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Puberty is defined as,"a period of rapid skeleltal and sexual maturation that occurs mainly in early adolescense". (Santrock, 1999)

Somewhere between the ages of 8 and 12 most youngsters and their parents begin to think about "life as a teenager". For many, adolescence is synonymous with puberty. Most are curious to know more about how it happens? What physical changes occur? Are there psychological and social changes as well?

Puberty is characterized by the onset of hormonal activity which is under the influence of the central nervous system, especially the hypothalamus and the pituitary gland, both of which are located at the base of the brain. The major consequences are the increased elaboration of the adrenocortical and gonadal hormones and the production of mature ova and spermatozoa (Oettinger, 1968). The hormones secreted at this time are testosterone and estradiol (Santrock, 1999). The pituitary gland drips androgen and estrogen which are sex hormones that circulate throughout the young body. The hypothalamus prevents this gland from secreting too much of these, but as children age, the hypothalumus can't regulate all the hormones being produced and the onset of puberty begins. These hormonal and body changes occur, on the average, about 2 years earlier in females (10 1/2 years of age) than in males (12 1/2 years of age).

PHASES OF PHYSICAL GROWTH

Puberty can be broken into three major time periods or phases. These are:

Prepubertal	This is the time before age thirteen in boys and before eleven in girls. Its duration for boys is approximately a year and a quater, and for girls it is slightly shorter.
Pubertal	This period contains the most nocticable growth spurt. It occurs between age thirteen and fifteen for males and between eleven and fourteen in females.
Postpubertal	Last for a year and a half in girls and is somewhat shorter in the case of boys.

Three main factors affect the timing of puberty. These are:

• Body weight and proportion of fat
• Genes
• Secular Trend (the tendency of each new generation to experience puberty earlier than their parents)

PHYSICAL CHANGES

The age at which puberty is declared to begin depends in part upon the criteria of onset. The most common physical markers in girls include breast budding and the beginning growth of pubic hair. These occur at an average age of 10 to 11 years. Menstration occurs at about 11 to 13 years of age. In boys, the beginning of growth of pubic hair and the enlargement of the testicles occurs usually during the ages of 12 to 16 years, whereas enlargement of the penis and ejaculation take place from 13 to 17 years of age (Oettinger, 1968).

Early and Late Maturers

Not all adolescents begin puberty at the same time. In fact, there is a great deal of variation. Some youngsters may begin and complete their pubertal changes before another child begins experiencing any physical changes. This is sometimes a concern to the child and the parent, but it is all very normal.

Body build varies according to age of maturing. Late maturing boys have been found to have a of slinder build, longer legs, and are relatively weaker at the ages when they are lagging in size behind their classmates. Early maturing boys, on the other hand, are usually large, strong, and have broad hips. Late maturing girls have slightly broader hips than those who mature early. Late maturing individuals of both sexes tend to have slightly broader shoulders than those who mature early (Bayley, 1943).

Body Proportions

The different parts of the body grow at different rates and reach their maximum development at different times. For example:

• The period of most rapid growth for leg length, sitting and standing height, and chest depth and breadth comes within a relatively short time of accelerated development (Shuttleworth, 1937).
• Measurements of boys reveal that stem length (length of the head and trunk with legs flexed to 25- degree angle as opposed to sitting height) grows less in the prepuberty and first half of the puberty period and more in the second half of the puberty period and postpuberty period than is true of leg length.
• There is a strong tendency for short- stemmed boys in the prepuberty perod to remain consistanly short- stemmed (Stolz and Stolz, 1951).

This process is referred to as asnychrony.

Primary Sex Characteristics

Primary sex characteristics refer to those sex organs and processes whose function is to produce offspring. During childhood the sex organs of both boys and girls are small in size, are inconspicuous, and do not produce germ cells for reproduction. With the onset of puberty all this is changed. The sex organs grow in size. They become more conspicuois, especially in the case of boys. They also become functioning in that they produce sex cells. The period at which functional maturity occurs, the pubescent stage, is the true dividing line between the sexually immature and the sexually mature individuals (Hurlock, 1955).

