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Puberty is the stage of development when the body makes its great leap forward from childhood into adulthood. This is achieved by several metabolic processes in the physiology of boys and girls and is accompanied by psychological changes in the mood, drive and general behaviour.
As a result of puberty, the adolescent undergoes rapid bodily changes, grouped into 4 categories.
- Physical growth/body size
- Body proportions
- Development of sexual characteristics
Changes in physical growth: Boys and girls undergo a period of a rapid physical growth in terms of height and weight which is known as growth spurt.
- The growth spurt begins with a weight gain of 26 pounds in boys and 20 pounds in girls. This weight gain is largely due to accumulation of fat around legs, arms, abdomen and buttocks. After initial weight gain a spurt in height occurs and some of the fat is redistributed.
- The increase in height during growth spurt is striking among boys, usually they grow between 3 to 5 inches or 7-12 cms and girls between 2 ½ to 4 ½ or 6-8 cms.
- Age at which the peak/maximal growth occurs is approximately 14 years for boys and 12 years for girls, difference appears to remain constant.
Physical changes are caused by hormonal secretions. Hormones are chemical agents secreted into blood stream by pituitary gland which is referred to as the master gland, which lies at the base of the skull. A portion of brain, hypothalamus signals this gland to produce hormones which in turn stimulates other adrenal glands and secretes sex hormones. As the sex hormones enter the blood stream, changes in physical growth and sexual development occur.
Changes in body dimensions:
As the puberty approaches, the body proportions and parts of both boys and girls under go changes. Most noticeable of these changes are the growth of hands, feet and legs which takes place at exaggerated rates but also account to different time tables.
This dramatic change is as a result of growth of long bones in the body, which contain growth plates composed of cartilage at ends, which rapidly increases on account of adding to the growth of the bone.
Finally, the bone stops growing around 18 years for girls and 20 years for boys. It occurs once the epiphyses at the end of bones close.
In addition to the skeletal structure, there is spurting of muscle growth during this period. In both boys and girls muscular development occurs rapidly at the same time as their height increase.
The acceleration in muscle development is accompanied by increase in strength. After completion of puberty there is a decline of fat in both.
In boys, the decrease is more significant and girls retain a greater proportion of fat to muscles than boys.
In addition to these differences in the amount of fat, there is also a difference in the distribution of fat. In girls, fat is added to thighs, breasts, buttocks giving shape to the body. In boys it is added to arms, legs, shoulders, hence they look stronger.
Subtle changes that occur in individuals that transform the child into adult are-
- The baby face disappears, with fore head becoming higher and wider.
- Mouth widens and lips become fuller.
- The head looks smaller in proportion to the body length, due to the growth of extremities at a faster rate.
Development of sexual characteristics/sexual maturation/sequential development of sexual characteristics
The physiological event associated with puberty is sexual maturation. It includes series of changes in reproductive organs, known as primary and secondary sex characteristics.
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Primary sex characteristics refers to the organs that carry to on the reproductive function, ex. ovaries, fallopian tubes and uterus for girls. The increased levels of hormones stimulate certain internal changes which signal the reproductive potential. In girls, the uterus grows and menarche during the I st menstrual period signals fertility, where as the discharge of seminal fluid containing sperm in boys.
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Secondary sex characteristics refers to those that distinguish the sexes from each other but play no direct part in reproduction. The hormonal secretion initiates these changes which contribute to sex differentiation. The prominent change is in the physique .
Secondary sex characteristics in boys
Secondary sex characteristics in girls
- Shoulders and hips: by the end of puberty, boys have wide shoulders, relatively narrow and slim hips, where as girls develop wide and more rounded and narrow shoulders.
- Breasts: Another significant change is the development of breasts and enlargement of nipples, which is more prominent among girls, due to the growth of the breasts buds which occurs when a small contraction of fat causes a slight rise in the breasts.
- Voice: The voice of boys and girls also change as the larynx enlarges and the length of vocal cards increases. In boys, the change is quite prominent and is referred to as breaking of voice.
- Hair growth: In boys, appearance of pubic hair becomes darker and coarser, facial hair, hair above the upper lip and on other parts of the body- chest, hands, legs and arm pits etc.
- Arms and Legs: arms and legs become sharper. This is more in girls compared to boys.
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