Adolescent Growth and Development
Adolescence is the time between the beginning of sexual maturation (also known as puberty, from the Latin pubertas, meaning adult) and the beginning of adulthood. Adolescence usually spans the years between ages 13 and 19. Adolescence includes physical growth and emotional, psychological, and mental change. Psychological maturation occurs as the child acquires adult-like behavior. During this period, adolescents are expected to become capable of adult behavior and response. Adolescence is a period of many transitions. During the teen years, adolescents experience changes in their physical development at a rate of speed unparalleled since infancy. Physical development includes rapid gains in height and weight. During a one-year growth spurt, boys and girls can gain an average of 4.1 in. (10.4 cm) and 3.5 in. (8.9 cm) in height, respectively. This spurt typically occurs two years earlier about for girls than for boys. Weight gain results from increased muscle development in boys and body fat in girls.
Hormones play two different roles in adolescent development, the organizational role and the activational role. The organizational role is the ability of hormones to generate different patterns of behavior in the male and in the female brain, respectively. Already in the prenatal age, the hormones organize the brain differently. The activational role is the ability to initiate the modifications related to puberty and to differentiate them for male and females. During and just before puberty, the hypothalamus both stops the inhibition upon the factors able to initiate puberty and begins to produce substances that set the puberty in motion. The first signal begins due to higher concentrations of leptin, a protein produced by adipocytes of the fat tissue. The hypothalamus stimulates the hypophysis to secrete hormones able to promote the overall growth of the body and to maturate the gonads, as well as the adrenal cortex and thyroid. Scientists suggest that adrenal cortex maturation is involved in sexual attraction. Hormone concentrations are due to gland activations that are controlled by several mechanisms of feed-back.
The development of primary sex characteristics includes the further maturing of the gonads, the testis in boys, and the ovaries in girls. In both sexes, hormonal regulation of reproduction is regulated by the brain. Until eight weeks of gestation, the brain is organized in a female direction irrespectively with the gender of the fetus. Successively, testosterone, for example, organizes the male brain in patterns of behavior, many of which may not appear until much later. Hypothalamic gonadotropin releasing hormone (GnRH) controls release of both luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH acts primarily on endocrine cells of the gonads. FSH acts primarily on gamete-producing cells. Both sexes produce androgens and estrogens. Testosterone, the main androgen produced in the testis is converted to dihydrotestosterone (DHT) in many tissues. Estradiol, the main estrogen, is made from testosterone by the action of the enzyme aromatase. Both the ovary and testis produce peptide hormones that have feedback effects on the hypophysis. Inhibins are hormones that inhibit FSH secretion. Activins stimulate FSH secretion as well as spermatogenesis, oocyte maturation. Children (both males and females) with a deficiency of GnRH will not mature in the absence of gonadotropin stimulation due to lower levels of androgens and estrogens.
Secondary sex characteristics can be considered traits which give an individual an advantage over its rivals in courtship. During puberty, changing hormonal levels play a role in activating the development of secondary sex characteristics. These include: (1) growth of pubic hair (pubarche); (2) Growth of the breasts in girls (thelarche) (3) menarche (first menstrual period for girls) or penis growth (for boys); (4) voice changes (for boys); (5) growth of underarm hair; (5) facial hair growth (for boys);(6) nighttime ejaculations (nocturnal emissions; "wet dreams" for boys) and (7) increased production of oil, increased sweat gland activity, and the beginning of acne.
Normal growth is categorized in a range used by pediatricians to gauge how a child is growing. The following are some average ranges of weight and height, based on growth charts developed by the Centers for Disease Control and Prevention (CDC): briefly, at 12 years of age a male, should be 54-63.5 in. (1.37-1.6 m) and a female 55-64 in. (1.4-1.6 m) The weight would be 66-130 lb. (29.9-58.9 kg) and 68-136 lb. (30.8-61.7 kg) respectively. At 18-years-old, a male would be 65-74 in. (1.7-1.9 m) tall and a female 60-68.5 in. (1.5-1.7 m). The weight would be 116-202 lb. (52.6-91.6 kg) and 100-178 lb. (45.4-80.7 kg), respectively. Growth not only involves length and weight of a body, but also includes internal growth and development, including the brain. Growth also affects different parts of the body at different rates; the head reaches almost its entire size by age one. Throughout childhood, a child's body becomes more proportional to other parts of his/her body. Growth is complete between the ages of 16 and 18, at which time the growing ends of bones fuse. Although a child may be growing, his/her growth pattern may deviate from the normal. Ultimately, the child should grow to normal height by adulthood. Teens frequently sleep longer. Research suggests that teens actually need more sleep to allow their bodies to conduct the internal work required for such rapid growth. On average, teens need about 9.5 hours of sleep a night.
Teens' brains are not completely developed until late in adolescence. Studies suggest that the connections between neurons affecting emotional, physical, and mental abilities are incomplete. This could explain why some teens seem to be inconsistent in controlling their emotions, impulses, and judgments. The advances in thinking can be divided into several areas, including the development of advanced reasoning skills, as well as formulation and testing of hypotheses, demonstrating agreement or disagreement, questioning, giving examples, and making distinctions and connections. Advanced reasoning skills include the ability to think logically about multiple options. It includes the ability to think hypothetically. Adolescents also develop abstract thinking skills. Abstract thinking includes faith, beliefs and spirituality. Additionally, adolescents develop the ability of "meta-cognition." Meta-cognition is awareness of one's own thinking process, and involves the ability to think about how one is perceived by others. Meta cognition involves of skills that are genuinely transferable and can, therefore, be applied in different settings, resulting in an improved ability to learn.
