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Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction.It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles in a male.
Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Until the maturation of their reproductive capabilities, the pre-pubertal physical differences between boys and girls are the external sex organs.
Despite some genetic sex differences, environmental factors play a large role in biological changes during adolescence. For example, girls tend to reduce their physical activity in preadolescence [45] [46] and may receive inadequate nutrition from diets that often lack important nutrients, such as iron. [47]
On the other hand, a person may be hypersexual, which is a desire to engage in sexual activities considered abnormally high in relation to normal development or culture, or suffering from a persistent genital arousal disorder, which is a spontaneous, persistent, and uncontrollable arousal, and the physiological changes associated with arousal.
Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty.Among researchers who study puberty, the Tanner scale is commonly considered the "gold standard" for assessing pubertal status when it is conducted by a trained medical examiner. [5]
Physical growth in stature and weight occurs for 15–20 years following birth, as the individual changes from the average weight of 3.5 kg (7.7 lb) and length of 50 cm (20 in) at full term birth to their final adult size.
For example, a male may develop breasts and other feminine characteristics, while a female may develop a deepened voice and facial hair. This is called heterosexual or contrasexual precocity. It is very rare in comparison to isosexual precocity and is usually the result of unusual circumstances.
This type of stress causes minor physiological and hormonal changes to the young child; these changes include an increase in heart rate and a change in hormone cortisol levels. [4] The first day of school, a family wedding or making new friends are all examples of positive stressors. [4]