Physical Changes During Adolescence

Core concept

These changes typically begin earlier in girls (around 10-12 years) than in boys (around 12-14 years), though the exact timing varies from person to person. Hormones — chemical messengers released by glands in the body — control the pace and pattern of these changes; the pituitary gland, often called the 'master gland,' signals other glands to begin producing the hormones responsible for puberty. These changes are a completely normal part of human development.