What Have You Learned?

1. Question 14.1

   What are the first visible signs of puberty?

   For girls, the observable changes of puberty usually begin with nipple growth. Soon a few pubic hairs are visible, then peak growth spurt, widening of the hips, the first menstrual period (menarche), full pubic-hair pattern, and breast maturation. For boys, the usual sequence is growth of the testes, initial pubic-hair growth, growth of the penis, first ejaculation of seminal fluid, appearance of facial hair, peak growth spurt, deepening of the voice, and final pubic-hair growth.

2. Question 14.2

   What body parts of a teenage boy or girl are the last to reach full growth?

   Height, weight, and muscle continue to grow until approximately age 20, especially for boys. A final pubic hair pattern in boys and full breast growth in girls are the last to develop.

3. Question 14.3

   How do hormones affect the physical and psychological aspects of puberty?

   In girls, estrogen triggers menarche and may contribute to depression. In boys, androgens produce sperm and trigger spermarche, and, in a small number of boys, may also contribute to the onset of schizophrenia. In both boys and girls, hormones awaken their interest in sex.

4. Question 14.4

   Why do adolescents experience sudden, intense emotions?

   Not only are the brain and the body affected by hormones, but behavior is as well. Surges of emotions and sudden lustful impulses are partly hormonal, but thoughts can cause physiological and neurological processes, as well as result from them. The hormones of puberty make young adolescents more vulnerable to stress, and thus quicker to become angry or upset. Those emotions can increase hormone levels.

5. Question 14.5

   Why is eveningness a particular problem during adolescence?

   Eveningness results in someone being naturally more alert in the evening than in the morning. Exacerbated by the pubescent phase delay, eveningness puts adolescents at high risk for antisocial activities because they are awake when adults are sound asleep. Sleep deprivation can cause insomnia, nightmares, and mood disorders, and falling asleep while driving can also result. School performance is impacted since learning is more difficult for those lacking sleep.

6. Question 14.6

   Why might some high schools decide to adopt later start times?

   A phase delay in the sleep–wake cycles occurs in teens due to the hormones of the HPA axis during puberty. Thus, many teens are drowsy and have difficulty focusing in the morning. Adolescent learning is better in schools that start after 8 a.m.

7. Question 14.7

   What are the gender differences in the growth spurt?

   Girls experience their height growth spurt an average of two years before boys do. Girls’ height growth spurt usually precedes menarche, whereas boys’ height growth spurt usually follows spermarche.

8. Question 14.8

   What are the ethnic and cultural differences in the timing of the changes of puberty?

   According to research, about two-thirds of the variation in age of puberty is genetic, which is evident across cultures. While an entire group may reach puberty sooner or later than North American children, the differences between boys and girls, with girls maturing faster, is evidenced across cultures. Body fat, socioeconomic status, living in an urban environment, and stress all play a role in onset.

9. Question 14.9

   How would society be affected if puberty occurred for everyone a few years later?

   The same processes would occur, only they would be delayed. A resulting benefit would be maturation of the frontal lobes, thereby allowing for more logical thought and control over the limbic system that governs hormones. Perhaps there would be less tumult in the process of puberty.

10. Question 14.10

    Why is early puberty more difficult for girls than for boys?

    Early-maturing girls tend to have lower self-esteem, more depression, and poorer body image than do other girls. Because boys mature on average two years later than girls, they may tease an early-developing girl due to being unnerved by a sexual creature in their midst. Early-maturing girls also have more difficulties with self-image, tend to have older boyfriends, and are more susceptible to drug and alcohol abuse and domestic violence.

11. Question 14.11

    Why is late puberty more difficult for boys than for girls?

    Late developing boys tend to be more anxious, depressed, and afraid of sex. Girls are less attracted to them, and coaches less often want them on their teams.

12. Question 14.12

    What is the pattern of growth in adolescent bodies?

    Growth proceeds from the extremities to the core. Thus, fingers and toes lengthen before hands and feet, hands and feet before arms and legs, arms and legs before the torso. This can cause a teen to be awkward and clumsy. To complicate matters further, growth is not always even.

