lack of adequate fat cells can delay pubertal onset

Estradiol and Testosterone levels stay the same in children until puberty

By the mid-teens, estradiol (the most important estrogen) production is about eight times as high in females as it was before puberty, but only about twice as high in males.In males, testosterone (the most important androgen) production is about 20 times as high by the mid-teens as it was before puberty, but in females it is only about four times as high.

puberty begins in the hypothalamus by releasing GnRH every 2 hours, beginning once leptin levels reach a set point

leptin is produced by fat cells so lack of adequate fat cells can delay pubertal onset

four levels of control that control the physical changes at puberty. 1 hypothalamus monitors sex hormones against the set point 2 pituitary gland, controlled by hormones secreted by the hypothalamus. hormones of the pituitary regulate the activities of the testes and the ovaries. “sex hormones” produced mainly by the testes and ovaries bring physical changes

Androgens are produced by the adrenal gland as well as sex glands, increases in ACTH produced by pituitary gland ramp up production of androgens in adrenal glands

Girls hit growth spurts 2 years before boys, usually age 11

Pubertal growth is asynchronistic, meaning some parts grow faster than others

Gonadotropins are sex hormones that stimulate growth of gametes, FSH LH

Primary sex characteristics involve the production of eggs and sperm and the development of the sex organs.

Secondary sex characteristics are other bodily changes of puberty, not including the ones related directly to reproduction.

Females are born with about 400,000 immature eggs in each ovary. By puberty, this number has declined to about 80,000 in each ovary. Once a girl reaches menarche (her first menstrual period) and begins having menstrual cycles, one egg develops into a mature egg, or ovum (plural: ova), every 28 days or so. Females release about 400 ova over the course of their reproductive lives.

the majority of a girl’s menstrual cycles in the first 2 years after menarche do not include ovulation, and in the third and fourth years only about one third to one half of cycles include ovulation. It is only after 4 years of menstruation that girls consistently ovulate with each menstrual cycle

males have no sperm in their testes when they are born, and they do not produce any until they reach puberty. The first production of sperm in boys is called spermarche, and it takes place on average at age 12. Once spermarche arrives, boys produce sperm in astonishing quantities. There are between 30 and 500 million sperm in the typical male ejaculation, which means that the average male produces millions of sperm every day.

Both males and females grow hair in their pubic areas and underneath their arms. Both also grow facial hair. Increased hairiness on the arms and legs is more pronounced in males, but females also grow more hair on their limbs at puberty. Boys also begin to grow hair on their chests, and sometimes on their shoulders and backs as well, whereas girls typically do not.

Sweat glands in the skin increase production, making the skin oilier and more prone to acne, and resulting in a stronger body odor. Both experience a deepening of the voice as the vocal cords lengthen, with males experiencing a steeper drop in pitch.

one fourth of boys experience enlargement of the breasts midway through puberty, but usually the enlargement recedes within a year.

In Kenya, boys show the first physical changes of puberty before their female peers

In a study of Chinese girls found that pubic hair began to develop in most girls about 2 years after the development of breast buds, and only a few months before menarche. This is a sharp contrast to the pattern for the girls in Tanner’s studies, who typically began to develop pubic hair at about the same time they developed breast buds, usually 2 years before menarche

African American girls were found to begin developing breast buds and pubic hair considerably earlier than White girls. At age 8, nearly 50% of the African American girls had begun to develop breasts or pubic hair or both, compared with just 15% of the White girls. This was true even though Black and White girls were similar in their ages of menarche.

Emerging adults are no longer vulnerable to the illnesses and diseases of childhood, and with rare exceptions they are not yet vulnerable to diseases such as cancer and heart disease that rise in prevalence later in adulthood. The immune system is at its most effective during the emerging adult years

puberty begins earlier in cultures where good nutrition and medical care are widely available

Reaction range means that genes establish a range of possible development and environment determines where development takes place within that range.

For girls in the United States, the average age of menarche is currently 12.5

in nearly all cultures, adolescents of both sexes tend to be closer to their mothers than to their fathers

Distancing is not as common in Latino families or in divorced mother-headed families

Early and late maturation positives and negatives for boys and girls p. 61-62

Theory of genotype p. 63

Puberty rituals are more common for those in traditional cultures

Male puberty rituals typically require the young man to display courage, strength, and endurance

Know about active and passive and evocative genotype-environment and what that means p. 63-64

Biology and environment p. 63

Possible effects of age-grading in schools p. 61