Chapter 9

hormonal changes in adrenal gland

occur from 6-9 years

continue through puberty

most people think of as puberty

sexual maturationand development of reproductive maturity

begins 9-10 years old in girls

10-11 in boys

boys first ejaculation

main class of male hormones

girls have some too

main class of female hormones

some in males too

an androgen key to puberty in boys

testosterone rises, external genitalia grow, height increases, voice changes

estrogen that plays important role in female puberty

estradiol increases, breasts grow, uterus matures, skeletal changes occur

pituitary gland releases hormones for growth

thyroid also plays a role

initially secreted at night during puberty

later also during the day

adrenal gland secretes cortisol

differences in research

some find higher levels of testosterone leads to aggressive behavior

high level of adrenal androgens sometimes leads to anti social behavior

hormones themselves are not responsible for behavior

for menarche to happen body fat must make up 17% of body

106 +- 3 lbs starts menarche and ends puberty growth

anoerexic girls dont menstruate

hormone released by fat cells

may signal that girl's body has enough fat

higher in girls than boys

puberty brings most rapid growth since infancy

arives 2 years younger in girls than boys

9-11, 11-13

beginning of middle school girls generally taller, no by end

those who are shorter or taller before adolescence generally stay so during

follows same pattern as height

50% of adult weight gain occurs in adolescence

girls gain avg of 18 lbs in one year and peak

boys gain 20

beginning, girls outweigh boys, end boys out weight girls

adolescent girls gain wider hips

boys shoulders grow

boys faces become more angular

girls have rounder/softer faces

characteristics in order:

increase in penis/testicle side

pubic hair

voice change

spermarche

maximum body growth

hair in armpits

facial hair

breasts enlarge/pubic hair appears

hair in armpits

height, hips widen

menarche

early are irregular

some don't become fertile till 2 years after 1st period

exploration and experimentation

bridge between asexual child and sexual adult

involves indication about sexual orientation

making out, petting, sexual intercourse

8-10 girls at age 15 and 7 in 10 boys have not

1 in 5 are virgins at 19

usually occurs middle-late adolescence

STDs

pregnancy

US adolescence pregnancy rate is 8x as high as norway

US has one of the highest adolescent child bearing rates

often drop out of school

at risk for more pregnancies

the infants are at risk for low birth weight

likely to come from low SES

stay up late

hard to wake up

sleep average of 9 hours 25 min

45% get inadequate sleep during the week

hormones push wake time to an hour later

melatonin: hormone: produced by brain's pineal gland

secreted at 9:30 in early adolescent but later at 10:30

less sleep results in depression, illness

accidents, homicides, suicides

more than half are accidents

alcohol plays a large role

overweight: 17%

US adolescence eat more junkfood than other countries

2/3 of US adolescents exercise twice a week

80% in other countries

34% in lowest fittness category

higher risk for eating disorders:

girls who felt negatively about their bodies in early adolescence

girls who are sexually active and in pubertal transition

less then 1% ever develope anoerexia

relentless persuit of thinness through starvation

3 main characteristics:

weight less than 85% of normal weight

intense fear of gaining weight

distorted image of body shape

10x more likely in girls than boys

binge and purge eating

fear of food/becoming over weight

anxious/depressed

usually at or above average weight

typically starts in late adolescence or early adulthood

number using illicit drugs has been declining since 90s

US has highest rate of adolescent drug users

alcohol and cigarettes declining in US

11-15

think in abstract and more logical ways

adolescent's verbal problem solving ability grows

hypothetical-deductive reasoning

ideaism

heightened self-consciousness reflected in the belief that others are as interested in them as they are

imaginary audience: think everyone is judging them

personal fable: no one unerstands

invincibility

risky behavior

decision making