1. Puberty
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puberty

2. Introduction Puberty is a period when
Endocrine and gametogenic function of GONADS have developed to a point when REPRODUCTION IS POSSIBLE
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3. Introduction Age and time of onset of puberty
Variable
Between ages of 10 to 14 yrs
General decline in age at which puberty occurs
Occurs earlier in girls than in boys ( 1 or 2 yrs)
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4. Testosterone Levels at Various Ages
Secretion occurs in male fetus before birth
During neonatal period
Some testosterone is secreted
This is followed by period of quiescence (pre-pubertal)
At puberty gonadotropins are secreted
Activation of gonads
Plasma Testosterone
Pre- pubertal
fetal
Puberty
Adult
senescence
neonatal
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5. Testosterone Levels at Various Ages
At puberty gonadotropins are secreted
Activation of gonads
Final maturations of gonads occur
Plasma Testosterone
Pre- pubertal
fetal
Puberty
Adult
senescence
neonatal
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6. In Females GnRH, pituitary gonadotropins and estrogens
Secreted at low levels throughout childhood
Follicle maturation and menstruation do not occur
Female sex accessory organs remain non-functional
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7. Changes at Puberty in Girls
Increase in release of GnRH
Stimulation of ovarian follicle development
Estrogen secretion
Which induce changes in
Accessory sex organs
Secondary sex characteristics
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8. Changes at Puberty in Girls
First event
Development of breasts (the-larche)
Followed by Pu-barche
Development of axillary and pubic hairs
Followed by menarche
First menstrual periods
Irregular
An-ovulatory
Regular ovulatory periods occur after about a yr
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9. In Boys Accelerated growth of testes Spermatogenesis sets in
Interstitial cells
Secrete testosterone
Increase in growth of accessory organs of reproduction
Epididymis, vas deferens, seminal vesicles, prostate, penis
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10. In Boys Secondary male characteristics occur Scrotal skin thicken
Growth of hairs (face, trunk, axillae, pubic hair)
Growth of larynx – change of voice
Muscle mass
Aggressiveness
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11. In Boys and Girls Adrenarche
Increase in secretion of adrenal androgens
Occurs at the age of
8 to 10 in girls
10 to 12 in boys
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12. In Boys and Girls Increase in secretion of adrenal androgens
Occur without any change in secretion of cortisol or ACTH
Probably due to change in enzyme system
Pregnenolone channeled to androgen pathway
?? Or to secretion of adrenal androgen stimulating hormone (AASH) from the ant. Pit
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13. Control of Onset of Puberty
Gonads of children can be stimulated by gonadotropins
Their pituitaries contain gonadotropins
Hypothalamus contain GnRH
However gonadotropin are not secreted
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14. Onset of Puberty Leptin It appears there is
Leptin is a hormone secreted by the hypothalamus
Has the effects of
Decreasing food intake
Increase energy consumption
It appears there is
Critical body wt that must be attained
For puberty to occur
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15. Leptin vs Onset of Puberty
Young women athlete engaged in strenuous exercises
Lose weight
Stop menstruation
Girls with anorexia nervosa
If they start to eat and gain weight
They start menstruation
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16. Leptin vs Onset of Puberty
Experimental observations
Obese mice that cannot make leptin are infertile
Fertility is restored by injection of leptin
However
The exact role of leptin in the causation of onset of puberty not clear
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17. Precocious Puberty Occurs when signs
Of sexual maturations appears before the age of
8 yrs in girls or
10 yrs in boys
Term implies premature development of
Adult pattern of sexual function
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18. Precocious Puberty Gonadal maturation occurs Pseudo-precocity
Spermatogenesis and ovulation
May be sufficient for procreation
Pseudo-precocity
Premature development of secondary sex characteristics
Due to excessive gonadal steroid
From gonadal or adrenal tumors
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19. Causes of Precocity In normal child
The hypothalamic – Pituitary – gonadal axis
is functional before puberty
It is thought to be under inhibitory influences from other parts of the brain
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20. Causes of Precocity Sexual precocity occurs when
Inhibition is released prematurely
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