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