GROWTH AND DEVELOPMENT

Adolescence is influenced by CNS-mediated hormonal ac­tivity. Physical growth occurs simultaneously with sexual maturation. Adolescents typically experience gains of 20% to 25% in linear growth. An adolescent growth spurt last­ing approximately 24 to 36 months accounts for most of this somatic growth. The age at onset, duration, and ex­tent of the growth varies between males and females and among individuals. In females, the growth spurt usually begins around 10 to 14 years of age. It begins earlier in fe­males than in males and ends earlier, with less dramatic changes in weight and height. Females usually gain ap­proximately 5 to 20 cm in height and 7 to 25 kg in weight. Most females have completed their growth spurt by 16 or

ADOLESCENT PERIOD

The adolescent period, which extends from 13 through 19 years of age, is a time of rapid changes in body size and shape, and physical, psychological, and social functioning.

Adolescence is a time when hormones and sexual matura­tion interact with social structures in fostering the transition from childhood to adulthood.

The development tasks of adolescence include achieving independence from parents, adopting peer codes and mak­ing personal lifestyle choices, forming or revising individual body image, and coming to terms with one's body image.

17 years of age. Males begin their growth spurt later, but it usually is more pronounced, with an increase in height of 10 to 30 cm and an increase in weight of 7 to 30 kg. Males may continue to gain in height until 18 to 20 years of age. Increases in height are possible until approximately 25 years of age.³⁴

The changes in physical body size have a characteris­tic pattern. Growth in arms, legs, hands, feet, and neck is followed by increases in hip and chest size and several months later by increases in shoulder width and depth and trunk length. The period of these rapid and dramatic changes may be difficult for the adolescent and parents. Shoe size may change several times over several months. Although brain size is not significantly increased during adolescence, the size and shape of the skull and facial bones change, making the features of the face appear to be out of proportion until full adult growth is attained.⁶,³⁴ Muscle mass and strength also increase during adolescence. Sometimes, there maybe a discrepancy between the growth of bone and muscle mass, creating a temporary dysfunc­tion with slower or less smooth movements resulting from the mismatch of bone and muscle. Body proportions undergo typical changes during adolescence. In males, the thorax becomes broader, and the pelvis remains narrow. In females, the opposite occurs: the thorax remains nar­row, and the pelvis widens.

Organ systems also undergo changes in function, and some have changes in structure. The heart increases in size as the result of increased muscle cell size. Heart rate de­creases to normal adult rates, whereas blood pressure in­creases rapidly to adult rates. Circulating blood volume and hemoglobin concentration increase. Males demonstrate greater changes in blood volume and higher hemoglobin concentrations because of the influence of testosterone and the relatively higher muscle mass.

Skin becomes thicker, and additional hair growth oc­curs in both sexes. Sebaceous and sweat gland activity in­creases. Plugged sebaceous glands frequently result in acne (see Chapter 61). Increased sweat gland activity results in perspiration and body odor. The eyes undergo changes that may contribute to increased myopia. Auditory acuity peaks in adolescence and begins to decline after approxi­mately 13 years of age.

Voice changes are of significant importance during adolescence for both sexes; however, the change is more pronounced in males. The voice change results from the growth of the larynx. There is more growth of the larynx in males than in females. The paranasal sinuses reach adult proportions, which increases the resonance of the voice, adding to the adult sound of the voice.⁶,³⁴

Changes in the endocrine system are of great impor­tance in the initiation and continuation of the adolescent growth spurt. The hormones involved include growth hor­mone (GH), thyroid hormones, adrenal hormones, insulin, and the gonadotropic hormones. GH regulates growth in childhood but is essentially replaced by sex hormones as the primary impetus for growth during adolescence. The exact role of GH in the adolescent growth spurt is unclear. Thyroid hormone, a significant hormone in the regulation of metabolism during childhood, continues to be important during adolescence. The relation of thyroid hormone to the other hormones and its role in the adolescent growth spurt is unclear. The thyroid gland becomes larger during adolescence, and it is believed that production of thyroid hormones is increased during this period. Insulin is nec­essary for appropriate growth at all stages, including ado­lescence. Insulin must be present for GH to be effective. The pancreatic islets of Langerhans increase in size during adolescence.⁶,³⁴

The anterior pituitary gland produces the gonado­tropic hormones, follicle-stimulating hormone, and lu-teinizing hormone. These hormones influence target organs to secrete sex hormones. The ovaries respond by secreting estrogens and progesterone, and the testes re­spond by producing androgens, resulting in the matura­tion of the primary sex characteristics and the appearance of secondary sex characteristics. Primary sex characteristics are those involved in reproductive function (i.e., internal and external genitalia). The secondary sex characteristics are the physical signs that signal the presence of sexual maturity but are not directly involved in reproduction (i.e., pubic and axillary hair). Androgens initiate the be­ginning of the growth spurt. Sex hormones, including an­drogens, also conclude height growth by causing bone maturity, epiphyseal closure of bones, and discontinua­tion of skeletal growth.

The dramatic and extensive physical changes that occur during the transition from child to adult are matched only by the psychosocial changes that occur during the adolescent period. It is not possible to develop one guide that adequately describes and explains the tremendous changes that occur during adolescence because the experi­ence is unique for each adolescent. There are, fortunately, some commonalities within the process that can be used to facilitate understanding of these changes. The transition from child to adult is not a smooth, continuous, or uniform process. There are frequent periods of rapid change, fol­lowed by brief plateaus. These periods can change with little or no warning, which makes living with an adolescent difficult at times.

One thing that persons who deal with adolescents must remember: no matter how rocky the transition from child to adult, adolescence is not a permanent disability! Eighty percent of adolescents go through adolescence with little or no lasting difficulties. Health care professionals who care for adolescents may need to offer support to wor­ried parents that the difficulties their adolescent is experi­encing, and that the entire family is experiencing as a result, may be normal. The adolescent also may need re­assurance that his or her feelings are not abnormal.^6,34

Common concerns of adolescents include conflicts with parents, conflicts with siblings, concerns about school, and concerns about peers and peer relationships. Personal identity is an overwhelming concern expressed by adoles­cents. Common health problems experienced by adoles­cents include headache, stomachache, and insomnia. These disorders may be psychosomatic in origin. Adolescents also may exhibit situational anxiety and mild depression. The health care worker may need to refer adolescents for spe­cialized counseling or medical care if any of the health care concerns are exaggerated.

Parents of adolescents also may have concerns about their child during the adolescent period. Common concerns related to the adolescent's behavior include rebelliousness, wasting time, risk-taking behaviors, mood swings, drug experimentation, school problems, psychosomatic com­plaints, and sexual activity.³⁴ Adolescence is a period of transition from childhood to adulthood and is often filled with conflicts as the adolescent attempts to take on an adult role. Open communication between the adolescent and family can help make the transition less stressful; how­ever, communication between parents and adolescents is more difficult.