Chapter 2Puberty, Biological Foundations & HealthBy Samantha Pickolick

Puberty: What is it? Puberty is a

period of rapid physical maturation involving hormonal and bodily changes that take place primarily in early adolescence.

1. Determinan

ts of Puberty

2. Growth Spurt

3. Sexual

Maturation

4. Secular

Trends in Puberty

5. Psychologic

al Dimensions

1. Determinants of Puberty Heredity Weight at Birth Hormones The Endocrine System Growth Hormones Sociocultural and Environmental

Factors

Heredity & Weight at Birth “Puberty is not an environmental

accident.” Usually occurs between ages 9 and 16. Girls: with low birth weight on average

begin puberty 5 o 10 months earlier than the norm.

Researchers have found rapid weight gain in infancy is related earlier pubertal onset.

Hormones• Main class of

male sex hormones

Androgens

• Main class of female sex hormones

Estrogens

• Chemicals that travel through the blood stream

Hormones

Boys: higher levels of androgens are associated with violence and acting out.Girls: higher levels of estrogens are linked to depression and emotional arousal.

Levels of sex hormones are regulated by two hormones secreted in the pituitary gland:

FSH (follicle-

stimulating hormone)

LH (luteinizing hormone)

The Endocrine System (Pt. 1) Involves the

interaction of the hypothalamus, the pituitary glands, and the gonads.

• The higher portion or the brain that monitors eating, drinking, and sex.

Hypothalamus

• The endocrine gland that controls growth and regulates other glands.

Pituitary Glands

• The sex glands—testes in males & ovaries in females.

Gonads

The Endocrine System (Pt. 2) These hormones are regulated by a negative

feedback system. “This negative feedback system in the

endocrine system can be compared to a thermostat and a furnace…The level of sex hormones is low in childhood but increases in puberty. It is as if the thermostat is set to 50 degrees in childhood and now becomes set at 80 degrees in puberty. At the higher setting, the gonads have to produce more sex hormones, and they do so during puberty.”

Growth Hormones Influence growth, as do estrogen and testosterone. Two phases of puberty are linked with hormonal changes:

Involves hormonal changes in the adrenal glands. Changes begin early, about 6 to 9 years old in girls and about 5 to 8 in boys. Generally considered time before puberty.

Adrenarche

Follows Adrenarche by about 2 years. Female’s first menstruation and male’s spermarche occurs mid to late in this phase.

What most people consider puberty. Maturation of primal sexual characteristics.

Gondarche

Weight & Body Fat Higher weight, especially obesity, is

theorized to be linked to earlier pubertal development.

Theory: the onset of menarche is influenced by the percentage of body fat in relation to total body weight.

Sociocultural and Environmental Factors

Adolescents in urban and well-populated areas reach puberty earlier than less developed and rural areas.

Children adopted from less developed areas and brought to more urban environments also develop early.

Early experiences that are linked to early puberty include: adoption, father absence, low socioeconomic status, family conflict, and child maltreatment.

A recent study shows that early exposure of daughters to serious paternal dysfunction (substance abuse, criminal defenses, and violence) followed by family disruption and departure of the father of the home were linked to early puberty as well.

3. Growth Spurt As much as 30% of an individual's height in

adolescence is unexplained by the child’s height in in elementary school.

50% of an adult’s body weight is gained in adolescence.

Improved nutrition, health, and socioeconomic conditions are also factors in a person’s overall height.

Girl’s increased hip width is connected with higher levels of estrogen.

Boy’s increased shoulder width is connected with higher levels of testosterone.

4. Sexual Maturation In many instances, a female might not

become fertile until 2 years after her period begins.

Males will notice maturation by deepening of voice, facial and armpit hair growth, and height growth.

Good to know: Precocious puberty • very early onset and rapid progression of puberty• Before 8 years old in girls, 9 in boys• 10x more likely in girls than boys• Would likely need to be medicated to halt gonadortopic

secretions until age appropriate.

Secular Trends in Puberty “patterns of pubertal onset over a

period of time, especially across generations.”

U.S. children mature physically up to a year earlier than European countries.

Early onset puberty is a growing concern across many countries, but mostly in the U.S.

5. Psychological Dimensions of Puberty Pt. 1

Far less research exists on male pubertal transitions than there is on female.

• Body Image• Being concerned

with body image exists throughout adolescents, but is more acute during puberty.

• Gender Differences

• In general, girls are less satisfied with their bodies and have more negative body images than boys.

Psychological Dimensions of Puberty Pt. 2: Early & Late Maturation

Late maturing boys studied in their 30’s had developed a stronger sense of self that early maturing boys.

Early maturing girls had more problems in school, were more independent, and were more popular with boys than late maturing girls.

Late maturing girls tend to look more tall and thin and are less likely to have mental disorders.

Early maturing boys have been more likely to be successful and less likely to drink alcohol or smoke cigarettes.

Are Puberty’s Effects Exaggerated?For many adolescents, the path through puberty is stormy, but for some it is not. What was your experience like?

