Kathleen Stassen Berger Prepared by Madeleine Lacefield Tattoon, M.A. 1 Part V Adolescence: Biosocial Development Chapter Fourteen Puberty Begins The Transformation of Puberty Possible Problems

2 Adolescence: Biosocial Development …the body changes of early adolescence rival those of infancy in speed and drama…the difference however is that adolescents are aware…

3 Puberty Begins Puberty –the time between the first onrush of hormones and full adult physical development… puberty usually last three to five years… many more years are required to achieve psychosocial maturity

4 Puberty Begins Puberty –menarche a girl’s first menstrual period, signaling that she has begun ovulation. Pregnancy is biologically possible, but ovulation and menstruation are often irregular for years after menarche –spermarche a boy’s first ejaculation of sperm. Erections can occur as early as infancy, but ejaculation signals sperm production. Spermache occurs during sleep (in a “wet dream”) or via direct stimulation

5 Puberty Begins Hormones –organic chemical substances that are produced by one body tissue and conveyed via the bloodstream to another to affect some physiological function. Various hormones influence thoughts, urges, emotions, and behavior

6 Puberty Begins –pituitary a gland that, in response to a signal from the hypothalamus, produces many hormones, including those that regulate growth and control other glands, among them the adrenal and sex glands –adrenal glands two glands, located above the kidneys, that produce hormones (including the “stress hormones” epinephrine [adrenaline] and norepinephrine) –HPA axis (leads from brain to body to behavior) the hypothalamus-pituitary-adrenal axis, a route followed by many kinds of hormones to trigger the changes of puberty and to regulate stress, growth, sleep, appetite, sexual excitement, and various other bodily changes

7 Puberty Begins Sex Hormones –gonads paired sex glands (ovaries in females, testicles in males) that produce hormones and gametes –estradiol a sex hormone, considered the chief estrogen. Females produce more estradiol than males do –testosterone a sex hormone, the best known of the androgens (male hormones); secreted in far greater amounts by males then by females

8 Puberty Begins Sudden emotions –behaviors that adolescents are best known for are emotional and sexual testosterone at high or accelerating levels stimulates rapid arousal of emotions, especially anger hormonal bursts lead to quick emotional extremes (despair, ecstasy) for many boys, the increase in androgens causes sexual thoughts and a desire to masturbate for many girls, the fluctuating estrogens increase happiness in the middle of the menstrual cycle (at ovulation) and sadness or anger at the end

9 Puberty Begins When will puberty Start? –…the average age of onset varies… the average age is between 11 and 12 but is still considered normal between the ages of 8 and14

10 Puberty Begins Genes –genes on the sex chromosomes markedly affect the onset of puberty –on average girls are about two years ahead of boys in height

11 Puberty Begins Genes –hormonally and sexually girls are ahead by only a few months –influence the timing of puberty in other ways as well

12 Puberty Begins Body Fat –genetic differences are apparent only when every child is well fed –stocky individuals begin puberty before those with thinner builds

13 Puberty Begins Body Fat –in both sexes chronic malnutrition delays puberty –secular trend a term that refers to the earlier and greater growth of children due to improved nutrition and medical care over the last two centuries

14 Puberty Begins Stress –the production of many hormones is directly connected to stressful experience via the HPA axis –affects pubertal hormones by increasing them –puberty tends to arrive earlier if a child’s parents are sick, addicted or divorced, or when the neighbor is violent and impoverished

15 Puberty Begins Too Early, Too Late –no one wants to be early or late, particularly too early for girls and too late for boys –early maturing girls have lower self-esteem, more depression, poorer body image, and boy-friends several years older –often isolated from their on-time-maturing peers, and tend to associate with older adolescents

16 Puberty Begins Too Early, Too Late –cohorts are crucial for boys –early-maturing boys live in stressful urban neighborhoods and are likely to befriend law- breaking, somewhat older boys –ethnic differences in age of puberty can add to ethnic tensions in high school, especially for boys

17 Nutrition …the changes of puberty depend on nutrition, yet many adolescents are deficient in the necessary vitamins or minerals

18 Nutrition Diet Deficiencies –few than ½ of all teenagers consume the recommended daily dose of iron –more girls are anemic due to iron depletion during menstruation –½ of adult bone mass is acquired from age10-20, yet few adolescents consume enough calcium

19 Nutrition Body Image –a person’s idea of how his or her body looks –puberty alters the entire body making it impossible for teenagers to welcome every change –girls diet to become thinner –boys want to look taller and stronger

20 Nutrition Body Image –stressed teenagers eat erratically or ingest drugs hoping to lose weight –Adolescents can give up, becoming lazy and fat instead of strong and thin –12% of U.S. teenagers are overweight –2/3 (62%) of U.S. girls and almost 1/3 of the boys are trying to lose weight according to survey of 14,000 school students (MMWR June 9,2006)

21 The Transformations of Puberty every body part changes during puberty transformation from a child into an adult is traditionally divided in two parts: growth and sexuality the third division is the transformation of the brain

