Physical Development in Adolescence

1. Physical Developmentin Adolescence

2. Balanced point of view • Adolescence is both biologically and socially determined • The length of adolescence varies among cultures-simpler societies may have shorter adolescence • Societies that require many years of education for successful economic life have greater extended adolescence period.

3. Puberty • Puberty growth is regulated genetically influenced hormonal processes. • Girls on average begin to reach puberty 2 years earlier than boys – girls 10, boys 12 • Current research is indicating that girls may be reaching puberty at earlier rates

4. Hormonal Changes • Growth hormone (GH) and thyroxine contribute to the gains in body size and completion of skeletal maturation • Estrogens are typically thought of as female hormones and androgens as male hormones-both types of hormones are present in each sex • Testosterone- the androgen released in large quantities by a boy’s testes- leads to muscle growth, body and facial hair, etc. • Estrogens-development of girl’s breasts, uterus, and vagina; female proportions, accumulation of fat, and beginning of menstrual cycle

5. HPG Axis • Active even before birth • In middle childhood it rises again and begins to tell the body it is ready for puberty • Protein Leptin tells the brain you are gaining fat – 11% may trigger puberty

7. The Endocrine System: HPG Feedback Loop HPG Axis: Hypothalamus Pituitary gland (master gland) Gonads (testes and ovaries) Gonads release sex hormones into bloodstream Androgens and estrogens

8. Endocrine System • Puberty occurs when hormone levels drop below ‘set point’ • Hypothalamus will stimulate the pituitary gland • Pituitary then stimulates gonads, which produce more androgens and estrogens • When levels in bloodstream become too high, the process stops • At puberty, the hypothalamus is less sensitive so the hormones allow the onset of puberty

9. Endocrine system • Both sexes produce androgens • Males usually produce more androgens than estrogens • Females produce more estrogens • Sexual attraction may begin with adrenarche-the stimulation of adrenal glands

10. Physical Changes of Puberty:Adolescent Growth Spurt Adolescent growth spurt Rapid acceleration in growth (height and weight) Simultaneous release of growth hormones, thyroid hormones, and androgens Peak Height Velocity (Time that adolescent is growing most quickly) – growth spurt is equivalent to that of a toddler

11. Physical Changes of Puberty:Adolescent Growth Spurt

12. Puberty Changes-Boys • Body size generally complete by 17 ½ yrs • Broadening of shoulders • Less fat in arms and legs • Larger skeletal muscles, heart and lung capacity • Spurt in strength, speed and endurance • Enlargement of testes and penis- one of 1st signs of puberty; development of pubic and underarm hair • Voice deepens • Spermarche-first ejaculation of seminal fluid-about 13 yrs of age

13. Puberty Changes -Girls • Growth spurt usually complete by 16 • Broadening of hips • Around age 8- start to add more fat in arms legs and trunk • Gross motor development gains are slow and gradual, leveling off at about 14 yrs • Development of breast-one of 1st signs of puberty • Pubic and underarm hair appears • Menarche- first menstruation-about 12 yrs in North American girls

14. Body dimensions • Changes in body parts do not occur at the same time • Result? • Clumsy • Body appearance may be awkward

15. What affect timing of puberty? • Children who are healthy and well nourished enter puberty earlier • Puberty occurs earlier in families where there is not a father or families with more conflict • Adolescents mature earlier in countries that are industrialized • Better nutrition • Better health care

16. Reactions to Puberty • Past generations-traumatic and disturbing • Girls today –mixture of positive and negative emotions-depends on prior knowledge and family members support • Boys know about ejaculation but few get information from parents- most get info from reading material • Boys get less social support

17. Parent-Child Relationships • Bickering and standoffs increase • Physical departure from family and psychological distancing from parents • Adolescence demonstrate new powers of reasoning possible reason for bickering

18. Early vs Late Maturation • Early Maturing boys- relaxed, independent, self-confident and physically attractive • Early Maturing girls- emotional and social difficulties, withdrawn, lacking self-confidence and psychologically stressed • Late maturing boys- anxious, overly talkative, attention-seeking behavior • Late maturing girls- physically attractive, lively, sociable and leaders in school. • Society favors- girlish shape for girls (late developer) and tall, broad-shouldered and muscular-early developed boys

19. Long Term ConsequencesVaries among cultures • Early maturing girls and late maturing boys have a difficulty “fitting in” because they are at the extremes of physical development • Teens feel most comfortable with peers that match their own biological maturity • Early maturing teens of both sexes seek out older companions-may have unfavorable consequences • Early maturing boys and late maturing girls admired in teen years may become rigid, conforming and discontented adults • Late maturing boys and early maturing girls less stressed in teen years became independent, flexible and cognitively competent

20. Brain development • Frontal lobe development lags behind emotional limbic system= impulsiveness, emotional storms, risky behaviors • When frontal lobe matures so do emotions and judgment. • Before prefrontal cortex fully develops, amygdala has major control

21. Nutritional Needs of Teens • During growth spurt, boys require about 2,700 calories a day and much more protein • Girls require about 2200 calories and somewhat less protein • Iron deficiency- most common problem in adolescence • Calcium, riboflavin (Vitamin B2) and magnesium may be limited in diet as well • Fad diets are too limited in nutrients and calories to be healthy for teens

22. Eating Disorders • At risk-girls with dissatisfied body images, growing up in economically advantaged homes where cultural concerns are weight and thinness

23. Anorexia nervosa • Parents have high expectations for achievement and social acceptance, overprotective and controllingAnorexia nervosa- individuals starve themselves because of compulsive fear of getting fat; 1 in 50 girls; peak age 14 and 18Lose between 25% to 50% of body weight and look painfully thinSymptoms- cessation of menstruation, or nonoccurrence of menarche, pale skin, brittle discolored nails, fine dark hair all over body and sensitivity to cold

24. Bulimia • Individuals go on eating binges following by deliberate vomiting, other purging techniques such as heavy doses laxatives and strict dieting • Repeated vomiting causes erosion of tooth enamel, and can cause life threatening damage to the throat and stomach • More common than anorexia, 5% bulimic girls have previously been anorexic • Bulimic are not just impulsive eaters; they lack self-control in other areas of their lives • Abnormal eating habits, feeling depressed, and guilty about eating-usually easier to treat than anorexia