10. Puberty Flashcards
What is puberty?
Puberty is a period of physiological transition where gonadal maturation occurs, leading to reproductive maturity. It involves the development of secondary sex characteristics, an adolescent growth spurt, and the achievement of reproductive competence.
What are the earliest measurable endocrine changes in puberty?
The earliest changes are alterations in gonadotrophin secretion. In childhood, gonadotrophins are secreted in low amplitude, low-frequency pulses, but in early puberty, their release is augmented, starting with sleep and eventually occurring throughout the day.
How does increased gonadotrophin secretion affect the body?
The enhanced gonadotrophin secretion stimulates ovarian steroidogenesis, which initially occurs without cyclical follicular activity. This increase in estrogen levels leads to breast development (thelarche), changes in body shape, an increase in uterine size, and a growth spurt.
What role do adrenal androgens play during puberty?
Adrenal androgens contribute to the growth of pubic and axillary hair (adrenarche). They also play a role in the timing of puberty onset and the maturation of the hypothalamic-pituitary-gonadal axis. The rise in adrenal androgens occurs about two years before pituitary and gonadal hormonal changes.
When can the earliest endocrine changes of puberty be observed?
The earliest endocrine changes may be evident as early as 6-8 years of age.
Why is the sequence of physical changes in puberty important?
The physical changes in puberty follow a fixed sequence, and deviations from this sequence may indicate underlying pathology. For example, menstrual bleeding won’t occur without other puberty signs, and vaginal bleeding in a pre-pubertal girl requires investigation for a pathological cause.
Who developed the classification system for pubertal development?
The stages of pubertal development are classified by Marshall and Tanner (1969).
What are the stages of breast development in puberty?
Stage 1: Pre-pubertal (no development)
Stage 2: Breast bud formation
Stage 3: Enlargement of the breast and areola, no separation of contours
Stage 4: Projection of areola and papilla, forming a secondary mound above the breast level, with increased breast size
Stage 5: Mature breast
What are the stages of pubic hair development in puberty?
Stage 1: No pubic hair (pre-pubertal)
Stage 2: Sparse, long, straight, slightly pigmented hair, mainly along the labia
Stage 3: Hair becomes darker, coarser, and curly, spreading over the junction of the labia
Stage 4: Adult-type hair, but the area covered is usually less than in most adults
Stage 5: Adult quantity, type, and distribution, may extend to the medial surface of the thighs
What are the stages of axillary hair development in puberty?
Stage 1: No axillary hair
Stage 2: Scanty axillary hair
Stage 3: Adult distribution of axillary hair
How long does the development from breast Stage 2 to 4/5 take?
The development from breast Stage 2 to 4/5 varies in duration, typically taking between 18 months to 5 years.
When does menarche typically occur in relation to breast development?
Menarche is a relatively late event in puberty, usually occurring after Stage 3 or 4 of breast development, and is preceded by the peak height velocity by more than a year.
How much height do women gain during the pubertal growth spurt?
The average growth spurt in women results in a mean height increase of 9 cm, and it occurs relatively early in pubertal development, about 2 years earlier than in men.
What happens to height after menarche?
Once menarche occurs, there is little potential for further growth, and height is unlikely to increase by more than 2.5 cm.
What factors influence the onset of puberty?
Several factors influence puberty onset, including general health, nutrition, and psychological well-being. Nutritional status is especially important for the activation of the HPO axis, menstruation, and maintaining ovulatory cycles