13. Question 14.13

    What problems result from the growth spurt sequence (weight/height/muscles)?

    Since bones typically grow faster than muscles and internal organs, adolescents are more prone to athletic injuries in adolescence than when they were younger, and can also move with greater awkwardness and clumsiness due to rapid but often uneven growth. Weight lifting can be dangerous because muscles are not mature.

14. Question 14.14

    Why are young adolescents particularly vulnerable to bone fractures?

    Because the height spurt precedes increases in bone mass, young adolescents are vulnerable to bone fractures.

15. Question 14.15

    Why are most adolescents unhappy with their appearance?

    Few teenagers welcome every change puberty causes in their bodies. Instead, they tend to focus on and exaggerate imperfections. Few adolescents are happy with their bodies, partly because almost none look like the bodies portrayed in the media.

16. Question 14.16

    Why would anyone voluntarily starve herself or himself to death?

    People suffering from anorexia nervosa refuse to eat normally because their body image is severely distorted; they may believe they are too fat when actually they are dangerously underweight.

17. Question 14.17

    Why would anyone make herself or himself throw up?

    Individuals with bulimia make themselves vomit after consuming thousands of calories in order to control their weight.

18. Question 14.18

    What problems might occur if adolescents do not get enough iron or calcium?

    Insufficient iron can cause anemia in adolescents, restricting muscle growth and strength. Insufficient calcium can lead to osteoporosis later in life.

19. Question 14.19

    Since adolescents have quicker reflexes and better vision than adults, why are they more likely to die in a motor vehicle accident than from any other cause?

    Because the frontal lobe is still maturing, emotions rule adolescent behavior. They take risks, such as driving fast and texting while they are driving. Thoughtless impulses and poor decisions are almost always to blame when teenagers die in motor-vehicle accidents.

20. Question 14.20

    How might the timing of brain maturation during adolescence create problems?

    The limbic system matures before the prefrontal cortex, thus creating a situation in which impulsivity reigns relatively unchecked by logical thought. Therefore, adolescents take risks that adults would never consider.

21. Question 14.21

    In what ways is adolescent brain functioning better than adult brain functioning?

    1) Faster reaction time; 2) Increased positive emotions; 3) Easier acquisition of new ideas; 4) Enhanced moral development; and 5) Willingness to question tradition and try new things.

22. Question 14.22

    What is the crucial difference between primary sex characteristics and secondary sex characteristics? Give examples of each.

    Primary sex characteristics, such as menarche and spermarche, are changes that enable reproduction. Secondary sex characteristics, such as breast development and facial hair, signal reproductive capability, but are unnecessary for reproduction.

23. Question 14.23

    Why is adolescent sexuality more hazardous now than it was five decades ago?

    Earlier puberty and fewer social taboos mean teens have sexual impulses and experiences at younger ages. Early sex correlates with depression and drug abuse. Most teenage mothers have no husbands to help them. Raising a child has become more complex and expensive, and fewer mothers of teenagers are available to help. Sexually transmitted infections are more common and dangerous.

24. Question 14.24

    Among sexually active people, why do adolescents have more STIs than adults?

    Biologically, teens’ bodies are not as equipped to fend off STIs as adults are, with girls being more susceptible than boys. Fully developed women have some natural biological defenses against STIs. In addition, sexually active teens are hesitant to seek treatment or alert their partners. In cultures or families where teenage sex is forbidden, adolescents avoid treatment for STIs until pain requires it. Adolescents with same-sex partners are especially reluctant to find treatment if their community considers homosexuality shameful.

25. Question 14.25

    What are positive changes in adolescent sexuality over the past five decades?

    Teen births have decreased in every nation. The use of protection has risen. The teen abortion rate is down.

26. Question 14.26

    What are some long-term effects of child sexual abuse?

    A longitudinal study found that abused children grow up to have negative attitudes, regarding sex as dirty, shameful, and dangerous. Although their body weight was in the normal range in childhood, 42 percent were obese in their 20s. Cognitive development—school achievement as well as language use—was also impaired. Among the most troubling results were much higher rates of self-harm, aggression, and repeated victimization—both sexual and physical abuse.