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Lecture: 05 Date: 09.15.04 Audio: Ch. 1 & 2 (mono) Human Development from Adolescence to Old Age
Lecture 5: Physical Development in Adolescence Today:
Definition of the period we call "Adolescence" Physical Development Introduction to the period we call "Adolescence" Adolescence is a social construction which has emerged relatively recently in human history not necessary a universal stage of development. Some distinctions within the period: Preadolescence roughly ages 1012 Early adolescence roughly ages 13 14 Late adolescence or "emergent adulthood" roughly ages 1820 Rites of passage are common in many traditional cultures.
Some examples: Traditional rites of passage often involve: Separating the youth from family. The beginning of the nudity taboo. Physical mutilation and trials of endurance. Physical Development during Adolescence
The physical aspects of puberty Factors that influence the timing of puberty How teens experience these changes. The reproductive endocrine system controls pubertal changes.
Pituitary Gland Hypothalamus
Thyroid Gland Adrenal Glands Gonads (sex glands) Puberty is suppressed until: The hypothalamus allows hormones to be circulated in greater quantities. Between ages 610, the adrenal glands gradually increase the level of androgens that are released (first sexual attractions often at this time) The pituitary gland releases LH and FSH which signals the sex glands (overies or testes) to mature and produce hormones (gonadarchy) Timing of this process is sensitive to body fat. First signs of puberty: In boys: enlargement of the testes and growth of the scrotal sac In girls: usually breast development ("budding"), but can be either the height spurt or the appearance of pubic hair. Average age ranges of major pubertal changes in North American Girls Event
Breasts begin to "bud" Height spurt begins Pubic hair appears Peak strength spurt Peak of height spurt Menarche Adult height reached Average
10 10 10.5 11.6 11.7 12.8 13 Range
613 813 614 9.514 10135 1016.5 1016 Average age ranges of major pubertal changes in North American Boys Event Average Range Testes begin to enlarge 11.5 913.5 Pubic hair appears 12 1216 Penis begins to enlarge 12 1114.5 Height spurt beings 12.5 10.516 Spermarche occurs 13 1216 Peak of height spurt 14 12.515.5 Facial hair begins to grow 14 12.515.5 Voice begins to deepen 14 12.515.5 Peak of strength spurt 15.3 13.517.5 Adult height reached 15.5 13.517.5 Precocious puberty has recently been re defined, after the findings from a largescale study of more than 17,000 girls. Some normallydeveloping girls show breast changes as early as 67. Delayed puberty having nothing happening in girls by age 13, or in boys by about 13 Secondary Sex Characteristics Include such things as the development of breast, pubic hair, axillary and facial hair, changes in proportion of hips and shoulders, etc. The growth spurt Peak growth occurs at different ages for boys and girls: Increase in body fat, by age Increase in muscle mass, by age Vocal changes: In boys, voice "break" at about 13 and voice "change" at 14 The vocal cords roughly double in length, lowering the pitch about an octave Girls' voices deepen as well. The Timing of Puberty
The secular trend over time. Contrasts in relation to environmental conditions The average age of puberty varies considerably around the world It's relatively early in the U.S., and relatively late in parts of the less developed world. We've seen a secular trend toward earlier puberty over the last 150 years. Nutrition and body fat influence the timing of puberty Other factors that appear to influence the timing of puberty: 1. 2. 3. Proximity to males: Presence of a father with which the girl has a close relationship : Later Fatherabsent home: Earlier Home with an unrelated male: Earlier Family and other stressors: Earlier Exposure to PCB's: Earlier Mortality and health issues
Death rates low, and dropping Males = 3 times more likely to die in adolescence than females Car crashes #1 cause of death for middle and late adolescence Low rates of disability and chronic disease "Serious problems" versus "common problems" Some very common health concerns: (Teens who sleep less are more likely to Fatigue and sleep deprivation show depressive symptoms and/or low self esteem.) Reduced health monitoring by parents. Acne How teens experience puberty: A normative, agegraded event with high variability in age. Menarche associated with "taboos" in many traditional cultures Teens tend not to talk about their experiences. Girls tend to be less happy with their bodies than boys. How does the timing of puberty affect other aspects of development? For boys: early maturers often enjoy a social status advantage. But earlymaturing boys are more likely to engage in substance use and early sexual activity. For girls: more friction with parents in those 7th graders who had been menstruating for a full year. Earlymaturing girls show less social poise, and tend to be more upset about menarche. Earlymaturing girls are at grater risk.... Earlymaturing girls are more likely to draw sexuallycharged responses from boys and men. Earlymaturing girls tend, initially, to be more popular with other girls as well as boys. But they are at greater risk for a number of potential health problems: smoking, drinking, drug use, eating disorders, depression, and earlier sexual activity. ...
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- Spring '04
- Pubic hair, Height spurt, major pubertal changes