Puberty 1 2132022 puberty Introduction n Puberty is

Puberty 1 2/13/2022 puberty

Introduction n Puberty is a period when n 2 Endocrine and gametogenic function of GONADS have developed to a point when REPRODUCTION IS POSSIBLE 2/13/2022 puberty

Introduction n Age and time of onset of puberty n n 3 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) 2/13/2022 puberty

n n 4 Secretion occurs in male fetus before birth During neonatal period n Prepubertal n senescence Adult n Puberty fetal neonatal Plasma Testosterone Levels at Various Ages Some testosterone is secreted This is followed by period of quiescence (prepubertal) At puberty gonadotropins are secreted n 2/13/2022 Activation of gonads puberty

n Prepubertal 5 At puberty gonadotropins are secreted n Activation of gonads Final maturations of gonads occur senescence Adult n Puberty fetal neonatal Plasma Testosterone Levels at Various Ages 2/13/2022 puberty

In Females n Gn. RH, pituitary gonadotropins and estrogens n n n 6 Secreted at low levels throughout childhood Follicle maturation and menstruation do not occur Female sex accessory organs remain non-functional 2/13/2022 puberty

Changes at Puberty in Girls n Increase in release of Gn. RH n n Stimulation of ovarian follicle development Estrogen secretion n Which induce changes in n n 7 Accessory sex organs Secondary sex characteristics 2/13/2022 puberty

Changes at Puberty in Girls n First event n n Followed by Pu-barche n n Development of breasts (the-larche) Development of axillary and pubic hairs Followed by menarche n First menstrual periods n n n 8 Irregular An-ovulatory Regular ovulatory periods occur after about a yr 2/13/2022 puberty

In Boys n Accelerated growth of testes n n n Spermatogenesis sets in Interstitial cells Secrete testosterone Increase in growth of accessory organs of reproduction n Epididymis, vas deferens, seminal vesicles, prostate, penis n 9 2/13/2022 puberty

In Boys n Secondary male characteristics occur n n n 10 Scrotal skin thicken Growth of hairs (face, trunk, axillae, pubic hair) Growth of larynx – change of voice Muscle mass Aggressiveness 2/13/2022 puberty

In Boys and Girls n Adrenarche n n Increase in secretion of adrenal androgens Occurs at the age of 8 to 10 in girls n 10 to 12 in boys n 11 2/13/2022 puberty

In Boys and Girls n Increase in secretion of adrenal androgens n n Occur without any change in secretion of cortisol or ACTH Probably due to change in enzyme system n n 12 Pregnenolone channeled to androgen pathway ? ? Or to secretion of adrenal androgen stimulating hormone (AASH) from the ant. Pit 2/13/2022 puberty

Control of Onset of Puberty n n 13 Gonads of children can be stimulated by gonadotropins Their pituitaries contain gonadotropins Hypothalamus contain Gn. RH However gonadotropin are not secreted 2/13/2022 puberty

Onset of Puberty n Leptin n n Leptin is a hormone secreted by the hypothalamus Has the effects of n n n It appears there is n n 14 Decreasing food intake Increase energy consumption Critical body wt that must be attained For puberty to occur 2/13/2022 puberty

Leptin vs Onset of Puberty n Young women athlete engaged in strenuous exercises n n n Lose weight Stop menstruation Girls with anorexia nervosa n n Stop menstruation If they start to eat and gain weight n 15 They start menstruation 2/13/2022 puberty

Leptin vs Onset of Puberty n Experimental observations n n n However n 16 Obese mice that cannot make leptin are infertile Fertility is restored by injection of leptin The exact role of leptin in the causation of onset of puberty not clear 2/13/2022 puberty

Precocious Puberty n Occurs when signs n Of sexual maturations appears before the age of 8 yrs in girls or n 10 yrs in boys n n Term implies premature development of n 17 Adult pattern of sexual function 2/13/2022 puberty

Precocious Puberty n Gonadal maturation occurs n Spermatogenesis and ovulation n n Pseudo-precocity n n Premature development of secondary sex characteristics Due to excessive gonadal steroid n 18 May be sufficient for procreation From gonadal or adrenal tumors 2/13/2022 puberty

Causes of Precocity n n In normal child The hypothalamic – Pituitary – gonadal axis n n 19 is functional before puberty It is thought to be under inhibitory influences from other parts of the brain 2/13/2022 puberty

Causes of Precocity n Sexual precocity occurs when n 20 Inhibition is released prematurely 2/13/2022 puberty