The Fundamental Changes of Adolescence: Biological Transitions Flashcards
What is puberty?
It is the period during which an individual becomes capable of sexual reproduction. Hormones regulated by the endocrine system lead to physical
changes. No new hormones are produced and no new bodily systems develop
at puberty.
What does the endocrine system do?
It produces, circulates, and regulates hormone levels in the body.
What are hormones?
Specialized substances secreted by endocrine glands
What are glands?
Organs that stimulate particular parts of the body to respond
in specific ways
what are gonadotropin- releasing hormone neurons? (GnRH)
Neurons in the
brain that play important roles at puberty
What does the hormonal feedback loop do?
Levels of sex hormones are regulated (to a set point) by the hormonal feedback system composed of
the hypothalamus, pituitary glad, and gonads.
What is the process of the hormonal feedback loop?
The hypothalamus monitors sex hormones and then controls the pituitary gland, which signals the gonads, which release sex hormones.
What is adrenarche?
The maturation of the adrenal gland that takes place during adolescence. Changes in the brain system regulate the adrenal gland, which is also
the system that controls how we respond to stress.
What is cortisol?
A hormone that is produced when a person is exposed to
stress.
What triggers puberty?
Something in middle childhood reawakens the HPG axis and signals that the body is ready for puberty:
• Presence of mature sexual partners
• Sufficient nutritional resources
• Physically healthy enough to begin reproducing
Other factors:
- genes predispose onset at a certain age
- more fat cells, more exposure to light, triggers puberty earlier
What are the brain chemicals that stimulate the onset of puberty?
Kisspeptin : A brain chemical believed to trigger the onset of
Leptin : A brain chemical produced by the fat cells that may play a role
in the onset of puberty through stimulating kisspeptin.
Melatonin : A hormone secreted by the brain that contributes to
sleepiness and that triggers the onset of puberty through its impact on
kisspeptin.
How do hormones influence adolescent development?
Organizing Role:
•Prenatal hormones “ program” the brain to be masculine or feminine
(like setting an alarm clock)
•Patterns of behavior as a result of this organization may not appear until adolescence (e.g., sex differences in aggression).
Activating Role:
•Increase in certain hormones at puberty activates physical changes
(e.g., secondary sex characteristics)
What are the affects of hormonal changes of puberty?
-enters puberty looking like a child; within 4 years or so, has
the physical appearance of a young adult.
-average individual grows about 10 inches taller, matures sexually,
and develops an adult proportioned body.
-brain changes in size, structure, and function at puberty.
What is Adolescent growth spurt?
The dramatic increase in height and
weight that occurs during puberty.
What is Peak height velocity?
The point at when the adolescent is growing
most rapidly.
- girls - 3.5 in per year
- boys - 4.1 in per year
What is Epiphysis?
The closing of the ends of the bones, which terminates
growth after the adolescent growth spurt has been completed.
What is the body dissatisfaction among adolescents?
- Increase in height is accompanied by increase in weight, which results
from an increase in both muscle and fat. - End of puberty: boys’ muscle to fat ratio is 3 to 1; girls’ ratio is 5 to 4
- Rapid gain in fat frequently prompts girls to become overly concerned
about their weight. - Girls most susceptible to feelings of body dissatisfaction with their bodies are those who mature early and begin dating early.
- Boys’ feeling about their looks revolve around how muscular they are.
What are Secondary sexual characteristics?
The manifestations of sexual maturity at puberty, including the development of breasts, the growth
of facial and boy hair, and changes in the voice.
What are tanner stages?
A widely used system that describes the five stages of
pubertal development.
What are the tanner stages for a male?
Stage 1: infantile stage, birth-puberty, genitalia increase slightly, no pubic hair
Stage 2: scrotum begins to enlarge, some reddening & change in scrotal skin texture, sparse growth of light hair
Stage 3: penis has increased in length & small increase in breadth, further growth of scrotum, public hair spreads and is more coarse & dark
Stage 4: length & breadth of penis increased, scrotum further enlarger & scrotal skin is darker, hair is adult in character but smaller area
Stage 5: genitalia adult in size, hair fully grown to a triangle
What are the tanner stages for a female?
