• By: Terri
  • Date: May 25, 2010
  • Time to read: 2 min.

Very brief notes.

Growth spurt

  • females 2 years earlier than males
  • due to steroid hormones, GH, insulin-like growth hormone
  • adrenal androgens not involved


  • male increase muscle mass
  • female increase fat deposition in hips & breast
  • increase in sebaceous glands & thickness of secretion in male
    • female have oestrogens: more fluid
  • larynx enlarge in males
  • increase androgens
    • pubic & axillary hair

Stages of development of genitals, pubic hair and breast

  • read from notes

Sequence of male puberty

  • testes growth
  • penis, scrotum & pubic hair growth
  • axillary hair
  • 1st ejaculation (wet dream)
  • growth spurt
  • facial hair
  • adult height

Sequence of female puberty

  • breast buds appear (thelarche)
  • pubic hair appear (pubarche)
  • growth spurt
  • axillary hair
  • pubic hair matures
  • breast mature
  • menarche (1 year after peak growth)
  • adult height

Mechanism of puberty

3 changes in the endocrine homeostatic function

  • Adrenarche
    • selective maturation of zona reticularis
      • increase DHEA
      • cause axillary and pubic hair growth
    • 2 year of growth spurt & menarche
  • Decrease repression of the gonadostat
    • hypothalamic-pituitary system regulating LH/FSH
    • From late infancy to 8 yo, LH & FSH remain low
      • hypothalamus & pituitary highly sensitive to the –ve feedback of low levels of oestrogen?
      • intrinsic central inhibition of GnRH
  • Gradual amplification of the peptide-peptide (GnRH-LH/FSH) and peptide-steroid (FSH/LH-steroids) interaction leading to gonadarche

Pubertal onset

  • Gradual loss of sensitivity of gonadostat
  • hypothalamic maturation
  • noctural pulsatile GnRH secretion
    • increase amplitude & frequency GnRH pulses
  • Increase LH & FSH
    • LH pulses initially in sleep throughout the day
  • Oestrogen & testosterone?
    • gonadarche
  • 2nday characteristics
    • menarche, ovulation

Critical weight hypothesis

  • Critical weight must be attained before the activation of the hypothalamo-pituitary-gonad axis & growth spurt can occur
  • Critical weight for growth spurt: 30kg
  • Critical weight for menarche: 47kg

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