A D OLESCEN CE 12E L A U R E N C E S T EIN B E R G CHAPTER 1 BIOLOGICAL TRANSITIONS Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education CHAPTER 1 OVERVIEW 1 Puberty An Overview The Endocrine System What Triggers Puberty How Hormones Influence Adolescent Development Somatic Development The Adolescent Growth Spurt Sexual Maturation The Timing and Tempo of Puberty Variations in the Timing and Tempo of Puberty Genetic and Environmental Influences on Pubertal Timing Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education CHAPTER 1 OVERVIEW 2 The Psychological and Social Impact of Puberty The Immediate Impact of Puberty The Impact of Specific Pubertal Events The Impact of Early or Late Maturation Obesity and Eating Disorders Obesity Anorexia Nervosa Bulimia and Binge Eating Disorder Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education PUBERTY AN OVERVIEW Puberty Term comes from Latin word pubertas adult It is the period during which an individual becomes capable of sexual Hormones regulated by the endocrine system lead to physical No new hormones are produced and no new bodily systems develop reproduction changes at puberty Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education THE ENDOCRINE SYSTEM 1 This is the system responsible for producing regulating and circulating hormones in the body It produces circulates and regulates hormone levels in the body This system tells the body when hit is time to start puberty No new hormones are produced Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education WHAT TRIGGERS PUBERTY 1 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 Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education WHAT TRIGGERS PUBERTY 2 Onset of puberty is stimulated by certain brain chemicals Kisspeptin A brain chemical believed to trigger the onset of puberty 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 Other factors influence onset of puberty Genes predispose onset at a certain age More fat cells and more exposure to light trigger puberty earlier Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education HOW 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 Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education SOMATIC DEVELOPMENT Effects of hormonal changes of puberty are remarkable Individual enters puberty looking like a child within 4 years or so has the physical appearance of a young adult The average individual grows about 10 inches taller matures sexually and develops an adult proportioned body The brain changes in size structure and function at puberty Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education THE ADOLESCENT GROWTH SPURT 1 The simultaneous release of growth hormones thyroid hormones and androgens stimulates rapid gains in height and weight Adolescent growth spurt The dramatic increase in height and weight that occurs during puberty Peak height velocity The point at when the adolescent is growing most rapidly Epiphysis The closing of the ends of the bones which terminates growth after the adolescent growth spurt has been completed Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education THE ADOLESCENT GROWTH SPURT 2 Figure 1 2 a Height in centimeters at different ages for the average male and female youngster b Gain in height per year in centimeters for the average male and female youngster Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education Access the text alternative for these images THE ADOLESCENT GROWTH SPURT 3 Body Dissatisfaction Among Adolescent Girls Sex Differences in Muscle and Fat 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 Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education SEXUAL MATURATION 1 Puberty brings a series of developments associated with sexual maturation 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 Tanner stages A widely used system that describes the five stages of pubertal development Copyright 2020 McGraw Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw Hill Education SEXUAL MATURATION 2 Table 1 1 The sequence of physical changes at puberty Source B Goldstein 1976 Age of First Appearance Years for Girls 1 7