set of biological processes that change the immatuer child into a sexually mature person

part of a gradual process

girls = 10.5 - 15

boys = 11.5 - 17

decline in age for achieving puberty in developing countries

primarily due to better health/nutrition

1) Adrenal gland - starts 6-8, peaks in 20s

androgens cause growth of hair, skin changes, and sexual desires

2) HPG Axis - 9-10 yrs

hypothalamus triggers pituitary to secrete hormones which triggers the gonads to begin secreting hormones (testosterone and estrogen)

1) genetics: same age as parents

2) weight: higher BMI = earlier

3) Nutrition: high calorie diets = earlier

4) stress: adaptive to mature earlier

5) climate/environment

youth progress through events at different rates but all generally follow the same sequence

physical changes:

1) body growth

2) sexual maturation

growth spurt: increase in size, weight, strength

uneven growth: asynchrony, hands, feet, and legs first (gawky)

increase in appetite

increase in size and activity of oil-producing glands

muscle-fat ratio changes: girls more than boys

girls start growth earlier, boys continue for longer

physical changes that directly involve the organs of reproduction

changes not directly involved in reproduction

external, involved in distinguishing male and female

(hair, voice changes, skin, adam's apple, breasts)

boys get more androgens (testosterone) for muscle growth and body size

girls get more estrogen for breast and uterus maturation, fat accumulation, and to regulate menstruation

girl's first menstruation

typically around age 12.5

based on genetics and fat

adolescents more aware of changing body

media shows physical strength for boys and thinness for girls

inrease risk of eating disorders

girls at 13-14 yrs

boys at 14-15 yrs

majority become sexually active between ages 15-19 years

adolescents have highest STD rate

20% of sexually active teen girls become pregnant each year

having an older boyfriend increases the chance for girls

peer pressure has a strong influence on timing and frequency of sexual activity

early development of subcortical structures:

1) amygdala - emotions

2) striatum - seeking out "rewards," thrill-seeking behavior

slow development of frontal lobe:

involved in controlling behavior

suggests overproduction of synapses then pruning

"use it or lose it"

debt due to:

-early school start time

-biological clock shifts forward, teens stay up later and wake up later

reduced REM sleep leads to impaired learning