Puberty
A period characterized by sexual maturity and biological changes driven by the HPG axis (hypothalamus, pituitary gland, and gonads).
A Secular Trend
A historical trend toward earlier onset of puberty and increasing adult height compared to previous generations, likely due to better healthcare and nutrition.
Asynchronous Growth
Unbalanced growth where different body parts grow at different rates; for example, hands and feet grow faster than arms and legs, sometimes causing an “awkward” appearance.
Epiphyseal Closure
The process where the long bones stop growing, marking the end of physical height increases (typically age 16 for girls and 17.5 for boys).
Primary Sex Characteristics
Biological changes and body areas directly responsible for reproduction and the ability to conceive a child.
Secondary Sex Characteristics
Physical markers of sexual maturity that are not involved in reproduction, such as breast development, voice changes, and facial hair.
Menarche
A female’s first menstrual period, occurring at an average age of 12.5 in North America.
Spermarche
A male’s first ejaculation, typically occurring around age 13.5.
Imaginary Audience
An aspect of adolescent egocentrism where a teen assumes that others are as intensely interested in their appearance and behavior as they are themselves.
Personal Fable
The belief that one’s own thoughts and emotions are special, unique, and that one is invulnerable, which can lead to increased risk-taking behavior.
