Human Growth and Development

Human Growth andDevelopment Chapter Fourteen Adolescence: Biosocial Development PowerPoints prepared by Cathie Robertson, Grossmont College Revised by Jenni Fauchier, Metropolitan Community College

Puberty Begins Period of rapid physical growth and sexual maturation typically completed three to four years after first visible signs Person attains adult size, shape, and sexual potential

Puberty begins with hormone production in brain hormones from hypothalamus trigger production in pituitary glands in turn this triggers hormone production in adrenal glands and sex glands (gonads) To regulate body functions and changes, many hormones follow this route, the HPA (hypothalamus/pituitary/adrenal) axis Hormones

At puberty, the pituitary gland activates the gonads, or sex glands (ovaries in females, testes in males) One hormone in particular, GnRH, causes increased production of estrogen in females and testosterone in males Hormones, cont.

Direct Effects on Emotions Rapidly increasing hormone levels precede rapid arousal of emotions Hormonal levels correlate with quick shifts in emotional extremes For boys this increase precipitates thoughts about sex and masturbation For girls hormonal changes during menstrual cycle produce mood changes

Indirect Effects on Emotions Hormone levels produce visible signs of sexual maturation, which in turn create expectations of new maturity social responses to biological signs trigger adolescent moods and reactions One’s culture affects thoughts of sex first sexual intercourse occurs at different ages in different cultures

Normally, body changes begin to appear between ages 8 and 14 It’s hard to prepare without knowing what changes will be and when they’ll appear individual may grow a little taller and put on some weight The Timing of Puberty

Sex, Genes, and Weight Girls on average are about two years ahead of boys Menarche and spermarche Timing can be affected by genetics, ethnicity, and body fat individuals with stockier builds experience puberty earlier chronic malnutrition limits fat, thus delaying puberty by several years

Stress in Families Family conflict may cause earlier onset of puberty or irregular periods stress levels affect hormone production stress probably affects hormones causing puberty Stress hypothesis gained support when researchers identified two factors influencing early puberty conflicted relationships with family unrelated man living in the home

Too Early or Too Late Early-maturing girl may be teased and is embarrassed Age of menarche is a strong predictor of age at first intercourse Late-maturing boys may be shunned Early-maturing boys are socially popular and often sports heroes

Too Early or Too Late, cont. • Low self-esteem of off-time maturation lingers • Early-maturing girls become mothers sooner • Late-maturing boys marry later and are less likely to be leaders

Defined as a sudden, uneven, and rather unpredictable jump in the size of almost every part of the body The Growth Spurt

Increase occurs in bone length and density feet and fingers lengthen, then arms and legs, then torso Weight gain becomes rapid Height increase follows Timing: for girls, 10–14; for boys, 12–16 Wider, Taller, Then Stronger

Other Body Changes Organ growth torso grows as internal organs grow lungs triple in weight and size (breathing rate decreases) heart doubles in size (heart rate decreases), total volume of blood increases physical endurance in exercise increases lymphoid system decreases in size hormones may cause changes in oil, sweat, and odor glands of the skin eyes change—may cause nearsightedness

Primary sex characteristics—parts of the body that are directly involved in reproduction: vagina, uterus, testes, penis Primary sex organs grow girls: uterus grows, vaginal lining thickens menarche—first menstrual period boys: testes, penis, scrotal sac enlarge spermarche—first ejaculation of seminal fluid Primary Sex Characteristics

SecondarySexCharacteristics Secondary sex characteristics—body characteristics not directly involved in reproduction but indicating sexual maturity breasts females accumulate fat in both sexes, diameter of areola around nipples increases

hair • voice lowers, especially in males • body hair becomes coarser and darker • new hair growth in armpits and in genital area

Adolescence is generally healthy time Minor childhood illnesses less common; major adult diseases rare Health of adolescents is more likely to be harmed by their own actions Hazards to Health

Need for good, healthy calories is greater due to growth spurt many adolescents become fat and flabby—due not to excess food, but lack of exercise Adolescents generally eat enough but not the right foods snack with friends too much fat, sugar, empty calories; too little calcium Poor Nutrition

Poor Nutrition, cont. • only one in five U.S. high school seniors consumes RDI of five servings of fruits and vegetables • inadequate milk consumption is troubling, as calcium is major contributor to bone growth • one-half adult bone mass acquired during adolescence

Poor Nutrition, cont. • fewer than half of all teenagers consume RDI of iron • females do not get enough iron, while menstrual cycle depletes iron; therefore, may become anemic

Poor Nutrition, cont. • Nutritional deficits sometimes arise from distorted body image • Body Image—person’s concept of how his or her body appears • developing a healthy body image is an integral part of becoming an adult • negative-self appraisal has a major impact on self-esteem

With puberty occurring earlier than it used to in the United States, and marriage later, long period between first sexual urges and marriage More than 25 percent of teens are sexually active by age 14; about one-half active by high school graduation Sex Too Soon

Sexually active teenagers have higher rates of most common STDs—gonorrhea, genital herpes, syphilis, and chlamydia—than any other age group Risk of exposure to HIV virus increases if a person is already infected with other STDs has more than one partner in a year does not use condoms during intercourse Sexually Transmitted Diseases

Younger adolescents within two years of beginning menarche are at increased risk for many complications because their bodies have not matured risks include spontaneous abortion, eclampsia, stillbirth, C-section, low birth weight women who have given birth before age 16 tend to be shorter and sicker as adults and live less long Teenage Pregnancies

Teenage Pregnancies, cont. • Older adolescents are at less physical risk but have their own set of problems • after birth of baby, educational and vocational achievement slowed down • babies have a higher risk of prenatal and birth complications than other babies • problems are linked to culture and cohort

Sexual Abuse Defined as the use of unconsenting person for one’s own sexual pleasure Child sexual abuse—activity that arouses the adult and excites, shames, or confuses a person under age 16 abusers of adolescent girls—usually male relative or friend abusers of adolescent boys—usually male not in family

Drug abuse—ingestion of drug so that it impairs user’s well-being Drug addiction—dependence on a drug or behavior that makes user feel physically or psychologically at ease Drug use—ingestion of a drug regardless of amount or effect Nations differ considerably in use in-laws and culture influence usage religion influences usage Drug Use and Abuse

Link between their occasional use and later drug abuse and addiction repeatedly found characteristics: violence, early sexual activity, and school failure drug use both cause and symptom of adolescent problem The Gateway Drugs

The Gateway Drugs, cont. • Tobacco • decreases food consumption • interferes with absorption of nutrients • reduces fertility • most physically addictive drug of all • Alcohol • more harmful in adolescence • correlates with abnormal brain development

The Gateway Drugs, cont. • Marijuana • seriously slows down thinking processes, especially memory and abstract reasoning • may cause lack of motivation and indifference toward future

Almost every teenager tries one of the gateway drugs by high school graduation, most have tried all three experimentation happening earlier than previously Experimentation and regular use daily use and abuse increases throughout late adolescence Patterns of Adolescent Drug Use

National culture makes a difference In Europe, adolescents show increased drug use adolescent girls in United States as likely to smoke as adolescent boys; in Asia and African few women smoke drug use changes in frequency, composition, mode of delivery, and in form Cultural Differences in Drug Use

Human Growth and Development