Stage 1: no breast development, no public hair
Stage 2: breast budding, small amount of public hair along vaginal lips
Stage 3: breast more distinct, no separation between the two, hair is darker/coarser
Stage 4: breast further enlarged, greater contour, nipple/areola forms second mound, hair now adult in type but covers a smaller area
Stage 5: breast fully developed (size varies), contours distinct & areola receded into contour of breast, hair now adult in type & distributed in an inverse triangle.
What is the variation in time & tempo of puberty?
There is no specific average age at onset or duration of puberty.
There is no relation between the age at which puberty begins and the rate of pubertal development. Ethnic differences exist in the timing and rate of pubertal maturation:
•Black mature females (1st); Mexican American females (2nd); White
females (3rd).
•Difference is probably not due to ethnic differences in income, weight,
or area of residence.
•Non White girls may be exposed more often to chemicals that stimulate earlier puberty.
What is the genetic disposition of puberty timing?
Genetic disposition is best thought of as an upper and lower age limit, not a fixed absolute.
What are the environmental influences on puberty timing?
Two key environmental influences exist: nutrition and health.
•Puberty occurs earlier among those who are better nourished..
•Delayed puberty is more likely among individuals with a history of protein and/or caloric deficiency.
•Chronic illness and excessive exercise also linked with delayed
puberty.
What are familial influences on puberty timing?
Early pubertal maturation in girls is related to several factors:
•Father absent families, conflict ridden households, having a stepfather,
and sexual abuse
•Tension in the family and stress, which affects hormonal secretion
•The presence of a stepfather, which may expose the adolescent girl to
pheromones that stimulate pubertal maturation
•Pheromones : A class of chemicals secreted by animals that stimulate certain behaviors in other members of the species.
What are the differences in timing of puberty in different groups?
-Across countries, age at menarche occurs later when malnourished or
suffering from chronic disease
-Median age range of menarche in Africa is 14 to 17; in United States it
is 12 to 13 ½
What is the secular trend?
The tendency, over the past two centuries, for
individuals to be larger in stature and to reach puberty earlier, primarily
because of improvements in health and nutrition.
What are the immediate impacts of puberty?
Physical changes of puberty affect self
image, mood, and relationships.
Puberty and Self
Esteem:
•Impact of puberty on self esteem varies by gender and ethnicity.
•White girls are particularly likely to develop poor body images.
Puberty and Adolescent Moodiness:
•More fluctuations throughout the day than adults
•Not solely due to hormones
•Greatly influenced by environmental factors, such as shifts in activities
What are the changes in sleep patterns during puberty?
- Delayed phase preference: A pattern of sleep characterized by later sleep and wake times, which usually emerges during puberty
- Caused by interaction of biology and environment
- One of most important factors: timing of secretion of melatonin shifts later
- Environmental factors: Internet, television, electronic media
- Provide reason to stay up
- Early school schedule contributes to sleep deprivation.
What does insufficient sleep lead to during adolescence?
- Depression
- Alcohol, tobacco, drug use
- Obesity
- Cognitive impairment
- Delinquency
How does puberty affect family relationships?
Puberty increases conflict and distance between parents and children, regardless of whether adolescent is early or late maturer.
Distancing effect is not consistently observed in ethnic minority families.
Research is inconclusive but increased conflict/distance could be due to changes in various changes in adolescents’ lives:
•Hormones
•Physical appearance
•Psychological functioning
American majority culture: Relations become cooler, Conflict increases, Physical closeness less likely
Traditional cultures: Girls often grow closer to mothers
How does puberty affect peer relationships?
Physically mature male and female adolescents are more likely than their less mature peers to be involved in cross sex romantic activities.
•Depends on social norms of peer group
•Also depends on prevailing expectations about dating age
•Not associated with having platonic relationships with other sex peers
What is the impact of puberty events on females?
Reactions to menarche are less negative than in the past.
•May be attributable to more information provided about menstruation
•Link between negative attitudes and menstrual discomfort
Modern Day America: Feel more “grown up”, Increase in social maturity, Prestige with peers
Other Cultures: Girls provided little to no information, Fear and dismay, Some cultures have negative beliefs about menstruating
Premenstrual Syndrome (PMS)
What is the impact of puberty events on males?
