Puberty

Posted by e-Medical PPT
It is a physiological phase lasting 2 to 5 years,during which the genital organs mature.The first sign of pubertal development is usually breast growth (thelarche), followed by appearance of pubic hair (pubarche), then (axillary hair), then (menarche).

Adrenarche
means increased activity of the suprarenal cortex at puberty with increased production of adrenal androgens which lead to appearance of pubic and axillary hair.

Cause of puberty:
During childhood , the hypothalamus is extremely sensitive to the negative feedback exerted by the small quantities of estradiol & testosterone produced by the child's ovaries .
As puberty approaches , the sensitivity of the hypothalamus is decreased and subsequently , it increase the pulsatile GnRH secretion .
The anterior pituitary responds by progressive secretion of FSH and LH associated with increased secretion of growth hormone .
The ovaries respond to the increase Gonadotrophin secretion by follicular development & estrogen secretion .
Estrogen causes development of the genital organs and the appearance of the secondary sexual characters .
With increased estrogen secretion , menarche and cyclic estrogen secretion occurs .

Factors affecting the initiation of pubertal development :
1 - Height and weight ratio (nutritional factors).
2 - Maturation of the hypothalamus .
3 - Increased neurotransmitter output in CNS .
4 - Onset of adrenal androgen activity 

FEMALE PRECOCIOUS PUBERTY
It means menarche or appearance of any of the secondary sexual characters before the age of 8 years.
1 - True precocious puberty
It is due to increased production of pituitary gonadotrophins.
2 - False(pseudo-precocious puberty)
It is of peripheral origin.
It is due to secretion of sex hormones; (estrogen or androgen) which is not dependent on pituitary gonadotrophins as in case of estrogenic or androgenic ovarian tumors.
3 - Incomplete precocious puberty .
In this case only one pubertal change as breast development is present before the age of 8 years without the presence of any other pubertal changes and in absence of increased estrogen production.
The other pubertal changes occur at the normal age.


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