Puberty
Definition:
“The period during which adolescents reach sexual maturity and become capable of
reproduction”
“The process of physical changes through which a child’s body matures into an adult body
capable of sexual reproduction.”
What causes puberty to begin?
o All reproductive hormones exist at birth but go into ‘hiding’ at around 4-6 months
then reappear 10-12 years later.
o This occurs because a signal gets ‘turned on’ by a molecule that is produced by a
gene known as: KISS 1 (makes kisspeptin – it initiates secretion of GnRH which
activates gonadotrophins).
o Puberty is regulated by the maturation of kisspeptin neurons and by interactions
between kisspeptins and leptin.
o Kisspeptins have been recognised to act upstream of GnRH and have been shown to play a
vital role in the control of the hypothalamic-pituitary-gonadal axis via regulation of
gonadotrophin secretion, onset of puberty, and control of fertility.
o Puberty is initiated by activation of the hypothalamic pituitary gonadal axis (HPG
axis)
o The secretion of gonadotropin releasing hormone (GnRH) from the hypothalamus
stimulates the pituitary gonadotropins, known as LH and FSH.
o Luteinizing hormone (LH) and follicle stimulating hormone (FSH) which in turn
regulate the production of sex steroids, necessary for pubertal development and
reproductive capability.
, Timing of normal puberty:
o Girls – Normally begins between 8-14 years, (average around 11 years old) present
with breast budding then pubic hair. Onset of growth spurt occurs with breast
budding. Menarche occurs at end of puberty.
o Boys – Normally begins between 9-15 years old (average around 12 years old)
develop testicular & genital enlargement, then pubic hair. Although initial onset of
puberty like that of girls, growth spurt occurs mid-puberty (around 2 years later).
Definition:
“The period during which adolescents reach sexual maturity and become capable of
reproduction”
“The process of physical changes through which a child’s body matures into an adult body
capable of sexual reproduction.”
What causes puberty to begin?
o All reproductive hormones exist at birth but go into ‘hiding’ at around 4-6 months
then reappear 10-12 years later.
o This occurs because a signal gets ‘turned on’ by a molecule that is produced by a
gene known as: KISS 1 (makes kisspeptin – it initiates secretion of GnRH which
activates gonadotrophins).
o Puberty is regulated by the maturation of kisspeptin neurons and by interactions
between kisspeptins and leptin.
o Kisspeptins have been recognised to act upstream of GnRH and have been shown to play a
vital role in the control of the hypothalamic-pituitary-gonadal axis via regulation of
gonadotrophin secretion, onset of puberty, and control of fertility.
o Puberty is initiated by activation of the hypothalamic pituitary gonadal axis (HPG
axis)
o The secretion of gonadotropin releasing hormone (GnRH) from the hypothalamus
stimulates the pituitary gonadotropins, known as LH and FSH.
o Luteinizing hormone (LH) and follicle stimulating hormone (FSH) which in turn
regulate the production of sex steroids, necessary for pubertal development and
reproductive capability.
, Timing of normal puberty:
o Girls – Normally begins between 8-14 years, (average around 11 years old) present
with breast budding then pubic hair. Onset of growth spurt occurs with breast
budding. Menarche occurs at end of puberty.
o Boys – Normally begins between 9-15 years old (average around 12 years old)
develop testicular & genital enlargement, then pubic hair. Although initial onset of
puberty like that of girls, growth spurt occurs mid-puberty (around 2 years later).