Less is known about boys’ reactions to first ejaculations.
•Usually not discussed by boys
•Link between cultural differences in response to first ejaculation and
views of masturbation
•Enjoy the pleasurable sensations of it
•Feel more grown up
•Guilt, surprise, fear
•Rarely get info from parents prior to experience
What is the impact of early or late maturation?
Adolescent are aware of whether they are early or late relative to
classmates.
•Their feelings about themselves are influenced by comparisons
•Early maturers are likely to be “pseudomature.”
Perception of being an early or late maturer is more important in
affecting one’ s feelings than the reality.
Behavior is more closely related to how old the adolescent feels, not
necessarily how physically mature he or she is.
What are the effects of early & late maturation in males?
Early Maturation: •Popularity, achieve greater success
•Better self esteem
•More favorable body image
•More drug and alcohol use, delinquency, precocious sexual activity
•Greater impact of victimization/being bullied
•Possibly elevated rates of depression and anxiety
•More intense temper tantrums and depression during puberty
Late Maturation:
•lower school grades
•substance use, deviant behaviour into early adulthood
What are the effects of early & late maturation in females?
Early Maturation:
•Poorer self image
•Higher rates of depression, eating disorders, and panic attacks
•More often victims of rumors, gossip, and sexual harassment
•Eating disorders
•Cultural values of image: tall and thin
•Draws attention of older boys / start behaving older
-One pro - popularity
Late Maturation:
•teasing
•negative body image in later teens
- more positive body image later in teen years
How does puberty influence obesity & eating disorders?
Weight gain sometimes results directly from physical changes of
puberty.
•Basal metabolism rate : the minimal amount of energy used by the
body when resting.
•It drops about 15% in adolescence.
•Normal weight gain and changes in body composition lead many
adolescents to become concerned about weight.
What is BMI?
Body mass index (BMI) BMI): A measure of an individual’s body fat, the
ratio of weight to height, used to gauge overweight and obesity.
What are the correlates and consequences of obesity?
Correlates and Consequences of Obesity
•Interplay of genetic and environmental factors
•Neurological factors: greater activation of reward centers, heightened
responses to food, poorer impulse control
•Too much high calorie, low fiber food
•Low activity levels
Obesity is especially prevalent among poor youth and among Black,Latino, and Native American adolescents.
Psychological consequences vary across ethnic groups and gender.
What is disordered eating?
:mild, moderate, or severe disturbance in eating
habits and attitudes.
What is anorexa nervosa?
Anorexa nervosa : An eating disorder found chiefly among young
women, characterized by dramatic and severe self induced weight loss.
- 1% of women, 3 times as common in females as in males
What is bulimia?
Bulimia An eating disorder found primarily among young women,
characterized by a pattern of binge eating and extreme weight loss measures, including self induced vomiting.
- 1.5% of women, 3 times as common in females as in males
What is binge eating disorder?
Binge eating disorder : An eating disorder characterized by a pattern of binge eating that is not accompanied by drastic attempts to lose weight.
- 3% of women
How can obesity be prevented and treated?
- Much attention focuses on availability of unhealthy foods and
beverages in homes and school
•Obesity is less likely to develop among adolescents who have good
relationships with their parents.
•Availability of parks and recreational facilities is linked to lower rates of
obesity.
•Although some weight loss programs have been shown to work, there is wide variability in success rates.
What is the prevalence of eating disorders?
Anorexia
•Observed all over the world
•Increased in prevalence over time
•Consistent level of heritability across cultures
Bulimia •Observed mainly in Western cultures •Increased between 1970 and 1990 but has declined since (parallels levels of body dissatisfaction) •More culturally determined
Eating disorders are best understood as manifestations of a more general psychological problem called “internalized distress.”
How do the hormones in the feedback loop of the endocrine system function and initiate puberty?
- Hormonal changes begin in hypothalamus
- Gonadotropin releasing hormone (GnRH) begins at puberty
- Increased GnRH occurs once a threshold level of body fat is
reached - Fat cells produce the protein leptin that provides the signal to
release GnRH
-Gonadotropins release once GnRH reaches the pituitary gland
What are the male and female gonads/sex glands?
