PHS 3341 Lecture 20: Reproduction 3
7 Dec 2016
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Document Summary
Maturation of the reproductive system leading to the reproductive capability. Starts earlier in girls (10-12 years of age) than in boys (12-16 years of age) In boys, early changes due to modest increase in androgen production by adrenal cortex. Increased gnrh secretion (increased pulse frequency) stimulates increased secretion of gonadotropins (fsh and lh) Likely due to decreased sensitivity to negative feedback of steroid hormones at hypothalamus. May also be due to reduced secretion of melatonin. Lh stimulates steroid hormone production by gonads: testosterone by testes, estrogen by ovaries. Testosterone promotes development of secondary sex characteristics and sex drive. Estrogen promotes development of secondary sex characteristics and sex drive. Menarche begins (onset at an average of 12. 5 years of age in north. May be associated with leptin production of adipose tissue - stimulate. Gnrh secretion; insufficient leptin is a likely cause of amenorrhea in cases of anorexia nervosa. Early menarche is probably due to better food and nutrition.