Teens demonstrate a heightened level of self-consciousness. Teens tend to believe that everyone is as concerned with their thoughts and behaviors as they are. This leads teens to believe that they have an "imaginary audience" of people who are always watching them. Teens tend to believe that no one else has ever experienced similar strong feelings and emotions. Teens tend to exhibit a "justice" orientation. They are quick to point out inconsistencies between adults' words and their actions. They have difficulty seeing shades of gray. They see little room for error.
There are four recognized psychosocial issues that teens normally deal with during their adolescent years. These include: 1) Establishing an identity. This has been called one of the most important tasks of adolescents. Over the course of the adolescent years, teens begin to integrate the opinions of influential others (e.g., parents, other caring adults, friends, etc.) into their own likes and dislikes. 2) Establishing autonomy. Some people assume that autonomy refers to becoming completely independent from others. They equate it with teen "rebellion." Rather than severing relationships, however, establishing autonomy during the teen years actually means becoming an independent and self-governing person within relationships. Autonomy is a necessary achievement if the teen is to become self-sufficient in society. 3) Establishing intimacy. Many people, including teens, equate intimacy with sex. In fact, intimacy and sex are not the same. Intimacy is usually first learned within the context of same-sex friendships, then utilized in romantic relationships. Intimacy refers to close relationships in which people are open, honest, caring, and trusting. Friendships provide the first setting in which young people can practice their social skills with those who are their equals. It is with friends that teens learn how to begin, maintain, and terminate relationships, practice social skills, and become intimate. 4) Becoming comfortable with one's sexuality. The teen years mark the first time that young people are both physically mature enough to reproduce and cognitively advanced enough to think about sexuality. Given this, the teen years are the prime time for the development of sexuality. How teens are educated about and exposed to sexuality will largely determine whether or not they develop a healthy sexual identity. More than half of most high school students report being sexually active. Many experts agree that the mixed messages teens receive about sexuality contribute to problems such as teen pregnancy and sexually transmitted diseases.
Teens begin to spend more time with their friends than their families. It is within friendship groups that teens can develop and practice social skills. Teens are quick to point out to each other behaviors which are acceptable and which are not. It is important to remember that even though teens are spending increased amounts of time with their friends, they still tend to conform to parental ideals when it comes to decisions about values, education, and long-term plans. Teens may become involved in multiple hobbies or clubs. In an attempt to find out where they excel, teens may try many activities. Teens' interests also change quickly. Teens may become more argumentative. Teens may question adults' values and judgments. When teens don't get their way, they may say, "you just don't understand." Teens may begin to interact with parents as people. Even though they may not want to be seen with parents in public, teens may begin to view parents more as people. They may ask more questions about how a parent was when he or she was a teen. They may attempt to interact with adults more as equals.
Teens may be clumsier because of growth spurts. If it seems that a teen's body is all arms and legs, the perception is correct. During this phase of development, body parts don't all grow at the same rate. This can lead to clumsiness as the teen tries to cope with limbs that seem to have grown overnight. Teens can appear gangly and uncoordinated. Teenage girls may become overly sensitive about their weight. This concern arises because of the rapid weight gain associated with puberty. Sixty percent of adolescent girls report that they are trying to lose weight. A small percentage of adolescent girls (one to three percent) become so obsessed with their weight that they develop severe eating disorders such as anorexia nervosa or bulimia. Anorexia nervosa refers to starvation; bulimia refers to binge eating and vomiting. Teens may be concerned because they are not physically developing at the same rate as their peers. Teens may be more developed than their peers ("early-maturers") or less developed than their peers ("late-maturers"). Being out of developmental step with peers is a concern to adolescents because most just want to fit in. Early maturation affects boys and girls differently. Research suggests that early maturing boys tend to be more popular with peers and hold more leadership positions. Adults often assume that early maturing boys are cognitively mature as well. This assumption can lead to false expectations about a young person's ability to take on increased responsibility. Because of their physical appearance, early maturing girls are more likely to experience pressure to become involved in dating relationships with older boys before they are emotionally ready. Early maturing girls tend to suffer more from depression, eating disorders, and anxiety.
Teens may feel awkward about demonstrating affection to the opposite sex parent. As they develop physically, teens are beginning to rethink their interactions with the opposite sex. An adolescent girl who used to hug and kiss her dad when he returned home from work may now shy away. A boy who used to kiss his mother good night may now wave to her on his way up the stairs. Teens may ask more direct questions about sex. At this stage, adolescents are trying to figure out their sexual values. Teens often equate intimacy with sex. Rather than exploring a deep emotional attachment first, teens tend to assume that if they engage in the physical act, the emotional attachment will follow. They may ask questions about how to abstain without becoming embarrassed or about how they will know when the time is right. They may also have specific questions about methods of birth control and protection from sexually transmitted diseases.
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Adolescent Growth and Development from World of Anatomy and Physiology. ©2005-2006 Thomson Gale, a part of the Thomson Corporation. All rights reserved.
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