Puberty

1
Puberty

• JP Slovak

2
Puberty

• Menarche at 13 Northern hemisphere
• 95 reach menarche between 11 and 15
• US 12.3 years
• Ovulation does not necessarily occur at menarche
• Slight risk of pregnancy
• Widening of pelvis
• Sweat and sebaceous glands more active
• Slight lowering of voice
• Increased metabolic rate
• Fat deposition
• Bone growth

3
males

• Pubic hair, face, chest
• Sweat glands odor
• Sebaceous glands
• Nipples become wider and darken
• Vocal cords double in length
• Scrotum and penis enlarge
• Spontaneous erections
• Nocturnal emissions
• Later skeletal muscle growth

4
Hormone levels

• FSH and LH both needed
• Both low in young children
• 9 to 12 fold rise in FSH and LH
• 1 to 2 years earlier in females
• Rise during sleep in both sexes
• GH increases also

5
Female hormonal changes

• First surge of LH menstruation
• May not be sufficient to cause ovulation
• LH surge does increase over the next months
• Estrogens
• Onset of breast maturation
• Continue increase until menarche
• Growth of pelvis
• Subq fat
• General growth of reproductive tract

6
Female hormonal changes

• Androgens
• Increase in DHEA and androstenedione
• Adrenal glands
• Growth of pubic hair
• Lowering of voice
• Sebaceous glands
• Growth of long bones

7
Male hormonal changes

• Gonadotropins and Androgens
• FSH and LH increase 10 years until puberty
• Subsequent rise in androgens
• Growth of accessory sexual structures
• Cause retention of N, Ca, and P
• Estrogens
• Rise slightly and before puberty
• Source is Sertoli cells
• Some males gynecomastia

8

• Androgens and Acne
• Increased secretions of sebaceous glands
• Become clogged pimples and blackheads
• Not caused by hygiene, masturbation or cured by
  sex
• Sleep loss, anxiety make worse
• Medicines and antibiotics
• UV light may help with sores
• May take up to 10 years to clear up

9
Mechanisms of Puberty

• Gonadostat Hypothesis
• Feedback regulation of FSH and LH at low
  threshold
• Very sensitive to low levels of steroids
• Set point increases at puberty
• More FSH and LH produced
• Gonadotropin surge develops late
• ½ of cycles are anovulatory
• 1/5 after 5 years
• Reason for late development is unknown

10
Mechanisms of Puberty

• Hypothalamic Maturation
• Relies on increase in GnRH
• Emphasis on CNS
• In Monkeys
• Increase in LH in absence of gonads
• Data suggest that adult level of steroids don ont
  contribute to mature patterns
• Puberty arises because of maturation of
  hypothalamus