Physical Development

What are the 3 phases of adolescence? Characteristics of each?

• Phases of adolescence

  • Early (11 or 12-14 years): rapid pubertal changes

  • Middle (14-16 years): puberty nearly complete

  • Late (16-18 years): achieves adult appearance & assumes adult roles

    • Boys (12.5-17.5): shoulder broaden, longer legs, gain more muscle, aerobic efficiency

      • Body growth complete by 18 yo

    • Girls (10-16): hips broaden, gain more fat

      • Body growth complete by 16 yo

What is the biological sequence of puberty?

Puberty begins with changes in the primary sexual characteristics—maturation of the reproductive organs (such as testicular enlargement in boys and ovarian activation in girls). This is followed by the appearance of secondary sexual characteristics like pubic hair, breast development, and voice changes, and then the adolescent growth spurt. Puberty ends when primary characteristics reach full reproductive maturity and secondary characteristics form the adult body shape.

- In Class Notes: 

• Growth spurt

  • First outward sign of puberty (12.5 for boys, 10 for girls) also considered onset of puberty 

  • Fastest physical growth since infancy and toddlerhood (children can double their body weight)

  • At its peak, children can grow 3-4 inches and gain 20 lbs per year

• Sexual maturation

  • Primary sex characteristics

    • Characteristics of the reproductive organs that allow for reproduction

  • Secondary sex characteristics

    • Body odor

    • Underarm and pubic hair

    • Breast growth in females

    • Voice deepening and facial hair in males

What are influences on the timing of puberty?

• There are individual differences in the timing of puberty. Why?

  • Heredity (genetic predisposition contributes substantially to timing of puberty)

  • Nutrition

  • Environmental 

    • Malnourishment and dangerous environment can suppress onset of puberty

What does correlational research tell us about whether early or late maturation is ‘good’ for girls and boys?

• Early maturing boys tend to be viewed as popular and well- adjusted, early maturing girls as unpopular. 

• However, adolescents of both sexes who reach puberty early report more psychological stress and depressed mood than their on-time and late- maturing peers. 

• They are also prone to deviant behavior, especially when exposed to other stressors.

• Early- maturing girls and late- maturing boys fit in least well physically with their peers. 

• For girls, the adjustment problems accompanying early pubertal timing are likely to persist into early adulthood.

What is the secular trend in menarche in industrialized countries?

• The average age of menarche declined steadily from 1900–1970 (about 3–4 months earlier per decade) due to better nutrition, health care, sanitation, and disease control.

• Since 1970, the trend has leveled off or slightly reversed in most industrialized nations, but rising obesity in the U.S. and some European countries has caused a modest continued shift toward earlier menarche.

What are the three main changes that occur in the brain during adolescence? What are the cognitive and social/emotional consequences of these changes?

• 1. Synaptic pruning increases
  – Thinking becomes faster & more efficient
  – Better planning and reasoning
  – Still inconsistent self-regulation under stress/peer pressure

• 2. Myelination increases
  – Faster communication between brain regions
  – Stronger working memory & executive function
  – Gradual improvement in impulse control

• 3. Dual processing theory

  • (know this) Connections between prefrontal lobe and hippocampus, the social or affective part of the brain the earlier part of the brain in the amygdala really override cognitive control network bc those areas are more developed than the cognitive control network 

    • That's why there is more risk-taking behavior

  • Changes in brain’s “emotional/social network” (amygdala and ventral striatum) OUTPACE changes in the “cognitive-control network” (frontal cortex)

Describe teenager’s health in general, health risk behavior including risk for injury, sleep habits, nutrition, and STIs/teen pregnancy.

• Sleep Habits in Adolescence 

  • Need 8-10 hrs

  • Sleep “Phase Delay”

    • Biologically, hormones shift sleep patterns 

    • Social habits, irregular sleep times during week 

    • Electronics at night 

  • Consequences 

    • Sleep deprivation 

    • Limits ability to learn, concentrate, problem solve, memory, mood 

    • High risk behaviors

• Health Risk Behavior Increases in Adolescence 

  • Teens engage in risky health behaviors 

  • STI’s & Teen Pregnancy

    • ST infection: 

      • 19 million new infections/year (CDC)

      • 50% ages 15-24 years 

      • 1 in 4 sexually active teens infected every year after accidents, suicides, and homicides are the leading cause of death especially for males 

• Increased Risk & Thrill Seeking 

  • “What were you thinking?”

  • “Thats the problem dad, I wasn’t”

Describe adolescent contraceptive use or no use, and why.

• US Adolescents Reporting Having Sex 

  • Almost 60% of boys 

  • And a little bit less of girls are saying they have had sex at least one time 

  • Only 51% say they used protection last time 

  • 25% use every time