1. The Biological Timeline
Adolescence is the period of life between the ages of approximately $11$ and $19$ years during which the body undergoes changes leading to reproductive maturity. Because adolescents cover the "teens" ($13$ to $19$), they are often called teenagers.
Puberty marks the physical onset of these changes. It begins when the body's reproductive organs start maturing, and ends when reproductive maturity is achieved.
2. Major Physical Changes at Puberty
- Sudden Increase in Height: The long bones of the arms and legs elongate rapidly under the influence of growth hormone. Girls often experience this growth spurt slightly earlier than boys, though both reach their full genetic height by around age 18.
- Change in Body Shape: In boys, shoulders broaden and chests widen. In girls, the pelvic region widens below the waist to support future motherhood.
- Voice Box (Larynx) Enlargement: In boys, the larynx grows much larger and protrudes as a visible bump at the front of the throat called the Adam's Apple. Vocal cords thicken, causing the voice to crack temporarily before settling into a deep pitch. In girls, the larynx remains small and produces a high-pitched voice.
- Sweat and Sebaceous (Oil) Gland Activity: Increased secretions of sweat and oil glands in the skin frequently cause acne and pimples on the face.