22 The Transformations of Puberty Growing Bigger and Stronger –growth spurt the relatively sudden and rapid physical growth that occurs during puberty… each body part increases size on a schedule; weight usually precedes height, and the limbs precede the torso

23 The Transformations of Puberty Growing Bigger and Stronger –growth proceeds from the extremities to the core fingers and toes lengthen before the hands and feet –the torso is the last body part to grow temporarily big-footed, long-legged, and short-waisted

24 The Transformations of Puberty

25 The Transformations of Puberty Sequence: Weight, Height, Muscles –bones lengthen and harden –children eat more and gain weight –when, where, and how much weight depends on heredity, diet, exercise and gender –girls gain much more fat than boys –by age 17 the average girl has twice as mush as her male classmate

26 The Transformations of Puberty Other body changes –organs grow and become more efficient –lungs triple in weight –adolescents breathe more deeply and slowly –the heart doubles in size and beats more slowly –blood pressure and volume both increase –weight and height increase before the growth of muscles and internal organs

27 The Transformations of Puberty Sexual Maturation –the second set of changes turns boys into men and girls into women

28 The Transformations of Puberty Sexual Body Changes primary sex characteristics –the parts of the body that are directly involved in reproduction, including the vagina, uterus, ovaries, testicles, and penis secondary sex characteristics –physical traits that are not directly involved in reproduction but that indicate sexual maturity, such as a man’s beard and a woman’s breasts

29 The Transformations of Puberty Sexual Activity –fantasizing, flirting, hand-holding, displaying, and touching are all done in particular ways to reflect gender, availability, and culture –hormones trigger thoughts and emotions, but the social context shapes through into enjoyable fantasies, shameful preoccupations, frightening impulses, or actual contact

30 The Transformations of Puberty Brain Development –the limbic system—fear, emotional impulse–matures before the prefrontal cortex (planning ahead, emotional regulation)

31 The Transformations of Puberty Caution Versus Thrills –interdisciplinary research is needed to integrate neurology and psychology –caution is needed, lest “incomplete brain development [becomes] an explanation for just about everything about teens that adults have found perplexing, from sleep patterns to risk taking and mood swings”

32 The Transformations of Puberty Uneven Growth –the immature prefrontal cortex may allow “troublesome adolescent behavior” –adolescents are capable of rational thinking –as in the rest of the teenager’s body, brain growth is uneven

33 The Transformations of Puberty Neurological Advances –with increased myelinaton, reactions become lightening fast –pruning occurs, and the dopamine system– neurotransmitters that bring pleasure–is very active –before these advances are complete–about age 25–new connections between one synapse and another ease acquisition of new ideas, words, memories, values acquired during adolescence are more likely to endure than those learned later, after brain links are more firmly established

34 The Transformations of Puberty Body Rhythms –brain rhythms affect body rhythms –the brain of every living creature responds to natural changes –puberty alters biorhythms –sleep patterns are irregular

35 Possible Problems growth and sexual awakening, emotional intensity and hormonal rushes, all can be quite wonderful maturation can cause problems 20% of young people have one problem or several—while 80% are not bedeviled by problems

36 Possible Problems Sex Too Soon –adolescent sexuality can be problematic puberty occurs at young ages—early sexual experiences correlate with depression and drug use raising a child has become more complex, which means that teenage pregnancy is no longer welcomed or expected sexually transmitted infections are more common and dangerous

37 Possible Problems Teenage Pregnancy –½ as common as it was 20 years ago in the U.S. –abortion rate had also decreased –contraception use is higher and teen intercourse is lower (MMWR, February 4th 2005)

38 Possible Problems Sexual Infections –sexual transmitted infection (STI) a disease spread by sexual contact, including syphilis, gonorrhea, genital herpes, chlamydia, and HIV

39 Possible Problems Protection –regular medical care can prevent and treat STIs –almost every teenager knows that pregnancy and STIs can be prevented –teenagers tend to confuse appearance and reality; well-dressed partners could have STIs

40 Possible Problems Sexual Abuse –child sexual abuse any erotic activity that arouses an adult and excites, shames, or confuses a child, whether or not the victim protests and whether or not genital contact is involved

41 Possible Problems

42 Possible Problems Drug Use and Abuse –innocence is reflected in drug use –few adolescents imagine becoming addicted –worldwide most young people use at last one drug before age 18

43 Possible Problems Variations by Nation, Gender, and Ethnicity –drug use varies from nation to nation –laws and family practices are a part of the reason for these variations –gender differences are apparent for most drugs, with boys having higher rates of use than girls

44 Possible Problems Harm from Drugs –adolescents think adults exaggerate the harm of teen drug use –drugs interfere with healthy eating and digestion –drugs appear to make problems better, which leads to abuse and addition

45 Possible Problems Learning from experience –generational forgetting the idea that each new generation forgets what the previous generation learned about harmful drugs