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Chapter 2: Biological Changes

by: Rachel Vigil

Chapter 2: Biological Changes HDFS 311

Marketplace > Colorado State University > HDFS 311 > Chapter 2 Biological Changes
Rachel Vigil

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Finishes the last part of Chapter 1 and then moves on to Chapter 2 Talks about the endocrine system, adolescent growth spurt, primary/secondary sex characteristics.
Adoles/Early Adult Development
Rotner, Jaime Marie
Class Notes
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This 4 page Class Notes was uploaded by Rachel Vigil on Thursday September 1, 2016. The Class Notes belongs to HDFS 311 at Colorado State University taught by Rotner, Jaime Marie in Fall 2016. Since its upload, it has received 25 views.


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Date Created: 09/01/16
Week 2:  Complete transition to adulthood is complete when... o Accepting responsibility for oneself o Making independent decisions o Being financially independent  Individualism: o Learning to stand alone o Self-sufficient o Values of independence and self-expression o Values of individualism vs collectivism or interdependence  In other countries, being able to join the military (Israel) or being able to support their family/parents financially (Argentina/India & China) Chapter 2:  Growth spurt, pubic hair, underarm hair, acne, changes in body shape, breast development and menarche in girls, first ejaculation and facial hair in boys  Average time from start to finish of puberty is 4 years.  Puberty, latin word pubescew, “to go hairy”  Body undergoes a biological revolution that dramatically changes the adolescent’s anatomy, physiology and physical appearance.  Small weight gain before puberty begins  Endocrine System o Consists of glands in various parts of the body. o Glands release chemicals called hormones into the bloodstream and the hormones affect the development and functioning of the body o Hormonal change begins in the hypothalamus  Begins to increase its production of GnRH (gonadotropin- releasing hormone)  Increase occurs once a threshold level of body fat is reached o Fat cells produce a protein, leptin that provides the signal to the hypothalamus. o GnRH affects the pituitary gland  Pituitary gland is an inch long at the end of the brain stem. o Pituitary gland increases ACTH o Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) stimulate  FSH and LH stimulate the development of gamete’s  Eggs in the ovaries  Sperm in the testes  Gonads increase the production of sex hormones  Two classes of sex hormones o Estrogen and androgens  MVP of estrogen is estradiol  8X increase in levels of estrogen than before in women  MVP of androgen is testosterone  20X increase in levels of testosterone before puberty in men o Set point is like a thermostat, when the body drops below it, it increases the amount of androgens/estrogens.  Adolescent growth spurt o Girls grow 3.5 inches/yr o Males grow 4.1 inches/yr  Grows mature two years ahead of boys  Asynchronicity- some parts of the body grow faster than the others.  Feet, hands and head grow first followed by the arms and legs  Torso, chest and shoulder are the last to grow  Muscle growth occurs. o Muscle to fat ratio for guys- 3:1 girls- 5:4  Shoulders widen more for boys than girls  Hips widen more for girls than boys  Heart becomes larger o Girls heart rate is about 5 beats per minute faster than boys  Vital capacity (amount of air that can be exhaled after a deep breath) increases for boys more so than girls.  Body Mass Index (BMI) ratio of height to weight  14% 12-17 Americans are obese  Peak bone mass happens in emerging adulthood as well as VO2 max.  Primary Sex Characteristics o Directly relate to reproduction o Boys: Primary- production of sperm, development of sex organs o Girls: Primary- production f eggs, development of sex organs  Secondary Sex Characteristics o Other bodily changes of puberty, not including the ones related directly to reproduction o Boys: Secondary- Hair growth, skin becomes rougher, sweat glands increase production o Girls: Primary- production f eggs, development of sex organs + breast buds  Females are born with 400,000 immature eggs in each ovary o This number decreases to 80,000 during puberty o Girls reach menarche, one egg develops into a ovum (mature egg) o Females release 400 eggs over the course of their reproductive lives.  Males have no sperm in their testes when they are born o They don’t produce any until they reach puberty. o Spermarch= the first production of sperm  On average happens at age 12 o 30-500 million sperm in a typical male ejaculation  Girls: Downy pubic hair--> Appearance of breast buds--> growth spurt--> growth of sexual and reproductive organs --> Menarche-->secretion of increased skin oil and sweat--> development of underarm hair  Boys: Growth of testes--> Appearance of pubic hair --> growth spurt--> increased growth of penis--> deepening of the voice--> secretion of increased skin oil and sweat--> development of facial hair  Kikuyu in Kenya: Boys begin puberty before girls o African American Girls: 50% start as early as 8 in comparison to 15% in white girls  Chinese: pubic girls develop 2 years after breast buds.  Similar environments variations in the order and timing of pubertal events appear to be due to genetics  The environment adolescents experience differs greatly both within and between countries. o - Diet/level of nutrition o -Food Production o -Medical Care o Stress  Ellis and Garber (2000) found that history of psychology in result in earlier pubertal maturation in daughters. o A mediator is a variable that explains the process in correlation. High levels of conflict was influencing the timing of puberty. o DIdnt impact sons as negatively  Belskey et al found that (2007) negative parenting is correlated with early menarche o Especially harsh control o Also found that parent-child conflict and coercion predict earlier pubertal timing for boys and girls.  Early parental involvement regulates timing (Romans et al 2003)  Effects of early maturation is especially negative for girls o Girls are at risk for  Depressed mood  Negative Body image  Eating disorders  Substance use  Delinquency  School Problems o Girls are valued for thinness in a females appearance. This explains why they have body image issues o Early physical development draws the attention of older boys, who introduce them to substances, delinquency etc.  Early maturing girls enter marriage and parenthood earlier o Age 24, women have more psychological and social problems  Late maturing girls suffer from teasing and negative body image  Early maturing boys have o More favorable body image o Higher popularity o They tend to be more involved with substance use, delinquency, early sex and emotional distress


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