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Chapter 2

PSY 3105 Chapter Notes - Chapter 2: Adrenal Gland, Feedback, Pubic HairPremium

5 pages91 viewsFall 2018

Department
Psychology
Course Code
PSY 3105
Professor
David Collins
Chapter
2

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PSY3105B Dr. David W. Collins
Psychology of Adolescence
Ch2 Puberty and Physical Development 12.09.18
Ch 1 MC What distinguishes a pop of a developing country from one of a developed country?
lower proportion of older people in the population
Puberty: body undergoes biological revolution that dramatically changes the adolescent’s anatomy,
physiology, and physical appearance
Hormones, Puberty, and Growth
Endocrine System - glands that regulate production of hormones that control growth
Hypothalamus monitor levels of androgens and estrogens in the bloodstream
Pituitary gland responds to the reduction in GnRH by reducing production of FSH, LH
Gonads ovaries and testes, they produce sex hormones
o lower levels of FSH and LH = reducing the amnt of sex hormones produced
o estrogens high in females, androgens high in males
o Adrenal glands release androgens as well DHEA, hormone that starts puberty and
associated with secondary sex characteristics (pubic hair growth)
Set point = sex hormones reach an optimal level and the hypothalamus reduces GnRH to being
this process
HPG (hypothalamus-pituitary gonads) Axis
Hypothalamus monitors levels of sex hormones via endocrine system; Feedback loop
o When sex hormone levels are too low hypothalamus signals pituitary with GnRH >
Pituitary signals gonads with increase production of LH and FSH to produce more sex
hormones
o sex hormone levels continue to increase until it reaches set point, then hypothalamus
decrease production of GnRH to stop feedback loop
Responds to hormone lvls in the blood each hormone has set point, particular lvl to maintain
At puberty, set point for hormones rises; increased hormones initiate physical and sexual dev
o Nature’s default is female, must add androgen to become male
Increase Production of GnRH hypothalamus is less sensitive to hormones, and thinks body needs more
Gradually increase production of gonadotropin-releasing hormone and make new set-point
New set point needed to meet threshold of body weight and body proportion
o ~23% body fat when menarchy occurs, more estrogen available (more mechs available)
fat cells produce leptin and provides the signal to the hypothalamus
o associated with increase of weight and onset of puberty in both sex
Insulin-like growth factor substance produced in liver that may be liked to onset of puberty
o IGF-I increases at puberty and returns to much lower levels afterward
Physical Development During Adolescence
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Adolescent growth spurtrapid increase in size; Girls start growth spurt two years earlier
Girls spurt from 10-16yo; boys spurt from 12-18yo
o 2-yr delay in boys allow them to grow at their childhood rate of 5cm/yr, they start
growth sport at taller starting point compared to girls = boys taller than girls
Height, weight, muscles, fat, body proportions change prior to puberty, boys and girls are very
similar in muscle mass
o Body fat increases more for girls than boys during puberty
o Boys produce more testosterone (linked to muscle growth) and develop more muscle
mass than girls; better ability to rid of lactic acid, and develop better lung capacity
Asynchronicitybody parts develop at different rates, extremities grow before the trunk
Sexual Development During Adolescence
Reproductive organs mature Ovaries (girls) produce egg cells or ova, Testes (boys) produce sperm cells
Genitals (penis, vagina) become more adult-like thicken, deepen in colour, get longer
Secondary characteristicsbreasts, penis and scrotum growth, spread of pubic hair
Evolutionary theory men produce sperm earlier b/c biological costs for them is low, therefore
start reproduction ops earlier; girls have a limited amount of eggs in a lifetime, thus starting
later allows for more time for development and maturation of the body for safe fetal growth
Tanner (physician) stages of puberty rate development of secondary sex characteristics during puberty
Order of Pubertal Events seq is fairly reg, timing is not (varying start time and duration)
o Girls appearance of breast buds, downy pubic hair, growth spurt, growth of sexual and
reproductive organs, menarche, secreting of increased skin oil and sweat, dev of
underarm hair
o Boys growth of testes, appearance of pubic hair, growth spurt, increased growth of
penis, deepening of voice, secretion of increased skin oil and sweat, dev of facial hair
Pubertal Caveat
Virtually all the studies considered in the order of pubertal development have been conducted
with White adolescents in the West
Some studies demonstrate the variations that may exist in other groups:
Kikuyu culture in Kenya - A reversal of the Western pattern
o Boys show the first physical changes of puberty before their female peer
African American Girls
o Many African American girls at age 8 (50%) were found to begin developing breast buds
and pubic hair considerably earlier than White girls (15%)
Chinese Girls Pubic hair began to develop in most girls about 2 years after the development of
breast buds and only a few months before menarche
o In sharp contrast to the Western studies, which found pubic hair and breast buds
developed together about 2 years before menarche
Menarche and Secular (change over time) Trend in recent centuries, puberty occur at younger ages
Menarche affected by nutrition, availability of health care, and levels of stress
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