Bio

• Puberty


  Period of lifespan in which an individual becomes capable of sexual reproduction
• Puberty


  • Three main changes: Rapid growth, Primary sex characteristics, Secondary sex characteristics
• Endocrine System


  Hormones regulated by the endocrine system lead to physical changes. No new hormones are produced and no new bodily systems develop at puberty. Includes ALL glands in your body that make hormones. Produces, circulates, and regulates hormone levels in the body.
• Hormones


  Substances secreted by adrenal glands
• Glands


  Organs that stimulate particular parts of the body to respond in specific ways
• Endocrine System


  • Gonadotropin-releasing hormone (GnRH) neurons: Neurons in the brain that play important roles at puberty. Hormonal feedback loop (Hypothalamic-Pituitary-Gonadal axis): Set point (e.g., thermostat) - When hormones dip below the "Set point" secretion of hormones increase
• HPG Feedback Loop


  HYPOTHALAMUS! PITUITARY! GONADS! GnRH LH and FSH Androgens and Estrogens NEGATIVE FEEDBACK LOOP
• The Endocrine System: HPG Feedback Loop
• Puberty: What else happens?
• Puberty: Changes at puberty in the brain that regulate the adrenal glands are also important because this is the same system that controls how we respond to stress.
• Puberty: Vulnerability to onset of psychological disorders. More responsive to stress. Excessive secretion of the hormone cortisol
• What Triggers Puberty?


  Onset is stimulated by an increase in kisspeptin. Leptin- stimulates it. Melatonin- suppresses it.
• Leptin


  Protein produced by fat cells. Must accumulate enough body fat. Rising levels of leptin signal hypothalamus to stop inhibiting puberty
• Melatonin


  Light. Evolutionary: Ultimate goal is to bear as many children as possible, so when someone has enough fat to bear children and senses the time is right to gather food (via light), time to start physical maturation.
• Activating Role


  At puberty
• Contextual influences on Puberty: Timing of physical changes in adolescence varies by Regions of the world, Socioeconomic class, Ethnic group, Historical era
• Example: Menarche (first menstruation) - U.S. average 12 years, Lumi (New Guinea) average 18 years
• Somatic Development


  • Average person grows about 10 inches during puberty! Adolescent Growth Spurt occurs about two years earlier for girls than for boys. Differences in adolescent body composition: Sex differences in muscle and fat - Boys have a muscle to fat ratio of about 3 to 1 and girls have a ratio of about 5 to 4.
• Physical Changes of Puberty: Adolescent Growth Spurt
• Physical Changes of Puberty: Body Dissatisfaction Among Adolescent Girls
• Physical Changes of Puberty: Sexual Maturation


  • Development of secondary sex characteristics. Measured in boys and girls by Tanner stages. Changes include: Growth of pubic hair, Changes in appearance of sex organs, Breast development.
• Sexual Maturation in boys

  • Growth of the testes and scrotum and presence of pubic hair. 1 year later, growth in height begins, accompanied by growth of penis and further development of pubic hair (coarser and darker). Facial hair, body hair and deepening of voice are later developments. Skin also become rougher and increased sweat glands (Acne, pimples, oily skin). Slight changes in breast development. At time of penis development, seminal vesicles, prostate and bulbourethral glands enlarge and develop. Male will experience their first ejaculation of seminal fluid. Boys are fertile before they develop an adult-like appearance.
• Sexual Maturation: Boys
• Sexual Maturation in Girls

  • Sexual development among girls is less regular. First sign is the elevation of the "breast bud". In 1/3 of females, pubic hair will precede breast development. Female breast undergoes the same changes regardless of breast size. Changes in shape of the areola and the nipple are better indicators of sexual maturation than breast size alone.
• Sexual Maturation: Girls
• VIDEOS ON FEMALE AND MALE PUBERTY
• Activity


  Parents often times need to describe puberty to their children when they start to experience it- and this can be tough! Pick one sex and discuss how you might describe the physical changes that the child is going to go through in terms that an early adolescent might understand.
• Variations in the Timing and Tempo of Puberty
• Genetic and Environmental Influences on Pubertal Timing


  • Differences in timing/rate among individuals in the same general environment result chiefly from genetic factors. Genetic predispositions: Upper and lower age limits, not a fixed absolute. Differences in the timing and tempo of pubertal maturation are a result of an interaction between genes and environment
• Individual Differences in Pubertal Maturation

  • Two key environmental influences: Nutrition, Health. Girls who are taller or heavier than their peers mature earlier. 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.
• Familial Influences on Pubertal Timing

  • Social factors in the home environment may influence the onset of maturation, especially in girls. Early pubertal maturation in girls is related to: Father-absent families, conflict-ridden households, having a stepfather, and sexual abuse. Tension in the family may induce stress, which, in turn, affects hormonal secretion. The presence of a stepfather may expose the adolescent girl to pheromones that stimulate pubertal maturation.
• Group Differences in Pubertal Maturation
• Declines in Age of Maturation
• The Immediate Impact of Puberty

  • Physical changes of puberty affect self-image, mood, and relationships with parents. This is true regardless of whether puberty occurs early or late. Self-esteem varies by gender and ethnicity. White girls are particularly likely to develop poor body images. Adolescent moodiness: More fluctuations throughout the day than adults. Not solely due to hormones. Greatly influenced by environmental factors, such as shifts in activities.
• Why are Adolescents So tired?!

  • Changes in sleep patterns: Emergence of a delayed phase preference in regards to sleep. Go to bed late and wake up late. Melatonin- plays a large role in puberty. Trend begins to reverse around age 20. Ironically, with these changes in sleep preferences, adolescents are least alert between the hours of 8-9 (school hours) and most alert after 3pm (after school). Fewer than 25% of adolescents get enough sleep.
• The Immediate Impact of Puberty
• Discussion


  We discussed some of the physical changes associated with puberty. What are some social changes that take place during puberty? How does puberty impact relationships with parents, peers, siblings and other individuals?
• The Immediate Impact of Puberty: Family Relationships
• Self-esteem varies by gender and ethnicity
• White girls are particularly likely to develop poor body images