Biological Foundations

1. The Evolutionary Perspective

2. The Genetic Process

3. Heredity-Environment Interaction

1. The Evolutionary Perspective Adaptive behavior: a modification of

behavior that promotes an organism’s survival in the natural habitat.

An extended juvenile period evolved because humans require time to develop a large brain and learn the complexity of human social communities.

Many evolved psychological mechanisms are domain specific. Information processing is one example of this.

Evolved mechanisms are not always adaptive in contemporary societies. Example: food shortages in the past have led us to gorge on food when made available and to crave high-calorie foods.

2. The Genetic Process Each of us carries a “genetic code”

that we inherited from our parents, and it is distinctly a human code.

Our entire genetic code gives instructions to grow a human made up of trillions of cells, each containing copies of the original genetic code. This code is carried by our genes.

Genotype vs. Phenotype• The “actual genetic

material”. • Not all of the genetic

material is apparent in our observed characteristics.

• The way a genotype is observed is through a phenotype.

Genotype

• Physical traits such as height, weight, eye color, and skin pigmentation.

• Also includes psychological characteristics such as intelligence and creativity.

Phenotype

3. Heredity-Environment Interaction Behavior genetics: field of study to discover the

influence of heredity and environment on individual differences in human traits and developments.

Twin StudyResearchers study the influence of heredity on behavior by observing twins.By comparing groups of identical and fraternal twins, behavior geneticists have found conduct problems were more prevalent in identical twins than fraternal ones.

Adoption StudyResearches study whether the behavior and psychological characteristics of adopted children are more like those of their biological parents, or more like those of their adoptive parents. Another form of this study involves comparing adoptive and biological siblings.

Heredity-Environment Correlations

Passive genotype-environment correlations occur because biological parents provide a rearing environment for the child.

Evocative genotype-environment correlations occur because an adolescent’s genetically shaped characteristics elicit certain types of physical and social reactions and environments.

Active (niche-picking) genotype-environment correlations occur when children seek out environments that they find compatible and stimulating. Adolescents select from their surrounding environment some aspect that they respond to, learn about, or ignore.

Shared and Nonshared Environmental Experiences

Shared environmental experiences are sibling’s common experiences. Nonshared Environmental Experiences are an adolescent’s unique experiences, both within the family and outside.

“Behavior geneticist Robert Plomin has found that common rearing, or shared environment, accounts for little of the variation in adolescent’s personality or interests. In other words, even though two adolescents live under the same roof with the same parents, their personalities are often very different.”

Do you have any siblings? If so, how did they influence your life?

Sleep Exercise & Sports

Nutrition In Adolescence

Health

Health in Adolescence Even as we become a more health-conscious

society, there are still many unhealthy habits we form. To stay healthy, we must develop better habits.

Health-compromising behaviors: drug abuse, violence, dangerous drinking, and risk-taking behavior.

Health-enhancing behaviors: exercising, eating nutritiously, getting adequate sleep, and making informed choices.

Risk-Taking Behavior 18 year-olds are considered “more

impulsive, less future-oriented, and more susceptible to peer influence” than adults in their mid 20’s.

This has to do with the prefontal cortex the brain’s highest level that is involved with reasoning, decision making, and self control, developing much later.

Health Services Adolescents see primary physicians less

than any other age group.In one study, parents of urban adolescents want health-care providers to talk their adolescents about sensitive health issues such as sexually transmitted infections, contraception, drug use, depression, nutrition, and stress. However, only 25% of the health care providers talked privately with adolescents during their last visit.16- 20 year-old males have significantly less contact with health-care services than 11-15 year old males

16-20 year-old females have more contact with health-care services than do younger females.

Staying Healthy Emerging adults have few chronic health

problems, and have fewer colds and respiratory problems than when they were children.

However, there are still habits we need to get rid of to stay healthy such as: Skipping breakfast Relying on snacks too heavily Smoking Failing to exercise Poor sleeping schedule

Nutrition One of the best ways to be healthy is by

having a healthy example.

A study shows that households with ample fruit and vegetable supplies and households where parents regularly ate healthy led to healthier eating habits by adolescents in those homes.

Eating family meals regularly led to better eating habits 5 years later.

Exercise & Sports It’s a fact: we get less active as we go

through puberty and progress through adolescence.

Only 17% of individuals meet the recommended amount of exercise (60 minutes) on the weekend.

Adolescents are more likely to engage in regular exercise when it has perceived importance among their friends or when they think it is important to have a positive body image.

What Determines Our Workout? Family, School & Technology.

Friends & FamilyThe best way to encourage young ones to exercise is by being the example.

SchoolOnly 30% of 9-12th graders participate in physical activities 5 days a week.

TechnologyThe more adolescents engage in TV and computers the less likely they are to do physical exercise.

Sleep When given the opportunity, on average

adolescents will sleep 9 hours and 25 minutes. Most get considerably less than that.

Only 31% of students get more than 8 hours of sleep on a school night.

Not sleeping can lead to horrible health habits.

Early class times may cause grogginess, poor performance on tests, and inattention in class.

How many hours of sleep did you get last night?Do you feel well-rested most days?