel development

Nutrition and Eating-Related Problems Healthy diet includes proteins, carbohydrates, fats, and minerals and vitamins. Malnutrition – Nutritional deficiency caused by inadequate intake of calories, protein, vitamins, or minerals. 12 million Americans lived in families that “sometimes” or “often” did not have food or money to buy food. In developing countries, 230 million children under 5 are seriously malnourished. WHO Database of Malnutrition:

Nutrition and Eating-Related Problems

Short- and long-term effects of malnutrition Stunted growth Reduced muscle and body mass in adolescents Female adolescents show delayed menarche Impede fetal growth Babies born with low birth weight, smaller brain size, and impaired mental and motor behavior Lowered intelligence Perform less well in school Into adulthood, suffer physical and intellectual deficits that limit ability to earn a good wage

Nutrition and Eating-Related Problems Obesity – Most frequent nutritional problem in US Percentage of US obese children and adolescents tripled from 1960s to % adults over 20 are obese African American and Hispanic children and teens higher rates of overweight and obesity than Caucasian Americans Rely more on fast foods and processed foods Less physically active Surgeon General Call to Action:

Nutrition and Eating-Related Problems

Eating Disorders – Pressure to be thin high for women and girls. Increasing in males. Anorexia Nervosa – Distorted body image, intense fear of gaining weight, and refusal to maintain a healthy weight. 1 out of 100 female adolescents. Bulimia Nervosa – Binge eating followed by purging, fasting, or excessive exercise. 2-3 out of 100 female adolescents. etr.htm Both are likely caused by a combination of genetic, social, and psychological factors.

Chart on Slide 4: from Cook, J. L., & Cook, G. (2005). Child development: Principles and perspectives (1st ed.) (p. 131). Boston: Allyn and Bacon. Chart on Slide 5: from Cook, J. L., & Cook, G. (2005). Child development: Principles and perspectives (1st ed.) (p. 132). Boston: Allyn and Bacon. Babies on Slide 10: from Cook, J. L., & Cook, G. (2005). Child development: Principles and perspectives (1st ed.) (p. 137). Boston: Allyn and Bacon.

Babies on Slide 12: from Cook, J. L., & Cook, G. (2005). Child development: Principles and perspectives (1st ed.) (p. 139). Boston: Allyn and Bacon. Chart on Slide 15: from Cook, J. L., & Cook, G. (2005). Child development: Principles and perspectives (1st ed.) (p. 142). Boston: Allyn and Bacon. Chart on Slide 18: from Cook, J. L., & Cook, G. (2005). Child development: Principles and perspectives (1st ed.) (p. 142). Boston: Allyn and Bacon. All other images retrieved from Microsoft PowerPoint Clip Art.