CHAP 11 and 12

• Adolescence


  Developmental transition between childhood and adulthood entailing major physical, cognitive, and psychosocial changes
• Adolescence is not a clearly defined physical or biological category - it is a social construction
• In traditional and preindustrial cultures, children generally entered the adult world when they matured physically or began a vocational apprenticeship
• In the Western world, adolescence was first recognized as a unique period in the life span in the twentieth century
• Adolescence lasts longer and is less clear-cut than in the past due to earlier puberty and increased training required for higher-paying occupations
• Adolescence


  • Offers opportunities for growth in cognitive and social competence, autonomy, self-esteem, and intimacy
  • Also a time of risk including death from accidents, homicide, and suicide
• Adolescents in the US today are less likely to engage in risky behaviors compared to the past
• Puberty


  Process by which a person attains sexual maturity and the ability to reproduce
• Hormonal changes that initiate puberty

  1. Hypothalamus releases GnRH

  2. GnRH triggers rise in LH and FSH

  3. LH and FSH exert different effects in boys and girls
• Adrenarche


  Stage of puberty between ages 6-8 where adrenal glands secrete increasing levels of androgens like DHEA
• Gonadarche


  Stage of puberty marked by maturing of sex organs and increased sex hormone production
• Puberty typically begins at age 8 in girls and 9 in boys, but has a wide range of normal ages
• Puberty takes about 3-4 years to complete in both sexes
• Primary sex characteristics


  Organs directly related to reproduction, which enlarge and mature during adolescence
• Secondary sex characteristics


  Physiological signs of sexual maturation (such as breast development and growth of body hair) that do not involve the sex organs
• Sequence of pubertal changes

  1. First external signs are breast tissue and pubic hair in girls, enlargement of testes in boys

  2. Pubic hair becomes coarser and darker

  3. Voice deepens, especially in boys

  4. Skin becomes coarser and oilier, leading to acne
• Adolescent growth spurt


  Sharp increase in height and weight that precedes sexual maturity
• Girls' growth spurt typically occurs 2 years earlier than boys, so girls 11-13 are taller, heavier, and stronger than boys the same age
• Girls typically reach full height at 15, boys at 17
• Spermarche


  First ejaculation, or production of sperm, in boys
• Menarche


  First menstruation, a sign of sexual maturity in girls
• The average age of menarche in US girls has fallen from over 14 years before 1900 to the current 12.8 years
• Black girls experience menarche 6 months earlier on average than white girls
• Secular trend


  A trend that spans several generations, such as earlier puberty and increased adult height and weight
• The secular trend in earlier puberty may be associated with a compensatory delay in full pubertal maturation
• Factors influencing the pace of pubertal development

  • Higher standard of living
  • Better nutrition and health care
  • Reaching a critical body weight
• There may be a compensatory delay in pubertal maturation that is associated with earlier puberty. In other words, children may be starting puberty earlier but spending more time to reach full sexual maturity
• Factors that influence the pace of pubertal development

  • Higher standard of living
  • Undernutrition (insufficient food supply or disease)
  • Being healthier, better nourished, and better cared for
• The average age of sexual maturity is earlier in developed countries than in developing countries
• Spermarche


  Boy's first ejaculation
• Menarche


  Girl's first menstruation
• Most girls experience a growth spurt 2 years earlier than most boys, so between ages 11 and 13 girls tend to be taller, heavier, and stronger than boys the same age
• Secular trend


  Trend that can be seen only by observing several generations, such as the trend toward earlier attainment of adult height and sexual maturity, which began a century ago in some countries
• A contributing factor in the United States during the last part of the twentieth century may have been the increase in obesity among young girls
• Girls with a higher percentage of body fat in early childhood and those who experience unusual weight gain between ages 5 and 9 tend to show earlier pubertal development
• Leptin


  A hormone associated with obesity that may be the link between body fat and earlier puberty in girls
• Leptin may play a permissive role for puberty to start, meaning it needs to be present in sufficient amounts for puberty to occur, but leptin alone does not initiate puberty
• Having a high body mass index in childhood or being obese appears to delay puberty in boys rather than accelerate it, though being overweight rather than either thin or obese results in an earlier start to puberty in boys
• Exposure to endocrine-disrupting chemicals, such as those found in some plastics, flame retardants, and pesticides, appears to be related to earlier pubertal timing
• Earlier menarche is associated with maternal smoking during pregnancy