Ovaries
Testes
What are sex hormones?
Estrogens - most important is estradiol
Androgens - most important is testosterone
What does the Adrenocorticotropic Hormone (ACTH) do?
Causes the adrenal glands to increase androgen production
What are the primary sex characteristics for females?
- Egg production
- Menarche is first menstrual period
- Ovum is a mature egg, released every 28 days or so, females release about 400 over their lives
- Changes prepare body for sexual reproduction
- Female releases an ovum with each monthly cycle
- Female doesn’t start ovulating at first menstruation
What are the primary sex characteristics for males?
- Sperm production
- Spermarche is first production of sperm
- 30-500 million sperm per ejaculation
- Changes prepare body for sexual reproduction
- Male penis and testes grow
What are the secondary sex characteristics for females?
Bodily changes that are not directly related to reproduction
- Hair growth in pubic areas, under arms, face
- Hairiness on arms and legs increases
- Sweat glands in the skin increase production
- Females experience breast growth
What are the secondary sex characteristics for males?
Bodily changes that are not directly related to reproduction
- Hair growth in pubic areas, under arms, face
- Hairiness on arms and legs increases
- Sweat glands in the skin increase production
- Deepening of the voice
- Males grow hair on chests, shoulder, and back
What is the female order of pubertal events?
Pubic hair – Breast buds – Growth spurt – Growth of sexual and reproductive organs – Menarche – Underarm hair – Secretion of increased skin oil and sweat
What is the male order of pubertal events?
Growth of testes – Pubic hair growth – Growth spurt – Growth of penis – Deepening of the voice – Spermarche – Underarm hair – Secretion of increased skin oil and sweat – Facial hair
What are the changes in physical functioning in relation to heart, lungs, physical performance, bone mass, oxygen uptake, and cardiac output during puberty?
- Heart size doubles and heartrate falls. By age 17 average girl’s heartrate is 5 beats faster than the
average boy’s - Lung vital capacity (amount of air that can be exhaled after a
deep breath) increases rapidly (more for boys than girls) - Boys overtake girls in physical strength
- For most people, the peak of their physical functioning
comes during emerging adulthood. - Reaction time fastest in 20s
- Peak bone mass reached in the 20s
- Maximum oxygen uptake - Peaks in early 20s
- Cardiac output - Peaks at age 25
What are the changes in physical functioning in relation to weight during puberty?
Obesity: Exceeding a specific body mass index (BMI)
- About 20% of American adolescents are obese
–Diet and exercise major cause: fast food diet, American lifestyle more automobile oriented, steep decline in physical activity from middle childhood to
adolescence, soft drink and junk food machines in schools
How does culture influence the timing of puberty?
- Puberty begins earlier in cultures where good nutrition and medical care are widely
available. - Secular trend - Age of menarche decreasing
- Within countries, adolescent girls from affluent families menstruate earlier than
girls from poorer families. - Reaction range genes establish a range of possible development and environment determines where it takes place within that range
What are cultural responses to puberty?
- Majority of cultures have some kind of ritual initiation into adolescence
- Menarche often initiates a monthly ritual that lasts throughout a woman’s reproductive life.
- Puberty rituals for males do not focus on a particular biological event. Typically require the young man to display courage, strength, and endurance. Often violent. Seen as necessary to face life’s challenges as a man
What are the 3 genotypes and their environmental effects?
Passive genotype - environmental effects: Difficult to separate genetic and environmental influences
because parents provide both. Strong in early childhood, diminishes during adolescence
Evocative Genotype - environmental effects: Person’s inherited characteristics evoke responses from others
in their environment, –
effects remain stable from childhood through adulthood.
Active Genotype - environmental effects: People seek out environments that correspond to their
genotypic characteristics. Minimal during early childhood, Increases during adolescence.
What is a feedback loop?
A cycle which 2 or more bodily functions respond to and regulate each other
What is a set point?
A physiological level or setting that the body attempts to maintain through a self-regulating system
What is the hypothalamus?
part of the brain that controls the pituitary gland
What is the pituitary gland?
one of the cheif glands responsible for regulating levels of hormones in the body
What are gonads?
glands that secrete sex hormones (male-testes) (female-ovaries)