Male sex organs

The male sex organs consist of both external and internal gentilia. Those on the outside of the body are the penis and the scrotum, or sac, contaning the testes. Those on the inside of the body are the vas deferens and its associated parts, the prostate gland and the urethra. Each of these parts has its own role to play in reproduction. The penis, which is a cylinderlike structure on the outside of the body, is the male organ of sexual union. Early in puberty it begins to grow, and the base, as well as the region around it, becomes covered with pubic hair. The appearence of this hair is used by many as the criterion of sexual maturity in boys (Hurlock, 1955).

Female sex organs

The female reproductive organs lie mostly inside the body. In the prepuberty years, the growtth of the reproductive organs may result in the enlargement of the abdomen, which is the source of much embarrassment and concern to the girl. Gradually, as the bony framework enlarges, there is sufficient space in the abdominal cavity for these organs. The abdominal wall then flattens, and the pouchy "tummy" of the prepubescent girl disappears. The most important part of the female reproductive appartus consists of two ovaries, the organs producing the ova or eggs. Throughout childhood, the ovaries are small , undeveloped, and functionally immature. At puberty, theses eggs begin to ripen, one approximately every 28 days, or every menstrual cycle. It enters the fallopian tube, or passageway from the ovary to the uterus, and then passes into the uterus, or womb. It later passes through the vagina, or passage leading from the uterus to the outside genital opening. The first definite indication that a young girl has to inform her of her sexual maturity is menarche, or first menstration (Hurlock, 1955).

Secondary Sex Characteristics

Secondary sex characteristics are responsible for the increasing differences in appearance experienced by adolescents. These characteristics or physical features play a role in mating, though they are not directly related to reproduction. During adolescence the gonadotropic hormones from the pituitary gland stimulate the gonads to increase activity. These hormones from the gonads not only stimulate the growth of the sex organs (i.e. the primary sex characteristics), but they are also responsible for the development of the secondary sex characteristics (Hurlock, 1955).

Girls

Studies of girls have revealed a maturational sequence for the development of secondary sex characteristics. When puberty is accelerated or delayed, the secondary sex characterisctics appear either earlier or later, but in the same sequence (Pryor, 1936). Most notably among these changes is breast development. There are four stages. These are: papilla stage, bud stage, primary breast, and secondary or mature breast

Boys

Studies of the developmental pattern of male secondary sex characteristics, like those for the girls, have revealed individual differences in the ages at which these traits make their appearance. Still, the sequencing of these is constant. The median age for voice changes, is 13.4 years, though some boys experience voice change as early as 11 years and some late as 16 years.

PSYCHOLOGICAL CHANGES

Along with physical changes, there are psychological changes teenagers go through during puberty. One of the major developmental tasks of adolsecents is to accept their changed body as a symbol of their changed self (Stolz and Stolz, 1951). Adolescents must adjust to the normal physical changes that accompany puberty and they need to accept their size and shape as the pysique they will generally have for the remainder of their life (Frazier and Lisonbee, 1950). Because of these physical changes, there is a drastic increase in the young person's preoccupation with their body. Shortness in boys and tallness in girls may cause genuine concern. Obesity commonly is a sensitive issue in adolscents of either sex.

In girls, being overweight may make them feel unattractive. Depending upon the distribution of body fat, it may suggest either infantile qualities or a physical sexual precocity which has no counterpart in emotional development. In boys, obesity may cause embarrassment because it suggests a "babyish" quality or because excessive fat around the hips looks girlish (Hurlock, 1955). Acne, another affliction common during puberty, almost universally causes emotional difficulties. Because acne is readily visible, it often serves as a focus for displaced guilt or concerns about sexuality or "dirtness," as though it somehow betrays one's secret thoughts and activities.

Because adolescents tend to experience anxiety in unusually intense ways, it is important for parents, teachers, and other adults to be responsive to the concerns of teens and to reassure them that in the end - all will be okay!

References:
Hurlock, Elizabeth B. (1955). McGraw- Hill Series Psychology
Grinder, Robert E. (1963). Studies in Adolescence
Oettinger, Katherine B. (1968). Normal Adolescence
Santrock, John W. (1997). Life-Span Development