Puberty Flashcards
What is puberty?
A stage of human development when sexual maturation and growth are completed and result in ability to reproduce
Which gender starts puberty first?
Females
What is the critical weight for female puberty?
47 kg
What is the usual age range for female puberty?
9-13
What is the order of onset of female puberty?
Breast bud formation
Pubic hair growth
Growth spurt
Menarche
What is thelarche?
Onset of secondary breast development
What is menarche?
Starting of period
What staging system is commonly used in puberty?
Tanner system
What is the tanner system for breast development?
Stage 1 = prepubertal
Stage 2 = breast bud stage - elevation of breasts and papilla
Stage 3 = further enlargement of breast and areola
Stage 4 = areola and papilla form secondary mound
Stage 5 = mature stage - projection of papilla only
What is the tanner system for pubic hair?
Stage 1 = prepubertal
Stage 2 = sparse growing of long hair
Stage 3 = darker, coarser and more curled hair - begins to extend laterally
Stage 4 = hair covering smaller area than adult
Stage 5 = adult in type and quantity
What is the age range for male puberty?
10-14
What is the order of onset of male puberty?
Testicular volume increases
Genital size growth
Pubic hair
Growth spurt
What is the tanner system for genital size?
Stage 1 = prepubertal
Stage 2 = enlargement of scrotum + testes
Stage 3 = enlargement of penis
Stage 4 = growth of penis breadth, scrotum skin darker
Stage 5 = adult genitalia
What is the tanner system for growth in females?
Stage 1 = 5-6cm per year Stage 2 = 7-8cm per year Stage 3 = 8cm per year Stage 4 = 7cm per year Stage 5 = no growth after 16 years
What is the tanner system for growth in males?
Stage 1 = 5-6cm per year Stage 2 = 5-6cm per year Stage 3 = 7-8cm per year Stage 4 = 10cm per year Stage 5 = no growth after 17 years
Why do males have a longer growth spurt?
Growth spurt is ended by fusion of epiphyseal growth plates
Oestrogen causes fusion earlier in females
What system initiates puberty?
HPG axis
Describe the HPG axis
Hypothalamus produces GnRH
Anterior pituitary produces LH + FSH
Gonads produce androgens + oestrogen
What is GnRH?
Gonadotropin releasing hormone
How is GnRH released?
Released in pulses from hypothalamus
What does LH act on in males?
Leydig cells
What does LH stimulate Leydig cells to secrete?
Testosterone
What does FSH act on in males?
Sertoli cells
What does FSH stimulate Sertoli cells to secrete?
Inhibin
What is the role of inhibin?
Produce negative feedback at pituitary
What does LH act on in females?
Theca cells
What does LH stimulate theca cells to secrete?
Androgens
Progestins
What is the role of androgens?
Act on granulosa cells
What is the role of progestins?
Increases inhibitory effect of moderate oestrogen
Prevents positive feedback of high oestrogen
What does FSH act on in females?
Granulosa cells
What does FSH stimulate granulosa cells to secrete?
Inhibin
Oestrogen
What is the role of oestrogen?
Moderate oestrogen = negative feedback on hypothalamus
High oestrogen = Positive feedback on hypothalamus = LH surge
What is leptin?
Adipocyte-derived protein hormone
What is the role of leptin?
Regulates neuroendocrine function
- accelerate onset of reproductive function
